I am currently trying to repair a customer's Saitek Corona electronic chess computer originally from 1987.
More info: https://translate.google.co.uk/trans.../Saitek_Corona
It requires 9VDC from 6 C size batteries or a 9V transformer via the 2.1mm barrel connector. He told me that he accidentally connected 30VDC to it and 2 electrolytic caps exploded.
It no longer works properly but its not completely dead though. I can turn it on by pressing Play and Go buttons together, which is the normal way to turn it on. Some LEDs light but it doesn't do anything else.
On the board there is a transistor-zener regulator that regulates the input voltage to 5V for the ICs. I replaced the exploded caps and tested all 1N4148/1N4007 diodes and transistors.
They tested OK with 0.6V drop on my multimeter in diode mode.
I've attached high resolution photos of the board and ICs.
The CPU is a W65C02P.
The RAM is a AS6C6264. I replaced the original but that made no difference. Same symptoms.
The program EPROMs are 2 UV erasable HN27C256AG-10's. They have stickers over the windows.
There are 2 large ICs labeled NEC 8919KX GAl (C) '87 SCISYS 184. The I could be an uppercase i, a 1 or lowercase L - im not sure.
I can't identify what these NEC 8919KX GAl chips are. I can't anything useful at all on Google. Certainly no datasheet.
On the board HELIOS is silkscreened next to them. I don't know what that means.
As they're large and there's 2 of them I think they might be I/O expanders or ASICs? Does anyone know what they are?
There is a 5.000MHz crystal on the board connected to one of the 8919KX GAI chips. When i probed it, i DID get 5.000Mhz on my multimeter so that IC appears to be working ok.
When I supplied 9VDC from my bench PSU to the barrel jack, i got 5V across the 100n ceramic bypass caps for the ICs.
So the transistor - zener is regulating and the 5V rail is not shorted. i get 70mA current draw at 9V on my bench PSU.
I don't know how to proceed further. I could buy a replacement W65C02P on eBay from china but they might be fake.
i think I read somewhere that there were/are a few different variants of the W65C02 and not all support the same instructions. Is that true?
If the EPROMS and/or the NEC 8919KX chips are corrupted/fried, there isn't really much i can do.
I can't find ROM images online so even if i ordered new EPROM chips, i wouldn't have any image file to program them with. I'd also need to buy a TL866II plus programmer, which is £38.30
Does anyone on here happen to have the same model chess computer and could read the ROMs for me? If i could get ROM images, it might be worth buying the programmer.
Links to items on eBay
W65C02: https://www.ebay.co.uk/sch/i.html?_f...c&LH_PrefLoc=2
27C256 ROM: https://www.ebay.co.uk/sch/i.html?_o...7C256&_sacat=0
TL866II Plus programmer: https://www.ebay.co.uk/itm/141701435348
More info: https://translate.google.co.uk/trans.../Saitek_Corona
It requires 9VDC from 6 C size batteries or a 9V transformer via the 2.1mm barrel connector. He told me that he accidentally connected 30VDC to it and 2 electrolytic caps exploded.
It no longer works properly but its not completely dead though. I can turn it on by pressing Play and Go buttons together, which is the normal way to turn it on. Some LEDs light but it doesn't do anything else.
On the board there is a transistor-zener regulator that regulates the input voltage to 5V for the ICs. I replaced the exploded caps and tested all 1N4148/1N4007 diodes and transistors.
They tested OK with 0.6V drop on my multimeter in diode mode.
I've attached high resolution photos of the board and ICs.
The CPU is a W65C02P.
The RAM is a AS6C6264. I replaced the original but that made no difference. Same symptoms.
The program EPROMs are 2 UV erasable HN27C256AG-10's. They have stickers over the windows.
There are 2 large ICs labeled NEC 8919KX GAl (C) '87 SCISYS 184. The I could be an uppercase i, a 1 or lowercase L - im not sure.
I can't identify what these NEC 8919KX GAl chips are. I can't anything useful at all on Google. Certainly no datasheet.
On the board HELIOS is silkscreened next to them. I don't know what that means.
As they're large and there's 2 of them I think they might be I/O expanders or ASICs? Does anyone know what they are?
There is a 5.000MHz crystal on the board connected to one of the 8919KX GAI chips. When i probed it, i DID get 5.000Mhz on my multimeter so that IC appears to be working ok.
When I supplied 9VDC from my bench PSU to the barrel jack, i got 5V across the 100n ceramic bypass caps for the ICs.
So the transistor - zener is regulating and the 5V rail is not shorted. i get 70mA current draw at 9V on my bench PSU.
I don't know how to proceed further. I could buy a replacement W65C02P on eBay from china but they might be fake.
i think I read somewhere that there were/are a few different variants of the W65C02 and not all support the same instructions. Is that true?
If the EPROMS and/or the NEC 8919KX chips are corrupted/fried, there isn't really much i can do.
I can't find ROM images online so even if i ordered new EPROM chips, i wouldn't have any image file to program them with. I'd also need to buy a TL866II plus programmer, which is £38.30
Does anyone on here happen to have the same model chess computer and could read the ROMs for me? If i could get ROM images, it might be worth buying the programmer.
Links to items on eBay
W65C02: https://www.ebay.co.uk/sch/i.html?_f...c&LH_PrefLoc=2
27C256 ROM: https://www.ebay.co.uk/sch/i.html?_o...7C256&_sacat=0
TL866II Plus programmer: https://www.ebay.co.uk/itm/141701435348
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