Help needed with an old 6128

[martw80888]

Hello all, this is my first post here (although I've been lurking for a couple of weeks)

Just dragged my old CPC6128 and CTM644 monitor down from my parents' attic, this was my first ever computer, bought for me at the tender age of 10 after bugging my parents to get me a computer for about 3 years. I gave it bit of a clean up, plugged it in and... it doesn't work :-(

The red power LED on the CPC lights up but that's it - completely blank screen.

The monitor appears to be working as far as I can tell - obviously no picture appears, but it behaves as I remember it doing back when I used it regularly. Also, it's still providing power to the CPC, evidenced by the power LED lighting up.

I'm guessing the problem lies with the computer itself - I remembered that hitting the Delete key or holding one key down for a while should produce a beep, and that's not happening, so I don't think it's something as simple as the picture signal just not reaching the screen.

So... any ideas? Looking at previous posts on this forum, I realise that the problem could be any one (or several) of many issues, but I'm not sure where to start or where to get replacement components from.

It would be nice to get it up and running, there's quite a sentimental attachment plus I've got a stack of games and a bunch of accessories (Multiface 2, Magnum light phaser, ROMbox containing DES, Genius mouse, "period" cassette player) that I'm itching to test.


Thanks in advance

[zeropolis79]

What a mouthwatering collection..

Either the graphics chip is malfunctioning or the display on the monitor.. Alternatively, there might be an issue with the monitor connection.

You might want to invest in one of these: AMSTRAD CPC 6128 TV CONNECTION KIT - PSU ADAPTERS & SCART CABLE | eBay

and if you get no pictures on a TV, then it is a problem with the computer. But be careful, on some modern TVs, you might only get a black and white display.

[Token]

Hi and welcome
Sad. I had this problem, all I know is that for me the RAM at least had a problem. On the first bank I had a chip that was seriously hot...

[Bryce]

Hi and Welcome,
        If you're not getting any picture or even a beep, then it's something more basic than the graphics chip or monitor. First off, open the computer up and re-seat all the socketed chips: ie: lift them slightly and push them firmly back in. Then try the computer again. Also, make sure the volume isn'T turned down, maybe it is beeping?

Bryce.

[martw80888]

Thanks for the replies and the welcomes

You might want to invest in one of these: AMSTRAD CPC 6128 TV CONNECTION KIT - PSU ADAPTERS & SCART CABLE | eBay

I have already had this idea, only from the other "direction" (as it were), I've got a cable coming which will allow me to connect other devices to the monitor (something I had planned anyway, my Sega Dreamcast gives an awesome picture through an old RGB monitor ;-)  ), so that should allow me to find out if the monitor is working properly.

        If you're not getting any picture or even a beep, then it's something more basic than the graphics chip or monitor. First off, open the computer up and re-seat all the socketed chips: ie: lift them slightly and push them firmly back in. Then try the computer again. Also, make sure the volume isn'T turned down, maybe it is beeping?

The volume was definitely turned up and definitely no beeps. I shall try re-seating the chips (probably at the weekend when I have some time) and report back.


Thanks again.

[zeropolis79]

Dreamcast via a CPC monitor - would never have thought of that..

[martw80888]

I was using an old Acorn AKF12 monitor with the Dreamcast, but it unfortunately went pop a month or so ago, lovely picture when it was working though.

I'm hoping to get the same results with the CTM using one of these: AMSTRAD CTM-644 RGB COLOUR MONITOR SCART ADAPTER CABLE | eBay

[redbox]

I was using an old Acorn AKF12 monitor with the Dreamcast, but it unfortunately went pop a month or so ago, lovely picture when it was working though.

I can highly recommend a Sony Trinitron 14" CRT.  There's loads on eBay.

Works great for all retro gaming, including the CPC 

[Token]

I'm hoping to get the same results with the CTM using one of these: AMSTRAD CTM-644 RGB COLOUR MONITOR SCART ADAPTER CABLE | eBay

I have one, tested with Atari ST.
But I had to reduce the brighness to 0 on the CTM 644-2. Still very flashy. I bought some resistor on Ebay 3 days ago. I wait them.


I didn't tried with my Amiga 500. It doesn't work with the C64.
(edit : xl doesn't!) Works with Atari 800XL and PSX.


Btw I have a MP-3 now, it was modded (but kind easy to do)
Of course the same image with the SCART adapter.
But very amazing with an old RF console. I never saw my Mattel Intellivision like this. Tested also a Pong console, so clean and accurate. Impressive picture!
I'm thinking to buy a VCS. Love more and more the CTM!


The other good with the MP-3 it add sound (and much better than expected), the bad: brightness/contrast button is useless since the SCART input...

[steve]

A long time ago, I used a CTM 640 with an Amiga 1200.

[Bryce]

I didn't tried with my Amiga 500. It doesn't work with the C64.
Works with Atari 800XL and PSX.

How are you connecting an 800XL to the CTM?

All Amigas will work on CPC monitors.

Bryce.

[Token]

How are you connecting an 800XL to the CTM?

All Amigas will work on CPC monitors.

Bryce.

When I received the SCART adapter I tested every oldies I have. I'll re-test with the XL soon.
The seller wrote that it worked with Amiga 500, I have no idea with the brightness: he also claim it works on Atari ST. No matter if the signal is too hot for the monitor.
I didn't tested the Amiga yet, I have no SCART cable but I use a 1084 anyway.
It has been reported that the color is very green with the A1200, but people manage to fix it without big problem.

Probs Couleurs Amiga A1200 / A500

[Bryce]

The XL only outputs S-video not RGB, so there's no way the CTM could display it without quite a bit of additional hardware.

Bryce.

[Token]

that's what I expected when I read your comment
I must have tested also with the 1084, or TV. Sorry.
PSX works??  

[Token]

The XL only outputs S-video not RGB, so there's no way the CTM could display it without quite a bit of additional hardware.

Bryce.

The XL could be used on the CTM with your S-Video adapter? I would also love to use the C64...

[Bryce]

No, my adapter can convert RGB to S-Video, but it won't convert S-Video to RGB, that's much more complicated. The XL and the C64 could be connected to a GT64/65 by connecting their composite signal to the LUM signal, but obviously just a green picture.

Bryce.

[Token]

Wow great info, as usual... Thanks Bryce!

[Token]

No, my adapter can convert RGB to S-Video, but it won't convert S-Video to RGB, that's much more complicated. The XL and the C64 could be connected to a GT64/65 by connecting their composite signal to the LUM signal, but obviously just a green picture.

Bryce.

I saw your explanation about S-video to RGB on an other thread. I wouldn't even think of it


The C64 near the GT64 looks like very cute toys
I tried without soldering. I couldn't make it work.


I connected C64: 4 Composite video
to GT64: 6 LUM


also added
Ground... (2 to 5)


I did also a test with 1 to 6, still with the grounds, and did many other random combinations, but never connected 8.







CPC:

[Bryce]

Strange. That should have worked. I'll try it out myself when I get a chance and see why it doesn't work. did it give anything at all? A Flickering picture? Diagonal lines?

Bryce.

[Token]

Indeed, something that looks to be text from BASIC. All in diagonal \\\\ a big multicolored line that roll too.
I have another C64 visitor. I'll also try, I really want it works, neeeed! =]

[Token]

hard to take what is looking like text

[Bryce]

Oh, looks like the signal is too weak or the levels not high enough. I'll check the signal on the scope when I get a chance and see what needs to be added to get it working.

Bryce.

[Token]

Cool


Btw I just soldered those resistors between an Atari STe and CTM. Works like a charm. Thank you! The values I choosed myself were a bit extreme. I took 270 ohm, I think 180 would fit my licking. 100,120,150 should be safe.


(couldn't resist ;P to put a resistor on the GT64, it reduced the brightness, but still a diagonal)

[martw80888]

If I may nudge this back on-topic...   

So it turns out that my monitor is knackered - it powers up but doesn't display a picture. If anyone thinks they can fix it and are able to collect it from Christchurch in Dorset you're more than welcome to have it, otherwise it'll go to the tip in a couple of weeks time as it's now of no use to me.

I opened up the CPC and re-seated the socketed chips. One of them, marked 40010, actually didn't seem to be seated properly, I'm wondering if the computer's taken a knock or two during its time in the attic and maybe that could have been the problem.

Also took the opportunity to fit a new drive belt to the disk drive - many thanks to whoever wrote the guide for doing that, very helpful.

I've ordered the TV connection kit, when it arrives I can test it again.

[martw80888]

So the TV connection kit arrived, hooked it up to my TV and all I get is this:

[attachimg=1]

(the pic's not great quality cos I had to take it in a hurry, but should show a light grey screen with black border)

shortly followed by just a blank screen. There's also a sound like electrical interference coming from the speaker. The disk drive LED lit up when I first powered it on, it didn't come on after that.

Is this terminal or can it be revived?