(Topic ID: 160589)

Apollo 13 Notes and Question


By Tickerguy

3 years ago



Topic Stats

  • 3 posts
  • 2 Pinsiders participating
  • Latest reply 1 year ago by DavidPinballWizz
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#1 3 years ago

Just picked one of these up in really good cosmetic but a bit rough electronic/mechanical shape.

The opto board in the trough was interesting. It was reading closed all the time; the traces looked ok even under high magnification. Interestingly enough when I hit the receiver with a laser pointer it went open (as it should when it "sees" light) and on reassembly for both sides it's working... Hmmm... me thinks I'll get new LEDs for both sides and expect to have to change those again. In addition the HV board for the DMD had a couple of cracked solder joints at the connector that led to the DMD going on and off with vibration; easily fixed. I may put a ColorDMD in the game eventually....

I have one obviously-burned flasher transistor at Q32 on the driver board, but no manual (yet; I have one coming) so I don't know the part number. What goes there? The rocket and two backbox flashers are inop, all others ok; there are no shorts (currently) at the sockets but obviously there was one..... If anyone has the specs on the drive transistors for the flasher block (looks like 8 channels) on the power board that will accelerate my finishing work on this one by a few days.

The short in the flasher circuit was probably related to a (very) poor coil repair made to the kickout on the rocket; the connector block was rotated 90 degrees to the right (!) and thus the connectors were hitting on the metal of the rampwork in the vicinity when the rocket cycled. The bracketing was loose enough to allow that to happen; the only thing that probably saved me from another blown driver transistor was plastic insulating sleeves on the coil connections... at the cost of fractured wiring to the kicker that only worked some of the time. Disassembly of that piece of things to get the coil out and re-form the retaining bracket so it can't do that again was "fun" in a not-so good way, but it's done and now all my toys are working.

ALL of the bail microswitches on the playfield had their bails sufficiently compressed to prevent them from registering reliably -- or at all (!) Sega, what were you thinking with this design? Meh.

I'm a Williams/Bally guy and finding that the usual Williams/Bally attention to actually being able to get at things (e.g. GI, etc) is utterly absent with this game. There are usually a few things on a WMS/Bally that are a minor pain to get to, but nothing that's ridiculously awful. Sega, on the other hand, appears to have paid exactly zero attention to being able to access anything post first-assembly on the playfield. Double-meh; disassembling multiple layers of playfield being the *only* means of getting to some of the GI doesn't push my buttons at all, but at least with LEDs I'll only do it once.

I like the game and got it at a very nice price (don't ask, it was ridiculous) from a private owner who I'm reasonably sure knew it had serious problems and no idea how to fix it..... it's back to fully playable and with the few remaining issues (e.g. the flasher circuit) fixed it'll be 100%. I've mostly-relamped it in LED and find it VERY tight on shot requirements and really maddening (in a good sort of way) to score well (plus my kid likes it), so this one is likely a permanent part of my collection. Surprisingly it still had batteries in it and there was NO sign of leakage despite the PO having no idea they were there nor any evidence he'd changed them during the time he owned it. (!!!)

#2 3 years ago

Grrrrr.... so I ripped the driver board out this afternoon and had a look at the obviously-burned transistor and the channel it's driving.

The flasher drivers are all TIP122s. 5A continuous rated, 8A surge. 65W power dissipation.

Now here's the problem -- that channel has 4 flashers on it -- 2 in the rocket and 2 in the backbox, all in parallel. ~0.8ohms cold for all of them "as wired" according to my meter between the V+ rail for them and the pin on the power board, including the wire (which is certainly good for something; a single brand-new flasher bulb out of my box shows a cold resistance of 1.8 ohms "bare" with the meter right on the bulb itself.) Of course when an incandescent lamp filament heats up its resistance goes up (quite a lot) but that's the surge load that transistor "sees" when it first switches on.

Since E = IR, E = 12 (really 12 regulated but we'll leave that alone for now) and R = 0.8 we can figure out the "shock" current to that nice switching transistor when the flasher fires.

I = 12 / 0.8 or 15. Amps, that is.

Gee, that makes the surge current on a cold flasher turn-on only twice the surge rating of that transistor, unless I'm doing the math wrong or reading the wrong datasheet (I don't think so.) No wonder that transistor cooked; it didn't even have to have a short in the wiring; expecting it to survive long at double its rated current is more than a bit unrealistic. Oh by the way, any other flasher circuit with more than one bulb on the channel is at some risk of the same thing given the TIP122s although with wire resistance and such you're probably (sort of) safe with two in parallel. There are some other doubles, but I believe that's the only quad (manual isn't here yet.)

Who was checking this stuff at Sega when they built the game?

A TIP102 is going in there and as soon as I can source 'em (Comet is out of the ones I want right now) and I'm going to stick SMD flashers in there which of course draw next to nothing. Until then the backbox ones are coming out of there to keep the surge load a bit more reasonable.

If you have an Apollo 13 and still have the factory 122s in the power board and the stock flashers in the rocket and backbox, change that transistor to a TIP122, the flashers to LEDs, or both.

2 years later
#3 1 year ago

Thank you for this post! I have the exact same problem right now but your post didn't show up earlier.
2 TIP122 later and a changed U4 now made me change the tip122 to a tip102 already.
I was in the evalution period now (only working with 2 flashers).

Strange that the other combinations don't suffer from this... because there are other 4x "#89" combinations in there.

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