Atari 800 questions

[Mrarkus]

Recently I have become a bit obsessed with the original Atari 800. Something about the build quality, the keyboard, and just old school charm.

 

Anyway, I do have few questions as it's a little harder to find information than for XL/XE lines... 

 

1. Is there any importance to main board, Power board, or CPU board revisions?

2. I'm installing Incognito and Sophia DVI in my main one. With the Sophia, looks like I will have to cut the RF shield to give it space. Any issues with that? I think that it would actually help with cooling.

3. I would love to get a matching 810 or two, but working models seem to be hard to find. Is there a version/revision that is best to look for?

 

Thanks!

[Sugarland]

1. Not as far as I know.

3. Yes the late model garage door types. They have a PCB (called the analog board) visible above the drive mechanism when looking into the door. The other 810 with a narrow slit disk slot (also called the 810T Analog), are all late models (Tandon mech) are all good except there is a plastic pivot pin that according to Best Elec break 100% of the time. They sell a replacement pin. The 810T for some reason is considered less desirable than a rev C analog MPI mech (garage door type).  I can say with personal experience that the MPI drives are more satisfying to insert and remove disks.

 

Strongly recommend you read the Atari 8bit FAQ on the 810's.

 

The Best page linked above has this text:

Quote

Best Atari 810 Tech Tip:  Atari 810 problems fall into a few different basic reasons / problems.  A dead (no LED or LED's works but no mechanical movement) 810 is usually a bad rear Atari 810 Power board.  It could also be a combo of both a bad rear power board and sideboard problems.  A mechanically working 810 disk drives that have Read (boot errors) or Write (can not format a SSSD 5 1/4 Floppy disk, which is one of the true tests of the health of any Atari 810 or Atari 1050 Disk drive) problems is usually a 810 5 1/4 Disk Drive mech. problem.  But could also be a combination of both a bad 810 disk drive mech. and bad 810 sideboard problems.  Early made Atari 810 Disk drives had two known major problems.  On early production runs of the 810 sideboards, they did not have the 810 Data separator board plug in upgrade daughter board (the WD 1771 disk controller chip plugged directly into the side board).  The second known problem was the single rear 810 power board.   Both were known to cause all kinds of problems with early Atari 810 disk drives and the only way to fix them was to add the 810 Data separator board and install the 810 improved rear power board.  The Atari 810 disk drives without the Data separator board had all kinds of Read and Write 810 Head problems.  The single 810 rear power boards had all kinds of speed problems that seem to change all of the time without making any kind of speed adjustments on the single rear 810 power board.  Both known 810 problems we latter fixed in the Atari 810 production run with a new plug in 810 Data Separator board (which cured most of the 810 Read and Write electronic data problems).  The second Atari 810 Major problem was cured with what is known within Atari Engineering as the Atari 810 Grass Valley board set (where in California it was designed).  This Atari Engineering Grass Valley 810 new board set cured all of the Atari 810 speed problems.  It consisted of a new redesigned / improved replacement 810 rear power board and a second daughter board (sat over the 810 Disk Drive mech. and was connected to the rear 810 board with a 10 pin wire harness and to the 810 Head wire harness).  The second Grass Valley 810 daughter board helped to separate and boost the Atari 810 disk drive Head signals.  Also the Atari 810 Disk Drives that used the Tandon 5 1/4 internal Disk Drive mechs, had a very high failure rate of the Tandon access front Lift door (like a garage door opening) white pivot pens breaking.  The second Gen. improved Tandon 810 lift door assemblies in stock.

 

 

Edited August 28, 2020 by Sugarland

[Pfaffa]

In answer to #2 The 400/800 RF Shield was designed to conform to a very strict set of FCC guidelines because it used normal TVs as a output. Later the FCC relaxed these guidelines to be more in line with those computers with monitors dealt with, so a smallish sized hole shouldn't have a major effect on anything else because overshoots current (and any sane) regulations by a wide margin.

[BillC]

6 hours ago, Mrarkus said:

2. I'm installing Incognito and Sophia DVI in my main one. With the Sophia, looks like I will have to cut the RF shield to give it space. Any issues with that? I think that it would actually help with cooling.

It should be possible to install Sophia inside the RAM card bay, attached to the GTIA socket via ribbon cable similar to how the U1MB connects to the OS/ROM sockets. The fact there are no RAM cards with Incognito installed leaves a lot of empty space for this. A mount could be made from a piece of unplated perf board that would plug into a RAM card slot.

[mimo]

1-No

2-No

3-Yes