DRO repair

Probably not.. AFAIR the newer ones need pins shorted to get them to start up and the load might not be enough to start, but I bet it would work. It's a big ugly box to hang off the back, but if that doesn't bother you, I don't see much of an issue.

Reply to
Spehro Pefhany
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Jameco and Marlin P Jones have modest quantities of surplus power supplies for VERY cheap, I suspect you can find one that will fit fine, with luck you may find one that is a drop-in replacement, assuming the power supply is not integral to the main board of the DRO.

Jon

Reply to
Jon Elson

Shorting the Green wire to ground will fire-up the supply.

Reply to
Tom Gardner

Cool! Even Electronics Goldmine has a bunch.

Reply to
Tom Gardner

Usually the power transistors fail in the switching circuit and also the filter caps. Switching power supplys cans give you all sorts of trouble. A sure fix is to just replace it with a new switching supply which can cost less than 25 bucks for some units. A cheap but effective way to mount it is with silicone sealant the good stuff. Make sure the surfaces are clean of all oils and dirt. I have replaced a ton of older supplies in cnc machine tools including a bunch of my own machines. The GE 1050 has all three of the old switchers replaced with the new ones including the 30 Amp. 5 volt unit. I just did a Monarch VMC175 for a customer that had his older power unit go bad. I stock one each of a 5, 12 and 24 volt switcher din rail mount unit.

John

John

Reply to
john

Something like this is what I would use, assuming it would fit inside the case and 5V only:-

If I order it by 9:00 pm tonight it's on my desk the next morning.

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For $16.80 I'm not going to do a lot of troubleshooting beyond looking at any fuses that may be present on the PCB.

Reply to
Spehro Pefhany

You may be right but I rarely allow chatter and it was an odd occasion that it happened, I was cutting short lengths of small tube about 6mm in diameter with a slitting saw in the spindle and it excited the system on my Harrison M300 so the lathe was certainly not struggling. The DRO is mounted on an arm extending forward from a pillar mounted to the back of the headstock as is fairly common. I compare the Newall against the Sony Millman on my BP which has never given me a problem in twice as many years of ownership. The Sony is fitted to an arm fitted the the column on the BP and it more regularly sees vibrations due to cuts compared to the Newall on the Harrison. The Sony has never exhibited any problems or software flaws whereas the Newall has shown several software flaws such as trashing of the linear error compensation values and losing the setting for what type of hardware it is. The hardware type is exhibited by it not knowing about tool offsets which shows it has had its hardware type reset or corrupted so it doesn't know whether it is a lathe or mill DRO, I was provided with the procedure to reset those settings if they became corrupted.

Reply to
David Billington

Who said anything about a "cheap" UPS. For critical applications only a dual conversion UPS will do the job. A line interactive unit comes in a distant second. A "standby" UPS is NOT a UPS.

Reply to
clare

It will work, but you need to put a load on the 12 volt supply for it to run (and short the green? wire to ground to turn it on)

Reply to
clare

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Depends on the PS (and particularly the age of the PS). Some of the older ones required a minimum load on the 5V to be able to also deliver a regulated load on the other voltages -- especially the +12V to spin up the disk drives). If you have one of those, you may need to add a power resistor as a dummy load to assure good regulation.

Other than that there is the fact that will almost certainly not fit inside the housing -- but if you replace the AC connector with a multi-pin one which is right for the voltages you need, you should be fine. The typical older power supply for a PC provides +5V, +12V (lots of current for those two), and -12V (just to complete the RS-232 voltages back then. Newer ones also produce something like +3 VDC to power the CPU chip, and often have a pair of pins which you have to connect together to turn on the power supply -- if the computer has a front panel button for power on/power off, instead of a bigger switch in the back or on the side.

So -- first determine what voltages you really need. +5 is almost a given, +12 maybe for some circuits. Maybe a weird voltage to power the plasma display (I think it looks like it has a plasma disply, based on the one which I found elsewhere last night)-- unless it is using a DC-DC converter to develop that from 5V or 12V. If it is, that could be what really failed -- if the LEDs light, but the digits don't.

Good Luck, DoN.

Reply to
DoN. Nichols

Given the nasty power you must have with the spot welder, I would suggest either a really good UPS (like the Best Power Systems (now only available used), which both keep the power going full time, and are based on a constant voltage transformer to absorb surges -- or at least use a Sola constant voltage transformer to control the surges. (I wonder whether they are still made?

Good Luck, DoN.

Reply to
DoN. Nichols

Exactly what I have for the power to the offices' computers! I've had a few failures in there over the years but probably not due to dirty power, just attrition.

Reply to
Tom Gardner

Form follows function!

Reply to
Tom Gardner

Yes, several reasons. Firstly, a computer PS gives an order of magnitude more power than you need or want (think: replacing fuse with a penny). Second, it has a fan. Airflow will pull gunk into the power supply. Third, it's not likely to fit inside (and will be a mechanical problem to mount nearby, and regulation suffers if it isn't close by its load).

Best would be to disassemble the unit and inspect the power supply it has. Repair cracks, replace scorched and damaged components, check fuses. It's likely the PS was ordered special, with some spares. The DRO manufacturer didn't repair dead ones, just swapped in a spare. And when the spares were gone, suggested 'buy a whole unit' because that's profitable for them. No one ever TRIED to fix a power supply.

Any good electronics tech can troubleshoot and repair what you have, or any careful technician can determine the exact power requirement for the unit (reverse-engineer the power unit) and find an off-the-shelf replacement.

Reply to
whit3rd

You obviously do not understand electricity - the device will only take the current it requires - regardless how "stiff" the supply is.

Not hard to prevent dirt from getting in and damaging the PS, and the regulation is not affected by distance AT ALL if the wire is heavy enough.

Or just do as suggested and use an external supply - oversize is NOT a problem - undersize is.

Reply to
clare

Not relevant. This is about blowing-the-fuse FAULT conditions. A small power supply will not (in case of an internal short circuit) melt the case of the DRO. A surplus computer power supply might.

Reply to
whit3rd

Agreed. Unless the power supply is designed to limit fault currents, which is typically only found in lab power supplies with adjustable current limit.

Proper filters on the air intake -- and also regular cleaning of the filters as dust and debris can build up and prevent airflow, leading to death by overheating.

You want the filtering to be good, because there is enough in the way of fine particulate metals in a shop's atmosphere, and that can build up a conductive path leading to failure.

Or -- if remote voltage sense is used. A feature not common in computer power supplies, but available in serious modular power supplies where there may be requirements for mounting the power supply some distance from the load.

However -- another possible problem with remote wires is that you need to add a couple of capacitors right at the load to compensate for the inductance in longer leads. Ideally, a large electrolytic capacitor to handle surges in current at low frequencies, and a small ceramic capacitor in parallel with it to handle high frequency loads (e.g. the switching spikes from logic circuits). Shorter lines will likely only need the high-frequency cap.

Indeed so. As for troubleshooting switching power supplies -- the problem is that many of the manufacturers treat the schematics as proprietary information, and a typical multi-voltage switching power supply tends to be sufficiently complex so troubleshooting without schematics is quite difficult. Much cheaper to find a replacement in most cases.

Oh yes -- the manufacturer of the device is almost certainly

*not* the manufacturer of the switching power supply used in the device. As an example, the Sun Fire V120 (a 1U high server machine made by Sun Microsystems) uses a power supply made by Delta Electronics Inc. And to add to the fun, while Delta has been a company in the US for a long time, this one was made by a branch in Thailand. (It looks similar to others with the same basic part number -- until you get to the "-03" suffix, which represents an extra cable and connector for control, remote sense, and for running a tiny computer buried in the main one for LOM (Lights Out Management) -- allowing rebooting, power-off/on, and other things from a remote connection.

I would *love* to have a schematic for these. I've got three failed out of seven at the moment. (Almost certainly pirated electrolytic formula failures. :-)

Enjoy, DoN.

Reply to
DoN. Nichols

What DoN said. Switchers are NOT easy to fix. You can't measure voltages and look for the ones askew; they all are if it's bad. (Chicken & egg) You can't blindly replace parts; the caps must have good ESR values, chances are the semicomnductors have house numbers, etc.

None of this matters if you are working at Delta with 100 Model 567's a week going by; THEN you know what is going on. But Reddy Milliwatt is just guessing.

Replace it.

Reply to
David Lesher

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