Almost dead Falcon 030

[toms01]

Hi,

I received a Falcon 030 board as a gift, which initially displays a black screen.
The following messages appear with the diagnostics module

-without keyboard attached:

without_keyboard.jpeg (101.16 KiB) Viewed 1081 times

-with keyboard attached:

with_keyboard.jpeg (118.96 KiB) Viewed 1081 times

Via RS232 I get:

Checking FPU...
EF FPU not found
Initializing PSG...Ok
I6 Checking exception handling.....

I would be very pleased to receive further experience reports and tips for further troubleshooting,
that could have something to do with this problem

Many thanks, toms01

[Badwolf]

How interesting! Both 0xXX0426, but with different top bytes.

0xFA... is the cartridge address.
0xE0... is the normal ROM address.

Odd that it's trying to execute ROM code for starters.


I'm not sure what 'bad instruction fetch' translates to at a low level, but I wonder if perhaps an address line is shorted or something? For example if A10 were always stuck at GND all addresses up to 0x0400 would be fine, but then you'd start seeing 0x0000 again. Easy thing to check anyway.

There's a document kicking around (try dev-docs.org) called something like the 'Falcon Service Manual'. This has a section that explains what to look for when you get a particular error in the cartridge.

Have a look for that.

Cheers,

BW

[toms01]

This first board is running again, it was a pretty messed up one and some fixes should not be undone:

Eco1488.png (320.26 KiB) Viewed 880 times

Eco1498.png (246.91 KiB) Viewed 880 times

This is a pretty old PCB and the CPU was also defective.
I now have two newer ones, both also have a black screen and it looks like the CPU remains at 8 MHz, not halted. Here we go again.

[toms01]

The second board is now also running. The CPU was also dead.

Symptoms:
- Black screen
- 8MHz CPU clock
- CPU not halted
- BERR always high

[Steve]

@toms01 I'm just wondering where you're getting these broken falcon boards from, local marketplaces?

[toms01]

A friend had them stored in his cellar, intended as spare parts. He bought them from various sources over the years.

[toms01]

I am looking for the pin assignment of the loopback adapters LAN port, RS232 and Midi

I found the DSP - it works:
1 - 26
2 -( 1k )- 21
3 - 22
4 - 19
6 -( 1k )- 21
11 - 24
12 - 13
15 - 23

RS232 could be the following:
2 - 3
7 - 8
4 - 1
4 - 9

[toms01]

I have a question about the audio loopback cable. I ordered this from Best Electronics, which is a simple voltage divider. Unfortunately, the analog audio burn-in test of the Diag-ROM 1.27b does not return a successful test. Does anyone know what is expected there?

[jwd]

Some Falcon loopback details :

2024-12-20_17h30_52.png (200.7 KiB) Viewed 626 times

[toms01]

Yes, thank you very much. This is exactly what my audio loopback cable looks like. A simple voltage divider. Have any of you ever used it and the Diag 1.27b with your Falcon and gotten positive results during the burn-in test?

Edit: Attention, you can also connect this cable the wrong way round, my Best Electronics cable was not marked “Headphone”