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Bally Solid State Feature Lamp Issue


poidapoida

Question

I have two feature lamps out on a Bally Fireball 2. I got what I think are the equivalent SCRs from Jaycar to replace the suspect ones. Before replacing the SCRs I tested the lamp socket and bulb by jumpering them to another feature lamp and tested continuity from the scr to the lamp and both were good.

 

The 9k Doomsday bonus SCR is a 2N5060 which I replaced with a ZX7010 from Jaycar and the lamp now works.

 

The other is the left Fireball bonus which uses MCR 106-1, but you can use MCR106-x and they will work apparently. So I replaced it with a ZX7006 from Jaycar. https://www.jaycar.com.au/c106d1-400v-4a-scr-to225aa/p/ZX7006 but the lamp still doesn’t work. I tested the new SCR using the diode setting on a MM and got just under .6v from cathode to gate but no reading the other way where it should have between 1.4v and 1.6v

 

I then pulled a MCR106-1 from the board that wasn’t running a lamp, tested it good, and then installed it. The lamp still does not work. Not sure what to test next to find the issue. Is it possible that the U chip would fail on one lamp, I have only seen mentioned that it tends to fail in on a group of lamps.

 

Cheers

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The answer is yes.

I have just had this exact same problem on a @Saber board. Paragon had a single lamp locked on and it ended up being the main chip. I have repaired a number of lamp driver boards and had not seen this before either.

Thanks for the Jaycar alternatives too :D

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The answer is yes.

I have just had this exact same problem on a @Saber board. Paragon had a single lamp locked on and it ended up being the main chip. I have repaired a number of lamp driver boards and had not seen this before either.

Thanks for the Jaycar alternatives too :D

@raysco is the master!!!

 

 

Sent from my iPad using Tapatalk

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The answer is yes.

I have just had this exact same problem on a @Saber board. Paragon had a single lamp locked on and it ended up being the main chip. I have repaired a number of lamp driver boards and had not seen this before either.

Thanks for the Jaycar alternatives too :D

 

Ditto to what Ray mentioned. I've most of my Bally SS games fitted with sockets on the "U chips" so I can just change/swap them over to narrow a problem down.

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Does the fireball bonus lamp light if you run a jumper wire from ground to the metal tab (anode) of the new SCR?

If not, you have a connectivity issue from the SCR to the lamp.

If it does, then you can manually test activate the SCR by hooking up a jumper wire to test point TP3 on the lamp driver board and then touch the other end of the wire on the gate leg of the SCR.

If the lamp does not light, then the SCR is faulty.

If it does light then go further upstream to U1.

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I tried grounding the SCR but the lamp still didn't light. I had tested continuity from the SCR to the lamp so don't think I have a connection issue. Having no way to test the U chip I put in a working lamp board from a Space Invaders. The problem lamp tested good, happy days as I thought the chip was at fault, but a burning smell appeared and it was the trace to Q49 totally cooked. I did replace the U chip from an old board with no change, but without being able test the chip I have no way of knowing if the chip was good. I think I may have done all I can and may be safer to send the boards off to Ken before I do more damage. Edited by poidapoida
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Thanks for the update.

Headers are a real fail point on these machines. I replace all pins and headers on any Bally of this era that comes to me.

However your fault description did not indicate this was where the issue might lie.

Ken is the board guru. :)

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@raysco I do have a lot to learn regarding troubleshooting and I am bumbling my way through thanks to AA and google. Even though I have new 0.1" connectors and pins I have always been hesitant to redo this size of connectors. But after seeing the difference new headers make I really should do them next. What crimpers do you use for this size?
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