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Syncrowave 300 - HF runs constantly.

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  • dt38k
    replied
    Low and behold as most of you all know, the syncrowave 300 has had its issues when it comes to the high frequency
    l have been able to let my girl sit alone in the corner for years until now and am trying one more time
    There is no tag to tell the serial number but after several conversations with Boone at Miller in the Tig trouble shooting department, it has been narrowed down
    He suggested ordering a service tech manual TM-350
    Not being a factory service center, they would not sell me one but I was able to find one on line and it is on its way
    The conclusion at the moment is either the high frequency transformer, or the capacitors are failing once heat becomes a factor
    When cold, I have HF on start and continuance
    When welding DC straight and the HF is in start, I have a perfect arc and the machine seems to be welding fine
    As the minutes go by, the HF arc begins to get shorter and shorter until it goes away completely and then I have to use the lift arc option
    I can tell that at least one or more of you involved in this thread knows how to read the schematics, something of which I admit cannot do
    Where I stand at the moment is I have unhooked all of the wiring at the lower junction strips and have cleaned the the CR 1 and CR 2 relays
    My plan is to relocate the relays into a separate box that I will fabricate here so that they will not be filling up with dirt and straighten out the wiring from the rats nest that is was
    The majority of the wiring is almost impossible to read due to the pour stencil printing
    As an example, telling the difference between the number 31 and 81 wires is a hair puller
    If I have the wires matched to the numbers, some have to be separated on their own circuit to be the correct path rather than be all tied together
    I have several that I need help separating correctly
    Numbers 31, 32, 81, 61, 68, and 86 that come to mind at this moment
    I have hope than someone can get me headed in the right direction before I burn something up that I will regret
    Thanks in advance, Randy
    Last edited by dt38k; 07-10-2019, 10:56 PM.

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  • Aeronca41
    replied
    Outstanding! Tough when you have two simultaneous problems to find, but you did it.

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  • Sked
    replied
    Originally posted by Aeronca41 View Post
    My next guess would be a shorted Q301 Thyristor on PC2.
    AND THE ANSWER IS:

    The problem of the constantly running HF was caused by a bad Q304 THYRISTOR on the PC2 Circuit Board. Thanks Aeronca41 for pointing me in the right direction.
    And to explain completely, the HF problem and the dirty welds I mentioned in the original description of my problem were not related. The dirty welds were caused by a leak in the gas hose running to the torch.
    Thanks to all for your input.

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  • Aeronca41
    replied
    Originally posted by Sked View Post

    OK. That sounds more like where I thought I'd be going. I may take a shot at replacing them, but looking into the PC2 boards raises another question. My machine has an older 039 195 board (mine is actually marked 039 196) as shown in the parts list from a 1975 owners manual. The Service Parts Manual I received a couple days ago is dated 1991 and does cover my serial number machine. On the subject of the PC2 Board the manual states for 052 790, the only PC2 Circuit Card shown, "This Circuit Card Replaces All Previous Circuit Cards And Is The Only Card The Factory Recommends Repairing". I notice there are no transformers, relays, or thyristors on this newer Circuit Card. I'm wondering if updating is the way to go. Thoughts?
    Could be, just seems like a lot of money. I'm not afraid to spend good $ on quality welders, (only Miller, Hobart, and an old Lincoln Century from 20+ years ago around my place) but it kills me to spend $500 on repairs when the individual part that's bad is only a few bucks. Of course, the key is finding the right component to replace.

    Don't know about Miller-not enough experience on different machines, but in the world I came from such guidance often meant there was an unreliable design that got updated. Like battle plans that don't survive first contact with the enemy, sometimes designs that look good in plant don't fare so well in day-to-day service-it can happen to anyone-less likely if you're good. (See comments/threads on Longevity-it had my interest for about 10 seconds, then I bought a Dynasty 200.) If you plan to use the welder a good long time, maybe it's worth the $500; the upgraded board may prevent future problems. Of course, you could spend the bucks then have the other board go bad-always a risk to be weighed with an old machine. Concern is that without actually troubleshooting the machine, it would be a real bummer to spend the $ and then find a shorted wire somewhere. Do you, or someone you know, have any troubleshooting/repair skills, including down to the component level on the board? If it's Q301, the part is probably about $5 (just a guess). Doubtful you can get it under the Miller part number at this point, but it's a generic part. Allied, Digi-Key, Mouser, etc. should have it, going by the specs on the parts list-should be able to find something that will work.

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  • ryanjones2150
    replied
    holy smokes, that an expensive part.

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  • Sked
    replied
    Originally posted by Aeronca41 View Post
    My next guess would be a shorted Q301 Thyristor on PC2.
    OK. That sounds more like where I thought I'd be going. I may take a shot at replacing them, but looking into the PC2 boards raises another question. My machine has an older 039 195 board (mine is actually marked 039 196) as shown in the parts list from a 1975 owners manual. The Service Parts Manual I received a couple days ago is dated 1991 and does cover my serial number machine. On the subject of the PC2 Board the manual states for 052 790, the only PC2 Circuit Card shown, "This Circuit Card Replaces All Previous Circuit Cards And Is The Only Card The Factory Recommends Repairing". I notice there are no transformers, relays, or thyristors on this newer Circuit Card. I'm wondering if updating is the way to go. Thoughts?
    Last edited by Sked; 09-23-2016, 05:10 PM.

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  • Aeronca41
    replied
    My next guess would be a shorted Q301 Thyristor on PC2.

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  • Sked
    replied
    Originally posted by aametalmaster View Post
    Does the HF run with the foot pedal unhooked?..Bob
    Yes.
    Unhooked with machine set to remote and the HF switch turned off. Also with any combination of switches and settings.

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  • aametalmaster
    replied
    Does the HF run with the foot pedal unhooked?..Bob

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  • Sked
    replied
    According to the Service Parts Manual I received a couple days ago, yes I have the correct relay. The one I have pictured IS the CR2 Relay. The CR1 Relay is next to it and it's different in that it's an open DPDT verses the CR2 which is an enclosed 3PDT. I replaced the CR2 with a new one I received today and the CR1 can be manipulated by hand being it's not enclosed. None of it made a difference. The HF still runs continuously as previously stated. Any suggestions?

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  • ryanjones2150
    replied
    your machine probably has several relays in it, are you sure you replaced CR2?

    I'm having a relay problem with one of my machines currently. That machine has at least five relays, four of which are clustered together (CR1-CR4) and they look identical but all have different specs.

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  • Sked
    replied
    Originally posted by cruizer View Post
    Yep, Cr1 or CR2, likely the latter
    Alright, that's not it. What else you got?

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  • Aeronca41
    replied
    I can't comment on whether that is CR2 or not-just don't know. I can tell you that Cruizer is seldom wrong. He has seen a LOT of machines through his shop.

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  • Sked
    replied
    OK. As long as the CR2 relay is the one I have pictured, I have one on order. Probably won't have it in my possession till next Monday.

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  • Aeronca41
    replied
    He thinks the relay is stuck on, all the time, regardless of panel switch positions.

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