Amstrad CPC464 ULA Chip Woes

[Womble]

Hi Guys - am a long term retro collector who has just stumbled into the wonderful world of Amstrad gear, my latest purchase is a stunningly mint CPC464 which sadly does not work.

Am a bit of a hardware nut (my main love is repairing arcade PCBs) and I have proven pretty much everything except the 40007 ULA chip. Its a rev0 machine with a heatsink'd ULA and with the Fluke 9010 analyser hooked up I can see that the write enable pin on the DRAM bank is never activated, also the /IRQ line is in a very bad state. The end result is that I am 99% sure the ULA in this machine is faulty. I also have a later rev2 version of the CPC464 but that uses the non-heatsinked 40010 ULA and I dont think the two chips are interchangeable, at least without a modification I can't really guess. The newer ULA just locks up the machine, and also locks up my analyser that sits in place of the CPU, but works fine in the newer machine.

My question is - does anyone have a spare older styple ULA they would sell me? This machine is so pristine it is such a shame it doesnt run.

Cheers

[Bryce]

Hi Womble,
       Welcome to the Wiki. I might have one lying around somewhere. I'll check tonight when I get home and let you know. However, I think the rev 2 should work in the older CPC without any modifications (unless someone knows different), so there may be a problem somewhere else on the board.

Bryce.

[arnoldemu]

 I have one, but I can't guarantee it works, it's been sitting in a box with other electronic components and it hasn't been protected.

I don't think you can use the 40010, unless there is a space for it on the board.
It doesn't have the same pinouts compared to the 40007.

[Womble]

Yes the 40007 and the 40010 ULAs have very different pinouts, and slightly different power requirements. I was considering building an adaptor to fit the 40010 in place of the 40007 to test it, but the alternative was easier. The Rev2 board has a space for a 40007 as well as the 40010 so I desoldered the holes, fitted a socket and the two 1/4 resistors the '07 needs on two of its power pins and dropped in my suspect chip. I got the exact same fault on the Rev2 board as I had on the Rev0 board - so it suggests the ULA is the cause of my fault.

Thanks for the offer Arnoldemu - I might take you up on that if I can't find a known good one, what would you want for it?

[dragon]

If i remember correctly,the shops  sell the stock of acid chips,can sell the gate arrays in stock new.

But  now I not remember,who is the name of the shops .

[Gryzor]

Wow, I wouldn't have expected for folks to have such things just lying around

[Bryce]

I doubt it too, but I sent him a few at the weekend, so his problem may be solved.

Bryce.

[Womble]

Hi Bryce

The ULAs arrived today and the both actually work, so the tall key 464 is now back on its feet. Need to track down some heatsink compound and I can put it all back together.

Many many thanks for your help, I seriously doubted I would ever manage to find a spare ULA for this, now I have it working and a spare for future CPC rescues.

Cheers

David

[Bryce]

Hi Womble,
     Great to hear when a CPC could be brought back to life Actually you should be thanking yoshi.doshi. He sent me those Gate Arrays a few weeks ago and I didn't have an immediate use for them, so I thought you could make more use of them (which proved to be correct ). You should be able to get heat paste in any PC shop. The modern silver-based stuff used on PC CPUs is much better than the stuff that was used back in the 80's.

If you don't need the second Gate Array you can pass it on or send it back and I'm sure someone in the future will be very grateful that it is available.

Bryce.

[Womble]

Indeed, useful chips to have handy. I wouldnt mind hanging onto the second one, I get pinged by folk with faulty gear from time to time, plus I tend to trawl ebay here looking for faulty retro-goodness so it will certainly find a home, either at my place or at a fellow antipodean collectors place.

[Bryce]

Oh good. As long as it's being put to good use and not collecting dust in a box, then it's in the right place

Bryce.