Atari 800 Fault

[kamakazi]

There is something about the 800 and other accessories from the same era of Atari computers that people need to know. The power supply to both the 800 and 1010 program recorder are identical. These power supplies only convert the voltage down to the voltage required by the computer/recorder. They voltage however is still in AC form and the circuits used to convert the say 12 volts from AC to DC reside in the computer/recorder themselves.

 

If you try to use a power supply that already converts AC to DC, you will end up damaging the computer/recorder or power supply or all. I know this cause the 800 and 1010 Program Recorder I had got hit by an unexpected surge and it blew my 800's power supply. I ended up having to use the recorders supply until my new one arrived.

 

Parts for these computers can be found at this address: www.atarisales.com

 

He also has many other items that are too numerous to list so if you don't see something, just email him.

[spudmanno5]

There is something about the 800 and other accessories from the same era of Atari computers that people need to know. The power supply to both the 800 and 1010 program recorder are identical. These power supplies only convert the voltage down to the voltage required by the computer/recorder. They voltage however is still in AC form and the circuits used to convert the say 12 volts from AC to DC reside in the computer/recorder themselves.

 

If you try to use a power supply that already converts AC to DC, you will end up damaging the computer/recorder or power supply or all. I know this cause the 800 and 1010 Program Recorder I had got hit by an unexpected surge and it blew my 800's power supply. I ended up having to use the recorders supply until my new one arrived.

 

Parts for these computers can be found at this address: www.atarisales.com

 

He also has many other items that are too numerous to list so if you don't see something, just email him.

 

where do you think the fault lies?

[1050]

where do you think the fault lies?

There is no fault?

 

kamakazi describes the situation almost accurately in that power supplys for the 800 are the same as the one for the 1050 drive and a few other Atari devices. They output 9 volts AC and you can't use 9 Volts DC for these circuits because inside the 800 and 1050, etc. are voltage doublers pumping the 9 Volts AC up to well over 12 Volts DC and then there are regulators to bring that down to exactly 12 volts and 5 volts as needed. The Voltage doubler circuits must have AC or they won't work at all. They must also have 9 volts AC at more than 3 amps in order to have well over 12 volts from the doubler circuits because a 12 volt regulator needs 13+ volts to work with. Voltage doubler circuits don't produce exactly double the voltage but they can get close if that is a design consideration - in this case it is not. They only wanted 13+ volts so that the 12 volt regulators could do a decent job of delivering exactly 12 volts DC, the goal of the 9 volt AC voltage doubler is not to reach 18 volts per se. It's just a term to describe a circuit and a method for achieving higher than 9 Volts DC from 9 volts AC. They use large capacitors to kick current in and out of diodes and other large capacitors bucking that current until the voltages start adding, there are also voltage triplers as well with no end in sight except for practical limits which pile up like dead bodies in a morgue real fast. Amperage delivered from a voltage doubler must be less than half of what you started out with so these things can't crank out much for amperage when it's all done and said.

 

Lightening will often take out a power supply especially if it is left plugged in all the time even when you are not using the device. I live rual so it's almost a guarantee - if you don't unplug it when you are done using it, you get to buy a new one right away. I can only place any fault upon myself in such a case.

 

And there is something else about these 9 Volt AC 31VA (3.4444 amp) power supplies that may come as news to some. Locked away inside the glued up case is a fuse that will blow if the output leads get shorted somehow. I cut them apart with a hacksaw and replace the fuse to recover more than a few of these power supplies and return them to a useful life. Dead power supplies sell dirt cheap.

 

I would never try to replace the Atari 9 Volt 31 VA power supply except with one that is rated for 4 amps at 9 Volts AC and they don't give those ones away either.

[LYNXGUY]

I am wondering if an actual Atari 800 Power supply (PSU) would solve spudmanno5 's problem ??

 

I can send him an extra one that i have but I have to find out what the shipping would be.

[spudmanno5]

hi

 

a friend of mine suggested it could be a voltage regulator problem inside the atari. one of the companies i asked also said it could be a POKEY chip problem. So here is wot i will do:

 

1) Look for Official Atari 800 PSU

2) Buy the new POKEY chip (i hear its easy to install in Atari 800)

 

Now if its a voltage regulator problem is there any Atari repair centres or anyone that could do this repair?

 

Regards

[mimo]

POKEY is an easy swap as everything is socketed on an 800

If I can find a spare I'll post it to you

As for repair, Algie may be able to help if you are lucky (he fixed a dead 1050 with vr problems for me)

 

Mike

[spudmanno5]

POKEY is an easy swap as everything is socketed on an 800

If I can find a spare I'll post it to you

As for repair, Algie may be able to help if you are lucky (he fixed a dead 1050 with vr problems for me)

 

Mike

 

ok yeah cook, thanks.

[spudmanno5]

hi

 

update here. i tried mimo's spare POKEY chip and i still get the same results. Whats more is the problem with the Atari 800 seems to have gotten worse. Now when i press play on the cassette player i get a pretty loud humming noise from the tv sound output. this happens with both the POKEY chips. my other options now is it try another atari PSU and then if that doesnt work get someone to repair it. anyone else got any ideas?

 

regards

Edited August 15, 2008 by spudmanno5

[1050]

anyone else got any ideas?

I hesitated to mention this before since I never had your exact symptoms but since I was trying to boot DOS disks in a disk drive of course I would have a different failure mode.

 

BUT on two 800s in my experiance, I had to replace the 6520 PIA with a new Hitachi 68B21 PIA chip to get the disk drive to ever work. What the PIA would have to do with Cassette functions I do not know, but I do know that early 6520 PIA chips were not the strongest ones made, and they fail a LOT. I think I've only had one 800 out of my three total that did not need a new one in order to boot up in fact, so that is a lot.

 

The 68B21 is a 2 Mhz PIA direct replacement for our 6520 which is also supposed to be a 2Mhz chip, the chip used to be available from JDR. Motorola so very much liked the 65xx PIA chip that they duplicated it exactly for use with their 68xx series of microprocessors and thus we get cheap, good parts still being made. The 68a21 or just plain 6821 is a one MHz chip - do not order it or use it, our 1.78 Mhz clock is too close to 2 Mhz for a 1 Mhz chip to work right.

[spudmanno5]

anyone else got any ideas?

I hesitated to mention this before since I never had your exact symptoms but since I was trying to boot DOS disks in a disk drive of course I would have a different failure mode.

 

BUT on two 800s in my experiance, I had to replace the 6520 PIA with a new Hitachi 68B21 PIA chip to get the disk drive to ever work. What the PIA would have to do with Cassette functions I do not know, but I do know that early 6520 PIA chips were not the strongest ones made, and they fail a LOT. I think I've only had one 800 out of my three total that did not need a new one in order to boot up in fact, so that is a lot.

 

The 68B21 is a 2 Mhz PIA direct replacement for our 6520 which is also supposed to be a 2Mhz chip, the chip used to be available from JDR. Motorola so very much liked the 65xx PIA chip that they duplicated it exactly for use with their 68xx series of microprocessors and thus we get cheap, good parts still being made. The 68a21 or just plain 6821 is a one MHz chip - do not order it or use it, our 1.78 Mhz clock is too close to 2 Mhz for a 1 Mhz chip to work right.

 

Can you still buy these chips?

[spudmanno5]

Hi

 

Disaster has struck! My friend has redone some of the psu in the Atari 800. Replaced caps, rectifiers, etc and the problem still exists! The worst thing is the distorted/fuzzy sound when the tape is running. I may have a look myself see if anything needs cleaning up but i am running out of options here. I am hopefully getting a Atari PSU and will soon get the 1010 tape recorder. Do you know anything else that could be wrong or that i can do? The symptoms of the fault are:

 

Sometimes crashes when using the cassette player keys

Distirted/fuzzy sound

LED Dim

 

Has anyone got any ideas what to do next?

 

Regards

[+bob1200xl]

Your best bet is to scope some of the circuits in the 800. Problem is, most people don't have one... Do you have a meter? Check the voltages - 9vac from the power supply going into the 800, 5vdc on the power busses. Measure for ac voltage on the 5 and 12 volt sources. There should be very little (<100mv or so). The 800 is modular - swap out the boards one at a time. (yes, you need a known, good 800 to do that)

 

It's not easy.

 

Bob

 

 

 

Hi

 

Disaster has struck! My friend has redone some of the psu in the Atari 800. Replaced caps, rectifiers, etc and the problem still exists! The worst thing is the distorted/fuzzy sound when the tape is running. I may have a look myself see if anything needs cleaning up but i am running out of options here. I am hopefully getting a Atari PSU and will soon get the 1010 tape recorder. Do you know anything else that could be wrong or that i can do? The symptoms of the fault are:

 

Sometimes crashes when using the cassette player keys

Distirted/fuzzy sound

LED Dim

 

Has anyone got any ideas what to do next?

 

Regards

[1050]

Can you still buy these chips?

Yes, my bad, sorry. I thought I left enough clues behind that you would find them. It's the seventh item on this page. You've probably got a local source for them if you look around some.

 

If the dim LED is on the 1010 recorder don't worry too much about that, just as long as it rolls the tape along. Recent work with my 1010 was very noisy, I was very surprised it could still work with so much hum and static going on but it did. My 1010 LED was not very bright, but crashing the 800 by pressing Recorder keys even just sometimes indicates maybe you need the 68B21 chip?

 

You really should get a voltmeter and measure your voltages, cheap, simple ones can be had for $20.

[spudmanno5]

Can you still buy these chips?

Yes, my bad, sorry. I thought I left enough clues behind that you would find them. It's the seventh item on this page. You've probably got a local source for them if you look around some.

 

If the dim LED is on the 1010 recorder don't worry too much about that, just as long as it rolls the tape along. Recent work with my 1010 was very noisy, I was very surprised it could still work with so much hum and static going on but it did. My 1010 LED was not very bright, but crashing the 800 by pressing Recorder keys even just sometimes indicates maybe you need the 68B21 chip?

 

You really should get a voltmeter and measure your voltages, cheap, simple ones can be had for $20.

 

Hi

 

Well the LED dim is on the Atari 800 itself. I have at the moment two xc12 recorders and get the same results from both. As far as i know, my friend measured the voltages on the Atari 800 and replaced come capactors and rectifiers, and from a voltage point of view, seems to be working. I might buy that 68B21 chip, its cheap anyway.

 

Update:

 

Earlier i said that the distorted humming sound from the tv sound output happens after i press play. But after further digging i found that it only happens when you turn on the computer with start pressed down, and it happens when you press return (so you dont need to press any tape recorder keys). BUT this only happens when the tape recorder is plugged in. No noise when it isnt plugged in!

 

Regards

[spudmanno5]

If the dim LED is on the 1010 recorder don't worry too much about that, just as long as it rolls the tape along. Recent work with my 1010 was very noisy, I was very surprised it could still work with so much hum and static going on but it did. My 1010 LED was not very bright.....

 

What do you mean when you say you got hum and static going on? is this coming from the tv sound output? what is normal behavior from an Atari when it loads a casstte game? (Apart from the normal loading sound!!!)

[+Stephen]

Update:

 

Earlier i said that the distorted humming sound from the tv sound output happens after i press play. But after further digging i found that it only happens when you turn on the computer with start pressed down, and it happens when you press return (so you dont need to press any tape recorder keys). BUT this only happens when the tape recorder is plugged in. No noise when it isnt plugged in!

 

Regards

 

Ah - that explains it. When you power up the Atari with Start held down, it attempts to load from the cassette deck after you press return. You are hearing the normal sound - IIRC a very high pitch noise. The normal Atari tape loading sounds were a steady squeal, with momentary "screeches". Not very pleasant to listen to. I still remember

POKE 65,0

 

Stephen Anderson

[kamakazi]

Steven is right on that part. Just "mute" your TV if the program recorder and the 800 load the program normally. You will only know this when the tape stops and the computer changes displays (depending on the tape). But, yes, the sound is annoying and if you've never heard it before, you would think that there is something wrong with the computer...but it's normal.

 

On a side note, and I know some have tried this, I wouldn't use a 5200 power supply should you ever have a problem. As far as parts goes...should you ever need them, got to these two websites and email them. Usually sending them an email would be about the only way to explain any problems you have and to see what parts they have on hand. Some of them can't list everything they have as well so you might actually come across some stuff that's rare (games and/or accessories).

 

Good luck to you and enjoy your 800!! I know I love mine.

 

The links:

 

Video 61 & Atari Sales

Best Electronics

 

Hope these help.

[spudmanno5]

Update:

 

Earlier i said that the distorted humming sound from the tv sound output happens after i press play. But after further digging i found that it only happens when you turn on the computer with start pressed down, and it happens when you press return (so you dont need to press any tape recorder keys). BUT this only happens when the tape recorder is plugged in. No noise when it isnt plugged in!

 

Regards

 

Ah - that explains it. When you power up the Atari with Start held down, it attempts to load from the cassette deck after you press return. You are hearing the normal sound - IIRC a very high pitch noise. The normal Atari tape loading sounds were a steady squeal, with momentary "screeches". Not very pleasant to listen to. I still remember

POKE 65,0

 

Stephen Anderson

 

are you sure this is normal? i dont this happened when i first got it. this humming sound comes out of the tv when there is no tape rolling and still goes on after the tape has loaded. it only goes away when you reset it.

 

regards

[spudmanno5]

Update:

 

Earlier i said that the distorted humming sound from the tv sound output happens after i press play. But after further digging i found that it only happens when you turn on the computer with start pressed down, and it happens when you press return (so you dont need to press any tape recorder keys). BUT this only happens when the tape recorder is plugged in. No noise when it isnt plugged in!

 

Regards

 

Ah - that explains it. When you power up the Atari with Start held down, it attempts to load from the cassette deck after you press return. You are hearing the normal sound - IIRC a very high pitch noise. The normal Atari tape loading sounds were a steady squeal, with momentary "screeches". Not very pleasant to listen to. I still remember

POKE 65,0

 

Stephen Anderson

 

are you sure this is normal? i dont this happened when i first got it. this humming sound comes out of the tv when there is no tape rolling and still goes on after the tape has loaded. it only goes away when you reset it.

 

regards

 

hhhmmm i wonder if i would if i would get the same thing if i had play pressed down already and then pressed return. thats the method i used and didnt get any humming that way!

[1050]

What do you mean when you say you got hum and static going on? is this coming from the tv sound output? what is normal behavior from an Atari when it loads a casstte game? (Apart from the normal loading sound!!!)

Just what I said. Coming from my Monitor is a lot of static and hum when I press Play on the 1010. I shut everything down and shot all the connections with tuner cleaner and that didn't make a bit of difference. I reseated all cables and connectors to no avail and had to give up eventually - it's just noisey and I don't know where it's coming from exactly. But it still works and that's just amazing considering how noisey it is.

 

But I don't know know what "normal" is all that much. I've loaded exactly two programs with my 1010 so I've not much of a record to go on. I'm also using an 800XL so my mileage is bound to be different anyway. But - boot with Start key pressed and hear a toot from the machine to indicate a Cassette boot is under way. The computer then waits silently for you to press Play on the Cassette deck and as soon as that is done you then press any key on the computer to start the computer into recieving data mode from the cassette. Then one waits until the program/game shows up.

 

I hear the screeching of the data while it loads, not the drone of the computer's Cassette boot indicator tone like you appear to be listening to? But superimposed on top of the tape's content is heavy handed hum and static here, but I understand some players are not noisey at all. Playing the tape in a standard cassette player shows that the static and hum is not on the tape at all, it must be coming from poorly designed circuits inside the 1010. I can't hardly believe that when I take a look at the expensive circuit board layout inside the 1010.

 

If your's is truely stuck in the Cassette boot indicator tone mode then you might have a defective 6520 PIA as I wondered about from the begining. The PIA is needed to fire 5 volts (motor control signal) down the SIO cable even on a Disk drive boot which is where I have my 800 experiance with so many bad 6520 PIA chips. It also handles SIO device interrupts, /proceeed, and /command signals.

[spudmanno5]

What do you mean when you say you got hum and static going on? is this coming from the tv sound output? what is normal behavior from an Atari when it loads a casstte game? (Apart from the normal loading sound!!!)

Just what I said. Coming from my Monitor is a lot of static and hum when I press Play on the 1010. I shut everything down and shot all the connections with tuner cleaner and that didn't make a bit of difference. I reseated all cables and connectors to no avail and had to give up eventually - it's just noisey and I don't know where it's coming from exactly. But it still works and that's just amazing considering how noisey it is.

 

But I don't know know what "normal" is all that much. I've loaded exactly two programs with my 1010 so I've not much of a record to go on. I'm also using an 800XL so my mileage is bound to be different anyway. But - boot with Start key pressed and hear a toot from the machine to indicate a Cassette boot is under way. The computer then waits silently for you to press Play on the Cassette deck and as soon as that is done you then press any key on the computer to start the computer into recieving data mode from the cassette. Then one waits until the program/game shows up.

 

I hear the screeching of the data while it loads, not the drone of the computer's Cassette boot indicator tone like you appear to be listening to? But superimposed on top of the tape's content is heavy handed hum and static here, but I understand some players are not noisey at all. Playing the tape in a standard cassette player shows that the static and hum is not on the tape at all, it must be coming from poorly designed circuits inside the 1010. I can't hardly believe that when I take a look at the expensive circuit board layout inside the 1010.

 

If your's is truely stuck in the Cassette boot indicator tone mode then you might have a defective 6520 PIA as I wondered about from the begining. The PIA is needed to fire 5 volts (motor control signal) down the SIO cable even on a Disk drive boot which is where I have my 800 experiance with so many bad 6520 PIA chips. It also handles SIO device interrupts, /proceeed, and /command signals.

 

ok my next move will be to purchase that 6520 PIA chip, dont think i can really do much more after that, but it is cheap so wont be too bad. am still awaiting the 1010 recorder too.

 

regards

[kamakazi]

Whoa...wait a minute. Hum only when the 1010 is used and not when the tape is in another player? This sounds like a possible ground wire has come loose somewhere inside the 1010. Not uncommon. Do me a favor. With the 1010s tape door open, press play and look behind the head to see if a wire has come loose or take a small screwdriver (jewel-style) and check the tightness of the screws holding the tape head in place. There is a small ground wire connected to the head and if the screws have come loose, they won't ground properly. There should also be one soldered to the tape head itself.

 

There is also another place to look. Take the drive apart and check on the mechanism for any ground wires going to it. If any have come loose over the years, chances are they just need to be tightened. Sorry people, but to me, this sounds more like a ground wire has lost connection instead of a chip or voltage issue, similar to what you would get if you didn't ground a record player to a radio properly, you get an annoying hum.

 

Again, take that drive apart and check for any ground wires that have come loose (usually a black or green wire). There's also the possibility that the PERIPHERAL ports on either the computer or tape drive may have had a solder connection give. Since the sound can be coming from either the drive or computer in this matter, check the drive first and THEN check the computer's peripheral port.

 

Hope this helps.

 

Forgot...fool the computer into thinking it's loading a cassette so the motor will turn on and press play on the drive. Don't worry, you aren't going to damage either component. Is the sound still there? If so, listen to the sound the motor in the drive is making even if you have to put it up to your ear and see if sounds the same as what's coming from your monitor. If so, then there is for sure a ground connection lost. In addition to the above mentioned areas, check the drive motor's connections as well and any ceramic capacitors connected to the motor. This particular part may need to be replaced as the purpose of this capacitor (may be ceramic (brown disc) or electolytic (canister shaped)) is to keep motor sounds from reaching your monitor's speaker.

Edited August 26, 2008 by kamakazi

[1050]

Sorry people, but to me, this sounds more like a ground wire has lost connection instead of a chip or voltage issue, similar to what you would get if you didn't ground a record player to a radio properly, you get an annoying hum.

I agree 100% but I'm not the guy with the bad chip and the noisey 800 that won't work or even the OP. But my noisey 1010 sure needs something alright. I checked all the points you mention though and thanks for the tips, but nothing is loose, and no wires broken that I can find anywhere - I was thinking the very same things as you when I gave up and relied on my can of tuner cleaner which in the past has worked minor miracles along these same lines. There is no cap on the motor that I can tell but I haven't disassembled it completly and probably won't. I'm thinking I'll swap mechanisms and belt with 2 other 1010s that I have untill I can isolate just which half of this thing is making all the noise and start there. Someday. Another one of those round "toit" projects. Thanks, again.

[spudmanno5]

well i have 2 xc12. and i to seem get the same results with. but i will try the other one and see if i get humming. but the one thing thats worse with the other one is the static is so bad that it almost seems the tv is out of tune! my mate who done the repair with the Atari 800, resoldered and checked both the peripheral/sio port and the recorder itself (plus the connection and cable). i think he would have spotted a ground wire fault and alerted me about it (although i will double check and text him). he did say that work need to be done on the sio port and especially the recorder and is was in bad condition.

 

as i saids the humming happens when the recorder is plugged in and after you do the bootup, start and return precedure. so even if there is no tape running it will do it (like the atari is waiting to receive data). but the annoying thing is some games, like one man and his droid, the humming will not stop (because the tape doesnt stop after loading) unless you unplug the recorder or press the reset button. although most games i got when the recorder has finished loading, the tape will stop automatically and so the humming stops.

 

anyway i think i will invest in that chip unless anyone else has any other ideas?!

[kamakazi]

When the tape stops, the hum stops. I'm still sticking with my theory on this one for a while. While no wires may have seemed to come loose...there is the possibility that any of the wires inside or outside of the components have gave. Try changing the SIO cable with a known good one or order a new one.