PAT9000 internal problem with power trip?

kiphartzell

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I have a PAT9000 that I am trying to get working. I recently acquired this unit and was able to briefly power up a known working Tempest board set for about 10 secs (working video on vector monitor) after which the PAT9000 now seems to constantly activate the power trip circuit. Since then, I haven't been able to get game power to work and according to the manual, all my voltages are faulty since all LEDs are lit when main power is on and game power is off.

My initial investigation found a burnt LM337 on the power trip card which has been subsequently replaced. I also recapped this card.

Even with a new LM337, I still have the voltage LEDs lit with game power off. When I try to apply game power (even with no game board hooked up) the Power Trip relays will not stay energized (will only briefly energize with the momentary toggle of "game power on" ). Looking over the schematics, it leads me to believe that there may still be a problem on the power trip card since that seems to drive the game power relay signal. An alternative may be a problem with the Switch Control PCB which seems to drive the +22v for energizing the coil in the relay.

Any suggestions on things to look at or try? I am not very familiar with the normal operation so I am just going by what the manual states as expected operation. Thanks.
 
I've got two working Pats. When main power is initially turned on, all the power indicator LED's light. When I turn on Game A, then Turn off Game A all the LED's go out.

As for the power trip problem. The only time I've experienced it so far was when a game actually had a short. Never had a problem with it tripping and no game being connected. Also when you say no game, you don't have a plug on Game a correct?

Let me get some more coffee and look at the schematics a bit.
 
According to the manual. When power is tripped, or I would assume turned off on game A (not main) then any remaining led indicators left on indicate the area where the power fault occurred.

The LM337 is for the -22 v

I would adjust both the +Var and -Var to make sure you have +-22v set correctly.

I would also check/replace both the 1ohm 5 watt resistors on the 22v lines.
One of my pats those resistors had gotten hot, and was causing me problems.
 
Talon, I was aware that you had some PATs from some of your other posts and I appreciate you taking some time to share your knowledge/experience. The PAT is new for me so even understanding "normal" operation mode requires some learning. Your first question, I see the same general power trip occurring whether I have a tempest board attached or just applying game power without a game plug attached (I have been leaving the side connector attached to the PAT since this is just a straight pass through to the 44 pin which is not connected to anything).

I'll also take a closer look at the -22v circuit on the power trip card and see if I can dig up some 1ohm 5w resistors to replace the two on the board. Other then the fried LM337, nothing else appeared hot/burnt, but worth an investigation. I do measure +5, +12, & -12 on the power trip board at the test points. I also see ~24v on the switch control board and at both sides of the relay coils (yellow/red wires & control wires). This makes me think that the relay coil is activated when the power trip card drives gnd on the RELAY GAME A/B to K1,2,3.

One other thing. So I am glad to hear that power LEDs are lit when just powering up the unit (no game power). The LEDs generally go off after I try the Game Power without a game though sometimes one or two of the LEDs stay lit, though not consistent which ones each time and sometimes they are all off. Again, not pointing to a specific fault.

Something worth noting..... this PAT was previously wired up with an external power supply for +5v & +12v instead of using the Reg/Audio II (and was working properly) including a relay to shut off the supply if 10.3v was shut off to the Reg/Audio II card. Supposedly, this is a more robust solution since the Reg/Audio II can be under powered for some games. If I can't figure out what is happening with the power tripping, I may try to reverse the power supply hack (though I was not the one that did it). I am just a little leery with how this hack works relative to what normal operation is with the Reg/Audio II board.
 
I would also remove the left hand 44 pin plug. That's where the 22v goes for games. Its possible there is a short in the wiring, or the plug itself.

I've never heard of such a power mod before, but then I've only been using mine for a short time as well. Never had any problems with the AR board. But it has been modified.

There is also a Tech Tip TT-007 from atari for a few fixes. I'll scan it in.
 
Nice, I'll confirm when I get home, but the Tech Tips explain at least two of the mods I saw on the Reg/Audio II board (and didn't understand). This too was bugging me because I have rebuilt several of this cards and never saw these mods before (the +/-15v regs and the extra resistor in parallel with the resistor in the big heat sink).

I'll also disconnect the right side Game A cable (44 pin) to see if that makes a difference.
 
Not much time to work on this last night... but did try applying Game Power without the rightside Game A cable attached. No change in symptoms. Though I did confirm that if I turn game power on, then switch off that all the power LEDs go off and stay off until I try to apply game power again.

One question; Without a game attached (including any plugs/cables), should the power LEDs stay on when the Game A Power switch is in the 'ON' position? My unit has power LEDs lit during the momentary switch position, but won't stay lit when in 'ON' position (perceived power trip issue).
 
Yes, It goes something like this.

Main Power ON LED's On
Game A power ON LED'S On
Game A power Off LED's Off. Some are a little slower to blink out.
Now you will have Main power on, and all LED's Off.

It could be that Game A power switch is not fully toggling. Make sure that switch goes all the way down, before flipping it up. It has to go past center to reset the power trip. If it doesn't completely reset after a power fail, it will have problems.
 
Okay, Just to Clarify. My Power LEDs go on when switch is push up into the momentary switch state (the manual indicates that this state bypasses the power trip circuit when in this position), but my power LEDs go off when the switch settles into the middle 'ON' state. From what you said, your LEDs stay on when switch is in the middle 'ON' position too. Again, indicating an issue with the power trip circuit.

One thing I can try is to swap the Game A power switch with a different one and see if this switch itself is faulty.

I am still thinking a problem exists with the power trip card and something besides the LM337 is fried. Can you confirm that the K1 relay has ~24v at both legs of the coil (W/GY & Y/R) when Game Power is off? What does W/GY measure when Game Power is turned on. I believe one of the 2N6044s on the power trip card should drive this to GND to activate the coil which in turn passes the power through the relay (particularly the 10.3v) to the Reg/AudioII card.
 
I can check the coil voltages when I get home tonight.

To turn game A power On, are you Flipping the switch up? or Down and releasing?

To reset power trip, the switch should go down. Then when you want to apply power the switch goes up.

The middle position/mom is for the trip reset. You must always go past it to the down position to reset. Then you can power back up.
 
Main power on, and Game power off. K1 relay between (W/GY & Y/R) is zero volts. Game A power on +24v

On Q2 2n6044 Main power on, Game Off. Gnd to Base ~.16v Gnd to Collector ~25v
Game A on, Gnd to Base ~1.3v Gnd to collector ~.7v
 
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Thanks for the voltages. The +24v across the coil when charged is black lead on W/GY and red lead on Y/R? What I measured was the Y/R to general circuit ground to check if the coil was getting the 24v fed. This told me that my problem is not with the +22v supply voltage from the Switch Control card, but the Game A Relay signal from the Power Trip card. BTW, when I measured from general circuit ground to the W/GY with game power off, I measured +24v too which must be the bleed through the coil. This makes sense since I think the 2N6044 drives the circuit to GND to close the DC circuit and charge the coil thus passing game voltages to the game card.

As for the game power switch, it starts the down position (perceived off), I toggle if all the way up and then let go and it settles in the middle position (which for me does not keep power on because the Kx coils don't stay charges). To retry, I move the switch all the way down and repeat process.

This weekend , I'll do some more circuit probing to see why the Game Relay signal is not working.

What is the extender card used for? I see it in the manual, but don't have one. Is it to extend the other cards outside the cage? It is a little hard to probe cards in the cage. I may have to rig up a finger board and 44-pin connector or something so I can test the cage cards outside the cage.
 
Yeah sounds like you've got a Relay A signal problem for sure.

The extender card is just that. Nothing but edge connector, and edge connector socket to allow you to take readings on the boards etc.

I may have an extra one, I think they are pretty common you might be able to find one.

Yeah it the game A power switch is going back to middle it's definitely faulting, it should stay in the up position. Have you tried Game B? It may fault because of problems with A though.
 
Would you want to sell your extra extender card or at least consider "renting" it for a month or so? Otherwise, I'll need to rig something while I debug the cage cards.... I'll also start a WTB post.... Thanks.
 
For the heck of it, with the power off, try removing and reinserting the power trip card a few times. I had a similar experience and it seemed to be related to a bad connection in the card socket. Let us know what it does afterwards.

Mark Hooks

Okay, Just to Clarify. My Power LEDs go on when switch is push up into the momentary switch state (the manual indicates that this state bypasses the power trip circuit when in this position), but my power LEDs go off when the switch settles into the middle 'ON' state. From what you said, your LEDs stay on when switch is in the middle 'ON' position too. Again, indicating an issue with the power trip circuit.

One thing I can try is to swap the Game A power switch with a different one and see if this switch itself is faulty.

I am still thinking a problem exists with the power trip card and something besides the LM337 is fried. Can you confirm that the K1 relay has ~24v at both legs of the coil (W/GY & Y/R) when Game Power is off? What does W/GY measure when Game Power is turned on. I believe one of the 2N6044s on the power trip card should drive this to GND to activate the coil which in turn passes the power through the relay (particularly the 10.3v) to the Reg/AudioII card.
 
Hey Mark, I have pulled all the cards out of the cage at least a couple of times and the power trip card a dozen times or so. No change. I will try cleaning the contacts with an eraser or some contact cleaner and see if that makes a different. I am thinking after the LM337 burnt up, several other components might be bad too. One is the 2N6044 since this drives the Game relay A signal to GND. Or the LM339 IC may now be bad. Anyway, I don't think it is a simple dirty contact issue. Thanks.
 
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