Tempest AR2 -5 issue

debaser138

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I've got an AR2 board in a Tempest that I rebuilt yesterday. Everything is good except the -5 is measuring over -15 inside the cab with the game board hooked up. Without the game board hooked up, it's measuring just under -15. Before you ask, I'm not sure what is was measuring before the rebuild as I didn't test it.

Now the really weird thing is that I used Dokert's AR2 test harness with the same power brick and the AR2 in the cab and the -5 is just fine. I see he used resistors to simulate a load.

Any ideas what could be going on? I think I may have some spare 7905's around, I just have to dig them up.

Rodney
 
Sounds like you may have an open break in the -5V from the AR-II to your board. Try doing a continuity check.
 
Sounds like you may have an open break in the -5V from the AR-II to your board. Try doing a continuity check.

Do you mean in the wiring harness in the cab from the AR2 to the game board?

I've tried this same AR2 and Tempest game board in two different cabs and it shows -15 in both.

Rodney
 
It could be a problem on the AR itself. Test from pin 3 of the 7905 to J10. It could be a bad solder joint or bad molex pin. Also make sure the case of the 7905 is isolated from the heat sink with an insulator and nylon screw.


Do you mean in the wiring harness in the cab from the AR2 to the game board?

I've tried this same AR2 and Tempest game board in two different cabs and it shows -15 in both.

Rodney
 
It could be a problem on the AR itself. Test from pin 3 of the 7905 to J10. It could be a bad solder joint or bad molex pin. Also make sure the case of the 7905 is isolated from the heat sink with an insulator and nylon screw.

From leg 3 of the 7905 to pin 9 of J10 it's good. The 7905 has the original rubber insulator with a nylon screw and doesn't show continuity with GND so it should be good.

I'm wondering if something on the game board could be causing this? If I test it with Dokert's AR2 test harness, it shows a good -5v. If I plug in the boardset, it shows -15v. Without the game board connected it measures around -14, which isn't all surprising since there is no load on the AR2 board.

In looking at the pinouts for Tempest, it doesn't appear to use -5 on the game board. Is this correct? If it is used, what exactly is using the -5? I'm assuming running the board at -15 (if Tempest does indeed use this voltage) could fry something.

It's a brand new 7905 but I think I'll install a new one and see if anything changes.

Rodney
 
Last edited:
Ok just installed a new 7905 and the -5 is dead on now. So it looks like the new 7905 was either bad or didn't like working on an AR2 board.

Rodney
 
Don't hold me to this (and I'm too lazy to pull schematics)....I don't think Tempest uses the -5VDC line.......so, it's not loaded.

Edward
 
Don't hold me to this (and I'm too lazy to pull schematics)....I don't think Tempest uses the -5VDC line.......so, it's not loaded.

Edward

I didn't think it did either as the pinouts don't show anything with -5v. Didn't have the schematics handy to check.

Rodney
 
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