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General Category => Amstrad CPC hardware => Topic started by: martw80888 on 20:03, 21 April 14

Title: Help needed with an old 6128
Post by: martw80888 on 20:03, 21 April 14
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
Title: Re: Help needed with an old 6128
Post by: zeropolis79 on 21:47, 21 April 14
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 (http://www.ebay.co.uk/itm/AMSTRAD-CPC-6128-TV-CONNECTION-KIT-PSU-ADAPTERS-SCART-CABLE-/320958725001?pt=UK_VintageComputing_RL&hash=item4abaa17b89)

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.
Title: Re: Help needed with an old 6128
Post by: Token on 23:01, 21 April 14
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...

Title: Re: Help needed with an old 6128
Post by: Bryce on 08:42, 22 April 14
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.
Title: Re: Help needed with an old 6128
Post by: martw80888 on 17:12, 22 April 14
Thanks for the replies and the welcomes

Quote from: zeropolis79 on 21:47, 21 April 14
You might want to invest in one of these: AMSTRAD CPC 6128 TV CONNECTION KIT - PSU ADAPTERS & SCART CABLE | eBay (http://www.ebay.co.uk/itm/AMSTRAD-CPC-6128-TV-CONNECTION-KIT-PSU-ADAPTERS-SCART-CABLE-/320958725001?pt=UK_VintageComputing_RL&hash=item4abaa17b89)

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.


Quote from: Bryce on 08:42, 22 April 14
        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.
Title: Re: Help needed with an old 6128
Post by: zeropolis79 on 19:00, 22 April 14
Dreamcast via a CPC monitor - would never have thought of that..
Title: Re: Help needed with an old 6128
Post by: martw80888 on 20:13, 22 April 14
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 (http://www.ebay.co.uk/itm/390344578694?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649)
Title: Re: Help needed with an old 6128
Post by: redbox on 21:06, 22 April 14
Quote from: martw80888 on 20:13, 22 April 14
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  :)
Title: Re: Help needed with an old 6128
Post by: Token on 22:47, 22 April 14

Quote from: martw80888 on 20:13, 22 April 14
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...
Title: Re: Help needed with an old 6128
Post by: steve on 23:34, 22 April 14
A long time ago, I used a CTM 640 with an Amiga 1200.
Title: Re: Help needed with an old 6128
Post by: Bryce on 08:02, 23 April 14
Quote from: Token on 22:47, 22 April 14
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.
Title: Re: Help needed with an old 6128
Post by: Token on 09:52, 23 April 14
Quote from: Bryce on 08:02, 23 April 14
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 (http://www.youtube.com/watch?v=JrpAWj60dws#)


Title: Re: Help needed with an old 6128
Post by: Bryce on 09:58, 23 April 14
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.
Title: Re: Help needed with an old 6128
Post by: Token on 10:07, 23 April 14
that's what I expected when I read your comment ;)
I must have tested also with the 1084, or TV. Sorry.
PSX works?? :) 
Title: Re: Help needed with an old 6128
Post by: Token on 10:27, 23 April 14
Quote from: Bryce on 09:58, 23 April 14
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...
Title: Re: Help needed with an old 6128
Post by: Bryce on 10:46, 23 April 14
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.
Title: Re: Help needed with an old 6128
Post by: Token on 11:00, 23 April 14
Wow great info, as usual... Thanks Bryce!

Title: Re: Help needed with an old 6128
Post by: Token on 00:56, 24 April 14
Quote from: Bryce on 10:46, 23 April 14
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 :P


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.




(http://ilesj.files.wordpress.com/2012/03/c64-av-pinout.png?w=450&h=171)


CPC:
(http://www.cpcmania.com/Docs/scart/scart03_b.jpg)
Title: Re: Help needed with an old 6128
Post by: Bryce on 08:16, 24 April 14
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.
Title: Re: Help needed with an old 6128
Post by: Token on 15:05, 24 April 14
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! =]



Title: Re: Help needed with an old 6128
Post by: Token on 15:50, 24 April 14

hard to take what is looking like text(http://s30.postimg.org/kbk167em9/GT64_C64.png)
Title: Re: Help needed with an old 6128
Post by: Bryce on 17:13, 24 April 14
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.
Title: Re: Help needed with an old 6128
Post by: Token on 19:32, 24 April 14
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)
Title: Re: Help needed with an old 6128
Post by: martw80888 on 14:39, 26 April 14
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.
Title: Re: Help needed with an old 6128
Post by: martw80888 on 15:21, 28 April 14
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?
Title: Re: Help needed with an old 6128
Post by: Bryce on 16:02, 28 April 14
Revivable. It's probably the CPU or a RAM IC. Time to get the soldering iron out.

Bryce.
Title: Re: Help needed with an old 6128
Post by: martw80888 on 16:23, 28 April 14
Hmmm.....  not too confident with a soldering iron tbh, I'd hate to ruin a salvageable machine through sheer ham-fistedness.

Where would I source suitable replacement components from and how much can I expect them to cost me?

Starting to wonder if I should just sell the whole lot to someone with more expertise.
Title: Re: Help needed with an old 6128
Post by: Bryce on 22:04, 28 April 14
If you send me the PCB I'll take a look at it. Depends how much you want that exact PCB working again, otherwise buy a new one.

Bryce.
Title: Re: Help needed with an old 6128
Post by: martw80888 on 16:24, 29 April 14
Thankyou for your kind offer, however I wouldn't want to impose. Having had a look around this forum I get the feeling that you have plenty to keep you busy :). Also, I'm not sure how much I want to send something like this through the post.

I have found someone locally (a guy my wife works with) who might be able to help me out.
Title: Re: Help needed with an old 6128
Post by: Bryce on 08:15, 30 April 14
Ok. If you've no luck locally get back to me. I'm not too busy at the moment, only 4 computers to fix this weekend :D

Bryce.
Title: Re: Help needed with an old 6128
Post by: martw80888 on 16:01, 20 May 14
I've had to delay fiddling with this for a little bit due to an extremely painful infected cyst developing on my shoulder and I haven't had much inclination to do anything recently.

Anyway, thought I'd have a tinker so I replaced the CPU, and no joy, still the same result, so I guess the problem lies elsewhere.

After a fair bit of thinking (I have quite a sentimental attachment to this thing), I've decided to sell the lot. I simply don't have the expertise to fix it and I think it would be better for someone else to take it on.

My whole collection will be going up on eBay over the course of the next week or so, and I'll be sticking to emulation from now on.
Title: Re: Help needed with an old 6128
Post by: CPC_Fan on 18:04, 20 May 14
martw80888 - If you do decide to sell your collection, I would be very interested in buying the ROMbox and multiface 2 from you. Maybe you could PM me so that we could do a deal?

Mark
Title: Re: Help needed with an old 6128
Post by: Gryzor on 18:53, 20 May 14
Too bad... Hope you still stay around here at least!
Title: Re: Help needed with an old 6128
Post by: martw80888 on 20:14, 20 May 14
I'm sure I'll still be lurking around. Although my main retro interest centres around the 16/32-bit consoles of the 90s, the CPC was my very first computer so I have a real soft spot for it :)
Title: Re: Help needed with an old 6128
Post by: Bryce on 20:27, 20 May 14
Why sell it? Send me the PCB and I'll fix it for you.

Bryce.
Title: Re: Help needed with an old 6128
Post by: martw80888 on 20:59, 20 May 14
Quote from: Bryce on 20:27, 20 May 14
Why sell it?

Because even if it was working I don't think I'd use it very often - emulation is enough to scratch the itch when I need to. I'd rather it went to someone else who did get more use out of it. Also, while Mrs. W. has been pretty accommodating so far when it comes to my retro-gaming passion, I know she's not tremendously happy about yet another machine plus games plus accessories taking up space in our tiny flat :)
Title: Re: Help needed with an old 6128
Post by: Bryce on 21:28, 20 May 14
I know the way. It's just a pity as it's your original from back then. I wouldn't part with my original CPC464 for the world.

Bryce.
Title: Re: Help needed with an old 6128
Post by: Gryzor on 12:25, 22 May 14
Second that. It's not just another machine, it's your machine!!!
Title: Re: Help needed with an old 6128
Post by: martw80888 on 13:08, 22 May 14
Believe me, it wasn't an easy decision, but I've made my peace with it.
Title: Re: Help needed with an old 6128
Post by: CraigsBar on 15:52, 22 May 14
Quote from: Bryce on 21:28, 20 May 14
I know the way. It's just a pity as it's your original from back then. I wouldn't part with my original CPC464 for the world.

Bryce.

I had no choice mine had to go. I was heading off to university and my parents needed the house empty. It was undergoing major underpinning and I could only take 1 machine with me. So I took the 6128+. And the CPC 464 (with damaged keyboard) went to the skip.

The 6128+ is still going strong, and has since been joined by a couple of CPC 6128s and another plus but I do sometimes wish I still has that original CPC 464.

Craig
Title: Re: Help needed with an old 6128
Post by: gerald on 17:23, 22 May 14
Quote from: CraigsBar on 15:52, 22 May 14
.... And the CPC 464 (with damaged keyboard) went to the skip ...
Looks like you have a really bad influence on keyboard health  :laugh:
Title: Re: Help needed with an old 6128
Post by: CraigsBar on 19:02, 22 May 14
Quote from: gerald on 17:23, 22 May 14
Looks like you have a really bad influence on keyboard health  :laugh:


I think it was more the fall down a flight of stairs that broke the spacebar on the CPC 464. Annoying in itself.. especially since I was halfway through a good game of Crazy Cars at he time!


Craig
Title: Re: Help needed with an old 6128
Post by: Bryce on 21:17, 22 May 14
You were playing Crazy Cars on a CPC on a flight of stairs?!?! wtf?  :laugh:

Bryce.
Title: Re: Help needed with an old 6128
Post by: CraigsBar on 21:26, 22 May 14
I had a Computer desk built into the landing as the house was not very big for a separate office!


I must have overly tweaked my joystick (ooer) launching the CPC off the landing and down the full flight of stairs. the only damage was the spacebar fortunately the monitor, 64k ram and DDi-1 detached themselves before this maiden unpowered CPC flight.


Having a 464 with a space bar that had very little plastic lect, no balance bar and no springs made typing a bit hit an miss from then on.


Craig

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