dead VCS (blank dark screen)

[MRAtari]

hi people

 

hopefully someone could help me with me old VCS!

 

basically it seems to be dead

 

when i turn it on with a cartridge in the slot i get a dark clear screen - no white noise and no sound

 

it's not the cartridge as i've tried loads

 

i've changed the RF module and cable, i've checked all solders and can't find any bad ones

 

any ideas?

[BigO]

With it off you get the standard "snow" and white noise, then when you turn it on the screen goes dark and sound goes silent?

 

Doesn't sound like a simple fix to me, but there are a lot more experienced repair-ers around here.

 

Does it do the exact same thing when you turn it on with no cartridge in the slot? (it doesn't hurt anything to do that)

 

 

 

 

Changed the RF module?

 

Edit: Oh, probably the switch box.

 

 

 

(We really do need a centralized, compiled troubleshooting hints & tips around here, but I can't find one. Guess I need to start reading and compiling)

Edited August 15, 2007 by BigO

[MRAtari]

hi

 

yes it's exactly the same with or without a cartridge

 

white snow and noise with VCS OFF then turn it ON and dark screen and silence

[atari5200dude]

I've never heard of that, are you getting full power? Is it on the correct channel? Have you tried several cartriges? Is it hooked up to your t.v tight or correctly?

[MRAtari]

yes it's getting full power (i have another PSU) it's the same with several carts

 

i've actually heard of this problem before so it's not uncommon

 

just dunno what it is!

[A.J. Franzman]

That's a very common symptom, usually caused by one or more dead IC chips.

[BigO]

That's a very common symptom, usually caused by one or more dead IC chips.

 

From your considerable experience, is it more likely one of the cheapo run-of-the-mill logic chips? (As opposed to the TIA or RIOT)

[Prodos8]

If the voltage across the 7805 is good, then its probably one of the three main logic chips (RIOT,TIA or 6507) in this situation. If they're socketed it not a problem if you have spares, otherwise if they're soldered on the board its a major hassle. I've got a Vader system that does this, but the chips are soldered down, so I gave up trying to fix it.

[MRAtari]

hi

 

i do have spares of the 3 socketed chips and have changed them 1 by 1

 

no difference

[Spirantho]

i do have spares of the 3 socketed chips and have changed them 1 by 1

 

Check the voltage on Vcc on those chips (one of the corner pins I think, can't remember which), if it's below about 4.9V then change your 7805 regulator.

 

If that's not it (And it often is) then things get more complicated and you'll need to start looking at transistors and stuff as they're the usual other culprits. I assume you've checked your capacitors and timing crystals for leakage!

 

If you don't know what I'm talking about, send it to A.J. Franzman. It's safer. I can repair it if you're in the UK.

[A.J. Franzman]

That's a very common symptom, usually caused by one or more dead IC chips.

From your considerable experience, is it more likely one of the cheapo run-of-the-mill logic chips? (As opposed to the TIA or RIOT)

IMO it's somewhat less likely to be the TIA, because that one usually fails in other ways before it gets to black screen mode, but really it could be any of them. If it's a 6-switch or Junior console, I would suspect the 4050 buffer much less than the CPU, RIOT or TIA.

[SINGLE TOOTH]

That's a very common symptom, usually caused by one or more dead IC chips.

From your considerable experience, is it more likely one of the cheapo run-of-the-mill logic chips? (As opposed to the TIA or RIOT)

IMO it's somewhat less likely to be the TIA, because that one usually fails in other ways before it gets to black screen mode, but really it could be any of them. If it's a 6-switch or Junior console, I would suspect the 4050 buffer much less than the CPU, RIOT or TIA.

 

 

Ever get this resolved? I discovered a heavy 6 that has the same symptoms.

[Foxsolo2000]

I always thought it was a great shame that the old 2600's didn't come with a power on light. It woudl have made diagnosis a lot easier if it was dead or not

[SINGLE TOOTH]

I always thought it was a great shame that the old 2600's didn't come with a power on light. It woudl have made diagnosis a lot easier if it was dead or not

 

Right. I was seriously considering throwing a LED or lamp on my heavy 6. But, I'll see if I can get it working first. I found some spare IC's to swap.

[SINGLE TOOTH]

Alright I fixed it. It was a break in the ribbon cable.