Heavy sixer video and heat problems.

[OptimusMaximus]

Hey yo! So, I did a video mod. It worked well for a bit then all the colors went very dark. No adjustments would work. I was sent a replacement mod and a sixer refresh kit. I replaced the video mod possibly it was a bad pcb but no change. I then started to do the refresh. I replaced the 2200 uf capacitor and no change in color. I then replaced the chicklets, C103 and C104 and the voltage regulator, A101...... Now I get no video at all and the voltage regulator is burning hot! Also the original power supply started clicking but it stopped now. I think it was over heating as well...... any ideas my friends??? Im getting ready to give this thing up!

[+save2600]

You install the voltage regulator correctly? Accidentally blobbed some solder, shorting any of the 3 leads together? Observed polarity on the electrolytic caps?

[OptimusMaximus]

Thanks for the quick response. Please explain further on observing polarity on the caps... Im going to check the solder now!

[OptimusMaximus]

This is the voltage regulator solder.

[nick3092]

Electrolytic caps have to be installed while observing the polarity. The chicklets you mentioned are not polarized and there is no "wrong way" to install them. On a large axial cap (like the 2200uf you mentioned) there is a stripe on the cap with arrows pointing to one end. That lead is the negative lead. On a radial cap, one of the two leads will have a similar stripe. That is the negative lead. It's also usually shorter than the positive lead.

 

It's best to observe the way the original one was installed before removing it. If you forget to check it, usually on the PCB there is a plus sign marking which hole is positive. If you accidentally installed one backwards, don't bother trying to reverse it. Get a new one. They get damaged fairly quickly when installed backwards. Even if they don't pop open (which is the normal failure mode when installed backwards), you should still get a new one.

 

Not sure if you were trying to attach a picture of the voltage regulator solder joints, but nothing came through.

Edited October 1, 2018 by nick3092

[+Stephen Moss]

The electrolytic should not be the problem, as it is before the regulator and would just go bang if inserted the wrong way around. It sounds more to me like something is drawing a lot of current, considering the work you have done I would...

Check for solder shorts between the GND and Output pins of the Regulator, and the pins on the capacitor on the regulator output

Check that the power connections for the video are the correct way around or temporarily disconnect the mod to see if the regulator still over heats

Check that the regulator is properly affixed against the heatsink area of the PCB, which is designed to take the heat away.

If you have replaced any IC's make sure they are in the correct way around.

 

Another, although less likely possibility is that the power unit was putting out too high a voltage which would result in excessive power dissipation and therefore heat in the regulator.

[OptimusMaximus]

Thanks to all of you who responded and helped out.. and your info did help.... I also got a hold of the Atari Field Service Manual and I think I could be an atari Tech now!!! (not really, but it is amazing to have) I replaced some swithes and had done a video mod and the video went dark, could still see the video but the color was all bad. I was sent another one, so I replaced it and I was sent a Sixer Refresh kit. Thats when the real fun started happening. My Polarity is/was good. I troubleshot everything so much, i even used a different power supply and got nothin. Then I decided to lose the Mod and go back to the original set up. It seems the voltage regulator has gone to a normal temp and my color is all back to normal... For now! Im super bummed because now my Heavy Sixer has 3 composite mod holes in the back and Im actually all good with the RF cable, I was a bit too ambitous. Just wanted to update anyone who saw this and say thanks but I'm sure I'll be back picking your brains soon!!!!

[Osgeld]

so rotten av mod install removed shit went away ... amazing

[+-^CrossBow^-]

so rotten av mod install removed shit went away ... amazing

Now now...no need to be that harsh. We are all in a state of learning things every day. This is no different. But yes some basics of electronics are needed when attempting to do any mod work on these older consoles. My guess based on what was being stated was that the VR had been installed backwards as well. But now I'm trying to find out why the AV mod would have caused such a strain on the VR? The basic transistor mod shouldn't really require that much extra current to be an issue so it had to be some wire crossing issue causing this. Perhaps the +5 to the video mod wire was shorting against ground somewhere?

[OptimusMaximus]

Thanks crosbow. I dont think my mod install was bad. And sure not bad twice. Its pretty straight forward. I thought I may have done the VR backwards as well but it wasnt. And once I removed the mod it wasnt burning hot. I am learning electronics now as well. Maybe some solder was crossing over to wires but I just dont think so because same results twice.

[+-^CrossBow^-]

Well, I can tell you that adding in extra stuff when we mod these consoles, also means that additional current is needed to power it all. The 2600s VR is only like .5amp or 500ma so it might already be near max as is. Whenever I mod a 2600 I always install a newer 1amp output version of the VR. For one I know it can handle the additional current draw that might be needed with the mods being done, and it will run a tad cooler since it won't be getting taxed as much as the original did and so should last longer in theory.

 

I also advise installing new 1amp or 2amp versions in 7800s for the same reasons.

Edited October 16, 2018 by -^Cro§Bow^-

[Osgeld]

and it will run a tad cooler since it won't be getting taxed as much as the original did and so should last longer in theory.

 

this is not entirely true, a 0.5 amp part with a 65c per watt will run the same temp as a 1 amp part with a 65c per watt when the same amount of power is being used

 

its possible to get parts with better thermal dissipation but one has to scrub the datasheet

Edited October 16, 2018 by Osgeld

[+-^CrossBow^-]

Thanks for the correction Oz! I've lucked out then with getting cooler running VRs I guess. Then again older VRs and especially those trying to pull max current or above will run hotter.

[Osgeld]

yea the old ones are well old and technology has gotten better so comparing a 1980's model to a 2018 model is a good difference,and current is only half the battle, dropping one's input voltage will signifigantly drop the heat produced

 

lets assume you get a typical 1 amp max 65c per watt run of the mill modern 7805

 

using the stock atari supply which rides ~11 ish volts under load (+ ripple but) and the atari is sucking 380ma ...one can assume

 

(((11 - 5) * 0.380) * 65) 148c rise without a heat sink

 

or if we drop that down to 9 volts

(((9 - 5) * 0.380) * 65) 99c rise without a heat sink

 

or if we drop that down to 7 volts

(((7 - 5) * 0.380) * 65) 49c rise without a heat sink

 

of course you can drop this by quite a bit even with just using a ground plane on the pcb as a heat sink like the 4 switchers do ... which is why they do it lol

[+-^CrossBow^-]

7 volts is barely enough to drive a 2600. I know because I've used one of those variable voltage adapters and once I put it down to 7.5 or 7v the atari had all kinds of strange colors on the screen although it was still technically working.

 

The input voltage is key though as you stated. I wish the adapter I use on my Genesis (Converted GameCube Adapater) to power all 3 systems didn't have so much. It has 3amps of current no problem, but it puts out a stead 13.5 volts without a load. I've not actually tested it under load but still..lot of juice.