CPC464 grey border black screen etc.

[pledg]

Thank you for your continued patience with my lack of electrical knowledge and this issue... I'm wondering whether I'll ever get it fixed???


Logic probe on pin 2 I get a high reading and nothing on pin 14? Should they be switching?

[Bryce]

Oh, that's not good. Pin 2 should be a 1Mhz squarewave. If this is missing, then you may have a damaged Gate Array (40007). Try isolating pin 1 of the 40007 (ie: bend it a bit so that it doesn't go into the socket. If you get 1Mhz on that pin then the GA is fine, but something is pulling the clock high (some other damaged chip). If the 1Mhz is missing from pin 1 then test that there is a 16Mhz signal on pin 8 of the 40007.

We WILL get this fixed.


Bryce.

[pledg]

Okay so bearing in mind my scope is rudimentary pin 2 is reading 40hz and pin 14 is about 4hz.

[Bryce]

Define rudimentary. What model or type of scope are you using?

Bryce.

[pledg]

Its a hand held effort I'm afraid... "ETEPON"


I have it set on 2vDC and 20ms.


So pin 1 of the 4008 I'm getting 200mhz and pin 8 I'm getting 30-40mhz.

[Bryce]

Oh dear. No, that won't be sufficient. It only has a bandwidth of 200kHz, so what it's measuring is probably just an aliased sample. You'll need something better to continue.

Bryce.

[pledg]

Ok so looks like I'm done for now! Any recommendations for a scope that won't bankrupt me would be appreciated.


I have a donor board so I may socket some other chips and swap them in the hope it may find the fault.


IC101, IC110, IC113, IC115, IC112, IC114 and the TC74HCUOP


If any of those stand out let me know what to check and which order may be best to swap them in...


Any checks I could do with a simple logic probe appreciated.


I could send both boards away but I'm loath to give up.


Anyway thanks for you help and patience.

[pledg]

I get don't get a reading with a logic probe from IC110 74LS132 and when I touch pin 2 I get blue vertical characters appearing on the blank grey screen?


Also Pin 1 of IC125 TC74HCUOP has no reading but logic probe on it gives same blue characters on grey blank screen? Pin 2 gives a high reading on the probe?


Any help?


Never give up!!!!

[pledg]

Would you have a 40007 or 40010 gate array chip I could purchase or know of anyone with spares available?

[Bryce]

What kind of price range would you consider spending on a scope?

Random results from touching pins doesn't really tell anything I'm afraid.

Bryce.

[pledg]

I suppose around the £100 mark preferable a compact model... Is it worth trying to pick up used one?


Any checks I do on my ROM chip with a logic probe?


Also my Gate Array chip is a 70008? I can't find any other reference to this version online only 40007 and the 40010?


Thanks...

[Bryce]

I suppose around the £100 mark preferable a compact model... Is it worth trying to pick up used one?


Any checks I do on my ROM chip with a logic probe?


Also my Gate Array chip is a 70008? I can't find any other reference to this version online only 40007 and the 40010?


Thanks...

Can you post a picture of your "gate Array". A 70008 is a processor! Maybe someone put the wrong chip into the CPC?

Be very careful buying used scopes, especially modern ones. People usually sell these when something is wrong. But I'll browse the interwebs and see if I can find something in that price range.


Bryce.

[Bryce]

For £100 the only half decent scope you'll get is the Hantek2C42. It's not great, but it's worlds ahead of what you have, you get a half decent multimeter too and Hantek are a relatively ok company for entry level scopes:

https://www.ebay.co.uk/itm/2-in-1-Hantek-Digital-Oscilloscope-Multimeter-70-40MHz-bandwidth-250MSa-s-2C42/333383533016

Bryce.

[pledg]

No! Please don't tell me it's as simple as that!!!!


Pease see attached PCB pic:


Thanks for the scope suggestion...

[Bryce]

Ok, that's a 40008 - a valid Gate Array for the 464. Not a 70008 as you said earlier. It still may be faulty, but at least it's the correct chip.

Bryce.

[pledg]

Yes sorry earlier typo... Where can I purchase a replacement?


As I said earlier I did purchased a donor board for parts but this board has the 40010 chip which I'm sure is dead also.

[Bryce]

Gate arrays (especially the 40010) don't die that often. I'd be suprised if both were dead unless the same person connected both machines to a 12V source or something similarly stupid.

@TotO did have some GA's in stock, not sure if he still has any left though.

Bryce.

[pledg]

Thanks...


What is the function of IC110 the 74LS132 I get no logic probe reading from this chip at all. All the other IC chips in the row give me a reading. Every time I touch it I get blue garbled characters appearing on the screen blank grey screen as if its trying to do something.


Thinking of swapping it out with the same from donor board?

[TotO]

I have to check. Probably few 40007, 40008, 40010 left for repair purpose. Just PM me if really required.

[Audronic]

Part    Description
40007   Gate-Array version 1 (20RA043) (uses a heat sink, same pinouts as 40008)  ? ? ?

40008   Gate-Array version 2 (HSG3130) (uses a heat sink, same pinouts as 40007)  ? ? ?

40009   32K ROM; BIOS and BASIC for CPC464 (English)

40010   Gate-Array version 3 (HSG3170) (no heat sink, different pinouts than 40007 and 40008)

40015   16K ROM; AMSDOS for CPC664/CPC6128 and DDI-1 disc interface

[Audronic]

Some more info on 40008 ? (From Grim)

Different versions of the Gate Array exist.
They basically all do the same things, but their technology and design have been improved in the latest revisions.

The first version of the Gate Array is the 40007 and was released with the CPC 464.
Some of them are mounted with a huge and ugly heat sink.

Later, the CPC 664 came out fitted with the 40008 version (and at the same time, the CPC 464 was also upgraded with this version).

This version is pinout incompatible with the 40007 (that's why the upgraded 464 of this period have two Gate Array slots on the motherboard, one for a 40007 and one for a 40008).

The CPC 6128 was released with the 40010 version (and the CPC 464 and 664 manufactured at that time were also upgraded to this version). The 40010 is pinout compatible with the previous 40008. ? ? ?

Ray

[Audronic]

@Bryce


? Is the 40008 in the wrong socket ? ? ?



The CPC 6128 was released with the 40010 version (and the CPC 464 and 664 manufactured at that time were also upgraded to this version). The 40010 is pinout compatible with the previous 40008. ? ? ?

Ray

[robcfg]

Taking a look at our scans of the CPC PCBs, it looks like only the first series, Z70100 MC0001A, had only a 40007 socket.


Beyond that, and previous to the 664 and 6128, 464 boards have sockets for both gate array types, and it's labeled "Amstrad 40010".


Edit:In the Gate Array page, if you check the picture of the decapped 40010, you'll see "LSI LOGIC CORP (C) 83" on the die.

[gerald]

Some more info on 40008 ? (From Grim)

Different versions of the Gate Array exist.
They basically all do the same things, but their technology and design have been improved in the latest revisions.

The first version of the Gate Array is the 40007 and was released with the CPC 464.
Some of them are mounted with a huge and ugly heat sink.

Later, the CPC 664 came out fitted with the 40008 version (and at the same time, the CPC 464 was also upgraded with this version).

This version is pinout incompatible with the 40007 (that's why the upgraded 464 of this period have two Gate Array slots on the motherboard, one for a 40007 and one for a 40008).

The CPC 6128 was released with the 40010 version (and the CPC 464 and 664 manufactured at that time were also upgraded to this version). The 40010 is pinout compatible with the previous 40008. ? ? ?

Ray

I am quite sure the 40008 has the 40007 pinout.
The only picture with a 40008 on the cpcwiki would confirm this.
I never had any in my hands so I only can trust the picture 

@robcfg The 40007 and 40008 die picture that you posted years ago seems to be identical (ie, 2 different decapped chip, but same design on same gate array techno)
Any chance that these where both 40007 ?

[pledg]

Thank you all for your input into this thread.


Trust me to end up with a board with an uncommon gate array in it!


So it seems that the 40008 is the same pinout and is meant to be in the 40007 socket?


I'll carry on trying to find the fault with this board.


Thanks...