DRO repair

I do not know anything about these units in particular, but the most common reason for any power supply to fail is bad electrolytic capacitors. Sometimes you can see these right away because the tops or bottoms are bulging, or electrolyte is leaking. They can also be checked without removing by using an ESR meter. Is this worth your time to troubleshoot and fix? One bad capacitor may mean the others are near the end of their lives.

Tom:-

Probably pretty easy to repair unless a custom transformer is burned up. If it don't smell of smoke, it ain't irreparably broke.

"Tom Gardner" fired this volley in news:UeCdnYMvWbm01LTNnZ2dnUVZ snipped-for-privacy@giganews.com:

Tom, As Anorton said, a common reason for power supplies to fail is for bad capacitors. However, with switching supplies, which this most likely is, bad caps usually take out a semiconductor or two while they're at it.

Two things:

1) IF the manufacturer hasn't removed or obscured all the part numbers, most of the stuff related to the power supply will be easy to source.

2) The inductor(s) will not be. They're often proprietary.

Don't rule out just a blown internal fuse, too. It happened just a couple of weeks ago to me with a high end "library quiet" AC unit I have. A fuse on the board, with NO way to change or check it without disassembling the unit!

LLoyd

LLoyd

Well, if you can determine the correct voltages for the power supply, then replacements should be available. If they have odd voltages there, they you might have to cobble two supplies together. If it is a simple rectifier/capacitor/linear regulator supply you should be able to fix it, if it is a switching supply, it is probably easiest to just replace the whole supply.

Jon

My neighbour has a Uniq DRO IIRC and I'll enquire about whether he has any info regarding the power supply. We had noted a software flaw in one routine where it defaulted to metric regardless of the setting but that could be lived with.

I have a Newall DRO and it failed due to what was likely a vibration induced failure in the power supply chip legs. The DRO display was mounted in a common manner on the headstock of the lathe and it failed when doing an operation which caused chatter which I rarely allow. Talking with a tech at Newall he mentioned that failure was common which didn't impress me for something which should have been designed for an industrial situation. I had looked for such problems but didn't look in that detail, next time I will.

I also should have asked about filtering the power to the unit. We are at the end of the line and get a lot of crap in our power and we run a big spot welder that noticeably dims the lights on cycle. How about a UPS on the DRO?

Switching power supplies (which this is likely to be) can be difficult to repair -- since schematics are hard to find. However, modular power supplies are pretty cheap -- find out the voltages needed (likely +5V and perhaps +/- 12V or +/- 15V) and look for a single power supply or multiple ones which will either fit in the existing housing, or if necessary, put them in an external housing, with short wires to the DRO. If you have to do this, you probably want some extra filter capacitors right at the connections to the DRO's logic boards to make up for the inductance in the wires.

Yes, get it back and see what power supply it needs. If it used a wall wart, some external power supply should be easy to find.

O.K. Doing a little web searching, it looks as though the power supply is internal, since there is an AC power cord connector ont he back -- so you might have to pull out that connector, go for power supplies in an external housing, and feed it through a multi-pin connector in place of the power cord connector.

At a guess, the power supply has at least +5V and +/- 12V, since there is what appears to be a pair of serial ports on the back though those are likely to be for the encoders in reality.

If it were mine, I would try replacing the power supply, even if it had to be done with an external one. The current power supply should be a module with the AC connector as part of it, or wired directly to it (perhaps through the rocker switch on the back). For that matter, is it possible that the rocker switch has gone bad?

Good Luck, DoN.

I put a UPS on the complete"computer" on the big CNC lathe at a clients - as well as on the mill. Solved a lot of issues.

Most cheap UPS's are not on-line, meaning they only cut in the inverter when the power completely fails. They have little filtering or surge suppression when the average voltage is normal. A surge suppressor might be a better choice, but most of those are really poor, too.

Jon

I concure with DoN. Check some simple things, then go for a replacement supply.

Power: DC 5V (15%) 80 MA.

Does that use a wall wart, Tom?

'Should be very easy to replace.

--Winston

Nope, no magic smoke smell!

Yea, I was thinking of an "Active" UPS.

Unfortunately, the PS is internal. I'm kinda' surprised that nobody seems to have parts.

80mA (400mW) doesn't sound like nearly enough. Maybe that's the power _output_ for the scales.

The "Sino" lathe DRO I have contains a small more-or-less open-frame

5VDC switching supply, just 5V out. about 140 x 60 x 40mm. I would expect yours is quite similar. Similar 25VA units are around $20 qty

(RS-232 for the last decade or two generally used +/-V generated from

5V or 3V using a MAX232 or similar chip).

Best regards, Spehro Pefhany

So get a good UPS..Crom knows they are all over the place in surplus outlets

Gunner

One bleeding-heart type asked me in a recent interview if I did not agree that "violence begets violence." I told him that it is my earnest endeavor to see that it does. I would like very much to ensure

- and in some cases I have - that any man who offers violence to his fellow citizen begets a whole lot more in return than he can enjoy.

- Jeff Cooper

A chattering lathe has prodigious vibration power, a major fraction of the motor output power, and if the DRO is rigidly attached to the headstock, I bet it got quite the shaking, to a degree that very few industrial (versus military) designs can handle. Especially if the chatter frequency happened to coincide with a mechanical resonance in the DRO.

If the DRO is instead attached to the cabinet or splash shield, it won't get quite the shaking, and may live longer.

Joe Gwinn

Imagine if it only needs 5v, I have plenty of old computer PS's, any reason I couldn't cob something external using one of those?

I have a heavy "C" channel arm attached to the head slide. The mill never does any HD work that causes vibration. It's more like a scalpel than a chain saw. I HAVE noticed that the guys leave it powered-up

24/7...that will stop!