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General Category => Amstrad CPC hardware => Topic started by: gerald on 19:07, 12 August 15

Title: Quick and dirty RAM test for CPC
Post by: gerald on 19:07, 12 August 15
Hi,

I've just made a small RAM diagnostic ROM for the CPC. It fully run from ROM and will let you know if the main bank RAM are OK or not.
To use it :
 - On all CPC, you will need a LowerRom board or an XMEM and program the provided .bin file. Use the xmem in boot mode.
 - On a plus, you can put the .bin or .cpr in a C4CPC free slot and start from it, or program the .bin on an EPROM in a salvaged cartridge.

The program first test the display area (C000-FFFF), should see something like :

The content of the screen will change during the test. So if nothing move, more than the ram may be wrong.
Something else is wrong if you do not see that screen at all.

Then it will display the results :
If all is good, the band will be all green :


In case of error, the bad data bit will displayed red

In this example, the 4 LSB bit are wrong.
Title: Re: Quick and dirty RAM test for CPC
Post by: Bryce on 23:18, 12 August 15
Unfortunately I can only press the like button once, but it deserves several. What a great tool. Unfortunately many won't have a second option to get it onto a Lower ROMBoard or x-mem, but for people like me, it will get a permanent place in my "toolbox".

Bryce.

Edit: Would it be possible to report down to the bit level? That way you know exactly what IC you need to swap :)
Title: Re: Quick and dirty RAM test for CPC
Post by: gerald on 23:33, 12 August 15
Unfortunately I can only press the like button once, but it deserves several. What a great tool. Unfortunately many won't have a second option to get it onto a Lower ROMBoard or x-mem, but for people like me, it will get a permanent place in my "toolbox".

Bryce.

Edit: Would it be possible to report down to the bit level? That way you know exactly what IC you need to swap :)
It is reporting to the bit level, but the pictures are only there as examples.  ;)
New one where all even bits are failing


Each bit is displayed during 8 raster lines.
Title: Re: Quick and dirty RAM test for CPC
Post by: Bryce on 00:11, 13 August 15
Now I can give it a second like too :)

Bryce.
Title: Re: Quick and dirty RAM test for CPC
Post by: skywalky on 21:51, 10 November 15
How can I use this test in a CPC 6128?
Ok, with a Romboard  :picard:
Title: Re: Quick and dirty RAM test for CPC
Post by: The Last Bandit on 22:56, 10 November 15
Very very nice indeed.  ;D 


Just out of curiosity what algorithms are you using ? Marching 1/0 etc ?
Title: Re: Quick and dirty RAM test for CPC
Post by: gerald on 10:42, 11 November 15
Very very nice indeed.  ;D 


Just out of curiosity what algorithms are you using ? Marching 1/0 etc ?
It does 4 passes of fill and check with FF/AA/55/00 pattern. This is more that enough to detect bad devices.
The code does not the use any RAM at all : just reigisters to store data and no call (no stack).


Title: Re: Quick and dirty RAM test for CPC
Post by: Munchausen on 11:57, 12 November 15
This is great :)

Are you counting bits 0-7 or 1-8 (0-7 I guess, just wanted to check...)?
Title: Re: Quick and dirty RAM test for CPC
Post by: gerald on 12:00, 12 November 15
This is great :)

Are you counting bits 0-7 or 1-8 (0-7 I guess, just wanted to check...)?
7-0  ;)
Title: Re: Quick and dirty RAM test for CPC
Post by: Munchausen on 12:09, 12 November 15
7-0  ;)

Cool :) direction doesn't matter... as you told us the even bits were bad in that image, that is enough information :)
Title: Re: Quick and dirty RAM test for CPC
Post by: Munchausen on 12:12, 12 November 15
I have a board with bad RAM I can use this on immediately...
Title: Re: Quick and dirty RAM test for CPC
Post by: VincentGR on 23:01, 12 November 15
This is amazing!!!

Can it be used direct to cpc's mobo or the rom board is the only option?

Title: Re: Quick and dirty RAM test for CPC
Post by: gerald on 23:06, 12 November 15
This is amazing!!!

Can it be used direct to cpc's mobo or the rom board is the only option?
You can use it in place of the OS ROM. But the goal is to debug, no to replace  ;)
The simple board to use is the LowerROM one.
Title: Re: Quick and dirty RAM test for CPC
Post by: gerald on 23:11, 12 November 15
Note also that this test may not work when damaged RAM are shorted to a point the voltage fall low enough to make code execution unreliable.
But in this case, the RAM are hot enough to spot them ;D
Title: Re: Quick and dirty RAM test for CPC
Post by: ||C|-|E|| on 04:02, 13 November 15
Thank you! It is actually really cool!  :D
Title: Re: Quick and dirty RAM test for CPC
Post by: Audronic on 06:09, 13 November 15

@gerald (http://www.cpcwiki.eu/forum/index.php?action=profile;u=250)
Would it be possible to make another to test Bank1 on a CPC6128, Please


Thanks   Ray
Title: Re: Quick and dirty RAM test for CPC
Post by: Bryce on 10:54, 13 November 15
If Bank 0 is working a Bank 1 RAM test can be done in BASIC.

Bryce.
Title: Re: Quick and dirty RAM test for CPC
Post by: Kris on 11:11, 13 November 15
Very good idea; any chance that you continue to develop this soft ? (integration of the RAM size, detail on address # tested etc...)
Thank you
Title: Re: Quick and dirty RAM test for CPC
Post by: gerald on 13:19, 13 November 15
Very good idea; any chance that you continue to develop this soft ? (integration of the RAM size, detail on address # tested etc...)
Thank you
My intention was to go a bit further than just the base RAM test, but >I have no roadmap yet.
Title: Re: Quick and dirty RAM test for CPC
Post by: TFM on 18:31, 13 November 15
Very good idea; any chance that you continue to develop this soft ? (integration of the RAM size, detail on address # tested etc...)
Thank you

For assessing RAM size you can use this one:

http://cpcwiki.eu/imgs/2/28/E-RAM_Test_2014.zip (http://cpcwiki.eu/imgs/2/28/E-RAM_Test_2014.zip)

It does not check the RAM, but tells you how much RAM your CPC can access. Upper limit currently 4160 KB.[nb]Also you can use the 'OS Infos' Utility from the FutureOS Utility Disc (version 7.10.2015) to show occupied / connected RAM in a graphical way.[/nb]


Title: Re: Quick and dirty RAM test for CPC
Post by: Kris on 11:34, 14 November 15
I know this soft; but the idea is to have all these tools into a single soft ;)
Title: Re: Quick and dirty RAM test for CPC
Post by: Bryce on 19:50, 03 December 16
Hi @gerald (http://www.cpcwiki.eu/forum/index.php?action=profile;u=250),
      I know it's an old thread, but tonight I used this RAMTest for the first time where I didn't know what IC was damaged. And it gave me very strange results. The computer (standard 6128) reported that D4 (IC131) was damaged = All green, red stripe for D4. However, as soon as I swapped D4, it then reported all red except D4 (green stripe). Is there any reason why the program might react this way?

Bryce.
Title: Re: Quick and dirty RAM test for CPC
Post by: gerald on 20:35, 03 December 16
Hi @gerald (http://www.cpcwiki.eu/forum/index.php?action=profile;u=250),
      I know it's an old thread, but tonight I used this RAMTest for the first time where I didn't know what IC was damaged. And it gave me very strange results. The computer (standard 6128) reported that D4 (IC131) was damaged = All green, red stripe for D4. However, as soon as I swapped D4, it then reported all red except D4 (green stripe). Is there any reason why the program might react this way?

Bryce.
My guess is that the other RAM are damaged as well. Why they did not show as such on the 1st test is a mystery.
I've just had a look at the test code and I realize that the code will not detect an addressing error (address bus stuck). That might be the case here.
I'll see how I can cover this case.
Title: Re: Quick and dirty RAM test for CPC
Post by: Bryce on 23:36, 03 December 16
Cool. Thanks for the feedback. I intend swapping all 8 anyway just to be sure. Unfortunately it's "one of those" CPC's where the build quality is far from ideal. The RAM ICs are all over the place! The pins on one side of all RAMs are just barely in the board and only soldered at the tips. The ICs are at about a 20° angle to the PCB.

Bryce.

Edit: Turned out that there was a broken track on the PCB that was sometimes making contact and sometimes wasn't. As soon as I bridged the break the other RAMs reported as good again, so only D4 was broken in the end.
 
Title: Re: Quick and dirty RAM test for CPC
Post by: 00WReX on 13:08, 06 July 17
Another successful diagnosis by Geralds excellent RAM test program.

I had a GX4000 that I ordered from Germany arrive today, It was the console only, and sold as 'Untested for parts or repair'.
I was not expecting much, and no surprise when I tested it and nothing but a blank screen (the LED lit nicely though  ;D ).

Anyway, first thing was to plug the C4CPC in with the RAM test prog in a slot selected by the dip switch.

The rest is in pictures... :D

[attachimg=1]
[attachimg=2]
[attachimg=3]
[attachimg=4]
[attachimg=5]
[attachimg=6]
Title: Re: Quick and dirty RAM test for CPC
Post by: tjohnson on 20:11, 07 July 17
Good result, why do people still stuff as untested that then it's broken?

Sent from my E5823 using Tapatalk

Title: Re: Quick and dirty RAM test for CPC
Post by: dragon on 20:31, 07 July 17
Because if they are untested, do you think maybe work and is cheap.


But if you see It  Broken, directly  you don't buy It.
Title: Re: Quick and dirty RAM test for CPC
Post by: gerald on 20:50, 07 July 17
Because if they are untested, do you think maybe work and is cheap.


But if you see It  Broken, directly  you don't buy It.
That's not always the case. I've bought may untested stuff that worked fine. And some "working" that did not.
Title: Re: Quick and dirty RAM test for CPC
Post by: remax on 18:12, 10 July 17
I am interested in the cable you use to connect the GX4000 video input to the CPC monitor. Did you build it yourself ?
Title: Re: Quick and dirty RAM test for CPC
Post by: CraigsBar on 21:39, 10 July 17
I've just done a RAM swap for Shaun. His gx4000 is now working fine using loan RAM from my speccy +3.

Sent from my ONEPLUS 3t using Tapatalk

Title: Re: Quick and dirty RAM test for CPC
Post by: CraigsBar on 21:40, 10 July 17
I've just done a RAM swap for Shaun. His gx4000 is now working fine using loan RAM from my speccy +3.

Sent from my ONEPLUS 3t using Tapatalk
Another GX4000 is saved. Praise the Lord (Sugar) (https://uploads.tapatalk-cdn.com/20170710/777a4f2e264027d8a46ca14bb296a00e.jpg)(https://uploads.tapatalk-cdn.com/20170710/6a9984bc714a44b5640a1e68c164e106.jpg)

Sent from my ONEPLUS 3t using Tapatalk

Title: Re: Quick and dirty RAM test for CPC
Post by: gerald on 22:28, 10 July 17
Nice fix ..... with locally grown DRAM  ;D
Title: Re: Quick and dirty RAM test for CPC
Post by: Shaun M. Neary on 22:59, 10 July 17
Nice fix ..... with locally grown DRAM  ;D

Was about to post this, but Craig beat me to it as that's my formally dead GX4000 board in Craig's capable hands. I had to send it to him after I nearly made a hash of the contacts trying to desolder the RAM (I'm actually not that bad, but my iron is a pile of crap), and to his eternal credit, he's done a fine job. But we wouldn't have had a starting point if it wasn't for yourself, Gerald. So thank you.

That RAM is temporary, it's out of Craig's Speccy +3, sadly it won't be coming back with me, but I've a batch of chips on it's way to me so two of em will be getting popped in there. =)
Title: Re: Quick and dirty RAM test for CPC
Post by: 00WReX on 02:28, 11 July 17
Hi All,

I feel I should mention something else I found after replacing the RAM (a few days later).

I was thinking about things a little more, and remembering a post by Gerald regarding the original GX power supply and a GX he fixed...

http://www.cpcwiki.eu/forum/amstrad-cpc-hardware/%28please-read%29-gx4000-with-original-power-brick-and-c4cpc/ (http://www.cpcwiki.eu/forum/amstrad-cpc-hardware/%28please-read%29-gx4000-with-original-power-brick-and-c4cpc/)

I think I may have been lucky with my fix in that I use a 5v power supply and run it off the CTM monitor.

If I had used a larger supply (9v) in the other socket, I may have blown the RAM again (or worse).
After re-reading the above post, I tested the protective diode that Gerald mentioned... D183 on the board (near the voltage regulator with the heatsink).
It appears mine is testing as shorted, therefore it would be doing nothing (no protection).
Running on 5v only is fine, as all the circuitry is 5v anyway, but beyond that I might have been in trouble.

Just thought I would mention this to anyone looking at fixing a 'dead RAM' GX400, as my assumption with these is that somewhere along the line, someone has used either a faulty GX power supply or simply a wrong voltage supply (or in the wrong socket).  And I'm also going to assume that if the RAM is fried in this situation, there is a good possibility the Diode is also taken out.

I would say it is well worth testing the diode as part of the RAM swap.

If the fuse (RAM) does not blow quick enough, the fix may not be so bASIC  :P

Cheers,
Shane
Title: Re: Quick and dirty RAM test for CPC
Post by: Shaun M. Neary on 02:47, 11 July 17
Upon reading that initial post, I'm under the impression that 9v and 2.2-2.5a (in the 11v socket) is fine if you wish to run it off SCART or CPC to SCART socket, as 6-7v is too low to power it on standalone.

The original Amstrad Power Supply was too much, and on top of that, complete rubbish to begin with caused many a fried RAM, with or without a C4CPC.
I know Craig's one runs off a 9v and he's had no problems either.

What about the rest of you lot?
Title: Re: Quick and dirty RAM test for CPC
Post by: 00WReX on 04:43, 11 July 17
Hey Shaun,

Yes, if the GX4000 is in normal working order then 9v (Only plugged into the 11v socket) is perfectly fine.
What I am indicating, is that if you have the situation like we have just encountered where the RAM is dead, then also check the protection diode D183.

If, like in my case this is shorted, then plugging the 9v into the correct 11v socket would also cause the 9v to go across to the 5v circuitry.
Basically, it would be just like plugging the 9v into the 5v socket.
The 5v regulator drops the 11v (or 9v) down to the required 5v if all is operating correctly.

As can be see from the schematic in Geralds post, a short on that diode would basically bypass the the 5v regulator.
If the diode is working correctly then it will 'block' the voltage in that direction, basically forcing it through the regulator.

I hope I have made sense  :)

Cheers,
Shane
Title: Re: Quick and dirty RAM test for CPC
Post by: Shaun M. Neary on 04:59, 11 July 17
Yep, makes sense, Shane.
Given how awful the power supplies that came with the machine in the first place, Christ only knows what damage they did to the boards and their respective components every time the thing was turned on.

I've even heard some horror stories about them frying consoles when you connected them to said power supply at the back while the power switch was accidentally on instead of off.  :o
Title: Re: Quick and dirty RAM test for CPC
Post by: Bryce on 10:22, 11 July 17
Just out of interest. How are you guys measuring the diode D183? In-circuit? Removed? In both directions?

If the diode is completely shorted, then using even a 5V supply could damage your GX4000 if the diode isn't replaced.

Bryce.
Title: Re: Quick and dirty RAM test for CPC
Post by: 00WReX on 11:57, 11 July 17
Hi Bryce,

I measured the diode using the diode tester on my multimeter, initially in circuit and then out of circuit.
Tested in both forward and reverse bias directions, both directions reading 0v on my meter (short), and this was the case in and out of circuit.
The new diode, tested out and in circuit, tested ~.5v forward bias and OL (open) reverse bias.

When the original diode was inplace I tested the RAM chip voltages and was getting around ~4.8v
Voltage on both sides of the voltage regulator was ~5v.

What would 5v potentially kill with that diode shorted ?

Cheers,
Shane
Title: Re: Quick and dirty RAM test for CPC
Post by: Bryce on 12:13, 11 July 17
If the diode is shorted you are essentially bridging the 7805 which ensures a perfectly regulated 5V rail. So if your 5V PSU is at 5.4V or is full of spikes, ripple noise and dirt, then all this is getting directly through to the 5V components.

Bryce.

Edit: Forget that. I just realised the 5V is the direct connection so I assume you would only be using a regulated supply. Need coffee....
Title: Re: Quick and dirty RAM test for CPC
Post by: 00WReX on 13:03, 11 July 17
Yep, regulated 5v supply into the 5v socket.  ;)

Cheers,
Shane
Title: Re: Quick and dirty RAM test for CPC
Post by: Bryce on 13:09, 11 July 17
Yup, and I'm on my third coffee at this stage. :)

Bryce.
Title: Re: Quick and dirty RAM test for CPC
Post by: CraigsBar on 21:59, 11 July 17
Diode tested... All good. 100% resistance one way and healthy continuity the other

If I did not have to dismantle the speccy +3 to get at some ram chips I'd test the 9v power now.
Title: Re: Quick and dirty RAM test for CPC
Post by: CraigsBar on 17:33, 16 July 17
All tested and working.... Albeit with the suspect speccy +2 ram. (https://uploads.tapatalk-cdn.com/20170716/05face1cb915bf08c052407f83f4a090.jpg)(https://uploads.tapatalk-cdn.com/20170716/25e7ff0051eee972385a0018011f9b50.jpg)

Sent from my ONEPLUS 3t using Tapatalk

Title: Re: Quick and dirty RAM test for CPC
Post by: LambdaMikel on 08:30, 07 December 17
It's probably a stupid beginner question, but can someone please explain how I burn this memtest.bin
lower rom using XMem? I am using "exrom.bas" from XMem tools disk A, and then it shows that ROM 0 = 64,  ROM 1 = 01, and LOWER ID = 71. So after "filename? " I loaded ramtest.bin, and tried all 3 IDs, but when  I booted in XMem boot mode, I either got a pixelated screen or colorful vertical stripes. What am I doing wrong? I am using a 6128.  After that, I have to run "setup" from XMem tools disk again, in order to get the XMem Firmware 3.14 back again, so it seems to be replacing some system roms, but it doesn't work. Thanks!
Title: Re: Quick and dirty RAM test for CPC
Post by: GUNHED on 16:31, 07 December 17

There are two possible ways...

When using the X-MEM and you want to install a new lower ROM (which is the case here I guess), then you can use my ROManager to install it. However it's a bit more work since you need to install FutureOS before. If you need a step by step guidance please let me know.


I don't remember if the FW 3.16 Flasher RSX can also be used for this purpose, but you can try ROM number &47.



Title: Re: Quick and dirty RAM test for CPC
Post by: LambdaMikel on 17:48, 07 December 17
I don't remember if the FW 3.16 Flasher RSX can also be used for this purpose, but you can try ROM number &47.

Tried that, but getting pixelated screen when booting from XMem.
Title: Re: Quick and dirty RAM test for CPC
Post by: GUNHED on 17:50, 07 December 17
Oh I see. The question is not to tell if Flasher has a problem or the ROM you flash.


You still can try ROManager.
Title: Re: Quick and dirty RAM test for CPC
Post by: LambdaMikel on 19:07, 07 December 17
I must say I don't know. Is there anything else I need to do in order to "prepare" ramtest.bin for lower rom flashing? AMSDOS headers or the like (shouldn't that be irrelevant for lower ROM?)
Title: Re: Quick and dirty RAM test for CPC
Post by: Audronic on 23:33, 07 December 17
@LambdaMikel (http://www.cpcwiki.eu/forum/index.php?action=profile;u=2172)
The last Picture above is very similar to a fault i just fixed (on a 464).


The ICs 104 - 105 - 109 - 113 Multiplexers 74ls153 area had some faulty chips and OPEN Tracks (Trace)


Have a look around this area.


Good luck
Ray
Title: Re: Quick and dirty RAM test for CPC
Post by: LambdaMikel on 05:20, 08 December 17
The last Picture above is very similar to a fault i just fixed (on a 464).

Hi AUdronic, I think there is a missunderstanding. This picture shows the perfectly fine working CPC 6128 which I am using to flash the XMem with the ramtest.bin lower rom... this is the picture that I am getting when I am booting ramtest.bin lower rom from the XMem on this 6128. Is the memtest not compatible the 6128? So my intent is of course to use the XMem with the memtest.bin lower rom in the broken 464 of course. Clear now?
Title: Re: Quick and dirty RAM test for CPC
Post by: LambdaMikel on 05:57, 08 December 17
OK, figured it out by now... it was my DSK / HFE image creation process which was bad.
Was able to flash and run it  now - thanks to all who helped!

Unfortunately, I am seeing a lot of red... probably not a good sign, uhh?  :-X :-[ :'( :doh:
Title: Re: Quick and dirty RAM test for CPC
Post by: Audronic on 06:56, 08 December 17
@LambdaMikel (http://www.cpcwiki.eu/forum/index.php?action=profile;u=2172)
Perhaps Just replace 1 (One) memory chip and re run the RamTest.
All Faulty ??


Good luck


Ray
Title: Re: Quick and dirty RAM test for CPC
Post by: LambdaMikel on 08:15, 08 December 17
Hi Ray,
which one should I replace first?

Michael
Title: Re: Quick and dirty RAM test for CPC
Post by: Audronic on 08:26, 08 December 17
Hi Ray,
which one should I replace first?
Michael


I don't think it matters as we want to see GREEN on the RamTest.
Please put a socket in as well.


Ray
Title: Re: Quick and dirty RAM test for CPC
Post by: LambdaMikel on 08:35, 08 December 17
AH, I see. So you are trying to figure out if replacing the RAM chip makes a difference at all.
Maybe some other components got burned as well. That's a good strategy.

Now where would I get RAM chips... hmmm. Will look on Ebay.
Title: Re: Quick and dirty RAM test for CPC
Post by: GUNHED on 15:53, 08 December 17
which one should I replace first?


The one which becomes warm at first, but looking at the picture, probably 2 chips are bad. Ask Gerald, he is the expert.  :)
Title: Re: Quick and dirty RAM test for CPC
Post by: Bryce on 16:32, 08 December 17

The one which becomes warm at first, but looking at the picture, probably 2 chips are bad. Ask Gerald, he is the expert.  :)

Actually the picture would suggest that all 8 RAM chips are bad which is quite unlikely, hence the "replace one to see if a green line appears" suggestion is a good idea. I also think that it's something other than the RAM, possibly one of the RAM buffer chips (74LS244 and 74LS373) or maybe just the enable signal to these (from the GA)?

Bryce.
Title: Re: Quick and dirty RAM test for CPC
Post by: LambdaMikel on 18:19, 08 December 17
Actually the picture would suggest that all 8 RAM chips are bad which is quite unlikely

But remember, I fried the whole thing with 12 Volts... for a couple of seconds before I noticed it.
Title: Re: Quick and dirty RAM test for CPC
Post by: gerald on 18:29, 08 December 17
OK, figured it out by now... it was my DSK / HFE image creation process which was bad.
Was able to flash and run it  now - thanks to all who helped!

Unfortunately, I am seeing a lot of red... probably not a good sign, uhh?  :-X :-[ :'( :doh:
Too much red to my taste.
While you could end with most bit at 1 with failing RAM (all 1 will give the red), I am worried that the pattern changes exactly when the border changes.
Any chance you can check the Gate Array in an other CPC ?
Title: Re: Quick and dirty RAM test for CPC
Post by: LambdaMikel on 19:18, 08 December 17
Any chance you can check the Gate Array in an other CPC ?


I am afraid this is my only 40010 CPC - my other CPCs have 40007 and 40008.
Title: Re: Quick and dirty RAM test for CPC
Post by: LambdaMikel on 19:21, 08 December 17
The board has a spare "socket" for the 40007 / 40008 Gate Arrays though. If it should turn out that the 40100 is defect, it could be replaced with 07 or 08... has anybody tried that before?


This is my board
http://www.cpcwiki.eu/index.php/File:CPC464_Z70200_MC0008C_PCB_Top.jpg (http://www.cpcwiki.eu/index.php/File:CPC464_Z70200_MC0008C_PCB_Top.jpg)


I am not sure I can spend so much time desoldering all the RAMs and then also to put in another Gate Array.


Awesome RAM test though, Gerald! 
Title: Re: Quick and dirty RAM test for CPC
Post by: LambdaMikel on 06:28, 11 December 17
    Any chance you can check the Gate Array in an other CPC ? I am afraid this is my only 40010 CPC - my other CPCs have 40007 and

Surprisingly, the 40010 is OK! Tested it in my CPC 6128  :)
Title: Re: Quick and dirty RAM test for CPC
Post by: LambdaMikel on 08:31, 15 December 17
My RAM arrived and it is almost working... however, RAMTEST still shows a red bar in the border.
What does that mean? Now more "grizzle snow" on the screen though, I suppose that is a good sign?
Title: Re: Quick and dirty RAM test for CPC
Post by: LambdaMikel on 09:07, 15 December 17
Missed some more tracks! Fixed now, thanks to all who helped!
You guys rock!!  ;D 8)
Title: Re: Quick and dirty RAM test for CPC
Post by: robcfg on 13:11, 15 December 17
Cool! So glad you could get it running again!
Title: Re: Quick and dirty RAM test for CPC
Post by: VincentGR on 13:58, 15 December 17
Another one saved!!!
Congratz  :)
Title: Re: Quick and dirty RAM test for CPC
Post by: 00WReX on 02:16, 16 December 17
The thrill you get when it springs back to life is very cool, I'm sure you just experienced that feeling.
Congratulations on working through it.  ;)

And yet again, another big shout out to Geralds 'famous' RAMtest.  ;D

Cheers,
Shane
Title: Re: Quick and dirty RAM test for CPC
Post by: LambdaMikel on 19:25, 16 December 17
The thrill you get when it springs back to life is very cool, I'm sure you just experienced that feeling. Congratulations on working through it.  ;) And yet again, another big shout out to Geralds 'famous' RAMtest.  ;D

Ineed, a marvelous feeling it is! I was like "yeaaah"  ;D

Without RAMTEST I probably wouldn't have started the repair - the group's good support was also essential.
Title: Re: Quick and dirty RAM test for CPC
Post by: DanyPPC on 19:45, 16 December 17
Really great tool to test ram on our machines !
Title: Re: Quick and dirty RAM test for CPC
Post by: llopis on 01:01, 31 July 18
Does someone know if you can use this RAM test with ROMBO, or is it just with something like X-MEM?
I'm asking because I got my ROMBO sooner than X-MEM, and while I'm able to load all sorts of other ROMs, this one just brings up the boot text with the blue background, puts a few garbage pixels on screen and freezes. I even tried it in slot 0 just in case, but that causes a constant reboot.
Any suggestions?
Title: Re: Quick and dirty RAM test for CPC
Post by: Bryce on 11:37, 31 July 18
There are essentially two ROM0's in a CPC. The LowerROM (Firmware) and UpperROM (BASIC). This ROM needs to be mapped to the LowerROM area, so ROMBO can't be used as it can only replace the Upper portion of ROM 0.

Bryce.
Title: Re: Quick and dirty RAM test for CPC
Post by: rpalmer on 13:46, 31 July 18
While bryce is correct that the current rombo cannot replace the internal lower rom. A modification to it can replace the internal ROM 0 (both upper and lower).
This would achieved by:
a. Detecting ROM 0 as being the current ROM being addressed (either upper and lower).b. Detecting that the ROMEN signal is active.c. Finally inserting your own ROMDIS signal (from the expansion bus) to the internal ROM when A15 is also low and in parallel engaging the external ROM 0 (for lower half).
rpalmer

Title: Re: Quick and dirty RAM test for CPC
Post by: llopis on 14:14, 31 July 18
There are essentially two ROM0's in a CPC. The LowerROM (Firmware) and UpperROM (BASIC). This ROM needs to be mapped to the LowerROM area, so ROMBO can't be used as it can only replace the Upper portion of ROM 0.
Thanks, that's what I figured, but I wasn't able to confirm it anywhere. I'll just keep waiting for X-MEM to arrive :-)
Title: Re: Quick and dirty RAM test for CPC
Post by: jonnixx on 22:25, 18 September 18
Hi,


I have two problems.
The CPC 6128 with standard RAM.
Original problem:
If the machine is cold (room temperature) then i can load the R-type Reloaded from floppy (3") and HxC and run the program.
... and then not cold the machine (after 3-4 minutes) press reset and can not load the game. (Freeze the program during loading)


Second problem:
The dirty ram test is failed. (attached picture)


I have replaced:
- 8 RAM modules (new rams: TMS4164-12NL)
- 74LS244 and 74LS373
Could you please help me?


Jonni

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Title: Re: Quick and dirty RAM test for CPC
Post by: gerald on 23:10, 18 September 18
Hi,


I have two problems.
The CPC 6128 with standard RAM.
Original problem:
If the machine is cold (room temperature) then i can load the R-type Reloaded from floppy (3") and HxC and run the program.
... and then not cold the machine (after 3-4 minutes) press reset and can not load the game. (Freeze the program during loading)


Second problem:
The dirty ram test is failed. (attached picture)


I have replaced:
- 8 RAM modules (new rams: TMS4164-12NL)
- 74LS244 and 74LS373
Could you please help me?


Jonni



Did you run the RAM test with a cold or warm CPC.
Also, there are other ICs involved in the RAM access. Mainly the gate array and the address multiplexors (4 74LS153 : IC104 IC105 IC109 and IC113)
The gate array being on socket it may suffer a bad connection when getting warm. Can you try re-seating it ?
Title: Re: Quick and dirty RAM test for CPC
Post by: jonnixx on 23:21, 18 September 18
Did you run the RAM test with a cold or warm CPC.Yes. Both.
i am waiting for 74LS153... next week, maybe...
Can you try re-seating it ?Yes. Tomorrow.
Is it exist any test program for GA?
Many thanks.


Title: Re: Quick and dirty RAM test for CPC
Post by: Audronic on 01:47, 19 September 18
Please send a Photo of the RAM test when the machine is COLD
Thanks    Ray
Title: Re: Quick and dirty RAM test for CPC
Post by: jonnixx on 08:43, 19 September 18
Hi Ray,
The ram test is same (failed) in both.Thanks.

Title: Re: Quick and dirty RAM test for CPC
Post by: jonnixx on 18:19, 20 September 18
Hi,
- GA re-seating is done- replaced 4 x 74LS153- replaced 2 x 74LS32- replaced 765 FDC
Memory test still failed as before.
any idea?  (GA?)

Regards,Jonni
Title: Re: Quick and dirty RAM test for CPC
Post by: gerald on 18:43, 20 September 18
Hi,
- GA re-seating is done- replaced 4 x 74LS153- replaced 2 x 74LS32- replaced 765 FDC
Memory test still failed as before.
any idea?  (GA?)

Regards,Jonni
Without looking at the RAM without a logic analyser, your last bet is indeed the GA itself.
Title: Re: Quick and dirty RAM test for CPC
Post by: jonnixx on 19:19, 20 September 18
Without looking at the RAM without a logic analyser, your last bet is indeed the GA itself.
I have oscilloscope (Tektronix) and multimeter and any other but i do not have logic analyzer.I am looking for a 8 channels logic analyzer ... now.
I will come back if i have a new logic analyzer.
Regards,
Jonni

Title: Re: Quick and dirty RAM test for CPC
Post by: LambdaMikel on 19:24, 21 September 18
A logic analyzer and oscilloscope is unnecessary for 99% of the repairs.
I suggest you get the CPC schematics and start doing some continuity checks first.
Next, get a 10 $ logic probe and check if the chips are getting their select signals, if
their outputs are active, etc. That way you can track down non-functioning chips and replace them. 

I have done a couple of quite challenging repairs, and none of them required an oscilloscope or logic analyzer. Unless you are very good at digital electronics, you will have a hard time understanding what's going on anyway.

The suggested method allowed me, for example, to perform this repair, so I know what I am talking about (that thing had about 20 defects - including broken traces, defect RAM, defect glue support chips, ...): 

https://stardot.org.uk/forums/viewtopic.php?f=3&t=15501&start=30&hilit=repair+problem (https://stardot.org.uk/forums/viewtopic.php?f=3&t=15501&start=30&hilit=repair+problem)

In addition, you will need people that can guide you through the checking process. Probably the most important thing.

Good luck! 
Title: Re: Quick and dirty RAM test for CPC
Post by: gerald on 10:40, 27 October 18
For those interested, I've added a zip file with the source code of the tool to the 1st post.You will need SDCC to compile it.
Title: Re: Quick and dirty RAM test for CPC
Post by: gotcha on 10:07, 02 November 18
I just noticed this post  :o This is very interesting, thanks @gerald (http://www.cpcwiki.eu/forum/index.php?action=profile;u=250) !

Yesterday, I used one of my 6128 as a test bench for testing the RAM of a old PC (they use the same RAM) https://forum.system-cfg.com/viewtopic.php?f=18&t=9388&start=30#p144477
I used a memchecker program (in German) that I had found some time ago. This solution worked because I believe I've put the potentially non working memory on the second 64K bank only. 
Can anybody confirm that IC119->IC126 is the second bank ?

But in case of a CPC with a failing first memory bank, the solution I was using until now (also given by @gerald (http://www.cpcwiki.eu/forum/index.php?action=profile;u=250) ) was to switch banks and/or disable a bank by removing the PAL and re-wiring the PAL socket.
This software solution looks ideal. I'm going to give it a try with the X-MEM  :D
Title: Re: Quick and dirty RAM test for CPC
Post by: gotcha on 10:23, 02 November 18
A logic analyzer and oscilloscope is unnecessary for 99% of the repairs.
I would say, yes and no.

Most of the issues on CPCs are indeed simply on-off switch to clean, keyboard to clean etc...

But when it comes to a problem on the motherboard, the scope is IMO more than useful, just to check clocks and some other signals like the video output, activity on busses etc....
For some problems, the logic analyzer is also needed. As an example, I've got a failing CPC and I didn't want to change blindly chips:Without logic analyzer, i could not have located the actual problem accurately.
Title: Re: Quick and dirty RAM test for CPC
Post by: LambdaMikel on 16:19, 02 November 18

But when it comes to a problem on the motherboard, the scope is IMO more than useful, just to check clocks and some other signals like the video output, activity on busses etc....
For some problems, the logic analyzer is also needed. As an example, I've got a failing CPC and I didn't want to change blindly chips:
  • With the scope, I detected that the synchro signal was not generated by the CRTC. Without a scope, you can't see this

My logic probe has a "pulse mode". With that you can check if the output / chip is alive and generating a non-steady signal. I used that mode to check RAM chips (chip select, RAS, CAS, inputs, output).

A logic probe is onle 30 €, whereas a scope that can be used for Mhz digital signals is a couple of hundred €,  even the cheap ones (there are little DSO pocket scopes for about 100 $, but they are toys and don't have the bandwith for digital signals, they are only useful for audio / analog really)

I am not saying that a scope and/or logical analyzer is not useful. But I would not advise people to get one if 99 % of the situations (including some of the ones that you have just described) can be analyzed perfectly fine with a logic probe.

And from a time management point of view, before you have figured out how to hook up and read and understand the databus and CRTC signals, you would have already replaced the CRTC with a fresh one. The good thing about the CPC is that it only has a couple of big chips... in principle, I am not a fan of blind repairs, but for the CPC it is possible. Buying a new CRTC is not only more cost efficient than buying an oscilloscope or logic analyzer, but also much more time efficient.

All this is of course only advice for people who are not electronic geeks and don't already have an oscilloscope and logic analyzer. So I would not suggest to people to buy such equipment in order only to repair a CPC (unless they want that equipment anyway of course).


Just my few cents.
Title: Re: Quick and dirty RAM test for CPC
Post by: Audronic on 23:35, 02 November 18
Hi All


I have just been working on SOME CPC464's and have made a table for the Bits used in GERALD's RamTest


It may be of some use  ?


Thanks.    Ray
Title: Re: Quick and dirty RAM test for CPC
Post by: GUNHED on 17:14, 03 November 18
Great! It would be even greater to know which bit corresponds to which RAM chip.


Just to be clear: It's the case that for every bit of a byte we have one physical RAM chip, right?
So if a bit is 'broken' in one byte it is probably 'broken' in all bytes, right?

Title: Re: Quick and dirty RAM test for CPC
Post by: Audronic on 22:46, 03 November 18
Ok Part 2


Ray
Title: Re: Quick and dirty RAM test for CPC
Post by: GUNHED on 03:20, 04 November 18
Awesome! Thanks!  :)
Title: Re: Quick and dirty RAM test for CPC
Post by: CanonMan on 00:59, 10 May 19

The program first test the display area (C000-FFFF), should see something like :

The content of the screen will change during the test. So if nothing move, more than the ram may be wrong.
Something else is wrong if you do not see that screen at all.


Is there any reason why it only tests ram from &C000 to &FFFF, rather than the whole 64k?


That's what appears to be happening in the source code.
Title: Re: Quick and dirty RAM test for CPC
Post by: gerald on 18:23, 10 May 19

Is there any reason why it only tests ram from &C000 to &FFFF, rather than the whole 64k?


That's what appears to be happening in the source code.
The way the DRAM is organised makes a 16K test enough to check all memory ROWs.
Screen addresses are then used to have a visual feedback.
Title: Quick and dirty RAM test for CPC
Post by: CraigsBar on 18:47, 10 May 19
.
Title: Re: Quick and dirty RAM test for CPC
Post by: SpDizzy on 23:37, 05 October 19

Hi guys!!
Does anyone could help with a diagnosis over the RAM test on attached image?
CPC 6128 AZERTY with grey screen on startup.
Several IC's so hot on both banks, reemplaced with new ones, socketed.
On the upper right side of the screen (as shown on the image) there are some blinking pixels on concrete positions.
(Sorry, green screen monitor test)
Thanks so much in advance,
Title: Re: Quick and dirty RAM test for CPC
Post by: TotO on 23:51, 05 October 19
It looks the 6th RAM IC is bad. (GREEN/RED rasters char-lines border)
Title: Re: Quick and dirty RAM test for CPC
Post by: SpDizzy on 00:14, 06 October 19
Thanks so much for response @TotO (http://www.cpcwiki.eu/forum/index.php?action=profile;u=290)
So it looks like IC132 is the culprit then, right?
Title: Re: Quick and dirty RAM test for CPC
Post by: llopis on 00:20, 06 October 19
It looks the 6th RAM IC is bad. (GREEN/RED rasters char-lines border)
Wait, are you sure? The bottom row is the LSB, and this looks like the third row to me. So I would say it's D2 that is faulty, so IC129. Or am I totally off?
Title: Re: Quick and dirty RAM test for CPC
Post by: TotO on 04:19, 06 October 19
I'm not at home. May be @gerald (http://www.cpcwiki.eu/forum/index.php?action=profile;u=250) could confirm what RAM IC number match with the 6th char line.
Title: Re: Quick and dirty RAM test for CPC
Post by: Audronic on 05:08, 06 October 19
@SpDizzy (http://www.cpcwiki.eu/forum/index.php?action=profile;u=2740)


What is the model number on the motor board ?
Can we have a photo of the Ram area on the motherboard Please to identify IC Numbers


The fault is at Data 2 ( Read from the bottom up ) 0-1-2

Thanks.  Ray
Title: Re: Quick and dirty RAM test for CPC
Post by: SpDizzy on 11:32, 06 October 19
Thanks for response @Audronic (http://www.cpcwiki.eu/forum/index.php?action=profile;u=1169)
It's a version 2 mainboard, PT NO Z70290.
Sorry for the mixture of IC's on attached image (it looks like international aid is needed for this, so any country is doing it's best)  :o
Title: Re: Quick and dirty RAM test for CPC
Post by: Audronic on 11:53, 06 October 19
@SpDizzy (http://www.cpcwiki.eu/forum/index.php?action=profile;u=2740)

Thanks for the Photo and the Board Number.

The rest DELETED

Ray
Title: Re: Quick and dirty RAM test for CPC
Post by: llopis on 12:18, 06 October 19
@SpDizzy (http://www.cpcwiki.eu/forum/index.php?action=profile;u=2740)

Thanks for the Photo and the Board Number.

It looks like it is IC121 Thats Faulty Data 2.

Ray
Is it the left column of DRAM or the right one? I thought it was the right one, but it's kind of non-intuitive.
Title: Re: Quick and dirty RAM test for CPC
Post by: gerald on 12:40, 06 October 19
Is it the left column of DRAM or the right one? I thought it was the right one, but it's kind of non-intuitive.
Yes, Left column is the Extension RAM. Base RAM is on the right.
Title: Re: Quick and dirty RAM test for CPC
Post by: Audronic on 14:43, 06 October 19
Deleted

Ray
Title: Re: Quick and dirty RAM test for CPC
Post by: SpDizzy on 19:07, 06 October 19
I AM ALIVE!!
Thank you all, folks, another little creature comes again to life.
Just to confirm, it was the 1ST BANK RAM D2, so IC129.
Thanks so much @gerald (http://www.cpcwiki.eu/forum/index.php?action=profile;u=250) for this amazing diagnosis memory tool!!


“I was benevolent and good; misery made me a fiend. Make me happy, and I shall again be virtuous.” :D