Help with a new atari vcs sixer

[benybob]

Got a new atari vcs in the mail today gave it a try and no video. so i opened it up to check out some things, and i found some bodge wires one on the switches and two resistors on the back of the board near the hex buffer.

Are these factory bodges or was the previous owner trying to accomplish something, either way i want to save this one from heading to the grave so any tips and help would be awesome.

[+DrVenkman]

That looks like it may have been some long-ago tech's idea to reduce the risk of static damage through the switches; the Field Service Manual recommends a Zener diode bodge as preventative measure against static, since they lack the 4050 buffer chip. Thus static can shoot straight from the switch to the RIOT (and it does damage them - I've had to replace two RIOTS, each where one of the two difficulty switches didn't register). 

 

However, I didn't think that procedure was needed or recommended for Sixers. Could've been the service guy's idea of "just in case." You can try removing it and checking continuity with reference to the system schematics. In any case, that old crusty flux should be cleaned up - looks very grungy and might well be marginally conductive. Of course, if you clean up the mess with isopropyl alcohol, you'll remove the hot glue mess holding it down and be able to see the bodge work more clearly.

[benybob]

Thank you for the advice, I plan to clean up the board tomorrow, and will be doing a console 5 restoration kit install when it arrives. I also ordered a new hex buffer, due to the bodge connection on it, I fear it maybe have been damaged in the past and this was some sort of fix.

[alex_79]

Are those wires connected to the upper metal shell of the switches? In that case they're likely a replacement for the adhesive "static strips" meant to discharge static when operating the switches.

If so, I'd leave them in place (and wire the power switch in the same way). Much better than Atari adhesive metal foil solution when you need to open the console for maintenance/repairs..

Edited March 7, 2021 by alex_79

[benybob]

Yes the way it’s configured at the moment it is essentially grounding the outer shell of all but the one power switch. 

[+DrVenkman]

3 hours ago, alex_79 said:

Are those wires connected to the upper metal shell of the switches? In that case they're likely a replacement for the adhesive "static strips" meant to discharge static when operating the switches.

If so, I'd leave them in place (and wire the power switch in the same way). Much better than Atari adhesive metal foil solution when you need to open the console for maintenance/repairs..

That’s basically what I said above. Those metallic tape strips are typically only found on 4-switch units to protect the RIOT chip. Whatever is going on with this machine is not factory stock and was like added by someone in years past. That bodge under the hot glue was probably added at the same time and may also be for static protection though it’s hard to tell. I’d like to see the board myself and trace the connections with schematics in hand to be sure. 

[benybob]

Maybe this will help you DrVenkman, Spent some time today getting the glue off and using some IPA to remove a lot of flux.

As you can see the two resistors both (10 K ohms 10 % tolerance) are connected from R225 and R226 up to the hex buffer.

does anyone have a thought on this bodge?

 

[+DrVenkman]

Those look like pins 7 and 9. Without looking at one of my own Sixers or going through the schematics, I have no idea what those resistors are all about. They look to be tying two different gates in the chip to wherever they're connected, but to what purpose I have no idea. I do know that's some old work - you typically don't see those brown 4-band resistors on anything these days 

[benybob]

So the mystery of this board keeps deepening I was looking over the board tonight and noticed a cut trace below the hex buffer next to c205 you can see it in the pictures above, also I think the work may have been done in 1981 on the shielding was a receipt with initials and a date stamp of 81, i may be wrong but I thought light sixers were out of production by then, I’m torn on this project part of me wants to just get it working again but I also want to figure out the history and what this Atari tech was trying to accomplish.

[benybob]

So after looking at the schematics and the board until I can dive deeper into this mystery my best guess is the Atari tech was trying to bypass the hex buffer and hook pin 7 and 9 up similarly to how the cx2600a boards are configured, anyone have any better knowledge to share.

[benybob]

installed a console 5 refresh kit today console is back in working condition, picture looks great on rf, but i am getting a lot of sound noise. may end up getting a uav kit but until then is there any easy known improvements that can be made to the rf signal? 

[+DrVenkman]

57 minutes ago, benybob said:

installed a console 5 refresh kit today console is back in working condition, picture looks great on rf, but i am getting a lot of sound noise. may end up getting a uav kit but until then is there any easy known improvements that can be made to the rf signal? 

Did the Console5 kit include ALL the caps, including the two little silver caps near the RF coil? If not, those are likely the source of your audio noise. If you replaced those already, you can try *very very gently!* adjusting the RF coil to see if you can improve the signal. But there are caveats - first, it's incredibly easy to break an RF coil by turning to hard and too far. You should never turn it more than probably an eighth of a turn or less. Second, you really need to adjust it while the system is on so you can see if it's having any effect, but you need to use a plastic or ceramic hex tool because a metal one will affect the RF signal you're trying to adjust.

 

If that doesn't help, something inside the RF modulator may be going bad. You can try opening it up and monkeying around in there, or finding one used from someone and transplanting it into your machine, but that's a LOT of work for what is never going to be as clean a signal as a composite or S-video mod. If the RF modulator is just dead or dying, it's probably better to just bite the bullet and install a mod unless you have a really good (emotional) reason to try to keep it in original configuration.  

[benybob]

yeah swapped out those also, i think i will just aim for doing the av mod, will be better in the long run. thanks for being my voice of reason.