[MrFluffy]

More fun, powered up, Y is moving fine, X axis dead. Swapped the plugs, and X axis moves as Y fine.
Swapped the servo packs, and X axis servo pack is blown, notice a bad fuse, and a bag of fuses taped to the supply (uh oh...) and it pops a new one when inserted. Also noticed it powered up and had good status as a drive on the leds on front and didn't blow its 3amp fuse until it was asked to move axis...

Checks price of used servopack thinking to just pick a good used one up, until I found what they fetch, $750 upwards. Thats not in the budget right now.
Roll up sleeves, strip bad servopack, its already broke so no loss having a look round. I sort of figured the problem is in the power drive side because its talking to everything until it gets asked to move the motor then it all goes to crap.

Found a manual for a older Yaskawa servo pack, back when they had circuit diagrams in. Figured mine was the same power electronics design (maybe with parallel mosfets instead of smaller transistors arranged in a darlington layout), decided the fets were most likely to suffer damage.
https://s3.amazonaws.com/Icarus/DOCU...anuals_489.pdf

Then, to the soldering iron, the FETS labed 1-4 on the silkscreen of the pcb can't be tested in circuit due to parasitic loss, so they had to be desoldered to check. And, out of four, two are blown. Now I have to desolder the diodes to the right and I want to take the bridge rectifier out and test it out of circuit too as I'm getting a funny reading. If its just these fets blown, its a $20 repair.
Theres another pcb on top of this with all the drive wizardy that reads the encoders etc, this base board appears to be the power electrical bits nicely segregated to make things easier.


Heres the datasheet for them. Theyre a standard pinout for mosfets.
Apache Tomcat/6.0.29 - Error report

How do I know two are bad? dvm on diode check if you dont know, theres a runthrough on youtube :-
https://www.youtube.com/watch?v=RBJGOOTEwfU

With two the gate stays on and slowly leaks away, and two it doesn't open at all.


More diagnostic work ahead though, the X axis doesnt work even with the "good" servo pack in it. The display looks like its travelling but physically its not moving, so I suspect whatever caused the servopack to go bad is still there and needs fixing before it strikes again.

All good fun though, learning about the innards quite a bit, and you can't buy learning like this in a book.

[MrFluffy]

And one last final update, the one I wanted to make. Its almost finished thanks to some wise words from JMullet and others. I say almost because I've decided that monitor has to go now for one the correct size for the hole as its annoying me because I can't get it mounted and sealed up neatly & the menu options don't align with the machines soft key physical positions. Plus a few other tweaks in the pipeline.
The screen size is a odd aspect ratio to commonly find in a desktop lcd, and I didn't want to spend a lot of money out to find the monitor couldn't cope witht eh low screen resolution. So to that end I've broken a old compaq armada that was wrecked but the screen worked, and I've ordered the lcd->vga driver board from ebay to convert it into a monitor. But it cuts.

https://www.youtube.com/watch?v=Z1KA9JqOtAo

[bassett]

Have a bf275 and would like to know if you had success with replacing the floppy drives.
have operated machine since new I would say that I was vague then but I would not ever buy another machine without circut drawings.

[MrFluffy]

Its ages since I was active on here bassett so sorry for the response delay, but popped on to ask about a renishaw probe retrofit for my vmc.
No I never replaced the floppy disks with a different drive. I have a stack of 5 working floppy disk drives now after bidding on various yahoo japan pc98 auctions, which as I've used the machine on about 9 occasions in x years is probably several lifetime's supply. I've mailed HxC on a couple of occasions about buying a vfo, but never got a conclusive reply of where/how to send payment so I've sort of given up on it. They are just hobbyists playing with retro computers/synths so I guess theyre not very bothered about us sodick owners.