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Atari 5200 2 port power issue


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#1 Jpc18 OFFLINE  

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Posted Sat Jul 1, 2017 6:55 AM

Hello everyone my name is Jon and I'm a console and game collector. I recently acquired a free 5200 from a friend who acquired a newer and cleaner version. He stated this one had color issues and the colors would fade or change I believe. He also stated I had to purchase an adapter, which I did off eBay. I plugged everything in, hit the power button and the red light didn't come on. I checked voltage on the adapter tip and got readings of 12v dc, which is close to 11.55 it's supposed to put out. I opened up the console, with the adapter plugged in and volt meter on the adapter plug port, I get 1.2 volts. It seems to me like the board is not getting enough power. I googled a good bit and couldn't find the answer. Anyone have any idea on what could be the issue and maybe point me in the right direction. Thanks

#2 AtariBrian OFFLINE  

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Posted Sat Jul 1, 2017 7:18 AM

Could be the power supply or something simple if you know how to solder ? Also , sometimes with the power button you have to hit it just right for it to work . I have one that is finicky .



#3 Jpc18 OFFLINE  

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Posted Sat Jul 1, 2017 7:37 AM

So the power supply could be bad even if it puts out the right voltage? Yea, I got a station at work. I've reflowed the power connector tabs on the board. Still shows 1.2 on the connector. Get 12v on the power plug not connected.

#4 SignGuy81 ONLINE  

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Posted Sat Jul 1, 2017 8:42 AM

So the power supply could be bad even if it puts out the right voltage? Yea, I got a station at work. I've reflowed the power connector tabs on the board. Still shows 1.2 on the connector. Get 12v on the power plug not connected.

 

If you are getting 12V while nothing is plugged in, then 1.2V at the same point when plugged in, it sounds like something is pulling the supply down.  I thought the 5200 got its power sent through the RF.   So do you mean you have 12V on the end of AC adapter plug and then the connector of the RF box has 1.2V when plugging into that?  If that is the case unplug the RF cable from the console and do the check again, to see if it is perhaps a problem in the RF box or the console.


Edited by SignGuy81, Sat Jul 1, 2017 8:45 AM.


#5 SignGuy81 ONLINE  

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Posted Sat Jul 1, 2017 8:53 AM

Anyway you could show pictures of where you are checking?



#6 Jpc18 OFFLINE  

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Posted Sat Jul 1, 2017 9:55 AM

Yes, and no this power brick plugs into the back of the 5200 not the rf. The 4 port 5200 power plugs into the rd block. I have a two port Atari 5200. Yea, I got to run up to my work place and snap a photo. Thanks.

#7 SignGuy81 ONLINE  

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Posted Sat Jul 1, 2017 10:03 AM

Yeah, it sounds like something in the console is pulling the supply down in the AC adapter.  May be a shorted voltage regulator.



#8 Mitch OFFLINE  

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Posted Sat Jul 1, 2017 12:15 PM

Yeah, it sounds like something in the console is pulling the supply down in the AC adapter.  May be a shorted voltage regulator.


That was my first thought. A failing voltage regulator can mess with the color as well.

Mitch

#9 Jpc18 OFFLINE  

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Posted Mon Jul 3, 2017 9:07 AM

Here are the pics of the motherboard. any way to test the voltage regular chips?

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#10 SignGuy81 ONLINE  

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Posted Mon Jul 3, 2017 11:26 AM

Take them out and do ohms test between the input and ground and output and ground.

 

EDIT:

 

That is just the simplest test to see if the regulator is shorted or not and will not let you know for sure if you have a bad regulator but will confirm a shorted one.  Do the tests and come back with what the readings were.


Edited by SignGuy81, Mon Jul 3, 2017 11:32 AM.


#11 DavidMil OFFLINE  

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Posted Mon Jul 3, 2017 11:43 AM

Are either of your voltage regulators (VR1 or VR2) getting very hot?  Even when the power is turned off?  Check the big

heat sinks for temps around the VR's, don't put your finger on the VR's (you may get a nasty burn).

 

DavidMil



#12 SignGuy81 ONLINE  

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Posted Mon Jul 3, 2017 11:49 AM

Whichever one is the hottest is the one you want to remove first and check.

 

EDIT:

 

I just got to thinking it might not be a good idea to plug your power adapter back up to the console and check that because you may risk damaging your power adapter because we know there is a short already, so you are probably better off to just remove both regulators and check them for shorts and we can go from there on the motherboard but don't plug the power adapter back into console.


Edited by SignGuy81, Mon Jul 3, 2017 11:57 AM.


#13 Jpc18 OFFLINE  

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Posted Tue Jul 4, 2017 7:02 AM

I don't know if it matters, but I checked it on board. Not plugged up. VR1 input .766 output 3.115.
VR2 input 574.3 output 338.1.

#14 -^CrožBow^- OFFLINE  

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Posted Tue Jul 4, 2017 8:14 AM

I don't know if it matters, but I checked it on board. Not plugged up. VR1 input .766 output 3.115.
VR2 input 574.3 output 338.1.

 

Since you have it powered up before, try testing their input voltage and output voltage really quick while plugged in a powered on.


Edited by -^CrožBow^-, Tue Jul 4, 2017 8:15 AM.


#15 SignGuy81 ONLINE  

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Posted Tue Jul 4, 2017 8:46 AM

I don't know if it matters, but I checked it on board. Not plugged up. VR1 input .766 output 3.115.
VR2 input 574.3 output 338.1.

 

I don't have time to look at a schematic at the moment but yeah go ahead and take out VR1 definitely.  I knew the output circuit was separate but I thought the input of them would both be the same parallel with the power supply which would make the short show on both inputs but like I say I'm not looking at a schematic, and the inputs could be separated by diode(s) which would cause the short to only show on the input that has the short.

 

Take the one out with the low ohms reading, check it again out of circuit too, then plug the unit in(leaving the one regulator out) and check the power at the connector again.


Edited by SignGuy81, Tue Jul 4, 2017 8:48 AM.


#16 Jpc18 OFFLINE  

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Posted Tue Jul 4, 2017 8:54 AM

In response to crossbow, I got them right here with the power supply plugged into the console. VR1 .791 input 283.5 output. VR2 621.4 input 424.8 output. Each one seems like they're higher except input on VR1 had minimal change.

Get back to you signguy81 if I get it taken out today. Thanks for the help guys.

#17 Jpc18 OFFLINE  

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Posted Tue Jul 4, 2017 9:30 AM

Voltage regulator 1 out of the board. Input 4.177 output 8.11. Voltage at the power connector on board with adapter plugged in still around 1.2 volts.

#18 SignGuy81 ONLINE  

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Posted Tue Jul 4, 2017 12:02 PM

Okay, you need to look at the circuit around vr1 on the board, see if the short was on the input side or output side where you pulled out the regulator

 

edit:

should be on the input side of where the regulator was since it is out now and still pulling down the power supply

 

with the power unplugged, do ohms check again on the input and output side where regulator was and get back with results


Edited by SignGuy81, Tue Jul 4, 2017 12:03 PM.


#19 SignGuy81 ONLINE  

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Posted Tue Jul 4, 2017 4:19 PM

This may help here http://www.digitpres...anual_rev_3.pdfgo to page 39 of 194 of the pdf. 



#20 zylon OFFLINE  

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Posted Tue Jul 4, 2017 4:26 PM

I'd look into the little IC near power switch and replace both regulators. You are going to fry something.



#21 SignGuy81 ONLINE  

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Posted Tue Jul 4, 2017 7:31 PM

That IC the guy mentioned above is a strong possibility of what the problem could be.  The way the circuit is setup with the transistors, if that chip were shorted, it wouldn't show up at VR2 when doing ohms check on that one but would show up on the other side.  Without doing any more power plugged in tests, what I would do is remove the chip(hopefully socketed chip), and then do the ohms check again where the voltage regulator was and see what you have then.

 

EDIT:

I just looked and it looks like the other VR, VR1 is set up the same as VR2 with the PNP transistor, so I think I was wrong on that.  If the chip is socketed still remove it and check, but I think your problem is going to be one of the caps in the circuit near VR1 on the input side of where the regulator goes.


Edited by SignGuy81, Tue Jul 4, 2017 7:44 PM.


#22 DavidMil OFFLINE  

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Posted Thu Jul 6, 2017 12:08 AM

With VR1 removed you may want to check the input voltage on the board.  It's possible that one of the power transistors is bad. 

MJE210 (Q6 or Q7).  If one is bad it may be 'starving' the VR.  If one is bad, I would swap out both.  Another possibility, but not

as likely, you may want to look at Q8,9,10.  They are all 2N3904's (very common), and usually have a very low failure rate.  But

at this point you want to cover all your bases.

 

DavidMil  



#23 Jpc18 OFFLINE  

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Posted Thu Jul 6, 2017 7:48 AM

Signguy81 the input side with voltage reg out is .972 and output is 290.1, actually moves around from 286 to 290. Output seems higher and input really low.

 

Zylon and Signguy81 the IC is not socketed as you can see in the first pic.

 

Signguy81 is this the cap your referring to? I'm used to the round barrel type caps and this green odd looking one seems to be the closest I see.

 

DavidMil am I supposed to be ohming these two on q6 and q7 with power plugged in or not. I think we are not plugging power back up for now so that nothing gets fried.

 

Sorry for the long delays, i'm busy at work and been seeing a heart doc for some breathing issues.

 

Thanks for all the help.

 

 

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#24 SignGuy81 ONLINE  

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Posted Thu Jul 6, 2017 3:58 PM

Yes, C43 and C130.  Take them out and then ohm same spot on the board as before the input and ground where regulator goes.  You can instead just lift one leg each of the caps rather than completely removing them.



#25 SignGuy81 ONLINE  

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Posted Thu Jul 6, 2017 4:00 PM

Also if Q6 or Q7 was shorted it will not cause a short across the input and ground of VR1, or VR2 so that would be the last thing I would look at, if at all.






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