Happ USB/PS2 Trackball Board Problem

[Dmod]

I've been hit by the dreaded bad board problem on my 3" Happ USB/PS2 trackball.  Mine seems to have a bad opto on the main board as it fails only in the vertical direction.

I've been unable to find a source for the optos (ALPR0J0001-HC) so it looks like I'll have to buy the replacement boards.

Has anyone figured out what's changed from the old boards to the new boards?

[u_rebelscum]

I've been hit by the dreaded bad board problem on my 3" Happ USB/PS2 trackball.  Mine seems to have a bad opto on the main board as it fails only in the vertical direction.

I've been unable to find a source for the optos (ALPR0J0001-HC) so it looks like I'll have to buy the replacement boards.

Has anyone figured out what's changed from the old boards to the new boards?

Err, I haven't seen either of the USB/PS2 boards but AFAIK, it's the board that usually goes bad, not just the optics.  Again no details, but the difference of the new boards are they don't fail like the old ones.  I'd love to hear about the actual differences (is it better chips, better solder, higher quality circuits?).

I know, not much help.

Someone with more knowledge?

[divemaster127]

I was told by happ revised with new chips
dm

[Dmod]

Err, I haven't seen either of the USB/PS2 boards but AFAIK, it's the board that usually goes bad, not just the optics.  Again no details, but the difference of the new boards are they don't fail like the old ones.  I'd love to hear about the actual differences (is it better chips, better solder, higher quality circuits?).

I bought my trackball less than two years ago and the main board is screened "Rev. D" which I think is the same revision as the replacement boards that have gone out.  I've ordered a replacement board from divemaster so I'll report on whether there's any detectable differences in the components.

FWIW, I measured the optos on both boards while removed from the trackball and plugged into the USB port.  The voltage across all the photodiodes were similiar (~1.0-1.2 V).  In this configuration all the phototransistors should be powered on with a low voltage drop across the terminals.  The main board voltages were around 2.5V and 3.5V... way too high I think.  The remote board was lower... around 1-2V.

Each phototransistor is wired directly to +5V and the input to the Holtek USB encoder.

So I think this points to a problem with the optos or the Holtek.

[Dmod]

I got my replacement board from divemaster today.  The good news is it worked on installation.  The bad news is I'm even more convinced the problem is with the optos which are unchanged between the two boards.

I'm attaching pictures of the boards.  The old board is on the left.  The new board is on the right.

Although both boards carry the "Rev. D" identifier, they are clearly different board revisions.  The only difference I could find (besides the screening) was that the crystal traces are now routed on the bottom of the board instead of the top.

As for parts, R1 was changed from 1200 ohms to 680 ohms which doubles the current into the diode side of the optointerrupters and could help in driving more light out of the diodes.  The crystal package was changed as well and no longer bonds to the top of the board.  The part number is changed from T06.000 to 6B0000B8AB.

The opto (ALPR0J0001-HC) and USB controller (HT82M98A) are unchanged between the two boards.  This is disappointing because I still haven't found a source for replacement optos.

On the new board, the voltage drops across the phototransistors are 0.5V and 0.9V, compared to 2.5V and 3.5V on the bad board.  The high voltages indicate that the phototransistors are not being driven 'on'.