[SwampDonkey]

Mine just shot up to 53V output and I cant figure out why. I made the mistake of plugging in a driver while the machine was on. Is there any reason why the large transformer would be affected? If so, any way to fix it?

[Moggot]

Mine just shot up to 53V output and I cant figure out why. I made the mistake of plugging in a driver while the machine was on. Is there any reason why the large transformer would be affected? If so, any way to fix it?

I'm assuming your working with a 1100; I'm not familiar with the 770 and I wouldn't assume they use identical control electronics (though there may be similarities).

Which transformer are you referring to? On the 1100 there are two, or at least two main transformers, XFM1 and XFM2. XFM2 is to the left of the large capacitor, XFM1 to the right. XFM1 is primarily powering the front panel controls, fan, limit switches and control board. XFM2 powers the DC Bus Board and (by extension) the motion controllers. It sounds like you're referring to XFM2.

Quoting the manual:

XMF2 reduces the voltage (230 VAC) to a nominal 48VAC which is sent to the DC Bus Board on wires L15 and L25. A full wave bridge rectifier on the DC Bus Board in conjunction with a 15000uf capacitor connected (wires 300 {common} and 301) to the DC Bus Board provide a nominal 65 VDC supply for the electronic Driver Modules which can be measured on wires 300 and 301

Are you measuring 53V across L15 and L25?

[popspipes]

I would think that the 48 volts is under rated load, in a no load condition it may float up to the 53 volts you saw.I havent checked mine to see what it actually reads. If its a capacitive power supply it can vary the secondary voltage with the load, if its an inductive supply, the output voltage will remain relatively constant as the current varies.

My machine took a dump yesterday, I re installed the restore disk and that didnt fix it, turned out to be a ribbon cable connector I think, I reseated all of them and its ran fine since.

[Moggot]

I would think that the 48 volts is under rated load, in a no load condition it may float up to the 53 volts you saw.I havent checked mine to see what it actually reads. If its a capacitive power supply it can vary the secondary voltage with the load, if its an inductive supply, the output voltage will remain relatively constant as the current varies.

My understanding (and I'm no EE by any means) is that the part in question is a simple linear transformer with no regulation. So output will vary with input voltage but I somewhat doubt it will sag very much with the sorts of loads to be expected.

The stated input voltage range of the mill is 200-250V (which conveniently covers all the typical three and single phase distribution types). If the nominal output of this guy is 48V, and that's attained at the spec. 230v, it's a roughly 4.8:1 ratio. At 250 volts input you should see ~50 volts. My guess is that 53V feeding the DC bus board isn't going to hurt anything, but it does make me suspect the transformer or line is out of spec.

Edit- mine has 205V going in and 44.7 coming out. Drives are at 57VDC.

[Philbobb]

I just checked mine, 240.5 VAC input, 51.7 VAC output. Looks to be about a 4.65:1 transformer. 53VAC would be about normal with a 246.5VAC input. Also checked the voltage at the drives and capacitor, 67.3VDC. I've had no issues with my machine.


Phil

[SwampDonkey]

Thanks for all your help guys. I still read 53V from the transformer to the bus board, but the DC power lines coming from the bus board read as 1 or -1 when checked with a multimeter/ voltmeter.

[SCzEngrgGroup]

Thanks for all your help guys. I still read 53V from the transformer to the bus board, but the DC power lines coming from the bus board read as 1 or -1 when checked with a multimeter/ voltmeter.

Are you using the AC or DC scale on your meter? For measuring on the transformer output, the meter must be set to AC volts. For measuring the power supply output (across the big filter capacitor) the meter must be set to DC volts.

If you see 50-55VAC across the transformer output, and don't see 65-70VDC across the filter capacitor, then your bridge rectifier is probably blown, or perhaps there is a fuse between the transformer and rectifier?

Regards,
Ray L.

[popspipes]

My machine is within .1 of what you list here.

I just checked mine, 240.5 VAC input, 51.7 VAC output. Looks to be about a 4.65:1 transformer. 53VAC would be about normal with a 246.5VAC input. Also checked the voltage at the drives and capacitor, 67.3VDC. I've had no issues with my machine.


Phil

[Moggot]

The DC bus board has a fuse for each 'output' and one 15 amp main fuse, F6. If the board isn't producing any DC voltage, that'd be the first thing to check.

It does sound like the meter still set to AC though; I know I did that while checking today. Took me a couple moments to recognize what was going on.