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Resurrecting my 800xl

800xl gtia video

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#1 isayx3 OFFLINE  

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Posted Thu Nov 10, 2016 11:51 AM

I found my original 800xl from when I was a kid in the garage. Did not have a power supply so I picked up a  61982 off ebay. When I turn it on I see scrambled video and hear a buzz. This happens when I use the RF out and when using composite out via the monitor port. I recently had a similar issue with a 2600 and swapping out the TIA worked. Could this be as easy as replacing the GTIA or does the buzzing indicate another issue? 

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#2 bob1200xl OFFLINE  

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Posted Thu Nov 10, 2016 12:02 PM

Looks like a bad power supply. Be careful. It may destroy chips in your computer.

 

Do you have a meter? Measure the DC output (should be 5v) and the AC output (should be 0).

 

What does your power supply look like?

 

Bob



#3 isayx3 OFFLINE  

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Posted Thu Nov 10, 2016 12:18 PM

Looks like a bad power supply. Be careful. It may destroy chips in your computer.

 

Do you have a meter? Measure the DC output (should be 5v) and the AC output (should be 0).

 

What does your power supply look like?

 

Bob

 

This would explain it....I'll test it with a meter. 

 

Which Power supply should i be looking for?

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  • ps.jpg


#4 isayx3 OFFLINE  

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Posted Thu Nov 10, 2016 4:03 PM

Looks like a bad power supply. Be careful. It may destroy chips in your computer.

 

Do you have a meter? Measure the DC output (should be 5v) and the AC output (should be 0).

 

What does your power supply look like?

 

Bob

Meter is reading about 7v. I was told that is fairly normal. Does this rule out the PS?



#5 shoestring OFFLINE  

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Posted Thu Nov 10, 2016 4:20 PM

7v is not normal at all. Those power supplies are known to fail with over voltage and will damage your computer.

You've just fried your DRAMs. Who told you 7v was normal ?

#6 bob1200xl OFFLINE  

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Posted Thu Nov 10, 2016 4:42 PM

The max voltage for operating TTL logic is 5.5 - 5.75v. 7 volts is way too high.

 

Bob



#7 isayx3 OFFLINE  

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Posted Thu Nov 10, 2016 6:32 PM

7v is not normal at all. Those power supplies are known to fail with over voltage and will damage your computer.

You've just fried your DRAMs. Who told you 7v was normal ?

A friend with a multi meter and familiar with electrical. Said that usually it will read high when testing but once in use it will drop down to 5v once it starts to regulate. I had a second person tell me the same thing.  

 

So when I hold down option or put in a cart it does seem the screen changes underneath all that noise. If the dram was fried wouldn't it just be constant? This is why my initial guess was video. Just trying to figure out my next steps...replace the power supply or look for DRAM if that is an option..or ?
 



#8 Brentarian ONLINE  

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Posted Thu Nov 10, 2016 6:56 PM

Trust the folks here about that power supply. If it reads 7v then don't try it again or you'll do more damage. I would throw that one away and obtain another (not that model though).

#9 isayx3 OFFLINE  

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Posted Thu Nov 10, 2016 7:08 PM

Trust the folks here about that power supply. If it reads 7v then don't try it again or you'll do more damage. I would throw that one away and obtain another (not that model though).

 

Yes definitely not trying it again....and lesson learned! The good thing is now I know how to use a multimeter :)



#10 shoestring OFFLINE  

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Posted Thu Nov 10, 2016 7:40 PM

Try a "switching adapter" solution.  Salvage the 7 pin din DC plug from your power supply ( then chuck the ingot in the bin  ) and use a 5v supply from a router or USB hub, splice the two wires and solder them to the end of your lead of your salvaged DC plug. You just have to be careful with the polarity if you do this yourself ( easy to screw up ).



#11 isayx3 OFFLINE  

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Posted Thu Nov 10, 2016 8:01 PM

Try a "switching adapter" solution.  Salvage the 7 pin din DC plug from your power supply ( then chuck the ingot in the bin  ) and use a 5v supply from a router or USB hub, splice the two wires and solder them to the end of your lead of your salvaged DC plug. You just have to be careful with the polarity if you do this yourself ( easy to screw up ).

Will try this...thanks

Is there anything in the plastic box that says "To Computer"  ?



#12 Tillek OFFLINE  

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Posted Thu Nov 10, 2016 8:45 PM

I've had 2 power supplies go bad in my time. The first just resulted in a color screen, solid with no sound. This was quite some time ago as it was my childhood 256k Rambo 800xl with an ingot. The drams were fried. I finally fixed it two years ago.

Same computer, two months ago, non ingot. Got the same thing you're describing. Was heartbroken as I thought it was the computer so tried another and got the same. Switched out the power supply and both computers were fine.

So I'd just say try another power supply before even thinking about worrying about anything else.

#13 BillC OFFLINE  

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Posted Fri Nov 11, 2016 12:37 AM

It's possible to keep using an over-voltage power supply by simply adding an 7805 regulator inline on the cable to the DIN plug.

A member of the local Atari Users Group in the late 80s did this to a failed INGOT power supply using a small piece of perf board, he was a technician with the telephone company.



#14 russg OFFLINE  

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Posted Fri Nov 11, 2016 4:34 AM

 

This would explain it....I'll test it with a meter. 

 

Which Power supply should i be looking for?

 

C061982 'The White Brick' (Upper left) 1.5A very reliable, rare
C061982 'The Black Brick' (Lower Left) 1.5A very reliable, rare
C061982 'The Ingot' (Center Top) 1.5A if this PS fails it can damage the computer. Not recommended for unattended operations. DISCARD it.
C061982 'The Box' (Top Right) 1.5A very reliable, recommended for XL/XE computers
C70042-011 'The Mini' (Bottom Center) 1A shipped with most XEGS systems, use the 'Logo' for continuous 1A operations
C70042-01 'The Logo' (Bottom Right) 1A very reliable

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Edited by russg, Fri Nov 11, 2016 4:35 AM.


#15 isayx3 OFFLINE  

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Posted Fri Nov 11, 2016 10:57 AM

Try a "switching adapter" solution.  Salvage the 7 pin din DC plug from your power supply ( then chuck the ingot in the bin  ) and use a 5v supply from a router or USB hub, splice the two wires and solder them to the end of your lead of your salvaged DC plug. You just have to be careful with the polarity if you do this yourself ( easy to screw up ).

 

This should work right?

 

Good news, the ebay seller refunded my monday....well it's good news if my 800xl isnt toast. I have hopes since the last time I turned it on it was not a black screen.

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  • ps.jpg


#16 isayx3 OFFLINE  

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Posted Fri Nov 11, 2016 12:24 PM

Success! So I did try the power supply above but when I tested it with a meter it was also running at 7v (cheap chinese product go figure). Dug up another power supply which test at 5V. 

Thanks so much for all the help...I learned a lot.

 

First thing I did?

 

10 Print "hello"  

20 goto 10

run   :)

 

 

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#17 Tillek OFFLINE  

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Posted Fri Nov 11, 2016 5:19 PM

 

This should work right?

 

Good news, the ebay seller refunded my monday....well it's good news if my 800xl isnt toast. I have hopes since the last time I turned it on it was not a black screen.

Why would you want your Monday refunded?

 

Glad you got it working again!


Edited by Tillek, Fri Nov 11, 2016 5:19 PM.






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