Anyone Familiar with the Bridgeport Power Feed circuit board F-6120?

I suspect one of the two field supply diodes might be burned out- D15 or D16. Check them both. 1N5053 I believe is the number; 2 amp, 800 volt. Should be easy to find a replacement, and cheap.
Mark S.
ps also check D5 and D6
 
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Interesting (and probably old) schematic- I've never seen pots (potentiometers or variable resistors) drawn that way.
A very serviceable circuit, not like new stuff with one big impossible to replace chip that does everything.
Each and every part in there could be found today.
Mark
 
Well, I took another quick look at the board searching for the diode bridge. I found it, and bridge is comprised of 40HF30 diode rectifiers. They are still available at $9 a pop. Each is rated at 300v and 40A. It also looks like what "smoked" on the case is not the DC switching wire. It is one of the 110v ac feeds TO the bridge that is missing a wire nut. I did not have time to dig out the multi-meter, but I will. I need to make some time and study this a bit more. Right now, my theory is, the 110v wire touched the case, and blew the fuse. The previous owner in his haste to figure out what happened, broke off the DC switching lead, and also put a new fuse in ( looked at the broken connector closely, and there are no carbon or fusion marks, just a clean fracture). I am making the assumption that the DC switching leads are series, NOT parallel. If that is the case, all connections must be in place for the motor to work, regardless of direction. However, those are assumptions, and not based in "advanced schematic digestion". I am only so-so on electronics, but I know enough to be dangerous. More to come
 
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Mark, I agree, that is an older schematic. However, this is an older unit. I also agree, there is nothing on the board that cannot be replaced. I figure that with some guidance from folks like you and Keith, I'll have this old girl chooching in no time...... and for less than $300. Those 40HF30 diodes are HUGE!

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Hi Mr. Fleming, so the wire that arced the terminal was not from the directional switch? I'm a little corn-fused.
Also, the power bridge has 2 large SCRs in there and 3 of the large diodes. Can't quite make out the number of the SCRs.
SCRs are easily checked with a battery and light bulb, if we need to. Hopefully those 5 parts are OK.
Have you checked/fixed the directional switch wires and tried to power the unit up? All the directional switch wires must be in place for the motor to run.
Mark
 
Mark, first off, just call me Tom. Secondly, I found a bare connection wire splice for the AC input to the diode bridge, and I am about 90% sure that is what arced to the case. After closely inspecting the DC switch spade, I did not see evidence of a "short". Only metal fatigue and a relatively clean break. No carbon. However, the AC input splice is just plain NASTY, and I believe that is what arced. I am going to put things "as they should be" and power it up to see if she chooches. If there is no joy, then the meter comes out and I go on a diagnostics trip..........
 
Tom: Ok yes put all the wires in order and try it out. If it blows the fuse then we'll grab the meter and get into it. I haven't lost a patient yet. LOL
Mark S.
 
Ok, Humpty Dumpty has been put back together again, and no change in condition.....no chooch.....no joy. Power indicator lights up when power switch is turned on, but other than that, the unit has no life. Nothing from the JOG button, and nothing when using the FOR/REV shift lever. I guess I am on to the next step. I'll have to come up with a way to insulate the circuit board, and power it up while it is not mounted in the unit (and put a ground jumper on it to the case). Then go component by component and see where the pixies die off.......:confused:
 
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