330 A/BP low output
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  1. #1
    Join Date
    Aug 2016
    Location
    Michigan
    Posts
    92

    330 A/BP low output

    I have a 330 Abp that looks pretty new. Got it for a low price. I've been welding AC stick mostly, but i noticed i have to turn it up a lot more than i expected to keep the rods from sticking to the work.
    Also i have nearly no ouput on DC. As in, i was burning 6011 1/8 rods at AC, center amperage range, with a RHC-3 remote controller at about 70pct. Switch the output to DC, and same rods have like zero power. The DC range selected was up to 260 amps. At MAX on the RHC, i almost can't hold an arc it's so weak.

    So i pulled the side covers, looks brand new in there, and pulled the ends of all the diodes. I thought maybe it had a blown diode or two. All diodes read on the DVM one direction and not the other on the diode checker. So i'm thinking the diodes are all right.

    Any ideas? I can't think why the output on DC would be so low with the diodes all being good.
    Miller 330 A/BP w/ WP-18 torch / WP-26 torch
    Miller CP-200 Haas / Kamp'd / CP-300 in process
    Homemade tig cooler
    Miller 30A /S-52E feeders

  2. #2
    Join Date
    Jun 2012
    Location
    Bemidji MN
    Posts
    13,401

    Re: 330 A/BP low output

    Did you check the input voltage jumpers?

    Is the large lever inside closed (set to stick)? It's the Balancing Resistor knife switch.
    Dave J.

    Beware of false knowledge; it is more dangerous than ignorance. ~George Bernard Shaw~

    Airco 300 - Syncro 350
    Invertec v250-s
    Thermal Arc 161 and 300
    MM210
    Dialarc
    Tried being normal once, didn't take....I think it was a Tuesday.

  3. #3
    Join Date
    Aug 2016
    Location
    Michigan
    Posts
    92

    Re: 330 A/BP low output

    Update : I know it's wired correctly, i had it working before. The knife switch is set to magnetic, and i did find a technical manual online which said to check open circuit voltage.
    It's got 82V open circuit, no effect whatsoever on either the front panel or remote amperage control. It's ALWAYS 82V. I'm poking around inside to find causes, but not much progress yet.
    Miller 330 A/BP w/ WP-18 torch / WP-26 torch
    Miller CP-200 Haas / Kamp'd / CP-300 in process
    Homemade tig cooler
    Miller 30A /S-52E feeders

  4. #4
    Join Date
    Aug 2016
    Location
    Michigan
    Posts
    92

    Re: 330 A/BP low output

    And now i'm thinking the OCV maybe shouldn't change on a constant current welder? I'm a little fuzzy on how the voltage characteristics should work on this type of welder. I don't have a way to check the voltage / current of the machine while striking an arc.
    Miller 330 A/BP w/ WP-18 torch / WP-26 torch
    Miller CP-200 Haas / Kamp'd / CP-300 in process
    Homemade tig cooler
    Miller 30A /S-52E feeders

  5. #5
    Join Date
    Aug 2016
    Location
    Michigan
    Posts
    92

    Re: 330 A/BP low output

    Got all the skins off and measured 45v ac at the input to sr3. It's supposed to read 24v ac. I checked sr5 and got 15v that's supposed to be there. I'm a little uneasy that the mag amp is shot.

    Edit. Whoops. 24vac at terminals 32 and 47. I didn't read it right.

    Sent from my LG-TP450 using Tapatalk
    Last edited by 86turbodsl; 09-11-2018 at 09:31 PM.
    Miller 330 A/BP w/ WP-18 torch / WP-26 torch
    Miller CP-200 Haas / Kamp'd / CP-300 in process
    Homemade tig cooler
    Miller 30A /S-52E feeders

  6. #6
    Join Date
    Nov 2014
    Location
    Phoenix, AZ
    Posts
    23

    Re: 330 A/BP low output

    Quote Originally Posted by 86turbodsl View Post
    Got all the skins off and measured 45v ac at the input to sr3. It's supposed to read 24v ac. I checked sr5 and got 15v that's supposed to be there. I'm a little uneasy that the mag amp is shot.

    Edit. Whoops. 24vac at terminals 32 and 47. I didn't read it right.

    Sent from my LG-TP450 using Tapatalk
    Appears that the Output Diodes may be weak. Have you checked the Fuse on the Welder for the Remote Control. With the foot RFC-23A foot pedal you can be more liberal with the High output setting range from high heat to low heat. With the Hand Remote the Rheostat tends to get warm quicker past the 50 percent range in the High Heat setting sending around 10 amps of heat through the welder remote wiring and burning the buss fuse for the remote. The Mag Amp should not read a dead short with a long beeping of the tester but should read a diode type range of around 480 units. If you test anywhere on the AC or DC side a Bad SCR will give a dead Short reading. Since the Mag Amp is responsible for utilizing low DC to Shuttle the AC Signal to the Rectifier Output the two cannot combine(Fail Together)as this will be a short within the control circuit. Ace Hardware and others sell the Breaker Pushbutton resetting style Buss Fuses.

  7. #7
    Join Date
    Aug 2016
    Location
    Michigan
    Posts
    92

    Re: 330 A/BP low output

    There were no fuses blown nor any bad components i could find. i poked around all night and didn't find any voltages that were wrong, any burned components, or anything out of place. It's like brand new in there. Like zero usage. After i got done with that, i pulled my long leads off and put the shop leads back on, and proceeded to lay some of the best 7018 beads on DCEP that i've ever done. All i can figure is i had bad connections somewhere. The new leads do have cheap chinese quick disconnects on them. Weird that 6011 ran ok-ish on AC, but moving to DC it just stopped working, but at this point, i can't find anything wrong and it welds fine in the shop, so with a big shrug i'm just going to go back to work. <SHRUG>
    Miller 330 A/BP w/ WP-18 torch / WP-26 torch
    Miller CP-200 Haas / Kamp'd / CP-300 in process
    Homemade tig cooler
    Miller 30A /S-52E feeders

  8. #8
    Join Date
    Mar 2010
    Location
    Ceres, California
    Posts
    3,272

    Re: 330 A/BP low output

    Remove remote control and put welder in panel. See if it welds better.Find a clamp meter you can borrow or buy.
    Has to be able to read DC and AC amps. For the remote to work right you have to turn panel control up higher than needed.
    Try and measure the weld current. it will vary with your arc length. The knife switch should be closed is stick.
    It bypasses a resister that is needed for TIG.

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