Fincor 2301 dc power supply

Took apart..scr not popped.both got hot enough to melt solder..ran about a minute..came back reversed motor wires.ran appx 10 seconds..quit.any ideas..scr's seem to test ok. Thanks
 
I'm not actually popping the scr..it's getting hot and blowing the solder off the pins on back of board..replaced the one that smoked in reverse.switched motor wiring back..ran 5 seconds then blew solder off the other one..loud pop.kicks house breaker when it blows..any ideas on which way to go..thanks Phil
 
What type of motor are you using here? Let's see it
M
ps You tested all 5 semiconductors with the jig? Did you test the SCRs for tab to anode continuity?
If you are blowing the house breaker you still have a dead short across the power line
I'm still thinking those are NOT isolated tab SCRs and you are putting a short across the power line as soon as you bolt them to the panel
 
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It would be good if you could plug into a GFI protected outlet to test these controllers, it would trip much more quickly and there would be less damage.
Here is what I would do: Get another unit ready with tested semiconductors. Before you mount the SCRs to the panel, measure the resistance with an ohmmeter across 1 and 4 of the terminal block. Then measure again after you mount them to the panel. If you get a different (lower) reading DON'T plug it in.
The SCRs will need insulating hardware, or you will need to replace with iso-tab types. (easier)
Mark
 
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image.jpeg The scr is not grounded to cover.bolts are nylon.made tabs out of plastic coffee can lid.scr has continuity on outside wires but not to center wire .tab to center wire .no continuity.the semi conductors pass current one direction but not the other.the motor is the Baldor gear motor I used on my vSd..1/7 hp I think..will wire up a gfi outlet b fore plugging up again..thanks very much for your help..
 
You did use a jig to test the SCRs? Continuity between outside leads sounds wrong. Shorted gate problem maybe- Gotta use the jig to be sure
M
sounds like you're doing everything right so far- coffee can lid plastic isn't the best material for that though. OK temporarily
Even if the controller was firing both SCRs at the same time the worst that would happen is the motor would run full speed, so I'm not sure what the problem is
 
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Verify for me: You hook up SCR to jig, lamp is off. Touch wire from gate to middle pin (anode) lamp lights and stays lit until you remove 12 volt supply?
Any other behavior means SCR bad. (no light, or light on without touching gate)
Mark
 
Used a 10v dc charger.automotive test light hooked on one wire..other wire a probe..all the scr I've tested so far pass current on two outside wires..on two bulb is dimmer when switching wires around..on two brightness same
 
Found on one board the solder on scr looked good but when removing board from cover both scr were loose at solder joints
 
Light doesn't power up when going from either outer wire to center..center wire does not have continuity to tab..maybe I'm testing the wrong way
 
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