Tempest power issues

ieure

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I have a non-working Tempest I picked up last year. Finally getting around to figuring out what all is wrong with it. I am new to this hobby, but pretty comfortable around electronics.

This is what is happening:

  • P1/P2 button lights on, but the game is 100% dead otherwise.
  • Spot killer off.
  • LCDs CR2/CR1 on the main and aux boards are on. I think these are just power indicators, but I'm not sure. Is that correct?
  • Loud hum from the speaker, no other sound. Sounds like a ground loop. Read that a bad big blue could cause hums, but I don't know if this would manifest this way. Stops if I disconnect J5, so it isn't (directly) the main power supply.
  • Nothing in test mode.

I adjusted the pot on the regulator board and I'm getting +5.5VDC on the +5 REG output, but only +4.4 on the PCB. I couldn't read anything with the negative lead on GND on the regulator and positive on +5 REG on the PCB connector. Schematics mention measuring the voltage between GND on the regulator and main PCB. I did this, and it was +50VDC. This seems alarmingly high, but I don't know what it means.

+5 REG lines on the harness have some repairs and I think those wires need to be replaced. Not sure how to do this — Looks like I can get some new end connectors (Molex?), solder or crimp to a new wire and string it through?

On the other hand, it feels like the regulator might be a problem. Topping out at +5.5 feels strange, and it's also responsible for sound, which is another symptom.

Ideas?
 
The basics first, I would do this

1. Unplug Game PCB

2. Test voltages at the 15 pin connector on the power brick, with the connector off. Compare to schematics

3. Plug 15 pin conn back in and test outputs from the regulator, compare with schematics.

ONLY if all the above are correct, plug in PCB and re-measure voltages at #3 above.

If voltages drop way too low, the PCB may have a short
 
(Trying to remember Tempesty stuff...)

If I remember correctly, the board takes two seperate power feeds: +5v, then a higher voltage (I want to say 22v?) for the vector generator (which gets regulated to 15 by regs on the board itself). I believe the +5v is the logic section and should make it play blind.

I would measure it using the +5v and a ground at the board. If it looks ok there check your +5v AND ground lines going back to the power supply board, but its not unheard of to get different readings considering how old and crusty the board edge connectors can get.

The fact that your p1+p2 buttons are solid lit tell me the board is at least getting close to +5v, but its not booting/running. (Another term is watchdogging). It's possible the voltage truely just is too low, but chances are the roms/cpu sockets are dirty and not making good connection (especially after moving the cab around). With the boards out you can carefully pull up each rom and the cpu slightly then push them back in to reseat them, but these are known for flaky sockets. The ROMS are the socketed chips all in the row along the one edge of the board, and the CPU is the chip thats about 3" and I think its a "6502".

On top of that...the plugs for the cable that go from one board to the other are also known culprits - but thats an easy fix...just resolder them (on both boards).

FYI - Some have luck getting these going with just basics like reseating chips, capping the power supply, etc, but these boards are pretty complex compared to others. It may help to find someone with a Tempest game that can test the boards for you, or perhaps send them to a Tempest repair guru like Talon on here for a "going through". With any luck it might just need sockets (and hopefully nothing in the vector generator).

The monitors are kind of a pain to work on but if you can solder ok they're not too bad. Just get the deluxe rebuild kit like someone mentioned before, the LV2000 upgrade, get some white heat sink compound for swapping the transistors (radio shack), and also open the HV cage and look for burnt resistors - chances are there may be some that aren't included in the kit.

Lastly - a tip regarding the rebuild kit - note what part number (P3xx) each board is and tell Bob when you order. There's a couple versions with different key parts in them.

Just pick away at it...its a pretty bad ass game once you get it working :)
 
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The basics first, I would do this

1. Unplug Game PCB

2. Test voltages at the 15 pin connector on the power brick, with the connector off. Compare to schematics

DC is fine but AC is way off. Getting ~10.4VDC on pins 1-3, but only 18.9VAC on 6/7 (should be 36). 8 gives 5.9v which is about right, 9 reads 4.5v. 10/11/13 are all supposed to read 50VAC, but only read 15.14, 7.49, and 29.29, respectively.

Edited to add: Negative lead was on pin 4 GND for all these measurements.

Does the big blue cap solve this, or should I be thinking about replacing it entirely?
 
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DC is fine but AC is way off. Getting ~10.4VDC on pins 1-3, but only 18.9VAC on 6/7 (should be 36). 8 gives 5.9v which is about right, 9 reads 4.5v. 10/11/13 are all supposed to read 50VAC, but only read 15.14, 7.49, and 29.29, respectively.

Does the big blue cap solve this, or should I be thinking about replacing it entirely?

The 18VAC is correct from both lines of the 36VAC - to gnd. The centre tapping is grounded, leaving 18VAC from gnd to each.

So the 36VAC is from line to line, not gnd

Make sense?
 
The 18VAC is correct from both lines of the 36VAC - to gnd. The centre tapping is grounded, leaving 18VAC from gnd to each.

So the 36VAC is from line to line, not gnd

Make sense?

Makes perfect sense. The other values add up to +50, so that seems okay, too.

On the regulator, I'm measuring 380mV on J10 pin 7 and 270mV on pin 10, way off the +15 / -15 they should be. Everything else seems okay. Checked the test loops, and the +10.3VDC test loop is measuring +13, the +/-22 are at +/-25… Probably all okay. Pulled the board to look for burned traces or bad solder joints, but everything seems fine.

R29 looks burnt, but meters okay.

I see that Q10 and C25 are on the +15 line and Q11/C26 are on -15. I pulled out the board and I cannot for the life of me locate any of them. Found Q2, Q5, Q7-Q9 on the big heatsink, but no Q10/Q11. C18-C24, C31, but cannot find C25/6. I don't see any traces under the heatsink except for the components sticking through — Q1 and something else.

What am I missing?
 
Double check you have the correct AR2 board in the machine

see here
http://www.elektronforge.com/AudioRegs.htm

Says Regulator/Audio II, p/n A035435. Looks like like the photo linked on that page. There's no -02 or -04 or anything. Handwritten on the board is 38-2961-02, so it sounds correct.

Looks the same as this:
AR2_2.jpg

… But that photo isn't large enough to read the labels on.

This is mine:


 
Makes perfect sense. The other values add up to +50, so that seems okay, too.

On the regulator, I'm measuring 380mV on J10 pin 7 and 270mV on pin 10, way off the +15 / -15 they should be. Everything else seems okay. Checked the test loops, and the +10.3VDC test loop is measuring +13, the +/-22 are at +/-25… Probably all okay. Pulled the board to look for burned traces or bad solder joints, but everything seems fine.

R29 looks burnt, but meters okay.

I see that Q10 and C25 are on the +15 line and Q11/C26 are on -15. I pulled out the board and I cannot for the life of me locate any of them. Found Q2, Q5, Q7-Q9 on the big heatsink, but no Q10/Q11. C18-C24, C31, but cannot find C25/6. I don't see any traces under the heatsink except for the components sticking through — Q1 and something else.

What am I missing?

Ok, on the AR2, have you got 36VAC on J9 (pin 4 to 5)?

Either the 36V is not getting there or Q10 AND Q11 are gone (Less likely)

See here for AR2 diagram
http://www.dsbelec.iinet.net.au/AR2_Schematic_Star_Wars_1st_Print.jpg
 
Makes perfect sense. The other values add up to +50, so that seems okay, too.

On the regulator, I'm measuring 380mV on J10 pin 7 and 270mV on pin 10, way off the +15 / -15 they should be. Everything else seems okay. Checked the test loops, and the +10.3VDC test loop is measuring +13, the +/-22 are at +/-25… Probably all okay. Pulled the board to look for burned traces or bad solder joints, but everything seems fine.

R29 looks burnt, but meters okay.

I see that Q10 and C25 are on the +15 line and Q11/C26 are on -15. I pulled out the board and I cannot for the life of me locate any of them. Found Q2, Q5, Q7-Q9 on the big heatsink, but no Q10/Q11. C18-C24, C31, but cannot find C25/6. I don't see any traces under the heatsink except for the components sticking through — Q1 and something else.

What am I missing?

When you say R29 meters ok did you mean it measures 10 ohms?

I would still replace it to be safe.

Loud hum might mean bad capacitor or rectifier (diode). You'd be able to see that with a scope. I'd recap the AR if you intend to keep the game for awhile for reliability and check all diodes for high resistance in one direction and low resistance in the other (check resistance with ohmeter and then reverse probes). Also check all wiring for good continuity.

Bill
 
When you say R29 meters ok did you mean it measures 10 ohms?

I would still replace it to be safe.
Yes, my multimeter shows it registering 10 ohms. I will replace it to be on the safe side, but it doesn't seem to be the cause of my problems.

Loud hum might mean bad capacitor or rectifier (diode). You'd be able to see that with a scope. I'd recap the AR if you intend to keep the game for awhile for reliability and check all diodes for high resistance in one direction and low resistance in the other (check resistance with ohmeter and then reverse probes). Also check all wiring for good continuity.

Bill
I don't have / have access to a scope. Is there some way to do this with a multimeter?

The hum is coming from the speaker, not any of the PS components.
 
Is it a hum or a tone? Like the test tone that the manual indicates it will make when that 1 rom is bad?
 
Is it a hum or a tone? Like the test tone that the manual indicates it will make when that 1 rom is bad?

It sounds like a 60hz ground loop. It happens when the game PCBs are unplugged, so I don't think it's a test tone.
 
It sounds like a 60hz ground loop. It happens when the game PCBs are unplugged, so I don't think it's a test tone.

Actually, I take that back. It still sounds quite like a 60hz hum, but it only happens when the PCB is connected.

Also, no neck glow on the monitor at all. I'm not sure where to go from here. Anyone know where I can find Q10/11, C25/26 on the aux PCB?
 
Hum could be a bad big blue (giant cap on power brick), or a bad transistor on the ar2 (see if any are getting really hot).

Hum could also possibly be the ballast for the marquee light...slide out the drawer and unplug the light to see.

Monitor most likely needs a full cap kit like I mentioned earlier...it probably has blown fuses.
 
Hum could be a bad big blue (giant cap on power brick), or a bad transistor on the ar2 (see if any are getting really hot).

Hum could also possibly be the ballast for the marquee light...slide out the drawer and unplug the light to see.

Monitor most likely needs a full cap kit like I mentioned earlier...it probably has blown fuses.

Yeah, F100/F101 looked okay to the eye, but are blown when I check on the meter. I was hoping to have a bit more to show before I pulled the monitor and recapped… At least know that the boardset was working.

Looking around more, I see that there are no wires on P10 pins 7-10… So the schematic is flat wrong when it says there should be +/-15v on those pins, it's got nowhere to go. So based on that, the power supplies are working fine. Still low voltage on the board's +5v test loop. Guess I'll replace those patched wires and see where that gets me.
 
I see that there are no wires on P10 pins 7-10… So the schematic is flat wrong when it says there should be +/-15v on those pins, it's got nowhere to go.

Whoa there !! :)

The schematics are right. Maybe you are at the wrong board or plug, earlier it was suggested J10 / P10 Pins 7 and 10 were for the -15V and +15V. This is on the AR2, somewhere you mentioned parts on the Aux board.

I hope you were looking at the AR2 plug J10/P10 pins 7 and 10
See here (regulator audio II - Top RHS of diagram)
http://arcarc.xmission.com/PDF_Arcade_Atari_Kee/Tempest/Tempest_DP-190-2nd-01B.pdf
 
Whoa there !! :)

The schematics are right. Maybe you are at the wrong board or plug, earlier it was suggested J10 / P10 Pins 7 and 10 were for the -15V and +15V. This is on the AR2, somewhere you mentioned parts on the Aux board.

I hope you were looking at the AR2 plug J10/P10 pins 7 and 10
See here (regulator audio II - Top RHS of diagram)
http://arcarc.xmission.com/PDF_Arcade_Atari_Kee/Tempest/Tempest_DP-190-2nd-01B.pdf

Okay. Here is what I see.

From the schematics:
zX3L9.png


On the AR2 board:

attachment.php


That's P10, which plugs into J10. There are no leads on pins 4, 7, 8, 9, or 10.

I'm measuring nothing on 7 or 10. +12 on pin 4, -5 on pin 9, even though there's nothing to pick them up on the connector. Is my wiring harness that screwed up?
 

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I should also mention that while I had the AR2 board out, I tried to trace back pins 7 and 10 of J10 to see where C25/26 and Q10/11 were. They don't seem to go anywhere — Just to an empty block near J10.
 
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