Atari 1050 drive not spinning...found unidentified upgrade

[Atari_Gregory]

Noted Atari 1050 drive not spinning (drive belt on and spin freely by hand)....further inspection revealed unidentified upgrade.

 

Any tips to fix issue and identify upgrade?

 

[+Nezgar]

Can you take a better picture of the board from the top so the chip numbers are readable? Or just indicate what the leftmost chip there is...

 

My guess is that PCB is either a clone happy or duplicator board, and since U8 has double-stacked 6810 chips, it may have also had a switch to toggle to run as a US Doubler compatible mode...

 

I can see the EPROM is a 2764, which would be the size to house only a Happy or Duplicator Rom, not also the US Doubler ROM. Can you check if there is another ROM present in the U10 socket?

 

 

As far as troubleshooting goes, if you have another 1050 I'd probably start by returning it to a stock configuration by swapping in an original ROM (U10) and 6507 CPU (U9) and possibly single 6810 SRAM (U8) to rule out the upgrade...

[stepho]

No sticker on the EPROM window.
Possibly UV light has erased the program.

[Mclaneinc]

Looks very much like a Lazer happy clone..Chances of the eprom being UV erased are small, unless the drive was sat with no top cover on then it's unlikely (but possible)

[+kheller2]

It’s another copy of these 

happy clone that can swap between ROMs (but yours is hard wired to only one). 
 

and another thread:

 

A first thing to do is to make sure all your drive connections are correct where they plug in.  Does the head move on power up or any signs of life when turned on?

 

Edited May 27, 2022 by kheller2

[cwilbar]

8 hours ago, stepho said:

No sticker on the EPROM window.
Possibly UV light has erased the program.

Does anyone actually have any experience of UV light turning corners and homing in on an EPROM inside a disk drive and erasing it ?  ?

I've seen countless EPROMs over the years with no stickers inside a device....  no problem.

And if you put one in direct sun, my guess (not tested) would be that it would take days before bit rot set in compared to the concentrated exposure they get in an eraser... which takes 5+ minutes to properly erase an EPROM.

 

I still usually put stickers over mine, but I don't immediately suspect one that doesn't have one. 

 

But in this case, I think the best way is to move it back to stock, and troubleshoot from there.  Upgrades add an additional variable to troubleshooting.

 

If that isn't possible I'd use a logic probe or scope and look at the clock, reset, address, and data lines of the CPU to try to determine why it isn't running.

 

[TGB1718]

Judging by the light covering on a lot of the chips (they look a bit grey), it may be it hasn't been stored in a nice dry place,

maybe start by cleaning and reseating all the socketed chips. 

[StickJock]

51 minutes ago, cwilbar said:

Does anyone actually have any experience of UV light turning corners and homing in on an EPROM inside a disk drive and erasing it ?  ?

Back in 1990, my manager told me about when he was trying to diagnose a flaky prototype.  Every time they leaned over the machine to probe some pins, the system started acting properly and the flakiness went away.  When they sat back, the problems returned.  Eventually, they figured out that it was the fluorescent lighting interacting with the uncovered eprom.  When they put a label over the eprom window, the problems went away.  Weird, huh?  Ever since, it's always been procedure to stick a label or tape over the windows every time.

[1050]

I remember a short piece from Intel back in the day stating that it would take 7 years of 24 hours sitting in standard office florescent lighting to have any effect. My observation is an encounter with static electricity will make them do anything conceivably possible, no waiting at all.