Help me fix my Vader!

[Chuck D. Head]

First of all, sorry for the cross-post / repeat post. I posted this the other day in Hardware, but it never seemed to show up right in the search or post list and in "my posts", it showed only the pic, so I thought it deserved a second chance..........

 

 

I bought a nice looking vader at a rummage sale, but so far, she's a no go. For the most part, just get a black screen, no matter the cart or positioning. Despite the awesome external condition, there was some rust residue in the bottom of the case when I opened her up, but as far as the circuitboard, the rust only barely hit the back edge. I cleaned the cart socket contacts with some sandpaper with no noticable difference. I checked the voltage regulator and it has 10.5v in and right at 5v out.

 

I went ahead and took the shielding off and the rust didn't appear to affect anything on the board, so I cleaned it up and then noticed rust at the bottom seam of what I assume is the RF box:

 

 

 

I tested it some more thinking the RF box was bad; some frying of the power switch easily produced random, recognizable sound effect and very clear vertical bars of color. I was thinking that my next move was to replace the CPU, but what do you guys think about the modulator box, if that's really what it is?

Edited March 31, 2011 by Chuck D. Head

[phuzzed]

If you are getting a black screen, but no sound, more than likely it's not the RF modulator.

 

 

My guess it is the CPU or the other two chips.

 

 

 

Generally speaking, the 2600 is a fairly solid machine. If the power supply and voltage regulator is good, then it's more than likely one of the three onboard chips.

 

 

Good luck!

[Chuck D. Head]

Here's the missing pic. Sorry.

 

[Chuck D. Head]

If you are getting a black screen, but no sound, more than likely it's not the RF modulator.

 

 

 

well, I would occasionally get sound when I started really frying the switch, and it would be very recognizable sounds from games also. What you say makes sense; it's not bad output, it's just wrong output.

[Benzman66]

I will say the same thing as I always do, it is either an IC chip issue or bad transistor, and so far, I have been pretty much on the mark.

Bad thing about the Vaders is that on most of their boards, the chips are soldered instead of being socketed which makes the repair tougher.

Say a prayer and hope yours might be socketed. Remove the silver cover over the middle of the board to reveal the chips and other guts.

Do a search as there are many threads showing pics and info on how to do the repair.

 

And I agree with phuzzed, if the problem was the RF modulator, you would be getting mainly snow or interference. If you can see colored lines and audio, then you can be assured it is probably ok.

Edited March 31, 2011 by Benzman66

[Chuck D. Head]

OK, thanks guys! The chips are socketed. I wanted to swap with my JR, but it's chips are soldered. I will order a CPU 10745 from Best Electronics and see what happens. The static foil strip across the switches is kind of messed up and they have them for $2.50 at Best. Are these strips really important? Should I bother?

[Benzman66]

I would think it might be the RIOT chip (10750) instead.

Many of the units I work on don't have the strips, although the Atari repair guide says they should.

For the price, it wouldn't hurt to grab a pair, but if you want to be cheap, you can make some out of aluminum foil like some other AA members do.

[Chuck D. Head]

OK, I will go ahead and order both CPU and RIOT as they are the most likely and cheaper two. If that doesn't work, I will look at the transistors or TIA. Thanks!!

[zylon]

99% of the "black screen" 2600's I've serviced just needed either the TIA or RIOT chip.