Miller Roughneck 1E diode help

[amethyst161]

S/N: HE805340


can anyone tell me which diode is missing from this pic? I have looked on diagrams and pics on the web but none show this diode on this board. Please help

In case you are wondering, the underlying problem is only getting 40VAC to outlets and 1.5V on weld jackets.

[amethyst161]

more info

I have replaced most of the diodes and I need to know the diode that is running vertically in between the two vertical columns of diodes, please.

[cruizer]

Yep, looks like 11 diodes altogether, so yep that vert one is missing. Look like they are all the same so update it a little and stuff in all 2 amp 600 volt units

[amethyst161]

But what number diode is it so I can make sure it is oriented correctly

[cruizer]

No one can tell you that unless they have one of those boards in front of them.

Look at whats left of the one on the board. Can't help you aftr that. I suppose that if it blows, its the wrong way. Your installaton really needs refining.

[cruizer]

The diagram ONLY shows the diodes in circuit. It does not show the diodes orientation on the board.

[duaneb55]

All 11 diodes are 3A, 600V and you can just barely make out the symbol on the board that the vertical one has the cathode (end with stripe) down.

[amethyst161]

I see that now that you have pointed it out. Thank you duaneb55. Will update asap with results

[snowbird]

pics that may help

sorry i know nothing about boards but out of curiosity i found that, maybe you saw it...

http://weldingweb.com/showthread.php...ghneck-1E-Help

i think duane been there done that

[amethyst161]

Thanks snowbird. But that image doesent have the diode in question

[amethyst161]

Going to take a few days to get diodes. I'm going to overhaul board with all new diodes and try again. I will update as soon as possible. I had one diode and replaced the missing one but still only getting 40VAC at outlets and 0.1-0.2 on weld jacks.

[amethyst161]

Getting Better

So I have since replaced all diodes. Got an unexpected call today on the sunday before christmas that the local shop had diode order come in. Now I have a few more questions.

1. I do not have the original weld/power/throttle switch. The throttle switch is missing but I do have the switch for Weld/Power that is mounted beside the throttle switch. Should it be depressed for Power and for Weld function or just for the Weld Function.

2. When checking the Voltage on the 115 outlet, somehow I am coming up with 200+ volts with the weld/power/throttle switch depressed and about 110VAC with it not Depressed.

3. I am getting 80V or so to the welding jacks when weld/power/throttle switch is depressed and the weld/power switch on face of machine is in the Weld position. Depending on RPM as i do not have a tachometer to correctly set the speeds everything varies a bit.

4. Does anyone know where the 12th diode is located, even a general area to start tracing. Most of the numbers on the wires are gone and I'm finding it difficult to trace it down.

[amethyst161]

any help

any help would be useful if you can answer any of my questions. I would rather understand the problem and then fix it rather than just having a fix. thanks guys

[duaneb55]

I do not have the original weld/power/throttle switch. The throttle switch is missing . . .

How is the exciter output circuit being completed for POWER mode and broken for WELD mode?