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Synchrowave 300 need help

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  • jjohn76
    replied
    Ok, that seems like a low value. Hopefully this picture is legible on screen. I traced out the signals and component values. IC5 is your negative feedback error amplifier. All of those signals (23-12 across the top middle) are either a reference current value or the measured current from your hall device. With the hall device unplugged, you should get somewhere around 4k - 6k ohms (it has a potentiometer in series probably used for calibration). If you're not getting a good voltage from your hall device, then that will keep your welder at full tilt.

    Also, it's worth checking your the amplifier on your hall device. First check resistance across the blue and yellow wire, then across the red and black wires, then across pin 6 and ground.

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  • stevew
    replied
    yes it was.

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  • jjohn76
    replied
    Steve, no worries. Looking back on it, you're really looking for the components that are causing the SCRs to fire full tilt. When you originally measured the low resistance on the current feedback circuit up above, was the hall device/board plugged in?

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  • stevew
    replied
    Hello John,
    I have to ask you to be patient as this may take me a while. I am checking everything you've mentioned and more I will let you know what I get soon.

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  • stevew
    replied
    ok 7 and 4 my multimeter just counts down. 4 and ground do the same as 7 and 4. 7 and ground show continuity. also I havent any amp gauge. r51 shows a value of 8.89. I have to log out now I will get back.

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  • stevew
    replied
    I am just very glad to have you you helping me. I will check what you have mentioned to the best of my ability and then Im sure I will have some more questions.

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  • jjohn76
    replied
    Sorry for not responding sooner Steve. Pages 23 and 26 have the relevant schematics, which look to be close for your boards, you would be the only one to confirm.
    Page 23 - is your panel ammeter tracking amp output correctly. If it is, then your Hall sensor is ok. If it isn't, then it could be your hall sensor, the opamp (triangle in the middle) or a bad capacitor/resistor. Check component values (pins 7 and 4, 7 and ground, 4 and ground should not show a short). You have a lot of parallel circuits, so your resistor readings may not be exact. Opens and shorts, or low values (singles, tens, maybe hundreds of ohms) would be worth further checking. You should have resistances across the hall sensor blue/yellow wires and red/black wires (shouldn't be open or shorted)

    Page 26 - I wrote on some other Sync 300 thread how that circuit works, but it's tough to go from writing to schematic. If I get a chance, I will try to draw out the major blocks on that schematic. Either way, since you're getting full amperage on Hi, I would first check the part of the circuit that compares the current you want to the current you're actually seeing. That all happens at IC5, pin 2. They're basically all added together. The signal flowing through resistor R51 is your reference current set at the panel/pedal. It will be negative, so check that it is not shorted to ground. Check resistance on pins 12,20-23 against IC5 pin 2 .Check those against pins 4 and 7 too (these should be very high resistance). I will see when I can print out the schematics and component values to get close to what you should be measuring. This circuit board doesn't flow too much current except for the right side and bottom left of the schematic, so the resistances from the signal pins should not be in the tens or lower.

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  • stevew
    replied
    Ok john,

    I am ready I believe how do you want to go about this?

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  • stevew
    replied
    Im not sure what it is Im suppose to verify.

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  • stevew
    replied
    ok john,

    I have downloaded manual what next?

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  • jjohn76
    replied
    Steve, if you could download the M version of the Syncrowave 300 manual (O350M_MIL.pdf), it has a main circuit board and amplifier circuit board plus schematics that look very similar to your boards. If you can verify the circuit boards, I can walk you through the schematics and boards to check what I would check.

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  • jjohn76
    replied
    Steve, I don't have the schematic for that main board, but let me check this weekend to see how it compares to what I have. Corrosion on that Hall amplifier circuit could be an issue, I'll post this weekend some things to check.
    Jon

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  • stevew
    replied
    hope this helps

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  • jjohn76
    replied
    Steve, you will only get one half of your rectifiers to show continuity to your electrode, so that is good. The other two plates are connected to your work clamp lug when set to AC. It sounds like your connections are ok. I'll dig into the schematics a bit more and get you some other things to check. Can you please send a photo of your main control board and the hall sensor/amplifier board?
    Jon

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  • stevew
    replied
    I checked the scr rectifier to torch connecter and only two of the plates are reading near zero. bottom plate and short center plate holding diode, two top plates are open. the contacts on all switches appear dirty but no corrosion. hall device amplifier board is quite ugly solder appears disintegrated. I can send pic if you would like.
    I rechecked pin 12 to pin two on ic5 and it reads 5.34 if this is low what might that mean?

    Thank you jjohn76

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