miller welder will not rev-up

[stan]

What would make our welder nor go to full power when I strike a arc. The motor starts ok. I checked the throttle pull down solenoid by hooking 12v th it and the motor power's up fine. Anyone have a suggestion on what the problem is? The welder is a Legend AEAD-200 LE Thanks San

[cruizer]

Idle board wonky, does the engine speed up on the auxillary use?

[stan]

Cruizer asked, does welder speed up in aux setting. No it doesn't. stan

[stan]

Cruiser. About the bad src. I will probably remove the covers tomorrow. Will I be able to see damage to the src? I know sometimes these electronic things go bad without any outside damage. Thanks for the help. I am completely in the dark when it comes to electronics. Stan

[stan]

With the covers removed I could see no heatsink with a scr. There is no circuit board anywhere in the machine. This welder is about 15 years old. It has about 260 hours use since new. Any idea where to go from here. stan

[cruizer]

Front face right at the bottom,

The idle circuit doesn't work by magic ya know...

[stan]

I wish I knew a little magic. The only heat sink behind control pannel is a rather large blue colored one with the neg. cable attached at one end, and the other end, the cable goes from the heat sink to the neg work clamp. The welder is more like 20 years old. Stan

[stan]

Well I just completely don't know what to do at this point. There are no circuit boards in this welder, none,zip, nada (a little mexican lingo) How did the welders get power to the throttle solenoid before the circuir boards came along? This is probably the set-up I have. Again thanks, Stan

[cruizer]

Whats the serial#

[stan]

The serial no. on the welder is JJ518696, and it is a Legend AEDA 200LE Stan

[cruizer]

OK, I've been going back too far in diagrams, you still have 2 boards, one is a voltage field board, the other being the idle. The idle board in question may not look like a circuit card (over serial# JH300534), rather it will be a little 1 1/2"x 1 1/2" red (or black) module with 6 terminals on it. I'm looking at the unit in front of me. It is attached under the lifting eye support, Can't miss it. You'll have to order one from a repair facility part #142725

If the unit is below JH300534, it would use a circuit board which is no longer available, so what you'd get upon ordering is the 142725 module to replace it which lists out at $94US

[stan]

Well I will be eating crow tonight for supper, it will be well done. You were right all along I found a circuit board when I was looking for the black box you in your last post. I will make no excuse for not seeing it, but it was in a tight spot. I also saw the finger heat sink on the c/b with two, what the parts breakwown calles a thyristor scr 8 amp 600 volts. Should I change these two components, first? If that isn't the problem then change out the black module 114 158 with the 6 connections. Don't giveup on me, looks like you are my only hope. stan

[cruizer]

OK, I'm working off a couple of computers right now, so bare with me.

You want to check CB4, thats the breaker going to the throttle solinoid,

You want to check if CR2 is closing. It's coil is connected to "C" & "E" off the idle module

To test the coil and throttle solinoid remove "C" from its connector and apply 12 Vdc to that relay terminal.

You also want to verify that "B" is hot (12Vdc) all the time after the engine is running
Sounds like the Module is hooped though

******Leave the field circuit board alone******

[boattrash]

I have a similar unit that wont idle down in weld mode. Solenoid works fine of course but what should I be testing on the idle board? Engine surges as well but welds ok and I get 120 volts out of generator.

[weldersales]

Legend

Your machine is a 1988 AEAD200LE, I believe. There should be two boards in the machine, each about 3" by 6". One is the regulator and the other is idle control. These can be repaired or replaced. The solenoid is fed through a circuit breaker. Your welder has the Onan B48M, right? Idle solenoid is round, about 1 1/2" in diameter and 5" long? weldersales