29 replies to this topic

[0078265317]

My 4 port finally stopped working. Opened it and everything looks fine. Hard to tell though. No video. Channel 2 or 3 no difference. Just grey or black screen. Box was fixed by phuzzed so it is not the box. Got to be the 5200. Red power light comes on just no video. Not electronics savy. What could be wrong. Or not worth fixing. And even on ebay used systems (even broken ones) are expensive. What gives?

[0078265317]

I checked with a volt meter and my 5200 ac adapter is using 17.33 volts. Could this be issue. Toco much power.

[zylon]

95% a chip is bad. Could be one of the 8 RAM chips, the little one by power switch or the GTIA.
Overvoltage can and does fry chips, but putting meter on unloaded power supply is misleading. Turn system on with a game inserted and test at the socket in switchbox to determine true voltage under load.

Edited by zylon, Mon Jun 13, 2011 9:18 PM.

[0078265317]

How is that. Put in a game and turn on sytem then. Then what? Test where. Where to put volt meter needles?

[zylon]

Test either at RF/power cord to board mounting point, or on points where socket connects to switchbox board.

[0078265317]

Sorry not following. If I take out the power or rf from the box it won't power. So if I plug it all in then where is the space to put the probes to test. Maybe a diagram would help. Don't want to take it apart again and damage something.

[zylon]

Try these 2 positions with system plugged in and running. I'm not taking my box apart this late.

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Edited by zylon, Mon Jun 13, 2011 10:12 PM.

[phuzzed]

This is a tough one.... This could be a number of things. Anything from a bad RAM chip to a bad CPU, GTIA chip, or BIOS. Reseat all the chips and try again.

In regards to power, that does seem a bit high. Most of my power supplies output around 14 Volts. Remember that these power supplies are unregulated, meaning that the voltage regulators inside the 5200 system should step it down the appropriate voltages (i think they step it down to 12 volts, but I am not 100% positive on this). The voltage regulators are attached to the huge metal heat sinks located near the back right (as you are looking down on the system). Since you are getting a screen, I don't think these regulators are bad, but the only way to tell is to test the output voltages.

I really wish I could help out more here. I know this has to be frustrating. Unfortunetly, this is one of those problems that is going to be hard to troubleshoot without another system to swap parts, to determine the culprit.

[0078265317]

I opened it up very quickly and used frogger to test. Tried both positions. I got about 15.26 - 28.

[0078265317]

http://www.AtariGuid...vice_Manual.pdf

[zylon]

If higher voltage than 5.2 gets to the chips, it will cook one or more. Regulators can fail after warmup and allow too much power through. For that, you'd have to run the system and put a lead on ground at the board and the +lead on the third leg(far right when looking straight at the regulator with legs downward) and see what is getting through. Replacing chips will not last long if they were killed by dying regulator.

[0078265317]

zylon, on Tue Jun 14, 2011 12:46 PM, said:

If higher voltage than 5.2 gets to the chips, it will cook one or more. Regulators can fail after warmup and allow too much power through. For that, you'd have to run the system and put a lead on ground at the board and the +lead on the third leg(far right when looking straight at the regulator with legs downward) and see what is getting through. Replacing chips will not last long if they were killed by dying regulator.

I'm going out for dinner. Show me a picture of the ground and third leg you are talking about and when I get back I'll check the numbers for you.

[phuzzed]

The voltage regulators do step it down to 5 volts---Not 12 like I previously stated. I have no idea why in the world I thought that.


Anyways, to test the voltage regulators, locate the voltage regulators, which are the black things screwed to the huge heat sink in the back. They will have three pins on them.


so, looking at the front of the voltage regulator, you have pins 1, 2, and 3


Pin 1: Input ---this should be your power supply voltage

Pin2 : Common

Pin 3: Output --- This should have an output of 5 volts, or pretty darn close.

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[zylon]

Use pic above and put -black lead on pin2 and +red lead on pin3. This is best checked with a warm running system. I have seen a few where it took extended play to show overvoltage.

[0078265317]

I only saw 1 that looked like the photo behind the 2 - 3 switch. It was about 6.45 volts.

Edited by 0078265317, Tue Jun 14, 2011 8:40 PM.

[0078265317]

I have no idea what I am doing. So sent it to zylon. Should get there in a few days.

[eightbitter]

Quote

I checked with a volt meter and my 5200 ac adapter is using 17.33 volts.

Are you sure that your power adapter is AC?

[zylon]

eightbitter, on Thu Jun 16, 2011 1:54 PM, said:

Quote

I checked with a volt meter and my 5200 ac adapter is using 17.33 volts.

Are you sure that your power adapter is AC?

All will be known after it gets here.

[0078265317]

zylon, on Thu Jun 16, 2011 2:28 PM, said:

eightbitter, on Thu Jun 16, 2011 1:54 PM, said:

Quote

I checked with a volt meter and my 5200 ac adapter is using 17.33 volts.

Are you sure that your power adapter is AC?

All will be known after it gets here.

Ya I'm not good with electronics. Maybe I was doing it wrong.

[0078265317]

According to the tracking number arrived at the local post office today. So we should know soon.

[zylon]

It's already fixed.

[0078265317]

So what was wrong with it?

[zylon]

I found VR2 to be failing giving me 6.2v on pin 3 so I removed and replaced VR1 & VR2. Power supply tested perfect here so the only way to get the ridiculously high readings from earlier would be if the voltage in the home is rather high. I'm going to guess it's 140vAC not 120vAC coming from the wall socket if earlier readings were correct. The GTIA chip was rather baked so that was replaced as well. Finally, adjusted the color to spec and put it back together.

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Edited by zylon, Mon Jun 20, 2011 9:27 PM.

[phuzzed]

Excellent! I'm glad you could get it fixed up! And thanks for sharing your findings with us.

Hopefully nothing else was weakened with the higher than normal voltage coming off of the voltage regulators.

[zylon]

Luckily for him, the chip had an open failure instead of a short which could've been much, much worse. I was actually able to make his chip work for about 3 minutes by applying direct heat from my soldering iron. This caused the internal wiring to expand and reconnect briefly. You could then play a game but would have to reheat to power back up.