Hi All
After 30+yrs my trusty 464+ has developed a problem, i'm hoping its not terminal as i will be devastated if it is.
The issue is that now when the system is turned on with the Burnin' Rubber/OS cart inserted i get a screen with a kind of pink background with blue matrix type lines through it & black banner.
Yet with any other standard game cart i get a screen with a pure black background & blue banner.
So by my logic that says to me the system can tell the difference between the carts but just cant process them correctly.
By reading through the forums here i'm guessing its either the ASIC or RAM that is the issue?
What should i do to start of trying to sort this out, bearing in mind i am not electronically minded so bear with me if i ask dumb-ass questions.
Thanks in advance.
More likely a RAM issue. Open it up and see if either of the RAM ICs are getting hot. As for repairs, if you don't think you can fix it yourself, you can send it (just the PCB) to me for repair.
Bryce.
I think i should be able to do a RAM swap, i have done a little soldering in the past, but i may take you up on that.
Are RAM chips easy enough to get hold of nowadays?
Yes, those chips are easy to find. Make sure to cut the pins and de-solder them seperately to ensure you don't damage the PCB and order sockets for the new chips to make things easier.
Bryce.
Well while i'm doing that are there any other upgrades or mods you'd recommend doing, might as well just do them at the same time.
Ok.... so what chips should i be checking on this?
Ok I have found that IC12 (KM41464AP-12) is getting burning hot, so I presume that's the likely culprit I need to replace, would that be correct?
DRAM are IC10 and IC12 on the right side of the ASIC
If you're changing them you also might just also add the missing 64K and go to 128K.To do so, just add IC11, IC13 (same pars as IC10/12) and R128 (10K) to enable 128K.
For a full conversion to 6128Plus : https://www.cpcwiki.eu/index.php/464Plus_Conversion (https://www.cpcwiki.eu/index.php/464Plus_Conversion)
Quote from: jockavelli on 21:08, 20 November 19
Ok I have found that IC12 (KM41464AP-12) is getting burning hot, so I presume that's the likely culprit I need to replace, would that be correct?
Yes. These are not supposed to be burning hot ;)
Quote from: gerald on 21:14, 20 November 19Yes. These are not supposed to be burning hot ;) [/size] [/size]
It was a bit of a surprise how hot it got, so yeah no wonder it ain't working.
On the IC is the 939 relevant or would one with a 909 be ok to use?
As for adding the 64k i'll need to have a look over that (several times) or find a video (to watch, several times) just to be sure i want to risk it.
Quote from: jockavelli on 21:33, 20 November 19
On the IC is the 939 relevant or would one with a 909 be ok to use?
That's either a batch number, or a date code. No need to worry about that number being different.
The important thing, is that the part code is the same (KM41464AP-12) or use an equivalent from a different manufacturer, but with the same or faster access timing (speed).
Mark
Brilliant, I thought it may be something like that but just wanted to be sure.
Now to source the chips & the correct socket!
Quote from: jockavelli on 21:33, 20 November 19
It was a bit of a surprise how hot it got, so yeah no wonder it ain't working.
On the IC is the 939 relevant or would one with a 909 be ok to use?
As for adding the 64k i'll need to have a look over that (several times) or find a video (to watch, several times) just to be sure i want to risk it.
939 = Manufactured in the 9th week of 1993
909 = Manufactured in the 9th week of 1990
Bryce.
Quote from: Bryce on 08:44, 21 November 19
939 = Manufactured in the 9th week of 1993
909 = Manufactured in the 9th week of 1990
Bryce.
Thant makes sense, also makes the system younger than i had thought.
I have found a few chips but i'm not sure of the correct socket to use, surely it can't be that hard to solder directly back on without the socket?
OR....
should i step away now LOL
The socket helps to make the soldering safer, but the main reason to use sockets is because ALL of these chips, even the new ones will be relatively old and prone to fail at any time. Using a socket means that the next replacement only involves pulling a chip from the socket and inserting a new one, with no soldering involved.
Bryce.
Quote from: jockavelli on 21:50, 21 November 19
I have found a few chips but i'm not sure of the correct socket to use, surely it can't be that hard to solder directly back on without the socket?
OR....
should i step away now LOL
You want a DIL socket with the same number of pins as the chip. And the same width.
Stamped pin sockets are cheaper, but some prefer turned pin sockets.
Modern quality 'dual wipe' stamped pin sockets (where the IC chip pin goes in between a receptacle such that there is a metal contact on two sides so the chip pin is in the middle) are more reliable than the older cheaper sockets (which only had metal on one side).
Turned pin sockets more reliable still, especially if subjected to multiple insertions/removals.
Mark
Quote from: 1024MAK on 14:45, 22 November 19
You want a DIL socket with the same number of pins as the chip. And the same width.
Stamped pin sockets are cheaper, but some prefer turned pin sockets.
Modern quality 'dual wipe' stamped pin sockets (where the IC chip pin goes in between a receptacle such that there is a metal contact on two sides so the chip pin is in the middle) are more reliable than the older cheaper sockets (which only had metal on one side).
Turned pin sockets more reliable still, especially if subjected to multiple insertions/removals.
Mark
I'm hoping to find what i'm looking for and get it all ordered next week, then take it from there.
Pretty sure i'll find somewhere doing the right sockets once i actually look properly.
Would a socket with these dimensions be the correct ones to get?
18 Pin - 22.86mm, 10.16mm, 4.80mm
Quote from: jockavelli on 23:23, 23 November 19
Would a socket with these dimensions be the correct ones to get?
18 Pin - 22.86mm, 10.16mm, 4.80mm
Yes ;)
Stamped pin socket datasheet here (https://static.rapidonline.com/pdf/400861_v1.pdf)
Turned pin socket datasheet here (https://static.rapidonline.com/pdf/63764_v1.pdf)
[Note that the above links are to a U.K. supplier that I use. Other brands/makes/suppliers are available...]
Mark
We'll seeing as i'm UK based too i think i'll stick with what you have used before.
on another note i managed to pick up a 6128 today for £5 with a Multiface Two still boxed...... no idea what it does yet, will read up on it later.
No screen or cables to connect to a TV so no idea if it works but it was £5 so would be silly to pass it up.
Quote from: jockavelli on 19:37, 24 November 19
on another note i managed to pick up a 6128 today for £5 with a Multiface Two still boxed......
Woah, what a bargain! How did you come across that one?
Quote from: Skunkfish on 14:09, 09 December 19
Woah, what a bargain! How did you come across that one?
Saw it at a car boot sale, no monitor for it so the guy couldn't say if it worked, don't think he knew what he had.
Okay, some small progress ;D
So the sockets arrived, i started the repair and noticed some black residue joining 3 pins together, no idea what it was.
I now have clean board with the socket in place, while i wait on the RAM arriving :( , which sadly i have just been told could now be sometime in February :picard: .
So if anyone has a spare RAM chip they are willing to sell me now or send me & i will replace it when mine arrive it would be appreciated :D [size=78%].[/size]
Good news the RAM arrived :)
Bad news, it appears both RAM chips have failed.
I only noticed this after replacing the first one, which i admit i found harder to do than i expected that is probably through lack of experience & confidence.
As such i cannot do the second one, i don't see an easy way for me to do it without messing something else out.
So.... is there anyone willing to help me out by doing the repair?
Bryce i know you said you could but i don't want to assume you are still willing to do so.
I have plenty of RAM as i bought 10 just in case as well as a few sockets.
No problem. Send it over (send me a PM for details).
Bryce.
Quote from: jockavelli on 12:00, 13 December 19
Good news the RAM arrived :)
Bad news, it appears both RAM chips have failed.
I only noticed this after replacing the first one, which i admit i found harder to do than i expected that is probably through lack of experience & confidence.
As such i cannot do the second one, i don't see an easy way for me to do it without messing something else out.
So.... is there anyone willing to help me out by doing the repair?
Bryce i know you said you could but i don't want to assume you are still willing to do so.
I have plenty of RAM as i bought 10 just in case as well as a few sockets.
If you are near Oxford I can also replace the RAM for you and save Bryce a trip to the post office :) However, if you need to send it by post anyway, I would totally send it to him :D
Quote from: ||C|-|E|| on 23:58, 13 December 19
If you are near Oxford I can also replace the RAM for you and save Bryce a trip to the post office :) However, if you need to send it by post anyway, I would totally send it to him :D
Im near Edinburgh, so needs to get posted anyway.
Then Bryce all the way :)
Quote from: ||C|-|E|| on 00:44, 15 December 19
Then Bryce all the way :)
Yeah that's the plan, its boxed & ready to go so hopefully i'll get to post it tomorrow.
Right in the middle of the Christmas rush. It should be here by February :)
Bryce.
Quote from: Bryce on 23:42, 15 December 19
Right in the middle of the Christmas rush. It should be here by February :)
Bryce.
I've just posted it... :doh:
I never even gave that a single thought, oh bugger i hope they don't lose it. :(
Maybe it will arrive already fixed! :laugh:
Well it arrived before Christmas and is currently languising on the healing bench. You've sent me enough parts to convert it to 128K. Do you want it converted or should I just leave it at 64K?
Bryce.
Edit: I've swapped the last RAM chip and the computer is up and running again. Your chip replacement was good, just the other RAM chip had failed too. Let me know if you want me to upgrade it to 128K while I'm here and the iron is hot.
Quote from: Bryce on 14:28, 23 December 19
Well it arrived before Christmas and is currently languising on the healing bench. You've sent me enough parts to convert it to 128K. Do you want it converted or should I just leave it at 64K?
Bryce.
Edit: I've swapped the last RAM chip and the computer is up and running again. Your chip replacement was good, just the other RAM chip had failed too. Let me know if you want me to upgrade it to 128K while I'm here and the iron is hot.
Superb, glad to hear she still has life in her lol
yeah go for it, not sure what the advantage is really but i'm sure there is one.
Well there are games that will only run on 128K, but you'll have to ask the others here whether it's worth it* as I'm not a gamer.
Bryce.
* Bryce officially opens a can of worms.
(https://miro.medium.com/max/1252/0*PCbE4DxTtuLBSZRC)
Your 464+ is now a 4128+. As soon as the post office opens again (Friday I think), I'll send it back.
Bryce.
Quote from: Bryce on 13:00, 24 December 19
Your 464+ is now a 4128+. As soon as the post office opens again (Friday I think), I'll send it back.
Bryce.
Superb, thank so much for that, you really didn't need to do it that quickly.
Just let me know what i'm due you & i'll get it transferred to you.
To be honest, I didn't rush it for you particularly. I have 26 computers in for repair at the moment and I'd like to get them all finished before the start of the new year. Yours was done first because I always clear the easy ones out of the way first.
Bryce.