Looking for Syncrowave 300 service manual
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  1. #1

    Looking for Syncrowave 300 service manual

    Hi guys, first post so some background.

    About 15 years ago I picked up a Miller 330a/bp with a cooler for an unbeatable price even though I really wanted a Syncrowave. It needed a little repair, but the worst thing I can say about that is that it never broke so I never had an excuse to replace it.

    Fast forward. I'm moving so it occurred to me to look around for a Syncrowave and I could sell the 330 out of my garage without having to move it myself. Looking around, I found an unbeatable deal at HGR. Got a Syncrowave 300 with all options except the spot timer along with a Coolmate-12 cooler on a cart. The new shop has 200A service, so power's not a problem.

    I got it hooked up and no weld output (well, no real surprise there, everything I've bought from HGR has needed some repair). I have fan, 120V at the aux outlet and voltage at the SCRs, but no HF or weld output (contactor and current are set to standard, HF on continuous). I got the range/AC-DC switch cleaned up - it was pretty dirty and I have a users manual and a schematic (printed big enough to read), but a service manual would be very useful to trace through the problems on this unit. I'm thinking probably one or more relays are not working. The serial number is JF888209, I think this is a mid 80s unit.

    I have an aluminum cantilever gate project I plan on using this for later this year. Can anyone help out?

  2. #2
    Join Date
    Oct 2016
    Posts
    92

    Re: Looking for Syncrowave 300 service manual

    miller will usually email you a copy of out of date manuals. Does it work in stick mode?

  3. #3
    Join Date
    Oct 2016
    Posts
    92

    Re: Looking for Syncrowave 300 service manual

    Ok, well, looks like miller doesnt like your serial number on their website. Its supposed to match your serial number range for the model you specified.

    Try this link.
    https://www.millerwelds.com/files/ow.../O350M_MIL.pdf

  4. #4
    Join Date
    Jun 2012
    Location
    CT
    Posts
    3,065

    Re: Looking for Syncrowave 300 service manual

    Call Miller with your serial number and they will sell you one for a nominal fee. They don't offer them as free PDFs like they do with the owner's manuals. I have seen the syncrowave 250 technical manual as a free PDF download on the internet (non-miller sites), but never one for the syncrowave 300.
    Millermatic 252
    Syncrowave 250
    Purox Metalmaster

  5. #5

    Re: Looking for Syncrowave 300 service manual

    That Miller link is the user manual which I have. It does have schematics, but not all of the trouble shooting info. The total trouble shooting info in that manual for no weld output is "check the circuit breaker" which is OK. There's no weld output in stick mode (I don't have my TIG torch at that location so I'm testing it in stick mode).

    I'll try calling Miller and see what they say.

  6. #6

    Re: Looking for Syncrowave 300 service manual

    Well, I have to say the folks at Miller are remarkably pleasant and helpful. Especially so when considering it's a 30 year old machine.

    Since this seems to be a common problem, I'll post the resolution when I track down the problem.

  7. #7

    Re: Looking for Syncrowave 300 service manual

    OK, I think I've found the problem. The optocoupler on PC1 is bad and it's an obsolete part from a defunct manufacturer. We'll see what Miller says about it. Putting a new lamp into it should fix it though.

  8. #8
    Join Date
    Jun 2012
    Location
    CT
    Posts
    3,065

    Re: Looking for Syncrowave 300 service manual

    REALLY??...that's interesting. I just looked at the tech manual for my syncrowave 250, and it doesn't show an optocoupler as part of my PC1 board. BUT this syncrowave has no pulse feature. I wonder if that is part of the pulser circuit on the 300. It uses a lamp and not an LED?
    Millermatic 252
    Syncrowave 250
    Purox Metalmaster

  9. #9
    Join Date
    Nov 2012
    Posts
    614

    Re: Looking for Syncrowave 300 service manual

    Quote Originally Posted by PaulAm View Post
    OK, I think I've found the problem. The optocoupler on PC1 is bad and it's an obsolete part from a defunct manufacturer. We'll see what Miller says about it. Putting a new lamp into it should fix it though.
    An optocoupler is a pretty simple device and they've VERY common in electronics. Who made your's and what's the part number and is there a date or date code on it? Hewlett Packard makes a lot of optocouplers, I would check with them and see if they can cross reference to one of there. If nothing else buy some and try them.

  10. #10

    Re: Looking for Syncrowave 300 service manual

    Turns out this is a very interesting part. When the contactor switch is set to standard, or the foot pedal is depressed, 24V AC is sent to this optocoupler through a resistor. This turns on the SCR drive. If you look on the schematic for PC1 it's over on the left labeled OI1.

    I managed to track down a spec sheet on it and, unlike almost all optocouplers made today, it uses a lamp and a light dependent resistor (unlike a photo transistor) which has an unusually large change in resistance from light to dark. I keep running into walls on this one. The lamp used has about half the wattage of the replacement ones I can find; I'm a little concerned that the extra heat might cook the ldr. If I can find an equivalent LDR, I can make up a replacement, but the ones I've found so far have an order of magnitude less resistance change.

    I can probably fudge an LED in there, but I'll have to deal with the AC drive and try to duplicate the soft start inherent with an incandescent device. Would be easier to just stuff in a replacement optoisolator.

    This one was made by Sigma with the part number 301t1-12b1. Magnetec was a second source with part number W301t1-12b1; both have been long obsolete.

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