Need Help! 98 Haas VFE DC Buss voltage too low


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Thread: 98 Haas VFE DC Buss voltage too low

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    Default 98 Haas VFE DC Buss voltage too low

    I am getting a 160 alarm for low voltage on our 98 VFE. We just moved our machine to a new location and our incoming power is different from our old location. Old location we were at 244-245V. New location we are 211-212V. At our old location I also was getting the 160 alarm and a Haas tech instructed me to just drop the tap range on the transformer to get the DC Buss voltage into an acceptable range. Details of that are in this thread here: https://www.cnczone.com/forums/haas-...-haas-vfe.html This worked for 3 years, but since moving the machine it appears this was a bandaid fix...

    Now that our incoming voltage is much lower even the lowest tap setting of 210-195V won't get the DC Buss voltage (as read on the diagnostics page on the Haas controller) above the necessary 145V. On the 210-195V tap the DC Buss on the controller says 140V. On the 226-211V tap the controller reads 127V.

    The Haas Tech again pointed to the Mangetek drive as the likely culprit. I called Precision Zone (who did the rebuild on our drive a few years ago) and they walked me thru all the measurements and it all checked out fine.

    Measurements on the Magnetek GPD515:
    (For 226-211V tap)
    L1-L2= 227.8v
    L1-L3= 229.1v
    L2-L3= 228.5v
    L1-g = 132v
    L2-g= 131.6v
    L3-g= 132.4v
    DC Bus= 312.2v

    (For 210-195V tap)
    L1-L2= 246.7v
    L1-L3= 248.2v
    L2-L3= 247.4v
    L1-g = 142.9v
    L2-g= 142.4v
    L3-g= 143.5v
    DC Bus= 338.8v

    I found this thread here: https://www.cnczone.com/forums/haas-...s-voltage.html that appears to be a similar problem to mine (or at least the solution looks like it would fix my problem). My issue is I'm not an electrical guy and I'm not sure where on the distribution card the "Bridge Rectifier" is so I can measure the voltage there. I see the A to D pot, which has some hot glue dabbed on top of it, but not sure where Bridge Rectifier is. I've attached a picture of the distribution card. If someone could point to the Bridge Rectifier that is apparently some where on this card and show where I should be measuring the voltage that would be super helpful.

    I tried to get the Haas Tech out to fix it for me, but he has yet to call me back to make an appointment to take my money... in the mean time, I'd like to see if I can fix it myself so I can get the machine back up and running.

    Thanks in advance for any help.

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    Attached Thumbnails Attached Thumbnails 98 Haas VFE DC Buss voltage too low-haas-vfe-distribution-card-jpg  


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    Default Re: 98 Haas VFE DC Buss voltage too low

    In the picture shown, you have 2 squares outlined in silkscreen. On the opposite side of the board in those locations are the bridge rectifiers. The "+" marked near 1 terminal of each square indicates positive output. Typically the opposite corner is negative. The other 2 terminals would be AC input.



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    Quote Originally Posted by JustTodd View Post
    In the picture shown, you have 2 squares outlined in silkscreen. On the opposite side of the board in those locations are the bridge rectifiers. The "+" marked near 1 terminal of each square indicates positive output. Typically the opposite corner is negative. The other 2 terminals would be AC input.
    So I should measure DC voltage on the pins circled in red?
    What voltage should these read? Both the same? Should both readings match the DC buss readout on the diagnostic page?

    Does the A to D pot adjust the controllers readout of both of these?

    Attached Thumbnails Attached Thumbnails 98 Haas VFE DC Buss voltage too low-pxl_20210609_223237269-2-jpg  


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    Quote Originally Posted by alpydawg View Post
    So I should measure DC voltage on the pins circled in red?
    What voltage should these read? Both the same? Should both readings match the DC buss readout on the diagnostic page?

    Does the A to D pot adjust the controllers readout of both of these?
    Just found a YouTube video explaining the ac input pins and the DC output pins. Shown in pic attached.

    Previous questions about correct voltage reading and how both of these relate to the DC buss reading on the controller still hoping for answers on

    Attached Thumbnails Attached Thumbnails 98 Haas VFE DC Buss voltage too low-pxl_20210609_223237269-3-jpg  


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    Default Re: 98 Haas VFE DC Buss voltage too low

    Sorry, can't help with questions about adjustments as I don't know this system at all. I just knew about where the bridge was. Good luck Edit: When I said "opposite" for the negative post I should have said "diagonally opposite". Your new picture is correct as to where to check DC voltage.



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    Quote Originally Posted by JustTodd View Post
    Sorry, can't help with questions about adjustments as I don't know this system at all. I just knew about where the bridge was. Good luck Edit: When I said "opposite" for the negative post I should have said "diagonally opposite". Your new picture is correct as to where to check DC voltage.
    I got it figured out. On my machine it should be 160V across the DC terminals. Mine read 167V. Just tuned the A to D pot until the controller displayed the same voltage. Problem solved!



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    Default Re: 98 Haas VFE DC Buss voltage too low

    Cool post. I have a buddy w/ one of these types. Will remember this one. The AtoD must be an Analog to Digital calibration pot (capn obvious) that tweaks the reference voltage used when converting to digital (adac) for numeric evaluation on the system. A Clamp circuit is also pretty common. OV must set the overvolage I suppose. Glad you solved it. But.. if this continues to degrade, and the DC Caps are likely suspects.... Just replace em' like noted in the other post.

    Quote Originally Posted by alpydawg View Post
    I got it figured out. On my machine it should be 160V across the DC terminals. Mine read 167V. Just tuned the A to D pot until the controller displayed the same voltage. Problem solved!




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98 Haas VFE DC Buss voltage too low

98 Haas VFE DC Buss voltage too low

98 Haas VFE DC Buss voltage too low