[JasonMiller]

1993 Okuma LR15
VAC Drive, not VACII, D22A


Here's the situation:

1. I was running some parts, came in for some lunch and when I made it back to the machine I had an SDU error, the top board of was off. Power down, power back up, top board remaind off. Upon inspection drive fuses F4 and F5 were blown.

2. Replaced fuses, they blew again.

3. Messed around in the cabinet, checked a few things, disconnected a cooling fan that looked sketchy, replaced fuses, restarted. Fuses OK! SDU top board boots normally. Un-estop the machine and after about 10 seconds (drive normally doesn't power for a few seconds) the SDU throws an error again. M1 on solid + light #3 -- UVP Power circuit under voltage. I can reset this alarm via the reset button at the bottom of the board but retrying has the same result.

4. Okuma maintenance manual reads a) source voltage low or b) screws on diode module loose -- voltage at the SDU breaker reads 220ish from leg to leg, I check the diode module screws and they are all tight. I think its odd the manual doesn't say to check the modules directly.. I did so anyway and the results are exactly opposite of what the manual expects.. maybe I am inspecting them incorrectly? I have ordered more anyway. Could this be the source of my problem?


To throw another wrench into things.. about a month ago I replaced the Opus power supply it was having some low dc voltage errors. I noticed in the process my machine was getting 250+ vac and changed the transformer taps on the machine down to 220v, this fixed a few random issues I have had over the years. I was quite disappointed that the tech who set it up in the first place never caught this problem.. sigh.

Ideas?

-Jason

[JasonMiller]

Also discovered a couple of the big ceramic resistors at the top the the SDU were not checking out to their specs -- the 15kohm was 9.9kohm and the 50kohm was 37kohm. Any idea where to get these? The 6 resistor one looks like it would be difficult to come by.

[Algirdas]

15kohm was 9.9kohm and the 50kohm was 37kohm

some measuring or understanding mistake, most likely. Anyway, big ceramic resistors are not precise.

[JasonMiller]

New diodes tested the same as the old... now what to do?