[regina]

I simply can't afford the 60% cost of new from Fanuc board repair the service places are charging. I have a bad top board on a 6058 triple drive. I have a good board so I have a means of comparison, and it would be nice to have a spare. It has a HV LED illuminated. Later on I am going to look up the diagnostics and see if I can find if the fault is to a specific axis. It seems like a lot of the faults on these boards are from aging electrolytic capacitors and optocouplers. There were a couple discolored resistors, which I removed and they actually checked ok, but it was easier to replace them with new than try to put the stubby burnt ones back in. I went on ebay and bought all replacement new capacitors of brands I trust, and all new optoouplers. All in all about $200.00 worth of parts, and enough to do several drives. Radwell wants $990 to repair this board. TIE wants $1500 for a replacement and doesn't even want my old board. I am going to do an experiment and replace these parts and see if it fixes the problem. Figure $200 is worth the risk. I don't think I can screw up anything up worse than it is. Has anyone ever done this before and lived to tell about it? It will probably take a month to get all the parts here. I'll post the results here. Next up would be a 6079 series drive.

[john-100]

if your going to repair many boards with suspect electrolytic capacitors

a ESR meter can be very usefull to find the faulty capacitors

pdf instructions
Attachment 414100
from
https://anatekinstruments.com/produc...esr-meter-besr

this is a less expensive ESR tester from China
https://www.amazon.co.uk/KKmoon-Tran...ords=esr+meter

John

[regina]

Well the capacitors came in so I swapped out all of them except for the really tiny ones. None that I removed tested very leaky. I did not test them for ESR. I think maybe the capacitor thing is a myth when it comes to the vintage Fanuc stuff. Every one was sealed in with epoxy on the bottom like I have never seen. I put the board back in and still have the same HV led illuminated. This time I connected the NC to the drive. The HV led went out, but in it's place I get an NC 424 y axis detect error and found the 721 diag paramater is 00000100. That crosses to a DCAL error on the Y axis. Supposedly. I'm finding that too literal of an interpretation of these fanuc errors can result in a wild goose chase. The maintenance manual points to a bad regen transistor module. That can only be if it is on the top board, because with a different top board that amp is fine. I'm not sure what direction to go in next. I don't think changing out all the optocouplers is going to solve this, and I'm finding these boards a pain to desolder the components especially where they are varnished in. I can try swapping components from y to z one at a time and see at what point the error switches with them, but I'm a little worried about damaging the board doing that much work on it. Has anyone been down this road before? Also, what's the best way to deal with this varnish without removing the solder mask or otherwise messing up the board?

[DALEK]

If you have a good and bad board on the desk in front of you, just take resistance measurements, with a good multimeter between one terminal or pin and all the other terminals or pins where it was originally connected, and compare them between boards. You may be lucky and find something obviously different. You could also compare resistances of the components while they are in place, with really pointy probes. This will tell you nothing about the component, but an obvious difference between the two boards may help you. In my humble opinion, passive components rarely fail. Zeners, diodes, transistors, or anything with a heatsink is more likely.

[regina]

That would have to be some amazing luck. There are thousands of pins to check with millions of combinations. Without some basic understanding of the circuit that would be like finding a needle in a haystack, made all the worse this being a triple axis drive. I do have a huntron for qualitative in circuit comparisons, but nothing has jumped out at me yet. One problem may be with simple tolerance drift of individual components, it might be hard to see. Also, the descriptions of these faults may be leading me in wrong directions. I don't understand why the HV LED goes out when I connect the NC, nor do I understand what controls the regenerative braking circuits. I can only guess that if 2 axis show good, and one bad, the faulty component must be one of three duplicate components on the board, or within an IC that controls all three Axis. I tried to work backward from the braking resistor with the huntron, comparing the other 2 axis with the bad one, but again nothing stood out. I see there is a optocoupler labled PCHV. I may try replacing that when those replacements com in, but I am really kind of shooting in the dark here.

[diydesk2019]

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