No video, no keyboard sound Atari 800 / PSU?

[spinnaker15136]

I posted on issues of my on 810. @DrVenkman was kind enough to post a link to the service manual.

 

Well it looks like I jumped the gun because the 800 itself is not working. I haven't had the computer out of the box in about 30+ years. At, first, I was not getting RF out but I assumed it was either my jury rigged connector or something with my TV, It was at least encouraging that I had a power light and I could hear the speaker when I pressed on the keyboard. The keyboard sound told me the CPU was alive ( I assume).

 

Well now I have a power light but no keyboard sound anymore.

 

 

I measured voltages.

 

-5V measure -5.26V.

12V measures 12.1V

But 5V is low, Measures 4.9V and saw it bumping 4.89V

 

Would this be enough to cause the CPU not to work?

 

Where can I find a schematic? I tried looking for it on the site @DrVenkman posted but could,'t figure out where the link would be.

 

Also, how do I remove the large, heavy metal shield? Is that one screw for the power supply the only thing holding it down?

 

 

[Kyle22]

The first thing I would do is clean the card edge connectors on the OS and RAM modules.

[spinnaker15136]

BTW Found a link to a schematic here.

 

http://www.jsobola.atari8.info/dereatari/literatdere/400_800sm.pdf

 

Can a mod move this to the Hardware forum? Just noticed it now. Sorry.

[spinnaker15136]

The first thing I would do is clean the card edge connectors on the OS and RAM modules.

 

 

I did reseat them. But I will give that a try thanks.

[+Nezgar]

Deleted... woops this thread is for the 800 not the 810

[spinnaker15136]

Cleaned the edge connectors of RAM, ROM and cartridge. Keyboard clack is back. Does this mean the CPU is alive? Or does something else cause the clack?.

 

I was not able to get down into the edge connectors on the mother board real well. Any tips on cleaning those? I don't recall ever cleaning one of those in all of the years I have worked with them.

[+DrVenkman]

Cleaned the edge connectors of RAM, ROM and cartridge. Keyboard clack is back. Does this mean the CPU is alive? Or does something else cause the clack?.

 

I was not able to get down into the edge connectors on the mother board real well. Any tips on cleaning those? I don't recall ever cleaning one of those in all of the years I have worked with them.

If by “clack” you mean the keyclick sound from the internal speaker, that’s a good sign.

 

To clean the edge connectors, with the machine unpowered, spray electrical contact cleaner into them and then work the circuit boards into and out of them several times, which will clean both the connectors and the edge contacts on the circuit boards. You can buy decent stuff like CRC-branded products at any auto parts store or Wal-Mart. Better would be Deoxit, but it’s hard to find locally. You can buy it on Amazon though it’s rather pricey. It works amazingly well, however.

[spinnaker15136]

If by “clack” you mean the keyclick sound from the internal speaker, that’s a good sign.

 

To clean the edge connectors, with the machine unpowered, spray electrical contact cleaner into them and then work the circuit boards into and out of them several times, which will clean both the connectors and the edge contacts on the circuit boards. You can buy decent stuff like CRC-branded products at any auto parts store or Wal-Mart. Better would be Deoxit, but it’s hard to find locally. You can buy it on Amazon though it’s rather pricey. It works amazingly well, however.

 

 

Yes exactly. But one thing. When I press on the system reset all I get is sort of a crackle, Can someone remind me what that sounds like?

 

I also seem to be getting video out. I can see a signal on my scope. Video is the second pin counter clockwise correct?

Edited April 8, 2019 by spinnaker15136

[RodLightning]

Another thing you might try is to press and hold the start key before turning on the power switch.

You should hear a buzz/beep sound from the internal speaker. This indicates it is waiting for a tape to load, so good sign.

[+DrVenkman]

Can’t recall the pinout off-hand but this thread has it. Also don’t know what you’re referring to as Pin 2. The Atari 800 DIN has several signals - Chroma, Luma, Composite and Audio, plus a Ground of course.

 

http://atariage.com/forums/topic/270769-atari-4-lead-video-cable-question/

 

Have you tried simply connecting the RF cable to an old switchbox or RCA-to-Coax adapter and running the signal into the Cable jack of your TV, or through an old VCR into the composite inputs on a TV? That’s easier than wiring up a video cable pin-by-pin.

[spinnaker15136]

Can’t recall the pinout off-hand but this thread has it. Also don’t know what you’re referring to as Pin 2. The Atari 800 DIN has several signals - Chroma, Luma, Composite and Audio, plus a Ground of course.

 

http://atariage.com/forums/topic/270769-atari-4-lead-video-cable-question/

 

Have you tried simply connecting the RF cable to an old switchbox or RCA-to-Coax adapter and running the signal into the Cable jack of your TV, or through an old VCR into the composite inputs on a TV? That’s easier than wiring up a video cable pin-by-pin.

 

 

As mentioned can't get RF to work but I don't know if it is my jury rigged connector or what. I have one of those adapters on order. Also just ordered a 5 pin DIN. Darn it had one too for years up until a couple of years ago. Tossed it with the video monitor I hooked up back in the day.

[spinnaker15136]

Another thing you might try is to press and hold the start key before turning on the power switch.

You should hear a buzz/beep sound from the internal speaker. This indicates it is waiting for a tape to load, so good sign.

 

 

A buzz. Thanks!

[Kyle22]

Now you can monitor the Motor Control pin on SIO. Boot with [sTART] then press [RETURN]. Watch the voltage change.

[spinnaker15136]

Got my RF connector in today. It's alive!

A little buzzing but as I recall that is normal with text, Waiting on the 5 pin DIN, hopefully with even better results.

 

Now I need to see if I can get the 810 up and running again.

 

 

 

Edited April 10, 2019 by spinnaker15136