A3000 issues... looking for advice on which components to check

dschallock · 06 November 2019, 23:50

Hello,
I have an Amiga 3000 that is sick.

With 3.1.4 Roms installed and everything else disconnected from the mother board I am sometimes getting the purple screen asking for the floppy but even when it does come up, the graphics start garbling more and more by the moment.
Also. It could be my imagination but it seems like the power supply fan is spinning lower speed than normal. I have test 3 different known good working power supplies all with similar results.

Just looking for suggestions on likely culprits to check.

Thank you!
-Dan

TjLaZer · 07 November 2019, 02:50

How is your monitor connected? VGA or RGB? Sometimes the build in flicker fixed develops an issue but the RGB output is fine.

r.cade · 07 November 2019, 03:52

What about with stock ROMs? One of my A3000's doesn't work the 3.1.4 AMD EPROMs that are sold, while the other one does (and no it's not ROM tower issue).

dschallock · 07 November 2019, 18:36

Both great suggestions and I thank you for them. Will test and report back.
Thanks!

Wrangler · 07 November 2019, 23:17

I'd want to clean out the power socket with isopropyl alcohol as a first step. The symptoms you describe could be bad power distribution from the socket - the motherboard browns out. It's a common problem with amiga 3000 and 4000 motherboards.

matt3k · 08 November 2019, 22:47

If the board took battery damage in its life, look around denise. Could be green in the socket or even the socket going bad. Clean with toothbrush or similar.

Try another denise.

imho, pickup either chucky's or hese's 3000D replacements. It will give you some new life...

Good luck!

idrougge · 08 November 2019, 23:57

The A3000 has four programmable PAL chips which may get bad with age or heat. This can lead to graphics corruption or unreliable chipmem.

They can be replaced by cooler GAL chips programmed with the same contents.

06 November 2019, 23:50	#1
dschallock Registered User Join Date: Jul 2016 Location: Northern California Posts: 174	A3000 issues... looking for advice on which components to check Hello, I have an Amiga 3000 that is sick. With 3.1.4 Roms installed and everything else disconnected from the mother board I am sometimes getting the purple screen asking for the floppy but even when it does come up, the graphics start garbling more and more by the moment. Also. It could be my imagination but it seems like the power supply fan is spinning lower speed than normal. I have test 3 different known good working power supplies all with similar results. Just looking for suggestions on likely culprits to check. Thank you! -Dan

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07 November 2019, 02:50	#2
TjLaZer Registered User Join Date: Sep 2004 Location: Tacoma, WA USA Age: 52 Posts: 1,915	How is your monitor connected? VGA or RGB? Sometimes the build in flicker fixed develops an issue but the RGB output is fine.

07 November 2019, 03:52	#3
r.cade Registered User Join Date: Aug 2006 Location: Augusta, Georgia, USA Posts: 548	What about with stock ROMs? One of my A3000's doesn't work the 3.1.4 AMD EPROMs that are sold, while the other one does (and no it's not ROM tower issue).

07 November 2019, 18:36	#4
dschallock Registered User Join Date: Jul 2016 Location: Northern California Posts: 174	Both great suggestions and I thank you for them. Will test and report back. Thanks!

07 November 2019, 23:17	#5
Wrangler Registered User Join Date: Sep 2015 Location: London, UK Posts: 414	I'd want to clean out the power socket with isopropyl alcohol as a first step. The symptoms you describe could be bad power distribution from the socket - the motherboard browns out. It's a common problem with amiga 3000 and 4000 motherboards.

08 November 2019, 22:47	#6
matt3k Registered User Join Date: Aug 2018 Location: NY / USA Posts: 290	If the board took battery damage in its life, look around denise. Could be green in the socket or even the socket going bad. Clean with toothbrush or similar. Try another denise. imho, pickup either chucky's or hese's 3000D replacements. It will give you some new life... Good luck!

08 November 2019, 23:57	#7
idrougge Registered User Join Date: Sep 2007 Location: Stockholm Posts: 4,332	The A3000 has four programmable PAL chips which may get bad with age or heat. This can lead to graphics corruption or unreliable chipmem. They can be replaced by cooler GAL chips programmed with the same contents.

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