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Smoking Fathom - Saucer Kickout

DRD

DRD

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Well, after doing al sorts of filthy jobs I brought fathom from the quarantine zone of my workshop into the house this morning. I checked all the fuses, changing 2 to the correct rating.

Left it running all afternoon, played about 20 games during this time, altered the dip and self test settings. All seemed fine. Changed a few bulbs. Started to finesse things like leaf switches. Turned the game off. Went to see a friend.

Came home. Another few games. All seemed well. Until smoke began to appear whilst I was playing this evening !!!!!! No fuses went. The solenoid on one of the saucers was smoking hot, as seen by the scorching here ...

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The sleeve struggled to cope, so closed up !!!!!!! ....

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Coil was hot enough to burn you, and retained heat for a long time

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I wonder whether this had anything to do with it .......

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Would you guys trust this board, of get straight onto altek ?

After all the time and effort over the past 2 weeks, this bl@@dy game now pulls this stunt.

Thank you
 

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You know what. My vector is stood next door to it. Fraction of the cost. Just as artistic. Not as well regarded, but i like it. And it does not blow up and nearly catch fire in two different places simultaneously whilst you are playing it !!!!!!

There endeth the lesson
 
Any game has the potential to do this at anytime... The board is repairable and the coil is replaceable. A modern altek might help you have peace of mind however I'd check the connector pins and replace as they may well be the cause...
 
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Do resistors just detonate like this ?? Is this a possible cause ?. Or will it likely be other components too ?

The underside of the board is ok actually

Any advice gratefully received as this is all new to me

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DRD said:
Do resistors just detonate like this ?? Is this a possible cause ?. Or will it likely be other components too ?
Click to expand...

Yes, when they have way too much current drawn through them. This is why checking that you have the correctly rated fuses in the game is important. However, the fuse for this section was either not effective (could be half a dozen reasons) or in a different part of the circuit so not doing it's job (protecting other components rather than those that went up in smoke). It's also why you should switch a game off immediately if you smell burning electronics or see any smoke!
 
Naaa, that board is repairable, I'd just clean it up and fix it, these things can happen to even a new board.

Serious question, what fuses are you using? I generally replace all suspect looking fuses whenever I buy a game, as they are often the wrong rating and/or Chinese crap.

Generally stick to brand name fuses from known suppliers like RS/Farnell not fake ebay rubbish (not saying you didn't - but that coil's had more than 2amp through it ;))


That resistor has torched itself because a huge amount of current has traveled through it, so the power transistor will have shorted from base to collector or base to emitter, pulling an amp through the base, instead of the usual few milliamps. You are definately going to replace all upstream components including the diode and IC, as they will have most likely suffered from the high current pull,

Make sure to scrub off all that carbonation as it will most likely be conductive now.

FYI you can replace the old transistors with better TIP102's

Might be worth changing the +5v filter cap while you are woking on the board too :)
 
Luke

Thanks for the guidance

I had already checked and changed all the fuses in the base of the cabinet before this episode. All fuses from Farrell. BUT I did not check the fuse beneath the playfield. It looks like it had a 4 amp one in it. After the horse has bolted, I have replaced with a 1 amp now

You are right, the transistor is fried. But the actual board tracks are all ok.

I have tip102 transistors in stock, and diodes. But I need to go to maplin to replace the carbonised resistor and buy the chip.

Do you know what I replace that IC with ? It has ca 3081 and RCA 936 written on it.

Thanks for the help
 
Hi steve. My game is a "cut and shut", with different serial numbers on the backbox and cabinet. The backbox is in much better nick than the cabinet so I haven't really paid much attention to the boards yet. I only really began playing the game (ie played more than a couple if games) yesterday to see what state the boards are in. I am on that today.

The flipper connections on the solenoid board were filthy and arcing so I cleaned then de-soldered and resoldered all the pins on the molex connectors. I did look at it under a magnifier, and gently cleaned the gaps between the pins with a mini wire brush, then pcb cleaner so I know that hadn't shorted anything

I am guessing that this game will have been stood for over ten years. The seller did enough to get it going. But it has needed a comprehensive detox of literally everything.
 
Hi,

The important part of the chip number is the 'CA 3081'. It's a 'Transistor Array' chip, containing seven separate devices, used as pre-drivers for the solenoid circuits.
 
Thanks for the advice.

I have got the game going again. New transistor and new resistor plus a good clean of the board. Have put a temp coil on the ball saucer for testing, it is only 100 turns out and is the right gauge wire

I am left with a residual problem though. The transistor that fried was dual use. The game has a solenoid expander. So the fried transistor controlled both the saucer where the coil was fried, and also a solenoid that dropped one of the inline drops

The inline drop solenoid was not damaged by the melt down. But it now fires far too often. When other solenoids correctly fire, it also fires at the same time

Might anyone know where to look for this one. Does this sound like the ca3081 chip ?

Thank you
 
The solenoid expander switches the +43v between 3 pairs of coils, thus re-using 3 drive transistors for 3 extra coils (depending on the position of the relay NO or NC)

Can you please clarify what you are saying is wrong? Are you saying that both items that share the same transistor are firing at the same time? That should not be possible as the relay should only be feeding power to one set of coils.

Alternatively, are you saying that the relay is stuck in the NC or NO position, meaning that one set of 3 coils are always firing, and the other set of 3 coils are not firing (but instead the other set are firing?)
 
Hi Luke

I have been rushing this in the hope I can get it ready for a league meeting at my house this weekend. I have six games including fathom and am borrowing two to get to the usual eight.

I cracked it. The kicker coil that fried last night had three lugs on it so had two diodes on it rather than the usual one. I only had a two terminal coil in my spares box to temporarily replace it, so I put it back with just one diode on. I did a temporary fix as i wanted to know if my solenoid board was ok (which it is). So I looked at my vector (next game out after fathom), and its saucer kickers just had one diode so I thought I would be ok.

I have now just done a hack, inserting a second diode on the replacement for the coil that fried last night, and this fixed it. Sorry to have bothered you unnecessarily.

I don't have your knowledge so rely on swapping boards and bits with a similar game to diagnose my faults. But on this occasion vector sold me a dummy.

The symptoms were that when four other coils fired on the game of during the test, another particular coil fired simultaneously and erroneously too.

Anyway thanks for all the advice guys as fathom is now working.

D
 
Don't diss the board. The stern board has better dip switches which are more clearly numbered

And you can detonate resistors on them, and the damned boards withstand it
 
the penny just dropped:rolleyes:

hopfully me and Benjarmin will be down this sunday ,
i can bring my spare driver board with me if you want me too:thumbs:
 
Yes please. Do bring one just in case. I think it is sorted, but with 35 yr old kit you just never know. I fried a tranny on my altek board today shoving it in fathom. New trannies from farnell due tomorrow to fix it. This board was in paragon, which has become innocent collateral damage in the fathom rebuild. Sorry paragon

Will be nice to see you. Have been rushing on fathom since I stepped in last week to host. Andy at mania has been extremely helpful, as have a number on the forum

I would be snookered without them
 
Just joking about the Stern board ;)

But really... PARAGON COLLATERAL DAMAGE?!?!?!? :eek:
 
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Paragon came with a snazzy altek board which has some inbuilt diagnostics

So I put on fathom hoping it might point me in the right direction of the erroneously firing solenoid. For some reason it popped a transistor and another 1a fuse bit the dust. Put it back into paragon and another 1a fuse bit the dust. This board uses MOSFET trannies, which I did not carry in stock

The cans of fuel in my garage and a full burning ceremony did seem like a possible solution at this point. You know, akin to when klf filmed themselves burning a million pounds. So this could have been the East Midlands/ poundshop version. But I counted to ten and figured that transporting them all across the lawn to my fire would have been quite tiring
 
What great service from Farnell. Bits always arrive within 24h if uk stock. Paragon happy now. Just a blown trannie
 
DRD said:
Don't diss the board. The stern board has better dip switches which are more clearly numbered

And you can detonate resistors on them, and the damned boards withstand it
Click to expand...

A later version of the Stern Sdu board (I think it's Revision 'F') extended the screened labelling to what might be considered an absurd degree, even including the 'Solenoid Select' binary codes required to select momentary solenoids, alongside each driver transistor.
 
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