Broken 6128?

[Blurredman]

Can you make a photo of the problem?

On the colour monitor it just displays one colour and the monitor can be turned on before the computer and it will boot up (maybe a fault of the green screen) the lines are just the green screen type of display.

On the colour monitor it displays a dark turquiose type colour. But has a mix of colours in it to make it that. Looking closer it has yellow andmaybe green.

I don't have the convenience of a digital camera..

[Blurredman]

 Got another 6128 today.

So I plug it into the monitor. Nothing, just a box.

Now, I have plugged both the new 6128 and the 464 i blew on the tv using the modulator, and they both show exactly the same thing, a red box in the middle..

I wonder which chip(s) is/are the culprit?

[Blurredman]

Well, here's some pictures. It's on a black and white TV, But you get the jist of it, I don't want to loose more technology 
Those are pictures of both the 464 and the new 6128.


As you see it's just a box, on a colour TV it is a red box with blue background (on both the 464 and the 6128). And on a colour monitor it is a turquiose box with a black background.

It is hard to make out because of the sun.




It doesn't make any sort of sound when turned on.

Any ideas?  Bryce suggested the RGB cable in the monitors having overcharge on them, and as such destroying the RGB connection on the board. Might this be the case? If so, how to fix?

[arnoldemu]

I don't see the pictures.

I disabled the 8255/AY in my emulator. BASIC starts up. Keyboard is not responsive and no sound.
Screen will probably roll, colours are good. So it seems the 8255 may not be at fault here.

For 6128: Points towards ram/PAL (memory management chip within 6128). Really not sure what the problem is you are seeing.

EDIT: Now I do.

Try removing the PAL 16L8 from the 6128 motherboard, see if anything changes (I doubt it).
I have overridden it before (but then the machine is 64k only), will see if I can find my info.
There are some links on the board that can be joined to override it too, but mine is just stuffing some wires into the socket that is there.

[Blurredman]

Can you not see the box in the telly!?!

There is a box, nothing rolls or scrolls, I've described the colour in my previous post.


EDIT


Is the 16L8 (Mine says HAL16L8 BTW) the controller for the 2nd lot of 64k memory?

[MaV]

Can you not see the box in the telly!?!

Is the 16L8 (Mine says HAL16L8 BTW) the controller for the 2nd lot of 64k memory?

The box is visible. It looks like the border is rendered, but not the bytes to be displayed on the screen.

And yes. The Pal chip controls the 2nd 64k on the 6128.

If you like to have in-depth info about these kind of chips:
http://en.wikipedia.org/wiki/Programmable_Array_Logic

It also explains, albeit shortly, the difference between PAL and HAL (negligible IMO).

[Bryce]

Well for large-scale industrial production the difference between PAL and HAL is minimal, but for a hobbiest there's a huge difference. HAL doesn't exist in the hobby world, whereas PAL can be really useful. And GALs are even more useful

Regarding Blurredmans broken CPC's, there's not a lot more he can do at this stage, there could be multiple problems, but without any measurement equipment, he has done all that can be done.

Bryce.

[Blurredman]

Hopefully some time in the next 24hours i'll have another 6128 (a third).

After buying a broken one, and breaking the 2nd. I'm going to pick this one up to see it working.


I have also measured the voltage of the monitor input cables and compared them to the two modulators I have.


The modulators show no voltage at all on any pins which I imagine to be normal being an input.
However the monitors show and output of 0.5V AC from the middle pin which I believe is the 'luminescence' pin? This must be the source of the two CPC's I have blown up.

What is this and can I be got rid of for future use without damaging more CPC's?

[Blurredman]

I've come into some good fortune, I've purchased two 6128's and a green screen. 

All working except the usual disc drive issue.

Origionally I was there to pick up the one, but he offered the other for an extra note. So here we are.

[Bryce]

Cool. Now stop plugging the other ones into anything!

Hope it didn't cost you too much. The lesson was expensive enough already.

Bryce.

[MacDeath]

Good cannibalising on CPC 6128 ?

RAM : get yours working CPC into the 256K world...AY : you can get a second one as extension, was done in a book...

Z80 : a classical CPU, perhaps to manage your new external soundchip arcade style ?

CRTC : some are good, others are bad, just make sure your working CPC has the best one.




Anyway a second disk drive is always good too... even if 3".

[Blurredman]

Anyway a second disk drive is always good too... even if 3".

I am planning the 5.25" route. Make use of my drives. Make a nice wooden case with switches for side and drive 

[Bryce]

The ABBA switch will have to be on the CPC, not the drive. you need to access pins inside the CPC that don't go to the drive.

Bryce.

[arnoldemu]

I want to know, does the new one work fine?

[Blurredman]

The various tutorials for fitting external disc drives aren't very detailed. As far as I was aware it was just an issue of touching pins 31 and 32 or something like that (haven't looked into it versy seriously yet) and I was wondering if that could be done by keeping just two card connectors and one pin connector. The pin connector being inside the box with wires from switches connecting to the various pins if that was possible. Am I right in thinking that there must be no twist in the cable at all aswel?


Yes arnoldemu, I bought two yesterday which work. Got one disc drive to work, but I have no flat belts for the others to work indefinately.

[arnoldemu]

The various tutorials for fitting external disc drives aren't very detailed. As far as I was aware it was just an issue of touching pins 31 and 32 or something like that (haven't looked into it versy seriously yet) and I was wondering if that could be done by keeping just two card connectors and one pin connector. The pin connector being inside the box with wires from switches connecting to the various pins if that was possible. Am I right in thinking that there must be no twist in the cable at all aswel?


Yes arnoldemu, I bought two yesterday which work. Got one disc drive to work, but I have no flat belts for the others to work indefinately.

For connecting my drives, I use an external pc power supply.
I use a PC floppy drive cable with the edge connector on it.
and a suitable 3.5" drive with ready signal.
All connected together very easily with no modification.

[Gryzor]

You bought two more? One has to admire your perseverance...

[MacDeath]

5"1/4 ? can you still find disk for those ?

You bought two more? One has to admire your perseverance...

And also broke them...
No wonder CPC are getting that expensive these days...

[Blurredman]

5"1/4 ? can you still find disk for those ?
And also broke them...
No wonder CPC are getting that expensive these days...

Sorry for breaking them, both were my fault, one by ignorance and the other by naivity. The other was broken before I recieved it.


Sure 5.25" discs are around, I just bought a pack of 10 unopened for just over £5. Plenty on ebay, many unopened boxes.  They're more fun then 3.5".

[MacDeath]

Thx to you my personnal collection got a recent raise up in value, the rarer the more expensive...
But pleaaaase, don't ever never put your hands on an Amstrad PLUS.
Those are already quite expensives. Why don't you just try ZX Spectrum instead ?


/joke


I remember well my first PC AT286 EGA had both 3"1/2 HD (1,44meg) and 5"1/4 HD (1,2 meg).

This was a complete luxury at the time, i was the happy guy who could actually do copy from both format at school.
So most games ended in my hands (actually my brother's hand... he was the specialist, I was the snotling gamer...)

Also this was great compaired to Amiga500 or AtariST owners... my games could use far less disks...
Anyway, most commercial games actually used DD disks (720K.. often a pair.) because not everybody had good HD drivers.

Good point was that most PC/16bit games of the era didn't need you to be a Hacker, but to only have access to a Photocopy machine.
Anti-Piracy was mostly through some stuff in original documentation or perhaps also the LucasArt card Disks test.

Most PC from the time had only one format or the other... rarely both.

Also having them in HD...

5"1/4 in HD were cheap as hell and could easily and safely be carried inside hardcover schoolbook.

But on CPC, what is the max format you can get with 5"1/4 disks ?
360K? 1,2 meg ?



The sad part with Amstrad's 3" disk was the lack of DD (720k) but on some PCW. and those are said to have so issues when writing in Normal "simple"  2x180k (2x178K)...


anyway :

[Blurredman]

Good post.


Why I use 5.25? Because I can, surely they're more fun to use then 3.5"? I have a 5.25" on my PC and a 5.25" on my CPC, I would be in the same situation if they were both 3.5".. Except, I have more unformatted and unused 5.25" discs then 3.5.  Plus, if I used 3.5", i'd get confused as I have soooo many 3.5" floppy discs with different formats, for PC, for Acorn etc. 


This makes it simple, 3" and 5.25" are for Amstrad

Since I don't have ParaDOS or any thing like that, the Amstrad formats the floppy the only way it knows how! 180k per side. I have a switch on the 5.25" for it to read the other side so I don't have to punch holes in my floppies and possibly wreck them trying

The discs I am using however can be formatted as 1.2MB IBM as they're High density. I'll need to post some picks of the final product. I have been given one of those external USB disc drive bays, the 5.25" floppy drive is a tad long, but some sellotape over the holes will not make you think twice 

[Blurredman]

Okay, I managed to get a hold of my fathers digital camera, and using the colour monitor this is the result:

[MacDeath]

Have you tried the little potentiometer at the rear of the monitor ?

[arnoldemu]

The 6128 really does look dead.
The CRTC hasn't been setup, could be dead z80 or anything.

The 464 is alive enough to setup the crtc, but I really can't say what is broken.

[Bryce]

Ok. So the monitor does work. That's a start.

Bryce.