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avatar_Rabs

Black Screen 664

Started by Rabs, 21:23, 20 December 22

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Bryce

Quote from: Rabs on 19:54, 27 January 23Is it me or are the PCB holes not quite wide enough for a standard socket?

More likely that you didn't get every last bit of solder out of every pin hole.

Bryce.

Rabs

Quote from: Bryce on 12:56, 28 January 23
Quote from: Rabs on 19:54, 27 January 23Is it me or are the PCB holes not quite wide enough for a standard socket?

More likely that you didn't get every last bit of solder out of every pin hole.

Bryce.
Thanks, I will look out for that next time but not sure that is it, I had to literally splay the socket pins to fit and only for the smaller 14 and 16 pin sockets. I had no problems with the bigger 28 and 40 pin sockets. Also I have never had a problem with a 6128. My normal process is to reflow all pins first with some fresh solder, then use a Hakko desoldering gun and repeat until the pins look clear then use a dry iron to just make sure each pin clicks loose and if not repeat. So far, I have not had any problems and the ICs all lift only cleanly. But can't believe the pcb has slightly wider hole placement than standard so must be me  :)

Rabs

Right that's it, I am done, back playing F15 Strike Eagle on my resurrected 664.

Thanks everyone for the help, much appreciated.

You cannot view this attachment.

Here are my two working 664s.

You cannot view this attachment.

I swapped the keys onto my other 664, which otherwise is very clean.

What did I learn from this?

What looks like corrosion on a PCB or on the ICs is bad news, get ready to trace tracks for two weeks  :)

A black screen could be a dead CRTC or ROM or track problems or all 3  :picard:

If BASIC does not start, check the ROMDIS from the disk circuit.

AY ICs are expensive, they need protection.

Beside a new membrane, the key contacts may need cleaning, check the resistance.

Odd things happen if the power is not stable, always check power is stable.


Again, thanks everyone for the help, off to look for my next project  :D



RetroCPC

#78
Rabs,

If I understand correctly, you transferred the New looking keyboard to the lower unit, and put the aged - yellowed keyboard into the upper unit? I guess you did this because the "Amstrad and FDD" metal nameplates / badges on the upper unit appear "Scratched" / Damaged? but to me, they appear to still have their plastic protective on them (which has bubbled). Normally you peel this plastic film off when you buy the unit.

As CPC664 are so valuable - and IF you unit still has the plastic film in place on the metal name plates / badges - I'd leave it on!!! (don't peel it off!!!)... :) Still having the protective shipping film on the badges only helps to increase your units value!!! If I'm correct, then I put back the New Keyboard!!! looks like the upper CPC might be really a little used "New" unit still with its protective shipping film!!!

Rabs

Quote from: RetroCPC on 19:43, 28 January 23Rabs,

If I understand correctly, you transferred the New looking keyboard to the lower unit, and put the aged - yellowed keyboard into the upper unit? I guess you did this because the "Amstrad and FDD" metal nameplates / badges on the upper unit appear "Scratched" / Damaged? but to me, they appear to still have their plastic protective on them (which has bubbled). Normally you peel this plastic film off when you buy the unit.

As CPC664 are so valuable - and IF you unit still has the plastic film in place on the metal name plates / badges - I'd leave it on!!! (don't peel it off!!!)... :) Still having the protective shipping film on the badges only helps to increase your units value!!! If I'm correct, then I put back the New Keyboard!!! looks like the upper CPC might be really a little used "New" unit still with its protective shipping film!!!

Hi, unfortunately not, what you see is corrosion on the metal nameplates. But thanks good to know.

RetroCPC

#80
Oh, What a shame - we could have had a good laugh :)

I've seen it before where people have left the film on and then complained how bad it looks years later....

Almost everything I have bought new (not that much) still has the protective film on which seems to upset everyone!!! - everyone seems to have the impulse to want to peel it off!!!

Anyway - well done with the repairs - well impressive list of issues... nice job :)

Also a note regarding the lead Pitch of the IC's - I've heard it said somewhere that Amstrad used a wider IC pitch the standard making it hard to fit IC's sockets - not sure which IC('s)... but have heard it mentioned before...

Anthony Flack

That is one good-looking 664 you have there.

eto

Quote from: RetroCPC on 20:55, 28 January 23Also a note regarding the lead Pitch of the IC's - I've heard it said somewhere that Amstrad used a wider IC pitch the standard making it hard to fit IC's sockets - not sure which IC('s)... but have heard it mentioned before...
Depends on the model. 

In the 6128 it seems to be all non-socketed ICs except for the RAM. In the 464 I have here, it seems to be all non-socketed ICs incl. RAM. In the Plus that I have here, the pitch seems to be the standard width for all ICs. 

Bryce

There were no CPC's produced with socketed RAM. If the RAM is in sockets someone swapped them or you have a prototype. The CPU, PAL and GA were the only IC's that came socketed from Amstrad production. As for the PCB pitch, it's exactly the dimensions it should be. If you varied this you would have major issues with the pick and place machines that populated the PCB in production.

Bryce.

eto

Quote from: Bryce on 12:27, 04 February 23There were no CPC's produced with socketed RAM.
sorry, probably not clear, I meant: for all ICs that are socketed by AMSTRAD (e.g. CPU, Gate Array), the pitch width is "normal". For all ICs that are not in a socket, AMSTRAD used the wider pitch width (e.g. AY-3-8912). 

The only exception to that rule (afaik) is the RAM of the 6128: In my 6128s RAM is soldered, but if I remove an IC I can directly put a socket in. With the 464s that I have that won't work. If I remove a RAM IC, a socket will not fit. 

Bryce

Quote from: eto on 15:02, 04 February 23
Quote from: Bryce on 12:27, 04 February 23There were no CPC's produced with socketed RAM.
sorry, probably not clear, I meant: for all ICs that are socketed by AMSTRAD (e.g. CPU, Gate Array), the pitch width is "normal". For all ICs that are not in a socket, AMSTRAD used the wider pitch width (e.g. AY-3-8912).

The only exception to that rule (afaik) is the RAM of the 6128: In my 6128s RAM is soldered, but if I remove an IC I can directly put a socket in. With the 464s that I have that won't work. If I remove a RAM IC, a socket will not fit.

That's strange. I've just measured some 464 boards I have here and the footprints (including RAM) are all exactly the correct 2.54 x 7.62/15.24 pitch. In which direction is the pitch incorrect on your 464?

Bryce.

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