Miller Syncrowave 180 SD only making half amperage on TIG

[forhire]

Today I came in to TIG a few small parts that I need to ship in the morning and my Syncrowave 180 SD is only making half amperage on TIG. Argh! I tried three different remotes and two different torches. Same results. It outputs about 75 amps at 15V when wide open. I've been burning 6011 and 7018 all week without any issues. It really couldn't happen at a worse time. It seems odd the voltage is maxed out but the amperage is less than half. AC voltage to the machine measures 240V (measured 245 actually). Any ideas what I should look for? Anyone every encounter this issue? Did my 180 finally bit the dust?

The manual doesn't say anything about low output in the troubleshooting section that I could find.

Model Name: Syncrowave 180 SD
Serial Numbers: LC578819 through LE069546
https://www.millerwelds.com/files/ow.../O360D_MIL.pdf

[G-ManBart]

Were you trying to weld TIG DC on steel/stainless using EN? Did you try AC or go back and try stick welding with it on DCEP again? If none of the experts check in soon it wouldn't hurt to pull the wrapper and look for loose wires and look at the big rotating switch that moves when you rotate the process selector lever...make sure nothing looks odd there. The fingers on that switch seem to attract all kinds of junk....wouldn't hurt to wipe them off and make sure everything is making proper contact.

I doubt the machine is really dead...not much that can't be fixed on them.

[forhire]

It burns rod no problem. No joy DCEN tig. I didn't try AC. I found a few posts over on Miller's forum that suggests this low amperage issue is a control board problem. I pulled the board to check number/version and I don't see any obvious damage. Everything looked tight and clean on the chassis. I sent out a RFQ to a few repair places that have experience with this board. I'll see what they say. I'm definitely going to check all the diodes before I send it out.

[ccawgc]

Before you attempt to have the pcb repaired. pull the rc6 plug and see if you can see the foot control with your ohm meter. since it is turning on we know A and B are ok.
we need to check the pot circuit. If it test ok then the problem is on the pcb. if E is open between the control pcb and the foot control then check the wiring and 14 pin plug connections. Provided you can still stick weld to over 100 amps.
If you can stick weld at any amps you set it at with no problems then we know part of the control pcb and the hall device are operating correctly. only the remote control input is messed up. Could be just the electronic switch on the pcb that switches from panel to remote control. or the buffer that drives the foot control.
C to D at the 14 pin plug should be 10 volts. Pin 4 and 5 on rc6 should be your 0 to 10vdc signal to the pcb. If you want check A1 on the pcb pin 7. see if there is a signal that goes up and down with the foot control. my guess it has failed.

[forhire]

Before you attempt to have the pcb repaired. pull the rc6 plug and see if you can see the foot control with your ohm meter. since it is turning on we know A and B are ok.
we need to check the pot circuit. If it test ok then the problem is on the pcb. if E is open between the control pcb and the foot control then check the wiring and 14 pin plug connections. Provided you can still stick weld to over 100 amps.
If you can stick weld at any amps you set it at with no problems then we know part of the control pcb and the hall device are operating correctly. only the remote control input is messed up. Could be just the electronic switch on the pcb that switches from panel to remote control. or the buffer that drives the foot control.
C to D at the 14 pin plug should be 10 volts. Pin 4 and 5 on rc6 should be your 0 to 10vdc signal to the pcb. If you want check A1 on the pcb pin 7. see if there is a signal that goes up and down with the foot control. my guess it has failed.

I put the board back in the machine this morning. Stick welds at any amperage I set without any issues. I tested AC and DC tig with the same 75 to 80 amp limit. I can control the amperage, it just maxes out at 75 to 80 amps. Same results with both my foot control and my finger control. I need to trace out the voltages but it really doesn't appear to be between the PCB and the control or the control itself.

Has anyone repaired one of these boards? The quote I have is $440 to send it out. Because it appears to work, just at a limited range amperages, I suspect an op-amp on input side and/or protection diodes.

[forhire]

I pulled one leg of the protection diodes on RC6. Diodes D1 thru D3 and good and D4 has failed shorted. The diodes are P6KE12A.Looking at the datasheet they fail shorted.
https://m.littelfuse.com/~/media/ele...asheet.pdf.pdf

So I'll start by replacing the TVS diode. Hopefully the diode did it's job and protected the LF347N quad op-amp.

[John T]

I pulled one leg of the protection diodes on RC6. Diodes D1 thru D3 and good and D4 has failed shorted. The diodes are P6KE12A.Looking at the datasheet they fail shorted..]

LOL...

you are a nut.

I KNEW you would be inside that thing...

You will get it figured out.

thanks for the pics and walk along.... I love your threads... always interesting.

[forhire]

LOL... you are a nut.
I KNEW you would be inside that thing...
You will get it figured out.
thanks for the pics and walk along.... I love your threads... always interesting.

Thanks. I ordered the parts today. The diodes were 32 cents. Even ordering 10, and springing another 60 cents for the op-amp, just in case, I still spent more on shipping than the parts.

These diodes are tvs (transient voltage suppressor) and fail shorted. The good ones measure about 0.6V in the forward bias and block in the reverse. The bad diode measures about 0.3V in the reverse direction. Because the reverse is around 50% of forward, and it is a protection circuit, I suspect this is why I'm seeing 50% output on the weld current. I'm thinking it's just this diode. We'll see once I have the parts installed. It will either be smiles or tears.

[ronsii]

Thanks. I ordered the parts today. The diodes were 32 cents. Even ordering 10, and springing another 60 cents for the op-amp, just in case, I still spent more on shipping than the parts.

These diodes are tvs (transient voltage suppressor) and fail shorted. The good ones measure about 0.6V in the forward bias and block in the reverse. The bad diode measures about 0.3V in the reverse direction. Because the reverse is around 50% of forward, and it is a protection circuit, I suspect this is why I'm seeing 50% output on the weld current. I'm thinking it's just this diode. We'll see once I have the parts installed. It will either be smiles or tears.

Funny I was just looking at that same datasheet on December 12th... A friends gate opener quit so I ripped it apart and thought the motor had shorted...they use the P6KE16CA TVS diodes across the motors to protect the control board... it had shorted! these are the bi-directional versions. I went ahead and got new motors for it too just because they looked a bit worn and they have been going for about 5 years!



Hopefully replacing those diodes cures it for you

[forhire]

Small world... my diodes are uni-directional. Good fix.

[ronsii]

Small world... my diodes are uni-directional. Good fix.

Thanks You did a great job of tracking down the failed component yourself

When I have to change out dip components I go ahead and pop in a socket just for the fun of it although I usually do it on more 'indoor' computer stuff ... hard to say if it might cause more problems with how a welders environment usually is or maybe you could dielectric grease the whole thing to head off any issues of corrosion affecting the socket connections??

[forhire]

Thanks You did a great job of tracking down the failed component yourself

When I have to change out dip components I go ahead and pop in a socket just for the fun of it although I usually do it on more 'indoor' computer stuff ... hard to say if it might cause more problems with how a welders environment usually is or maybe you could dielectric grease the whole thing to head off any issues of corrosion affecting the socket connections??

If I replace the op-amp I'll likely socket it. Being that the machine is nearly 20 years old and still fairly clean I'm not too worried. Generally vibration is the killer with sockets. When I did the serial chips on the lathe (Fanuc 0T-A) last year I socketed them. I really wish Fanuc would have done that from the factory. I had to pull the main board with the the backup batteries still connected (hot) while hoping to not lose all the settings... which I couldn't dump because the serial I/O chips burned up. I was sweating it. Maybe that's why Fanuc puts a 6 foot cable on the battery holder.

[forhire]

My theory was correct. I replaced diode D4 and I can now tig af full power. It is fixed.

I haven't put any time on it since fixing it this afternoon but due to how the TVS diodes fail shorted, and the short measured 50% of the forward bias, and it was clipping the output about 50%, I'm fairly confident I have it licked. It sure beat shelling out $500 bucks to send it out. Hopefully this helps anyone else with a similar issue.

Hopefully it's good for another 20 years.

[ronsii]

My theory was correct. I replaced diode D4 and I can now tig af full power. It is fixed.

I haven't put any time on it since fixing it this afternoon but due to how the TVS diodes fail shorted, and the short measured 50% of the forward bias, and it was clipping the output about 50%, I'm fairly confident I have it licked. It sure beat shelling out $500 bucks to send it out. Hopefully this helps anyone else with a similar issue.

Hopefully it's good for another 20 years.

Good to hear!!! so are you going to change the other diodes now as long as you have parts and so on??? or maybe it's better to leave it and then if/when the other\s fail you're all ready to fix it ??

[forhire]

Good to hear!!! so are you going to change the other diodes now as long as you have parts and so on??? or maybe it's better to leave it and then if/when the other\s fail you're all ready to fix it ??

The thought crossed my mind but it's working and I've already put on the sheet metal.

[Kelvin]

Great to hear it worked out with not a lot of $ out the door. Thanks for posting up the solution.

[forhire]

Great to hear it worked out with not a lot of $ out the door. Thanks for posting up the solution.

So far so good. This appears to be a fairly common failure mode with the 204446 main board.

[laurencen]

morning, see this is a old thread, I purchased a new 180SD some 15 years ago, long story but sat for 12 years as each time I tried to use it it would trip the breaker, only had 30 amp, couple years ago dug it out and moved it from the shop to work, plugged it in and on first impressions its working but not a lot of punch, never tripped a breaker so sent it to the repair depot, they changed the rectifiers, then came up with the board dead.

they wanted over 1000 dollars to replace and given the age and risk it may not be the issue decided against repair, it did work welding aluminum but tedious if over 3/32 thick.

this thread has given me hope, ordered the diodes and the chip, for under 20 dollars worth a try and have only 20 dollars to loose, my question did yo only replace the diode or the amp also

thanks in advance

[forhire]

morning, see this is a old thread, I purchased a new 180SD some 15 years ago, long story but sat for 12 years as each time I tried to use it it would trip the breaker, only had 30 amp, couple years ago dug it out and moved it from the shop to work, plugged it in and on first impressions its working but not a lot of punch, never tripped a breaker so sent it to the repair depot, they changed the rectifiers, then came up with the board dead.

they wanted over 1000 dollars to replace and given the age and risk it may not be the issue decided against repair, it did work welding aluminum but tedious if over 3/32 thick.

this thread has given me hope, ordered the diodes and the chip, for under 20 dollars worth a try and have only 20 dollars to loose, my question did yo only replace the diode or the amp also

thanks in advance

To weld full out on this machine you will need to be on a 60 amp breaker unless you really limit the duty cycle. When doing work at the farm, I've had issues with the 50A breaker tripping if I run near the duty cycle. Here at the shop, the 60A hasn't ever tripped. It's kinda small for heavy aluminum welding. My next tig will be a big bigger.

I only replaced D4 TVS. It has worked fine ever since.

If I recall the display showed low, so it wasn't like it was running weak and displaying full power, it only could pull half power. I went down the foot pedal rabbit hole initially because that's what it felt like.

[laurencen]

yes this one displays low, the odd thing full power tig aluminum it will not trip a 30a breaker

[laurencen]

yes this one displays low, hope to pull the board tomorrow and check diodes, is there a way how to test the rectifiers? not sure they are bad but have 4 extra

[forhire]

I didn't check mine but most rectifiers can be tested across the legs like a diode. Like a diode, they cannot be tested in the circuit so you need to remove a least half the legs.

I suspect one of the D1-D4 TVS (transient voltage suppressor) have fail shorted. The good ones measure about 0.6V in the forward bias and block in the reverse. My TVS D4 measured about 0.3V in the reverse direction. Desolder one leg and test. The data sheet is in post #5.

[laurencen]

well now Im depressed, pulled one end of diodes, only have a ohm meter anyway 3 of the 4 diodes with my tester were open no ohms, one 3rd from the edge was open one way and gave a resistance the other, the replacements all are testing open both ways. unsoldered all 4 and replaced with new, cleaned board and put it back in machine, upon powering up it looked normal.

when the pedal is pressed nothing, no gas flow either, all display shows just no life in the machine, it did fire up only low power previously.

will pull the board in the morning and see if anything is odd, is it possible this is the opp amp now or is there somewhere to look

thanks for all the assistance on this issue and hope to get this working soon

[laurencen]

so today checked hook up and everything was good, pulled the diode on end and they test the same as when they were before open both ways with the tester I have so took the opp amp out, put a socket and replaced it, will see what gives tonight, thinking something else else blown bit fingers crossed

[laurencen]

and it gets worse, installed the board, power up get a fizz and smoke from the board, now plan B, where do I look for a new board