Author Topic: Faulty 6128  (Read 3057 times)

0 Members and 1 Guest are viewing this topic.

Offline johnnyt

  • CPC464
  • **
  • Posts: 6
  • Country: gb
  • Liked: 0
  • Likes Given: 0
Faulty 6128
« on: 20:39, 10 May 16 »
Hi,


I think my trusty old 6128 has finally given up on me!   :(


It's connected to a CTM644 but when I switch on the 6128 the screen goes grey and lines move vertically up the screen. There is no border, it covers the whole screen. Is this as bad as I think it is?  :o


1. 6128 power light is on
2. There is a faint noise coming from the speaker which changes when the volume is adjusted - but prolonged key presses don't make a beep
3. CTM644 works with an analogue TV tuner (MP-3)
4. 12V and 5V power supplies from the CTM644 are fine
5. There are no physical signs of damage to the board and it worked fine the last time it was used


I looked at the service manual flowchart, it possibly suggests ULA (40010?). Any ideas whether this is likely or whether there are other possible causes? And is ebay the best place for parts?


Thanks for any help,


JT


 

Offline gerald

  • Supporter
  • 6128 Plus
  • *
  • Posts: 1.557
  • Liked: 1109
  • Likes Given: 265
Re: Faulty 6128
« Reply #1 on: 21:26, 10 May 16 »
If you don't have anything on screen and no sound on keypress (DEL/CLR), most likely failing chips are :
- Z80
- 40010
- OS ROM
- CRTC

The Z80 and 40010 are on socket, so you may try re-settling them.
Also none of these chips are not supposed to heat. A finger test may point the culprit.

For a replacement 40010, just check @TotO if he still have some in stock.

Offline johnnyt

  • CPC464
  • **
  • Posts: 6
  • Country: gb
  • Liked: 0
  • Likes Given: 0
Re: Faulty 6128
« Reply #2 on: 21:40, 10 May 16 »
Thanks Gerald!


I will trying removing and re-mounting the Z80 and 40010. Then see what happens!


I did check for heat on the chips but none were hot tbh - maybe need to leave it on for a bit longer!


Thanks again,


JT




Offline Higgy

  • CPC464
  • **
  • Posts: 19
  • Country: gb
  • Liked: 11
  • Likes Given: 3

Offline johnnyt

  • CPC464
  • **
  • Posts: 6
  • Country: gb
  • Liked: 0
  • Likes Given: 0
Re: Faulty 6128
« Reply #4 on: 02:10, 11 May 16 »
Thanks Higgy :) I've bookmarked them :)

I think I will need some bits! Just not sure which ones yet?

I left it on for a while and the Z80 was warm and the CRTC was too.

Should I start with the Z80 (cos it looks easier   ;D  ) ? and where do i get one?

*writes down shopping list*

Thanks
JT





Offline TotO

  • 6128 Plus
  • ******
  • Posts: 3.969
  • Country: fr
    • ?area=showdonations;u=4
  • Liked: 3065
  • Likes Given: 1855
Re: Faulty 6128
« Reply #5 on: 09:07, 11 May 16 »
Those business links are expansive (twice the real price). Just contact me if you prefert to get them cheaper...
I have some GA, CRTC and UK OS ROM chips in stock to repair your CPCs. (I have to check for CPU)  ;)
« Last Edit: 09:59, 11 May 16 by TotO »
"You make one mistake in your life and the internet will never let you live it down" (Keith Goodyer)

Offline johnnyt

  • CPC464
  • **
  • Posts: 6
  • Country: gb
  • Liked: 0
  • Likes Given: 0
Re: Faulty 6128
« Reply #6 on: 14:22, 11 May 16 »
Hi TotO,

Thanks, I think I was looking at your website earlier. I will try to remove the Z80 and 40010 and try re-mounting them. Need to find an IC puller first. If this doesnt work I will message you to get some bits!  :)

Thanks,

JT
« Last Edit: 14:35, 11 May 16 by ||C|-|E|| »

Offline ||C|-|E||

  • Administrator
  • 6128 Plus
  • *****
  • Posts: 1.866
  • Country: gb
    • index.php?action=treasury
    • Mundo CPC
  • Liked: 1044
  • Likes Given: 1152
Re: Faulty 6128
« Reply #7 on: 14:33, 11 May 16 »
@johnnyt
Your reply appeared in a tiny tiny font. I corrected it, that is why you see your message as "edited"  :)
« Last Edit: 16:07, 11 May 16 by ||C|-|E|| »

Offline Bryce

  • The Hardware Guy.
  • Supporter
  • 6128 Plus
  • *
  • Posts: 12.333
  • Country: wf
  • It's not broken, it just hasn't been fixed yet.
    • index.php?action=treasury
  • Liked: 4623
  • Likes Given: 484
Re: Faulty 6128
« Reply #8 on: 14:38, 11 May 16 »
Hi TotO,

Thanks, I think I was looking at your website earlier. I will try to remove the Z80 and 40010 and try re-mounting them. Need to find an IC puller first. If this doesnt work I will message you to get some bits!  :)

Thanks,

JT


A flathead screwdriver is all you need to remove the ICs. Just lever them carefully going from one end to the other until they're completely free.

Bryce.

Offline johnnyt

  • CPC464
  • **
  • Posts: 6
  • Country: gb
  • Liked: 0
  • Likes Given: 0
Re: Faulty 6128
« Reply #9 on: 17:09, 12 May 16 »
Thanks Bryce - I followed your advice and the chips came off nicely!  :)

Sadly after I remounted them the problem wasn't fixed - but worth a try!

Looks like I need some new bits ;-)

JT

PS thanks to the moderator for making my message readable! :-)

Offline Bryce

  • The Hardware Guy.
  • Supporter
  • 6128 Plus
  • *
  • Posts: 12.333
  • Country: wf
  • It's not broken, it just hasn't been fixed yet.
    • index.php?action=treasury
  • Liked: 4623
  • Likes Given: 484
Re: Faulty 6128
« Reply #10 on: 17:13, 12 May 16 »
I'd try replacing the Z80 first, however, it might be cheaper in the long run to send it to someone who has spares of all these parts.

Bryce.

Offline johnnyt

  • CPC464
  • **
  • Posts: 6
  • Country: gb
  • Liked: 0
  • Likes Given: 0
Re: Faulty 6128
« Reply #11 on: 17:25, 12 May 16 »
Thanks Bryce,

I was going to ask TotO for some prices and see from there.

JT