Service Manual Dynasty 350

[wumpscut223]

I appear to be the only one with that info, but it won't help you.

Only 2 checks to make

RC1 check for 325Volts bewteen RC1-1 to RC1-3, unit on at idle

RC2 check for +15 volts between RC2-1 to RC2-2 HF off
Check for 0 volts HF on

Or 700HZ betwwen RC2-1 and RC2-2 HF on

If that is there, all is happy and you need a new PC-7 Replacing parts on this board is probably NOT a good thing. as it may dynamite the rest of the machine.

cruizer - Thank you for responding!

I will check those voltages this weekend (hopefully). Right now I'm out of town for work. Please confirm with welder on and set to HF start mode:
RC1-1 to RC1-3 voltage at idle is 325V AC or DC?
RC2-1 to RC2-2 should +15 VDC pedal up?
RC2-1 to RC2-2 should 0 VDC pedal down?


I don't have a scope right so I can't check the 700Hz now but I can buy a scope if need be. I'd rather invest the $500 in a scope and fix the card for $15... but I will take your advice as we work through this. Thanks!

[cruizer]

Whoops, yes DC volts

[shovelon]

Just to rule this out.

I had a 350DX delivered that would only work on lift arc. It turned out to have a Canadian board in it instead of the USA board. When the correct board was installed it worked perfectly.

[cruizer]

Ummm, Canadain boards and US boards are the same.... CE (european) boards are different.

[shovelon]

Ummm, Canadain boards and US boards are the same.... CE (european) boards are different.

Perhaps that was what it was then. A call to Miller confirmed it though. The new board cured the start problem.

[wumpscut223]

The CE model is PC7 . . 235 476 The US Model is . PC7 . . 233 144

[wumpscut223]

I was finally home enough time to check the welder as requested. The results are below:

RC1-1 to RC1-3: 321VDC stable
RC2-1 to RC2-2: 0 volts pedal up or down
RC2-1 to RC2-2: Frequency is unstable when pedal is down and reads in the Mhz (most likely induced voltage from RF)

During testing the HF worked intermittently and gave both a very strong and sharp crackle while other times giving about a half crackle, DC voltage never showed on the RC2-1 to RC2-2. I wore rubber linesman gloves and welding gloves and wiggled the RC2 and RC1 wires while depressing the pedal. That did not change my results.

Cruizer... what do you think we should do now?

[romano]

Hi cruizer, I see this post is from 2013, but I have similar issue with a dynasty 350 ser# LH070326L it is the older version, with pc6 235540 and pc7233144 I checked voltages (pc6) RC16 have 15vdc -15vdc 24vdc -24vdc though RC14 pins 1,8 have a micro level of 700hz signal (I can see fuzzy change but can synchronize signal but is present when HF is on).

(pc7) the 325vdc is present RC1 1,3 and 15vdc is present RC2 1,2 if I remember the 15vdc doesn't go away when HF on.

I have two PC6 boards, and both act similarly I purchased second pc6 used, they said HF worked but really hard for me to know. all other functions of board seem to work with regards to menu on either board.

do you know how I might find a service manual? I called miller tech, but they didn't offer that option to me. Now the boards for this serial number are over 2k for pc6 and 1k for pc7 practically makes the machine not worth repairing. Also with the coated boards it is difficult to trace the circuit path. At least the boards are not painted like some circuit boards are.