miller trailblazer 251 no weld output

[jeff akin]

Just bought 1997 trailblazer 251 with 14 hours machine is pristine kept covered previous owner only used one job then parked inside shop and covered machine starts and runs perfect produces 120 volt a/c fine but no welding output checked 3 brushes all clean and free checked fuse under cover and wiggled all wires anybody have any ideas Thanks

[ironwings]

Possibly a full wave bridge Rectifier. Find it on rear panel or maybe on right panel when facing the control end. Check the terminal to terminal diods. Clipped corner is Pos. Clockwise: ac, neg. ac. back to pos. check from neg to ac, ac to pos. CC Neg to ac, ac to Pos. Keep your wires marked and recorded if you have to remove. It also How long since it was welded with?

[jeff akin]

Its been quite awhile since last used. Purchased from a fab company that does in shop fab work and bought machine new for a installation job and never used again. Machine is perfectly clean inside and out. Called Miller Tech support and they walked me through troubleshooting they say that the circuit card is fried. Checked card visually no sign of anything wrong, called seller he said take it to repair facility and he will pay for it. Thought that was mighty respectable since card alone is 800+.

[duaneb55]

Just curious, did you jump start it with a battery charger?

Got a unit SN?

If it turns out it does in fact need a new control board, best price on a new one would likely be here http://miller4less.com/advanced_sear...x=6&search.y=9 if you didn't send it off to one of many repair shops.

But before condeming the control board, make sure the PANEL / REMOTE switch is in PANEL and in addition to checking the bridge rectifier (SR2 to be exact), check all board connectors and harness connector PLG6/RC6.

[walker]

Ditto Duane, the two bottom switches need to be up for it to produce welding power.

[duaneb55]

Yep. Forgot to mention the CONTACTOR control switch.

[jeff akin]

miller tech had me check the following:
wires 43 and 44 had 170 v a/c
45 and 46 had 250 volt d/c
60 and 120 24 a/c
21 to 24 had .5 volt miller tech said that measurement condemns the board and gave me a part number of 188155 at a cost of 800+. I contacted the seller he said to take to shop and he will pay to have repaired. If it was my dime i would go to miller4less but Iam worried i would replace board and miss something and end up with another fried board. I asked seller if he had jumpstarted he said no but he has used charger to charge battery and start. I did notice that tig torch had been left on and laid against hf 251d box and arced against it. wonder if someone had started machine to let run and not realized torch was against box, there is small burn hole on box. But box turns on and gas control soleniods seem to work. but of course can't properly check. serial number is KH368280. THANKS

[jeff akin]

I did try the switches in remote contacter mode and in no remote mode and every possible combination.

[duaneb55]

Was that .5V DC between #21 to #24 at the board or at the brush leads? I would think the Miller tech would have you check at the board and if so I agree your test results would indicate a failed board.

Where were the "60 and 120 24 a/c" readings from?

Personally, I would give the previous owner the option to save a few hundred $$$ and let him know about miller4less fi fin fact the board is bad.

I can't pin-point a specific cause but I've lost count of how many Trailblazers quit welding due to a failed PC board following jump starting or boosting with a battery charger.

[jeff akin]

Took to shop Monday 1142 dollars to repair, Had bad pc board nothing else looked bad. Will e ready on Tuesday. thanks for help.

[dieselwelder]

I had the same machine..... Weld out just quit.... Miller replaced the pc board and dome other stuff...got it back and it would burn about two rods and then no more weld output... Took it back to the repair shop 3 times... They told me nothing was wrong with it...it sat on the load bank all day with no issues...finally I got a miller rep to come out to the job site and take a reading while I was welding....two rods into the weld and then nothing.... Miller rep tells me... Take it back to what ever repair shop it was and drop it off there... We'll have a new unit to you in a few days.... This machine only had 3 months left on the warranty too......

[beamwalker]

i have a 301tb that has 1900 hours on it that quit. ive already sank 1000 in it and it welded fine two days and quit