New Zealand Vintage Computer Forums

honestbob wrote:Just a couple of other questions.

1. Does the RF output work? That *may* have a direct feed from the TMS9929A VDP chip and bypass the daughterboard.

2. Can you hear the audio working / music playing when you plug in a games cart?
If you hear music you know that the CPU, RAM, and cart slot is working correctly

3. Edit - do you get a black screen plus a medium tone noise when you connect the SC-3000 to your TV? ie. the SC-3000 is kind of working, but not running the code on the cartridge correctly

I'm just looking for parts of the system that are / aren't working to narrow down the problem.

Mr Wojski wrote:
Hi Sorry to bump this really old thread however I am having the problem Number 3. that honestbob has described here. It tunes in to the TV fine however I just have a black screen with medium tone noise when i switch it on, have tried many different cartridges that i know work. Would love to hear if anyone has any Idea's on how to fix.

Ta

natshaw wrote:Hi all, am new here, nice to find this place! Am repairing a Sega SC-3000, (blank video output, using composite from video out 5-pin DIN socket), and think I have a faulty video daughterboard. There's no significant voltage present on the supply pins of the 3 x ICs on there. From what I can tell, there's a +9V feed from main board (red wire) - then some sort of DC-DC transformer using T101 and a few inductors, transistors, and diodes. I think that's where my problem is.

Has anyone worked on these before? I'd love to find a circuit diagram that covers that daughterboard, but can't locate one. Alternatively, anyone know what voltages I should see on the pins of the T101 transformer?

Machine is the Aus/NZ model.

Thanks in advance, any advice/questions/whatever much appreciated!