I was trying to track down some lighting issues (in test 1 mode) and I noticed the dreadful smell of "hot electronics". I busted out the IR thermometer and found that several components on my Processor PCB were very hot. Specifically, three board components were reading hot:
1) C17 (0.1uf 25V ceramic disc capacitor) reading 500F+
2) CR1 (Diode, Transient Supp. P6KE18) reading 250F+
3) C1 (tantalum, 1uf 35V axial capacitor) reading 250F+

I assumed that those are not normal operating temps, so I need to replace something. I just don't know what to replace, and what order to start replacing things.

I checked the fuses on the Power Supply Assembly (F1-F6), all are good and properly rated for their position.

If you look at the schematics from the manual, it appears that all three of these components are directly "downstream" from J9, which provides logic power and logic ground (see image below).

Guesswork:
1) J9 sending too much power to the board. But wouldn't a fuse blow?
2) Improperly fused. But I checked the fuses and they are right.
3) Bad component. But which one? And which do I start with?

If these components were easy to find, I would just replace them all. But, I'm having trouble finding the correct components. And, maybe it isn't any of the "hot" components that are causing the problem (though they may all be damaged by now and should be replaced anyways), so I'm not sure what else I should inspect / replace.

There is a resistor, R1 (4 OHM, 10W) in the circuit, so maybe that is the failing part allowing too much energy through to the components?. I don't know if that is reasonable - not an electronics whiz.

Any suggestions would be appreciated. Note: The machine works and plays without issue, but I'm thinking that the temps of these components is not normal so this is hopefully a preventative repair.

Oops... I'll try attaching these images again...

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Board reverse:

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Bump

So, not to be annoying, but... bump. Last try before going to Fry's and buying a bunch of components I probably don't need. Any takers...?

G-P-E

R1 does not get hot (until C17 starts getting really hot, then all the surrounding components catch some of that heat, including R1).

I'm new to this, so how can I identify the "signal ground" to check the LM323K ? As in, where do I put the black lead on the board? Also, another dumb question: I'm checking the voltage with the power on, right? (Did I mention I'm new to this ).

Travish

I know the picture of the back of the board looks like there is missing solder around that C17 joint. I must have looked at the picture then looked at the board 5 times before I was sure I wasn't seeing things. It's just the way the light is in the picture - freaky, actually. There is a normal amount of solder on that C17 joint. But it looks missing in the picture - I see why you'd think that. I'll post a new pic to show it from a different angle next time I take the board out.

After 2 minutes of being powered up:

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barakandl
Last night I pulled the cap completely off. I'm not sure what these numbers mean on my DMM's capacitance test. The value slowly increases the longer I leave the cap in. Does this help answer the questions you asked?

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Ooops, wrong mention tag.
@barakandI

G-P-E
I'm not sure I performed the measurement correctly, but here's my results. Also, I noticed that when I was taking the AC measurement, just touching the lead to the signal ground area was sufficient to read ~0.275... does that seem right?
I should add that I reattached C17 before performing the test.

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barakandl

I'm not sure what the "+5vdc" is. I'm attaching some pictures that might help you help me answer your question:

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Zitt
If you look at the images I just posted above, I believe those giant blue cylinders are the filtering caps you were referring to, yes? I usually don't mess with those because I'm a big chicken. Is there some test I can do (that probably won't kill me) to check those filtering caps?

How might one go about solving the heat problem if it is the ground plane? New board, or is there something I can repair?

Also, I said above that everything else was working, but I forgot to mention an issue I'm having with a non-functioning pop bumper. I started another topic for that issue, but just wondering if anyone who has been posting here sees a connection between the heat issue and the this other issue I have with the same machine.

https://pinside.com/pinball/forum/topic/atari-airborne-avenger-pop-bumper-not-working#post-3856489

Thanks to everyone who contributed helpful posts - I greatly appreciate the time you spend helping me.

I thought about adding a processor / power supply fan from a PC too. Good point.

I'm not sure what "normal" heat would be, but the area by the cap in question gets above 500F within 5 minutes - don't know how hot it will get at max. I usually solder on the board around 670F, so my concern is that if this isn't normal heat, it's going to start damaging other components, or at least soften their joints and make them come loose. Besides the fan, if there aren't any other DIY solutions, I guess I'll just run with it (and never leave the game on if I'm not home ).

Thanks everyone!

G-P-E :

I bugged a guy with a Middle Earth about this:

his response:

So, I think he's talking about what is labeled R1 on my board (the boards are similar enough, I think). *How* hot his gets, idk.

Also, thanks for showing the math on R1 wattage / heat - that helps me understand where the heat could be coming from. Your explanations are very clear and helpful.

I'm not sure if I'll tackle that next step that Zitt and you have cautiously recommended just yet. However, I'm having trouble with a pop bumper and no bites on the forum. Would you mind taking a look at my post if you have time?
https://pinside.com/pinball/forum/topic/atari-airborne-avenger-pop-bumper-not-working

G-P-E Zitt barakandl Travish

Well, I guess I need to apologize for vexing the posters on this thread because I inadvertently sent you on a wild goose chase, I guess.

I was concerned about the high temps from C17, etc. I *really* did smell hot electronics, which prompted me to check the board in question with my (non-invasive IR) thermometer and make this original post. However, something weird happened as I continued to work on this Atari. I was working on another issue while the machine was powered up and, to confirm my previous temp measures, I shot the IR at the suspect area from a different angle and got much lower temp values. This threw me off, so I dug out the temp probe accessory for my DMM (a feature I thought was useless before... you never know, I guess). The surface measurements with the DMM probe were *MUCH* different than my IR thermo. Weird. I kept testing different areas and found that:
1) The surface probe didn't show anything near the temps that the IR was showing.
2) R1 was, in fact, the hottest part ( G-P-E and others told me that R1 was the main suspect, but I thought the IR was showing hottest on C17).
3) The IR thermo has an issue; the laser pointer is not "sighted in" for close measurements. So, when I thought I was measuring C17, the IR lens was absorbing R1 heat. That is, R1 *IS* the hottest component on the board. (Thanks guys).
4) By measure of the DMM temp probe (and also, admittedly, one of my meat thermometers), nothing on the board gets above 160F. That is a huge difference from the IR thermo giving readings above 500F.

In conclusion, I should have thought:
1T) "These temps are way too high; no way I'm getting good measurements."
2T) "Maybe I should verify this data through another method..." (duh).

I'm attaching some images. I turned the machine on for 5 min., and then I took these temp measurements with the IR and the DMM surface temp probe immediately after powering down and unplugging the machine.

There is still the mystery of what the board / R1 was doing to the electromagnetic spectrum to generate the temps the IR was reading. I mean, the power was off and the IR was still reading really high temps... but... why?

Anyway, I found a "Bermuda Triangle" for IR temp measures on Atari boards - maybe this thread will be useful for future Atari Airborne Avenger users.

Thanks again to everyone who was scratching their head on this.

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And, for those who were concerned about J9, I reflowed / removed solder for that header (thanks for pointing out how jacked up J9 was). I tried my best to clean it up:

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