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Powcon the Legend - 300 SM, low OCV
- Thread starter sparky24
- Start date
Thanks for the great photos! The PowCon technology, with the wiring, transformers, SCRs, and heatsinks certainly is robust!
The SCRs are made by Westcode, but the part number 919000-1 must be unique for PowCon. I see them at $220, which is expensive!
The specs need to be 400 or 600 volts or higher, and at least 300 Amps. There are several similar "hockey puck" devices available from surplus stocks on eBay USA from about $20, such as:
International Rectifier 619411
International Rectifier S52K16A 1,600 volts 1,490 Amps
General Electric C390M 600 volts 850 Amps
Westcode WG6013 / ZA 1,300 volts 600 Amps
The SCRs are made by Westcode, but the part number 919000-1 must be unique for PowCon. I see them at $220, which is expensive!
The specs need to be 400 or 600 volts or higher, and at least 300 Amps. There are several similar "hockey puck" devices available from surplus stocks on eBay USA from about $20, such as:
International Rectifier 619411
International Rectifier S52K16A 1,600 volts 1,490 Amps
General Electric C390M 600 volts 850 Amps
Westcode WG6013 / ZA 1,300 volts 600 Amps
The tests for the SCRs that I described in Post #20 are looking for a short-circuit across the SCR or a short to the gate terminal.
To check that they actually work as electronic switches, you can do two tests - one low-voltage DC, the other at 110v AC:
For the DC test, connect the positive of a 12v battery to the anode of the SCR. Then connect the cathode to a 12v car bulb ( e.g. 21W indicator or 60W headlight ). The cathode side of the SCR is the same side as the red flexible wire.The other contact of the bulb goes to the negative of the 12v battery.
The bulb should not light. Connect a DC voltmeter between the gate ( the white flexible wire ) and the anode, then the gate and the cathode. There should be no voltage on the gate, it should be floating.
Turn the SCR on by applying a 3-volt positive pulse to the gate. Do this by putting two AA cells in series, join the negative to the cathode ( red flex ) and touch the 3v positive to the gate - white flex. The SCR should turn on, the bulb should light, and stay lit. When supplied with DC, an SCR stays "On" until the current flow is interrupted. About one volt will be dropped across the SCR.
Both of the SCRs should be the same, and both should pass this DC test, but I suspect that you will find Q2 is faulty.
For the AC test, you need a 3-wire ( grounded ) 110-volt AC mains cord, a 3-Amp fuse, and a light bulb - 60 or 100 Watts.
**Note that during this test the components will be at "Live" mains voltage !!
Connect the Hot ( black ) wire to the fuse, then through the fuse to the anode side of the SCR. The cathode side of the SCR goes to the light bulb. ( The cathode side of the SCR is the same side as the red flexible wire.) The other connection of the light bulb is to the Neutral ( white ) AC wire.
For safety, wire the positive of the trigger circuit ( 2 x AA cells ) to the gate ( white flex ) through an insulated pushbutton. The negative of the trigger battery goes to the cathode of the SCR ( red flex ).
Plug in the AC cord, and use an AC voltmeter to check the voltage on the gate terminal ( white flex ) against the anode, the cathode, and the ground wire. The gate should be floating, but I suspect that the gate of SCR Q2 will be "hot" because it is shorted internally, and this high voltage caused the damage to the pulse transformer.
When you push the button feeding the 3 volts to the gate, the SCR should be triggered "On" and the bulb should light. The SCR is now acting as a diode, so you lose half the AC supply and the light will be dimmed. With an AC supply, the SCR does not stay conducting, so the bulb will go out when you release the button.
To check that they actually work as electronic switches, you can do two tests - one low-voltage DC, the other at 110v AC:
For the DC test, connect the positive of a 12v battery to the anode of the SCR. Then connect the cathode to a 12v car bulb ( e.g. 21W indicator or 60W headlight ). The cathode side of the SCR is the same side as the red flexible wire.The other contact of the bulb goes to the negative of the 12v battery.
The bulb should not light. Connect a DC voltmeter between the gate ( the white flexible wire ) and the anode, then the gate and the cathode. There should be no voltage on the gate, it should be floating.
Turn the SCR on by applying a 3-volt positive pulse to the gate. Do this by putting two AA cells in series, join the negative to the cathode ( red flex ) and touch the 3v positive to the gate - white flex. The SCR should turn on, the bulb should light, and stay lit. When supplied with DC, an SCR stays "On" until the current flow is interrupted. About one volt will be dropped across the SCR.
Both of the SCRs should be the same, and both should pass this DC test, but I suspect that you will find Q2 is faulty.
For the AC test, you need a 3-wire ( grounded ) 110-volt AC mains cord, a 3-Amp fuse, and a light bulb - 60 or 100 Watts.
**Note that during this test the components will be at "Live" mains voltage !!
Connect the Hot ( black ) wire to the fuse, then through the fuse to the anode side of the SCR. The cathode side of the SCR goes to the light bulb. ( The cathode side of the SCR is the same side as the red flexible wire.) The other connection of the light bulb is to the Neutral ( white ) AC wire.
For safety, wire the positive of the trigger circuit ( 2 x AA cells ) to the gate ( white flex ) through an insulated pushbutton. The negative of the trigger battery goes to the cathode of the SCR ( red flex ).
Plug in the AC cord, and use an AC voltmeter to check the voltage on the gate terminal ( white flex ) against the anode, the cathode, and the ground wire. The gate should be floating, but I suspect that the gate of SCR Q2 will be "hot" because it is shorted internally, and this high voltage caused the damage to the pulse transformer.
When you push the button feeding the 3 volts to the gate, the SCR should be triggered "On" and the bulb should light. The SCR is now acting as a diode, so you lose half the AC supply and the light will be dimmed. With an AC supply, the SCR does not stay conducting, so the bulb will go out when you release the button.
Thanks for the great photos! The PowCon technology, with the wiring, transformers, SCRs, and heatsinks certainly is robust!
The SCRs are made by Westcode, but the part number 919000-1 must be unique for PowCon. I see them at $220, which is expensive!
The specs need to be 400 or 600 volts or higher, and at least 300 Amps. There are several similar "hockey puck" devices available from surplus stocks on eBay USA from about $20, such as:
International Rectifier 619411
International Rectifier S52K16A 1,600 volts 1,490 Amps
General Electric C390M 600 volts 850 Amps
Westcode WG6013 / ZA 1,300 volts 600 Amps
I wonder the specs on the first one, have been trying to find a datasheet on it. Looks like international rectifier was sold to "infineon technologies" .
I have contacted westcode for a datasheet and also trying to contact infineon.
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Probably the largest concern I have here in actually fixing this thing is if the control board has actually been damaged or not. If the board is damaged, it could be quite difficult to fix this.
I may just buy those SCR and give them a shot, worst case scenario I believe if they are not the correct specifications it will probably just burn out the new SCRs.
I may just buy those SCR and give them a shot, worst case scenario I believe if they are not the correct specifications it will probably just burn out the new SCRs.
Well, I installed two new SCR into it. Got them super cheap 17 a piece. Now the POWCON has 168 OCV but will not weld.
Thinking it is a control board issue, may try to troubleshoot the board a little... if I have any down time.
Sort of getting to the point where I wasted enough time though, unfortunately. If I have some free time, maybe I will take a stab at it.
Thinking it is a control board issue, may try to troubleshoot the board a little... if I have any down time.
Sort of getting to the point where I wasted enough time though, unfortunately. If I have some free time, maybe I will take a stab at it.
