Looking for a working early PL 400 Control board

[Northwinds]

And then stops or just spins?

Hoping the PO did not put too long a screw in there and jammed it into the windings of the transformer. Well your fuse test should tell you that.

It got tight coming out at the very end, looks like 3/4" screw

 

[Gepetto]

It got tight coming out at the very end, looks like 3/4" screw

That is the original screw. Those self tapping screws get the last threads near the tip clogged with the zinc die casting which is why it was harder backing it out.

 

[Northwinds]

I have a 8A 250V fastblo in the line now. Does the bussbar have to be isolated from the chassis before I plug this in? All the other wires that come off the tranny are still attached to the main ground between the fins

 

[Gepetto]

I have a 8A 250V fastblo in the line now. Does the bussbar have to be isolated from the chassis before I plug this in? All the other wires that come off the tranny are still attached to the main ground between the fins

You should be fine with the 2 main outputs wire nutted off as you have.

Now with your handy dandy meter you should also be able to check out the bridge rectifier by using the diode scale on the meter selector switch.

 

[Northwinds]

Which is the diode scale? DCA?

 

[Gepetto]

You should be fine with the 2 main outputs wire nutted off as you have.

Now with your handy dandy meter you should also be able to check out the bridge rectifier by using the diode scale on the meter selector switch.

Black meter lead in the COM meter input, red meter lead in the V-Ohm meter input

Measure between one of the AC inputs and the + and - terminals on the bridge, measure what the meter reads then reverse the leads and take the same readings.

 

[Gepetto]

Which is the diode scale? DCA?

The one with the little diode symbol Arrow into a bar

 

[Gepetto]

The one with the little diode symbol Arrow into a bar

Right above the ON switch indication on the meter. Do this while the amp is unplugged!!!!!!

 

[Northwinds]

Without touching anything, the meter reads 1

When I touch the probes to the tabs, there is no changes, when I cross the probes w/o touching the rectifier, it goes down to 0.00

 

[Gepetto]

Without touching anything, the meter reads 1

When I touch the probes to the tabs, there is no changes, when I cross the probes w/o touching the rectifier, it goes down to 0.00

Your 0.00 reading means that that leg of the bridge is shorted out.

 

[Northwinds]

With probes touching rectifier, no change

 

[Northwinds]

Your 0.00 reading means that that leg of the bridge is shorted out.

Joe, that's when I touch the probes together, I am not touching the BR

I move the probes around trying various positions and the meter never changes from 1

 

[Gepetto]

Joe, that's when I touch the probes together, I am not touching the BR

You are measuring in the wrong place Ron. Measure from one of the AC marked terminals and the positive terminal both directions, then do the same for the negative terminal and that same AC terminal.

Then move on to the second AC terminal and repeat the drill from above.

There should be 4 groups of readings, with 2 readings in each of the 4 groups.

 

[Gepetto]

Joe, that's when I touch the probes together, I am not touching the BR

I move the probes around trying various positions and the meter never changes from 1

did you try you meter on a good diode? Like one of the small diodes on the control board?

 

[Northwinds]

499
482
496
481

That's it, no readings in the other positions

 

[Gepetto]

499
482
496
481

And when you reverse the leads?

You should have something like this on a good bridge Ron...

1
550

1
525

1
565

1
545

 

[Northwinds]

When I reverse the leads, it stays at 1

 

[Gepetto]

When I reverse the leads, it stays at 1

That says the bridge may be OK Ron.

 

[Northwinds]

The readings are a lot lower then what you mentioned Joe, I think I would rather just get a correct one

Can I go ahead and plug this in and see if it blows the fuse? Do I have to reinstall the BR first or can it be left off?

 

[Northwinds]

I have to hit the bathroom, be right back