Try these guys http://www.alternativemachinetool.com/

Thanks for the link, but they don't seem to do any of the control/NC stuff - just the basic mill.

Heidenhain are very tight about its circuit information usually only let there agents work on them which is very frustrating for people who would like to fix there own gear.

Put a link up re the info you have found?

Does the fuse blow with the power supply[ies] disconnected from the rest of the circuit?

When you say most of the supplies seem ok how many do you have? I would think you would have 2 X 5V supplies one for your TTL and the other for the scales ,12V for the displays seems OK. for the fuse to blow I would expect the fault to be in the power supply.

The service manual's here: https://filebase.heidenhain.de/doku/oma_controls/CD1/tnc/150/gb/sa150.pdf

The on-load test voltages for the DC supplies (as listed in the manual) are:

+12V ±0.5 @ 0.15A Processor*

+5.16 ±0.08 @3.5A TTL

-14.9 ±0.6 @ 0.1A Switching reg.*

+15.0 ±0.6 @ 0.3A Analogue board

+45.2 ±1.5 @ 0.06A Switching reg.*

+11.2 ±0.25 @ 1.4A Display Unit

+21.6 ±0.8 @ 0.01A Display

* I suspect these may be translation (or translator's) errors.

Re. the fuse: Initially it blew when on load, but after the power supply failure has stopped blowing.

You've raised a good point, though; the original fault may be somewhere further down the line. Won't know 'til the supplies are fixed.

Hi JohnJD,

Had a look at that link , only 2 fuses shown would be on the input to the main transformer very basic protection.!

All the other voltage outputs apart for the heater appear to come from one regulating switching flyback converter section item 70.1 try working back from that item to see where the input voltage is missing. Item 73.1 looks like an overvoltage shutdown circuit referenced to the 5V and 11V outputs.There is just enough info to get you into trouble.

Sorry cant help more without the circuit detail.

Garth

Hi Garth, & thanks for the input.

The two fuses on the board (shown on the 'layout' drawing, page 15) are actually on the 2 x 2.1Vac lines from the transformer 2^ndary - the fuse which blew was the line fuse to the transformer 1^ary. I realize that there's nothing in the docs that would tell you that - even with the board on the bench, it's a case of buzzing it all through.

The flyback converter 70.1 is actually 'piggybacked' on the 5V switching regulator (70 with 70.01). The inductor in the switching regulator cct has extra secondaries which produce the ±15, +22 & +45V outputs - the broken line between 70 and 70.1 represents the inductive linking. It looks like it's just rectifying & smoothing these 2^ndary outputs.

But this seems to be where it's going wrong - none of these outputs is anywhere near what it should be. I'll get my 'scope on it tomorrow, but from prodding around with a meter it looks as if the inductor is U/S. I'll also try a dummy load on what should be the +5V output to make sure it's producing the right voltage on load (as I said in the OP, it's 6.3V off-load).

BTW, the overvoltage protection looks OK, and the /RESET output is sitting high.

Bit more reverse engineering to be done .

Cheers, John.

Hi JohnJD,

If there is a shorted turn on that tapped inductor it will drag the output voltages down I would suspect, The faulty winding will have an output voltage much further away from spec than the others, I would try to load up all the outputs to some degree and the bad one will probably not come up to spec. I wonder why the fault is not pulling enough power to blow the fuse again, possibly because the power supply is not in circuit the total load is not enough to blow the fuse? I hope these windings are separate not one large coil will make it easier to rewind.

Garth

"I hope these windings are separate not one large coil ..."

all-in-one, about 1½" x 1½" x 1". Looks a bit like a small mains transformer. If this is dead, I think it'd be easier to rebuild the whole power supply board with separate modules than to try getting the txfr rewound (given that there are no details, & it would mean either pulling it apart to check the windings, or designing from scratch).

Rebuild would not be too bad, as only the 5V & 11V lines need much current. 5V is easy, & 11V could be done with a 12V supply + a couple of series diodes to drop the odd volt, + maybe a zener to clamp it for low loads. The 45V rail is the only real odd-ball.

I'll (try to) post some pics tomorrow.

John