Motordome
Bally, 1986I rebuilt a power supply that was blowing F6 with new parts as per Marvin's. Including the bridge and that obsolete LM323 voltage regulator with that new solid state replacement. First time I ever used one. I asked the company if I need to eliminate anything on the board if I'm using it and they never replied back. After it was completed I put it back in the game and it burned up R3 and blew the F6 fuse again. Any ideas?
20201219_085305 (resized).jpgYou need to replace resistor R3 with a thick jumper wire and remove resistor R4.
Exact same circuit mod as required on the earlier Bally solenoid driver boards when retrofitting the EzSBC regulator:
https://www.pinwiki.com/wiki/index.php?title=Bally/Stern#Driver_Board_LM323K_5V_Regulator
Quoted from Quench:You need to replace resistor R3 with a thick jumper wire and remove resistor R4.
Exact same circuit mod as required on the earlier Bally solenoid driver boards when retrofitting the EzSBC regulator:
https://www.pinwiki.com/wiki/index.php?title=Bally/Stern#Driver_Board_LM323K_5V_Regulator
So R4 is just clipped and not jumpered? I'm confused as Pin Wiki talks about R49 and R50?
Quoted from JanS:So R4 is just clipped and not jumpered?
You don't want to jumper R4 - it sits directly across the output of the regulator which you don't want to short. Just remove R4.
Jumpering R3 is required to give the EzSBC a direct connection and current source to ground.
Fuse F6 is for General Illumination of the backbox. Was the power board rebuilt just because F6 was blowing?
Was the original LM323 proven to be faulty? They're not obsolete and are still available.
The PSU5 is supposed to have "Thermal shutdown and current limit protection". How much voltage is it getting between the mounting screw (common ground) and the input pin? The burnt area is on one of the input pins of the switch mode chip.
Is the material between the PSU5 and the power board PCB conductive?
Quoted from G-P-E:Yes, new parts are still available but unrealistically priced -
Indeed.
More price friendly LM323 sources, don't ask me where they source them:
https://www.marcospecialties.com/pinball-parts/LM323K
http://bigdaddy-enterprises.com/repairkits/bally_kits.htm#b-5vreghalf
https://www.jameco.com/z/LM323K-STEEL-Major-Brands-IC-LM323K-5V-3A-3-Terminal-Positive-Voltage-Regulator_23667.html
Quoted from Quench:Fuse F6 is for General Illumination of the backbox. Was the power board rebuilt just because F6 was blowing?
Was the original LM323 proven to be faulty? They're not obsolete and are still available.
The PSU5 is supposed to have "Thermal shutdown and current limit protection". How much voltage is it getting between the mounting screw (common ground) and the input pin? The burnt area is on one of the input pins of the switch mode chip.
Is the material between the PSU5 and the power board PCB conductive?
Ok there is 5 volts there. How could this thing burn up like that with 5 volts? The regulator had the insulator that was on the original regulator which is non conductive. Yes I figured I may as well rebuild it based on the age.
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Lower Burrell, PA