Strange issue with GVP 4060 alias T-Rex 2

[Fieldday]

Good morning,
I bought for 2 months a complete Amiga 4000 system from an Amiga collector. Okey, mainboard battery and some elkos leaked but I have repaired all. I also bought a GVP 4060DT and and this point I was very happy. But after 2 weeks to try this card to work my happiness moved to sadness. This accelerator won´t run in my system. I have changed both Amiga mainboard jumpers to internal. Changed jumpers on the card to the right positions, give them new RAM bars and pray to God.
Yesterday, I went to a good friend and he use a CPPC. We move the RAM from one card to the other and now the GVP runs on his system. Now we make some tests and after some hours the GVP card runs perfect. SCSI part is really fast with 9,2 MB/s. wow.
Now we put it into my system and... black screen. Argh, all jumpers are correctly on there right position on both systems. Put the card back to my friends Amiga and this card works again.
All custom chips are the same, voltage is okey (5V = 4,92V and 12V = 11,7V).
Now I am running out of ideas why this card spurned my lovely system.I learned that Amiga 4000 != Amiga 4000.
Maybe someone here has a good idea why I have so much trouble with this card.

best regards

FD

 

[abraXXious]

Check your rom speed jumpers on the A4k. When I upgraded an A4k from a3640 to Cyberstormk Mk III it was very unstable, until I dropped the rom speed jumper (dont ask me why).

Worth a shot.

 

[Zetr0]

@Fieldday

I woluld suggest looking into the obvious first,

Since you have a good friend to help you could ask him to test out compoents for you -

1. Power supply

These things are over 18 years old, and were not designed to see 5 years IMHO, would you have another to test


2. Motherboard (battery damage)

Inspect your motherboard for any signs of damage around the battery area, you will be looking for tarnished (black) tracks and traces

 

[Fieldday]

Hi,
changing the ROM speed jumper makes no difference.

My power supply is okey and my friends CPPC and my MK-1 works fine. I have on 5V = 4,92V and on 12V = 11,7V. That is perfect
Battery area is clean and working. I had checked all traces on there start - end point from the A4000 schematics.

The card seems to be working fine. I am not sure about the differences between my friends and my Amiga. :huh:

Maybe I will sell this card. I have no time to ask why.

Best regards

FD

 

[tk8783]

I agree that every Amiga 4000 seems to have it's own way. I had a Rev B Amiga 4000 that could not use a Picasso IV unless I put the motherboard to 20Mhz speed instead of the standard 25Mhz...

I'll hope you'll get it working though!

 

[rkauer]

How about swapping the mobo with the one of your friend? A 1x1 swap and maybe some $ for the work.

The GVP4060DT is an awesome card when it works.

 

[joekster]

My gvp 4060 is really really picky about ram. I would try running it without any ram to see if that's the issue...

 

[Fieldday]

Hi,
could you tell me your jumper positions for a test without installed RAM? Currently I have no time to make an investigate. Maybe this year on christmas or next year... in near future

Best regards

FD

 

[joekster]

Just pop-out the simms. The jumpers are only needed when ram is installed.

 

[Fieldday]

Good news,
after a very long session with my Multimeter I figured out that the Fast RAM Datapath IC was defect. I got a spare IC from my friend and after replacing the IC my GVP 4060 is now working well
Now I am a little bit confused when I ask me why. What makes the difference about Cyberstorm and GVP accelerator?

Okey, I am very happy about my success

Best wishes

FD