San Jose Computer 810's and Omnimon 800: Resurrection

[burkhart87]

Two unusual 810 clones from San Jose computer, an Atari 810, and a modded 800 became available as a non-working lot.  I couldn't resist.  I couldn't find any external or internal pics of the San Jose drives and I suspected the 800 had an Omnimon.

 

 

 

 

The 800 didn't display memo pad, only a black screen.  Using a SALT cart I narrowed the problem to very likely be the POKEY or PIA.  The Shift, A and S keys were problematic in the keyboard test, and would often result in this system error, which was new to me.  I couldn't find anything about this errror code 16 in any of the obvious places. ?

 

 

 

Swapping out parts with a working 800 confirmed it was an Omnimon board and that the PIA was bad.  Phew.  That's much easier to replace than the POKEY.

 

 

I had to de-solder the Omnimon switch to get the case apart.  The Omnimon board (without switch) worked when swapped into a working 800, but required the USR(49152) command in BASIC. Entering Omnimon via the switches didn't work.  Turns out a jumper between J and K on the Omnimon board is required to detect the switch commands.  This is diagrammed, albeit a bit cryptically, but not mentioned in the Omnimon install instructions.  The switch on the back of the 800 is an internal speaker on/off switch. 

 

This (bottom board in pic) looks like an attempt to modify one of the memory boards, but IDK.

 

 

 

 

Edited February 27, 2023 by burkhart87

[burkhart87]

The Atari 810 just needed a clean and lube.  It now boots and formats.  Front bezel was broken but these are available NOS on ebay.

 

San Jose #1 looks like a typical Tandon 810 inside.  This one looked as if it was posting upon boot but would give continuous boot errors.  Cleaned, lubed, re-seated boards and chips, found +12 and +5 V at the regulators.  So I started swapping parts with a working 810.  It looks to be a very early Happy 810.  The front toggle is write protect on/off.

 

San Jose #1 has a bad analog board.  More specifically, it has a bad CD4052BEXV from the analog board.  San Jose #1 writes, formats, and is recognized as Happy by Happy software by just swapping this chip with a working one.

I know I can get both upgraded 810 boards as a fix, and maybe I'll do that.  The other San Jose may need parts from the 810 power board (see below), so that would be convenient.  The CD4052BEXV does not appear to be available for a reasonable price, but the CD4052BE does.  I've ordered a few and I'll see what happens.

 

 

Both San Jose drives had broken or missing door mechanisms.  I got some 3D printed replacements from ebay that worked nicely and the replacements do not use those white pins that are usually the cause of failure. https://www.ebay.com/itm/165893137075

San Jose #2 powers up but doesn't spin.  I haven't done much else with this one.  It's also a Happy 810, but looks to be of a more recent vintage.  Somebody went nuts with thermal paste on the voltage regulators (a bit hard to see in the pic), so maybe that's where to start.

 

Edited February 27, 2023 by burkhart87

[+Nezgar]

The 810's aren't clones, but just surplus 810's that Atari sold to some resellers without cases, which they created cases for themselves before reselling. IMHO, these often look better than the original plastic cases.

 

You can see some references to these incarnations in the Atari 8-Bit FAQ:

B&C 810                            SS SD (B&C ComputerVisions house version of Atari 810)
Best Electronics 910               SS SD (Best Electronics house version of Atari 810)
Computer Palace RCP 810            SS SD (Computer Palace house version of Atari 810)
San Jose Computer Special Edition  SS SD (San Jose Computer house version of Atari 810) 

 

But ooh, it has a happy mod! You might have to go through a bit of trial and error to see which "version" it is, though with a 1983 sticker it might be a Rev 7. The switch at the front is commonly a write-protect/write allow switch, but with a happy in there it could be a fast/slow switch, which disables or enables the track buffer.

 

I guess the "Special Edition" designation was San Jose Computer's way of designating the Happy Enhancement.

 

Various revisions of the happy software are here if you ever get the drive to a working state:

https://forums.atariage.com/topic/283666-archive-of-happy-backup-software/?do=findComment&comment=4127979

 

 

[burkhart87]

34 minutes ago, Nezgar said:

 

 

Various revisions of the happy software are here if you ever get the drive to a working state:

https://forums.atariage.com/topic/283666-archive-of-happy-backup-software/?do=findComment&comment=4127979

 

 

I remember that thread.....I'll have to revisit it.

One of the San Jose drives is working, as I mention above.   It's the earlier happy board with no date on the chip, just a handwritten "HAPPY" sticker on top. It also has the rats nest of wiring and extra chips on the back of the 810 side board.

The second San Jose drive (non-working as of now) has the "newer" Happy mod, with only the pot soldered onto the back of the 810 side board and a Happy chip with a date.

 

 

Edited February 27, 2023 by burkhart87

[burkhart87]

The replacement chip for the CD4052BEXV, a CD4052BE (I don't know if there is a difference), worked and restored the San Jose Happy drive #1 to a functioning Happy 810.  This is the drive with the hand-wired side board and hand labeled "HAPPY" chip. Here are pics of the replacement chip and the source.  A cheap fix!  If you can trace a troublesome 810 to the analog board, check this chip. It's in socket A204.  I've got a few surplus CD4052BE's; let me know and I'll ship you one.

 

[burkhart87]

San Jose 810 #2 was more troublesome to diagnose and I'm not really sure if I have a definitive answer as to its woes.  As above, the drive motor did not spin on power up or boot.  This is the drive with the "newer" happy chip and autospeed mod above (and below).  11.9V and 5V on the power regulators. Swapping parts with a working 810 narrowed the issue a bit to the drive mech or power board, but I could not get any clear diagnosis.  Swapping necessitated unsoldering the autospeed mod. A drive mech from a working 810 swapped into San Jose #2 resulted in a working, Happy San Jose #2 drive.  However, the drive mech from San Jose #2 swapped into a working 810 maintained a working 810.  Hmmmm.  Many other combinations of swapped boards later, the only consistent negative result was the pairing of the San Jose #2 drive mech with San Jose #2 power board (San Jose #2 power board produced a functioning drive when paired with the working 810 drive mech).  Hmmmm.  With the working 810 drive mech in San Jose #2, I ran the happy software rpm test and it was low, ~278.  Set it to 288 with the pot on the power board, not the pot added by the autospeed mod.  Put the San Jose #2 drive mech back into San Jose #2 and presto, a working, happy 810.  Go figure.  Soldered the autospeed mod back up and no change, still a functioning happy 810.  The rpm had been bumped up to 295 however, so I used the power board pot to bring that back down to 288.  It looks like the documentation for this autospeed mod to happy 810's is missing, so I've tried to include some pics.  I have no idea how to test this mod, set it up, etc.  

 

[+DjayBee]

3 hours ago, burkhart87 said:

I have no idea how to test this mod, set it up, etc

Happy Software 5.2 has an auto-speed test in its "DIAGNOSTICs". 

 

 

If you own an original disk with 21 sector tracks for protection, try to copy it. Some of the SynXxx produtivity programs for example. (But there are also releases with 30+ sector tracks which I doubt will work.)

Edited March 9, 2023 by DjayBee

[burkhart87]

9 hours ago, DjayBee said:

Happy Software 5.2 has an auto-speed test in its "DIAGNOSTICs". 

 

 

 

That's the software version I used for the RPM tests above.  I'll take another look, but I don't remember an autospeed test.  The Happy 5.2 RPM test worked with the autospeed mod unsoldered, so I think it's a straight RPM test for happy-modified drives and not specific for testing the autospeed mod.

 

**Edit**  It is a speed test, see below.

Edited March 9, 2023 by burkhart87

[burkhart87]

I think I understand now 😃

 

While running, the 5.2 RPM test can be used to switch between two different RPMs via the SELECT switch, as it says right there on the screen .  One RPM (STD or standard) is presumably set via the pot on the power board and the other (slow, or OPT) set by the pot soldered onto the back of the side board.

 

Standard speed....press Select and.....

...slow speed.

[burkhart87]

Leads 1 and 2 of the autospeed pot are both soldered to a trace from pin 13 of the 6532/CO10750.  Lead 3 of the autospeed pot is jumpered to pin 7 of the LM2917 on the power board.  Both connections are in pics found above.  This looks like all that is required to install the autospeed mod.  Then use the Happy 5.2 software as above to set the speeds.

 

On 3/9/2023 at 2:30 AM, DjayBee said:

 

 

If you own an original disk with 21 sector tracks for protection, try to copy it. Some of the SynXxx produtivity programs for example. (But there are also releases with 30+ sector tracks which I doubt will work.)

Music Construction Set (EA)?

Bank Street Writer (Broderbund)?

 

Most of my other original disks are games.  I'll take a look.  It's not really a practical use of a Happy drive any longer as all of this stuff has been cracked already.  It's only for my own curiosity and a bit of digital archeology. 😃

[+DjayBee]

54 minutes ago, burkhart87 said:

Music Construction Set (EA)?

Bank Street Writer (Broderbund)?

MCS' longest track has only 19 sectors and Broderbund used only 18 sectors for its earlier titles.

 

You could check if you own one of these titles or perhaps one with 20-sector tracks. Tracks with up to 19 sectors can be written without slowing down the drive.

When the Happy software reads a disk and needs the slower speed, it will tell you in its screen output. So try copying a "candidate" and watch.

 

Disclaimer:

Most if not all Synapse titles with this 21-sector protection also have a weak sector for protection. Since the 810 Happy cannot create weak sectors, you must switch Happy Backup to "HWA Mode" for emulation of a weak sector. This mode does NOT work with all weak sector disks because it creates multiple different duplicates of the should-be weak sector (by sacrificing other sectors on the same track) and therefore had to be adapted for every particular title.

Edited March 10, 2023 by DjayBee