Trying some board debugging

[Duewester]

@atrax27407thanks for the heads up.

[Stuart]

On 11/11/2022 at 8:11 PM, InfiniteTape said:

I've gotten my hands on a couple of 9900's in case I need to swap them. Does anyone have a recommendation on sockets for those? I seem to remember the pin spacing is a little unusual.

 

Also, I know Thierry's page is out there for replacing the console ROMs, but it's complicated by the inclusion of in-circuit programming support. I don't really have a need for that extra capability, so does anyone know of a simpler design for swapping the console ROMs with EEPROMs?

Sockets - I use https://www.ebay.co.uk/itm/225089493552. Note that these are in the UK - can probably get the same thing more local to you if elsewhere. Note that the pin spacing is 0.1" - careful not to order the 'shrink DIP' sockets with closer spacing.

Edited November 12, 2022 by Stuart

[InfiniteTape]

On 11/12/2022 at 4:18 PM, Stuart said:

Sockets - I use https://www.ebay.co.uk/itm/225089493552. Note that these are in the UK - can probably get the same thing more local to you if elsewhere. Note that the pin spacing is 0.1" - careful not to order the 'shrink DIP' sockets with closer spacing.

Thanks! I've tried to order something that looks close from Mouser in the US.

 

@atrax27407, I'll reach out to you via PM about buying some programmed TMS5232. At some point, I'll spring for a programmer, but year-end isn't the best time.

[+FarmerPotato]

Once I just used two strips of 0.1” machine pin breakaway header. I also glued together wire wrap headers to get to 64 pins. 

[+Ksarul]

I actually have about 50 machine-pin sockets for the 9900 in one of my parts boxes. . .

[InfiniteTape]

I got my programmed roms from atrax27407, swapped those out, then swapped out the 9900. No change. I'll walk the troubleshooting tree again, but either the spare 9900 or RAMs I used are bad or something less likely such as the 74LS chips are bad.

 

For reference, these are the sockets I used for the 9900: Mill-Max 110-99-964-41-001000, Mouser #575-199964

[Duewester]

7 hours ago, InfiniteTape said:

I got my programmed roms from atrax27407, swapped those out, then swapped out the 9900. No change.

@InfiniteTape, did you try swapping their location? One is Lower and the other is upper. Maybe got them backwards?

And double check that 9900. I had some seating issues with mine but, I used a much more finicky socket setup. I used some round hole headers that I installed on a 9900 (to use as a guide) then soldered them onto the board. Worked great until I had to replace the 9900. Getting all those pins to align so precisely was a PITA (bent more than one pin out trying to get others aligned). And go over your soldering with a fine toothed magnifying glass.