Amiga 1200 - FPU - yellow screen

ngx · 11 June 2021, 17:55

I have problem with installation of MC68882RC50A FPU into Micronik RA-1208 expansion card with 8 mb memory in Amiga 1200.

The card itself works fine, however, RTC part of the card seems faulty. I don't have batteries in it and I use mainboard mounted RTC module instead.

After I put FPU into socket and power on, the screen goes yellow (RAM error) and power led blinks 9 or 10 times. No boot of course.

All jumpers should be ok, according to RA-1208 manual (frequency taken from MB). My PSU output is 5V 4A, 12V 1A, -12V 0.1A.

After I remove FPU from the socket, card works fine again.

Does this mean that FPU chip is faulty? Could faulty RTC part of the card cause this problem? Or, is there anything I missed during FPU installation?

GadgetUK · 11 June 2021, 18:47

If an FPU is bad (or cannot run at the clock speed it is using) - that will give a yellow screen!

ngx · 12 June 2021, 03:12

Is there any way to find out whether the frequency for FPU is correct? Could it be related to faulty RTC? Fast RAM on the card works without problems.

fluffkitten · 12 June 2021, 14:36

I've a GVP JawsII that has the same issue with a non-working clock (stupid clock in a can) and yellow screen when I fit an FPU it goes to yellow screen. I've put it down to a dodgy FPU ( as GadgetUK says) or a damaged accelerator.

Haven't really looked into it as I can still do what I want without the FPU.

ngx · 12 June 2021, 17:40

Does it mean that working RTC (if the card has one) is necessary for FPU operations? Are its cirquits somehow connected/related with FPU clock?

11 June 2021, 17:55	#1
ngx Registered User Join Date: May 2021 Location: Bratislava/Slovakia Posts: 6	Amiga 1200 - FPU - yellow screen I have problem with installation of MC68882RC50A FPU into Micronik RA-1208 expansion card with 8 mb memory in Amiga 1200. The card itself works fine, however, RTC part of the card seems faulty. I don't have batteries in it and I use mainboard mounted RTC module instead. After I put FPU into socket and power on, the screen goes yellow (RAM error) and power led blinks 9 or 10 times. No boot of course. All jumpers should be ok, according to RA-1208 manual (frequency taken from MB). My PSU output is 5V 4A, 12V 1A, -12V 0.1A. After I remove FPU from the socket, card works fine again. Does this mean that FPU chip is faulty? Could faulty RTC part of the card cause this problem? Or, is there anything I missed during FPU installation?

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11 June 2021, 18:47	#2
GadgetUK Registered User Join Date: Mar 2013 Location: Manchester Posts: 189	If an FPU is bad (or cannot run at the clock speed it is using) - that will give a yellow screen!

12 June 2021, 03:12	#3
ngx Registered User Join Date: May 2021 Location: Bratislava/Slovakia Posts: 6	Is there any way to find out whether the frequency for FPU is correct? Could it be related to faulty RTC? Fast RAM on the card works without problems.

12 June 2021, 14:36	#4
fluffkitten Registered User Join Date: Jun 2018 Location: Nottingham/UK Posts: 64	I've a GVP JawsII that has the same issue with a non-working clock (stupid clock in a can) and yellow screen when I fit an FPU it goes to yellow screen. I've put it down to a dodgy FPU ( as GadgetUK says) or a damaged accelerator. Haven't really looked into it as I can still do what I want without the FPU.

12 June 2021, 17:40	#5
ngx Registered User Join Date: May 2021 Location: Bratislava/Slovakia Posts: 6	Does it mean that working RTC (if the card has one) is necessary for FPU operations? Are its cirquits somehow connected/related with FPU clock?

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