TF536, A500+, cold boot black screen and power supply requirements

[Jossi]

Hi Everyone,

Are original A500 power supplies enough to power an A500+ and TF536?
I have 2 that haven't been repaired or reconditioned as far as I know.

When I cold boot with the TF536 installed I just get a black screen and nothing else.
No HDD, gotek or floppy drive activity.
It boots if I reset just not when I first turn it on.
I've tried with only the card installed and using ROMs 2.05, 3.1 and 3.2
and on a Rev. 6a board and using 2 different power supplies.
Both systems cold boot with a 68000 installed
I was wondering if the power supplies are likely to have issues due to age that is causing the problem or if it is
most likely the card itself.
I'm looking for someone to check the power supplies before I organise to send the card back for the retailer
to check over and thought I'd ask here to get some thoughts from others on the possible causes.

Regarding the power supplies.
The specs for them are:
1st PSU. This one is light.
P-No. 312503-020512
Input: 220-240V~50Hz 0.4A T1A
Output: 5v 4.5A
12v 1.0A
-12V 0.1A

ERG KARLSRUHE
Made in W-Germany

2nd PSU. This one is heavy.
P/No. 312503-06
Input: 240v~50Hz 60W
Output: +5V 4.3A
+12V 1.0A
-12V 0.1A
Speedy Tech
Made in Singapore

Thanks

[alenppc]

I have never observed this behaviour with the 536 and I have built probably over 200 of them, but I would suggest you measure the voltage at the floppy power connector on the motherboard. If you get less than 4.7V, then the Amiga chipset will fail to work and the machine may fail to boot.

If the measured voltage is higher, chances are your 536 has an issue and you should contact your builder for a replacement.

[Jossi]

Hi,

I checked the floppy connector voltages today
On one PSU I get 5.2v(red and black wires) and on the yellow and black I get -0.38v.

On the other I originally got a reading of between 4.2v and 4.7v at cold boot. I tested it again after a reset and got between 4.9v and 5.02v on red and black multiple times throughout the day.
I got between 11.5v and 12v on yellow and black.
I'm going to check again tomorrow afternoon after everything has sat unpowered for 18 hours.

Thanks

[alenppc]

The important thing is that the measurement is done on the motherboard and not on the PSU power jack, as the motherboard will cause a voltage drop. Anything under 4.75 will start causing trouble and under 4.7 the chipset usually won't boot at all.

[Jossi]

Thanks for the help.

I tested by connecting the floppy power cable to the board and running dupont wires from the power cable.
Would that be good enough or do I need to test directly from the header on the board?

Thanks

[alenppc]

Thanks for the help.

I tested by connecting the floppy power cable to the board and running dupont wires from the power cable.
Would that be good enough or do I need to test directly from the header on the board?

Thanks

Yes, that sounds fine.

[Jossi]

Hi,

I think there is something up with the card.
I am able to cold boot my A1200 with a TF1260 Rev. 5 CPU using the light PSU (ERG KARLSRUHE)
and have done so everyday for the last week.
I tried again with the A500 and TF536 and just got a black screen again.
I've contacted the retailer to organise sending the TF536 back for them to find out what is wrong.

Is there any software that can be used to run diagnostics while the TF536 is installed in the A500?

Thanks for your help,

Jossi

[alenppc]

I would check if it runs Diagrom from cold. If it doesn't boot until it has warmed up, then it's definitely an issue with the card.

[Jossi]

I would check if it runs Diagrom from cold. If it doesn't boot until it has warmed up, then it's definitely an issue with the card.

Hi alenppc,
Apologies for disappearing without replying. I had just changed jobs and had some major medical stuff going on. Everything was shifted to a shelf in the corner of the spare room and I completely forgot about it.
Every now and then I would remember I was going to ship it back to the store for them to look at and would get side tracked and forget. Eventually the warranty ran out. 14 days ago.

3 days ago I started the system with the diagrom installed.
Nothing happened. I flashed V2 of diagrom to a chip and tried again.
Nothing.
Installed the 68000 and it booted with both diagroms.

It turned out to be user error. I had previously broken a pin on the re-locator board and was connecting the TF536 directly to the CPU socket.
The TF536 would sit on the capacitor in front of the CPU socket. This made me think that the TF536 wasn't being seated properly in the CPU socket.
I happened to have another re-locator board in for use in another system and used that in the 500+.
I also found the manual for the TF536 which shows the re-locator board in use.
So now the system boots from cold, I left it off and unplugged over night, with out issue. I even manager to install workbench to a SD card via an IDE to SD card adapter.

With that sorted I now need to figure out how to replace the IDE header on my A1200 without making the soldering look like a hack job or frying the board.
I'll most likely find someone with the skills and proper tools and pay them to do it.

Thanks,