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2600 Vader with black screen


relo999

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Recently got a SECAM Vader 2600 as I wanted one simply for the weird palette it has. Tried powering it, but I only get a black screen which just tells me it powers on. No bars or anything, just black. Thinking it might be a secam related compatibility issue I RGB modded it, but still the same. (and in hindsight still should have gotten a B/W image if it was a secam related issue)

I've run down the common issues, so I've switched the TIA, CPU and Riot with known good ones with the same result, and I have checked the 5V regulator and incoming voltage and all of that is fine. There is also no clear damage to the PCB or components. Any other possible culprits I can check?

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Try checking pin 34 of the ROIT and pin 1 of the 6507, these reset pins should be pulled high to 5V DC, if not measure the voltage across the resistor that is connected to the pin.

 

If the reset pin voltages are correct check that...

5V is reaching pin 20 on the ROIT, pin 4 on the 6507 and pins 20 and 23 on the TIA and that GND is connected to pin 1 of the RIOT, pin 2 of the 6507 and pins 1 and 22 of the TIA  

 

If they check out then try and check for the clock on pin 39 of the ROIT, pins 27 and 28 of the 6507 and pins 11 and 4 of the TIA. If you have a multi-meter that can measure frequency up to 10MHz you should get a frequency reading, otherwise you will just have to go by voltage where anything other than a fixed 0 or 5V DC would suggest there is a clock signal.

   

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4 hours ago, Stephen Moss said:

Try checking pin 34 of the ROIT and pin 1 of the 6507, these reset pins should be pulled high to 5V DC, if not measure the voltage across the resistor that is connected to the pin.

 

If the reset pin voltages are correct check that...

5V is reaching pin 20 on the ROIT, pin 4 on the 6507 and pins 20 and 23 on the TIA and that GND is connected to pin 1 of the RIOT, pin 2 of the 6507 and pins 1 and 22 of the TIA  

 

If they check out then try and check for the clock on pin 39 of the ROIT, pins 27 and 28 of the 6507 and pins 11 and 4 of the TIA. If you have a multi-meter that can measure frequency up to 10MHz you should get a frequency reading, otherwise you will just have to go by voltage where anything other than a fixed 0 or 5V DC would suggest there is a clock signal.

   

reset pins are all 5V (well 1 is 4.5V but I guess that's within margin). 5V and ground are connected and the clock signal points all give +-1.5V (don't have a multimeter than can check frequency).

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Also tried reseating all other chips on the pcb, luckily all of them are socketed. But no luck. What I did find is by using my CRT to check for a signal and upping the brightness I do get very faint vertical lines when I power the system.

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Issue found. The CPU is dead. Tried replacing chips again thinking 2 might be dead and this time didn't use the RGB mod to test the image. So put all 3 main chips in the board, and it popped on just fine. Putting back the RIOT still kept it working, and putting back the TIA also kept it working. Only the CPU couldn't be replaced by the original. Might be the RGB mod was faulty or made some other mistake when testing the CPU last time.

I also learned my PAL TV can understand SECAM including color.
Now I just need to find a replacement CPU.

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