SABA Videoplay (German Fairchild Channel F) - Video issues

[patrickvogt]

Hi,

 

I've bought a faulty SABA Videoplay (German Fairchild Channel F) on eBay and looked inside to repair it. The problem is that the video which is generated from the console is faulty (see picture one and two).

 

I couldn't find anything obvious on the mainboard so far. Everything on the top looks clean. On the bottom side the traces look weird (see third picture). I don't know if this is intended or if this is a flaw of the pcb production? The console is 40 years old, so I think I can't expect that everything looks new and shiny.

 

When I start the console there is a pong like beep at the beginning.

 

In my opinion:

-It cannot be the internal ROM since the same happens with a cartridge

-It cannot be the power supply since I can mesaure all the voltages (-5V, 5V, 12V) on the Video RAM ICs

-It cannot be the RF circuit since then nothing would be shown on the TV. So the faulty video signal is already faulty before the video signal is going trough the RF circuitry.

 

So the only thing which could be faulty is in my opinion the Video RAM (either the Video RAM ICs or some traces / sockets / cold solder joints near the VRAM chips).

 

If I exchange two of the socketed RAM ICs the pattern looks a bit different (see difference between first and second picture)

 

I already ordered new RAM ICs but since I probably have to wait 4-6 weeks until I get them (German custom control), I thought maybe somebody else has a different idea what components/ICs I can check.

Edited January 31, 2016 by patrickvogt

[+KylJoy]

What happened with this issue, please?

[icemanxp300]

I'm going to guess you either have a bad chip of some kind like the video ram you mentioned or you have a broken trace. Not all traces are easy to spot. I had an n64 game that had a trace broke under the solder joint. Not that that is likely but just mentioning it.