Firepower Driver Bd Heat Question

bluestreak

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I've been reading Firepower threads for about 1.5 hours now but still not sure of my issue.
Every time I think I have the problem corrected it eventually comes back to haunt me.

Problem is the driver board lamp circuit transistors and power resistors become very very hot.
At the or near the same time fuse F2 for the solenoids blows. I don't know if it blows before or after the parts in the lamp circuit heat up. Parts in the solenoid circuit seem to be cool to warm, but not knowing when the fuse blows, it could have had time to cool off I suppose before I noticed it and machine starts acting crazy.
BTW, it does this while just sitting in attract mode. Never has while playing it that I recall.

I checked most, but not all of the controlled bulbs and they are GE44. I was thinking about replacing them with #47 bulbs, but anyone think that could be the issue?

I plan to recheck all of the solenoid circuits when I can get back to where the machine is, just in case there is a stuck switch or bad solenoid, but looking to see if anyone has any additional ideas as it is a 130 mile drive for me to get there.
I'm also confused as to why the lamp circuit is heating up so bad, or is that the way it is?

Thanks for any ideas.
 
Driver board heat is normal in that area, they ALL do that. A few ways to fix it, but different bulbs won't do it, it's the transistor power requirements that cause all that heat.
I have more info on my site about it.

http://www.siegecraft.us/blackknight3.htm

As to the fuses blowing for the solenoids. Are they locking up before the fuse blows? Does it still blow if you have the solenoid connectors on the driver board disconnected? Check your pop bumpers and slingshots, as those are "special" solenoids and can be activated at any time with a stuck switch. Also physically inspect all of the coils, see if any of them are baked brown or are frozen in place, that would indicate a stuck-on coil. Don't forget to inspect the flasher lamp circuits too, as those are run off the solenoids too.
 
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HHasse,

Thanks for the feedback and site link. Very good information on the driver board as I had the same thoughts on the power draw and any upgraded parts that could be put in replacing the out dated parts. I have already replaced the 2 Watt Lamp driver resistors with, I believe it was 5 watt to try to gain more heat dissipation and also raised them off the board more. Not much larger than the originals.
The replacement Transisitors are good knowledge and I will most likely do that in the future as I hate the amount of heat they are generating. Just not a good thing without heat sinks.

Regarding solenoids, I didn't notice any mechanical solenoids locking up and it takes hours or different days of being powered on for hours for the fuse to blow. I've measured the solenoids in the past and none were shorted or discolored but I didn't check the "special" solenoid switches as you suggested.
That was going to be one of my next tests, so thanks for confirming that possibility.
I'll take a look at the flasher circuits too as I was not aware a bulb could cause this type of issue, other than being too much amp draw.
This will give me a plan for my next trip up there. It's tough when it's not here when I have more time to work on it and I just don't like moving the pin more than needed.
Thanks again. Great information and help.
 
One thing we would do to help out with the heat generated was to remove every other lamp in the back box. This cuts half the draw and alot of the heat yet the game still looks well lit to the players.
 
One thing we would do to help out with the heat generated was to remove every other lamp in the back box. This cuts half the draw and alot of the heat yet the game still looks well lit to the players.

That works great for overall heat in the backbox, no doubt, but it doesn't solve the problem with the 200 degree resistors on the driver board. Personally, I prefer going full LED's for the GI lighting. With the right bulb choice it can look fantastic, and made a huge difference in heat too. Heat just plain kills the backglasses over time.

-Hans
 
cbuschief,

I guess I could see where that would help with overall heat in the backboard, but I don't believe those lights are driven off of the driver board which is where I'm having the main issue.
Good suggestion though for overall heat reduction.
Thanks
 
Apparantly I'm a slower typer than everyone else. :-0
I've triple thicked the back glass a while back so hopefully that will hold together over time even with the current heat.
I'm going to try to locate my temp meter and see how it compares to HHaase's readings to see if I'm even in the ballpark on the components.
Mainly curiousity on the temp comparison.
 
While rechecking voltages coming off the PS, I noticed there was high AC voltage on the DC circuits. Near 50+ volts as I recall. Not sure if the meter I was using is flakey or not as I tested the 2 large rectifiers and they tested OK open circuit.
I'm going to replace all of the caps on the PS as they appear original but I didn't get the value of the biggest cap in the backboard mounted on the bottom right standing upright. Thought I had a part list, but found out I don't.

Can anyone help me out by giving me the value of that cap? I think it may be C14 but not 100% sure.

A parts list would be helpfull too if anyone knows where to acquire one of those.I already have the schematics but no values on those.
 
While rechecking voltages coming off the PS, I noticed there was high AC voltage on the DC circuits. Near 50+ volts as I recall. Not sure if the meter I was using is flakey or not as I tested the 2 large rectifiers and they tested OK open circuit.
I'm going to replace all of the caps on the PS as they appear original but I didn't get the value of the biggest cap in the backboard mounted on the bottom right standing upright. Thought I had a part list, but found out I don't.

Can anyone help me out by giving me the value of that cap? I think it may be C14 but not 100% sure.

A parts list would be helpfull too if anyone knows where to acquire one of those.I already have the schematics but no values on those.

It's actually part 6C1, which only runs to the +18v circuit for the lamps. 30,000uf. You can use an Atari "Big Blue" as a direct replacement. Never seen one that really needed to be replaced though. I'd just do the power supply board caps first, and wait on doing the big blue.

It's the 12,000uf on the power supply board that usually causes that kind of AC ripple. Not the best rectifier circuit on those system 6 supplies.


-Hans
 
I had a problem once where THREE of the lamp driver transistors were shorted causing the power resistors to get extremely hot. Replacing the transistors solved the problem.
 
Thanks for the input Hhaase. I'll wait on replaceing big blue then.

Ken I went through and checked all of the transistors and had 2 of them bad, but that was many months ago and rechecked recently, but found nothing there.

If the PS Bd updates don't take care of the issue, I'll probably just have to get it back home where I can work on it during the weeknights to "get ur' done". Just hate moving these old machines around.
 
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