(Topic ID: 244565)

Bally EE, Lamp Driver SCR, Substitute 2N5064 for 2N5060?

By Pinslot

4 years ago

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8 posts
3 Pinsiders participating
Latest reply 4 years ago by slghokie
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Hi,

The 9000 light on the bonus doesn't work. Bulb and lamp holder are good. No voltage is getting to the lamp holder so I'm guessing it's connector 17 on J1 of the lamp driver board or Q13. The schematics state I need SCR 2N5060. I dug deep into my pinball toolbox and found a 2N5064. I googled it, but this is literally Greek to me (please see the attached image), so I turn to the electronics experts here.

BTW I determined that Q13 is bad by setting the DMM to diode/continuity and touching the two outside legs. There is no continuity. The other SCRs have continuity, so that means q13 is bad, right?

Looking forward to your input.

Stefan

BALLY_EE_SCR (resized).png

Pinwiki has a good breakdown on this. Just went through this on a Bally Beat the Clock... 5.4 Lamp Problems
Like the prior game system, Bally 6803 games did not use a lamp matrix. All controlled lamps are turned on via SCRs (silicon controlled rectifiers, either 2N5060s or MCR-106s) on the MPU board. The SCRs on the MPU must be refreshed (turned on) at 60Hz since SCRs turn off when the AC sine wave passes through zero (called the zero cross).

The usual techniques for dealing with lamp problems should be employed.

Lamp always on

It's probable that the associated SCR is shorted on.
Lamp never on

Verify that the lamp is good by testing it in a working socket (like the backbox).
Verify that the lamp socket is good by jumping from a known good lamp socket to the suspect socket. If the lamp then lights, the socket and bulb are good.
Verify that the wire has not been severed by "buzzing" between the lamp socket and the associated lamp drive connector on the MPU.
Verify that the connector is working correctly by "buzzing" from the associated lamp drive SCR on the MPU to the lamp socket.
Test the SCR using the diode test.
Verify that the SCR is being turned on by the 4514.

Jumper it to another known working bulb in test mode. If it lights then the bulb and socket are likely good. Then trace if you have continuity to the driver board. If not check the connecter that plugs into the board. The press in wire connections are the worst and sometimes it can just be that. If you have continuity and it still does not work then it is likely the SCR. Sometimes the diode can be bad, if you have them at the socket, and usually you will have 2 lights messed up controlled by 1 SCR (phase A and B). But depends on what era game you have.

Sorry, as to the swap-ability, there is another thread that says yes...https://pinside.com/pinball/forum/topic/2n5060-can-it-be-replaced-with-2n5064

Thanks a million! I'll try that.

MCR100 is a good sub too.

Thanks for all hints.

So, I took out the lamp driver board and measured the SCRs. This time Q13 gave the same readings as its neighbours. As the soldering iron was hot and ready to go I carefully reflowed Pin 17 on J1 and also re-did that connector.

I reconnected everything, fired up the game and made sure I had 9000 bonus. Again the light stayed off Both the bulb and lamp holder are new, and Q13 was good so I suspected my poor soldering skills were at fault. I wiggled the lamp holder: no light. Then I took a small screwdriver and pushed the ground wire hard against the base of the lamp holder.... And there was light! Doh! I simply squeezed the ground wire between the screw and the lamp holder and now its fixed. Really goes to prove that taking readings on electrical components in the game can lead to the wrong conclusions. Plus, I need to get a better soldering iron. The tip can't get a lamp holder base hot enough for the solder to "take" properly.

Thanks again for your help.

Pinslot also forgot to reference you to this site for TECH CHARTS. These can be SOOOO valuable when working through lamp/switch issues http://www.pinballrebel.com/pinball/cards/tech_charts.htm

Glad it was a "simple" fix. BTW, what game are you working on?

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