Manky Monkey Motors

My workshop inverter went bang last night, it's an old Glentronic gto type, lots of discrete components. As usual one of the thyristors has gone, taken at least 5 driver transistors with it. Luckily I have a spare thyristor, but if I cock up fixing the driver board it'll go bang as soon as I switch on....
No compressor, miller or lift until I fix it.
New one circa £850, and I'm on my last spares!
Huw

I have absolutely no idea what you're talking about!

Single phase 240v.to three phase 440v converter.

Nope. Gobbledegook.  :P

I'm with manky :)

I have a couple that also went wrong, I'll dig them out and see what make they are, if they are of any help to you give us a shout.

Change over to single phase motors? :D :D :D :D :D :D.mebee!

Maybe indeed, we'll see. Been out all day with our local rugby team, we lost, the first team won, so not bad really.
I have started stripping the control board, I'd rate my chances as 70% at best..
Huw

I'm up to 6 transistors, 6 jfets, 4 diodes, a few resistors and capacitors and pair of inverter chips. Once I've replaced all, I'll be testing the driver on a set of 12v bulbs, if it looks ok, then I'll connect the thyristor blocks.
The list sounds short, but I've removed and tested 18 transistors, 18 jfets, 18 diodes and loads of other stuff.
Maybe tomorrow night.
Trike build on stop....
Huw

bloody hell. ive lost track of how many of those drives ive thrown away!
although I'm sure if they were a tad more servicable and my own I'd have a closer look

Have you checked the flux capacitor?

ive put "replace failed Flux-capacitor" on my paperwork a few times

 ;D

Lol, you'd be surprised how close to the truth you are the manky. One of the failure modes of these is the dc link capacitors failing, I think I've changed two over the years.
Driver board now built up - testing soon.
Huw

"Soon" has taken longer than I thought. Tested the driver board tonight, it showed on phase not working - turned out to be a voltage regulator on the power supply board.
Now that's fixed, tested the high outputs, but need to solder some dropper resistors into the low outputs before testing them.
Getting closer.
The trike engine is out, welded the bracing bars, started prepping for paint.
Huw

Show us some piccies then matey.  :)

Lol, the inverter or trike?

Both!

I'm guessing my last post on this was at least 2 weeks ago? Anyway, the driver board issue was more serious than I thought, I eventually moved it onto a spare drive which I had on the bench - much easier to work on.
Once the power supply issues were sorted out it became clear that most (all but one) opto isolators were shot. I stripped some out of a spare board, soldered some ic bases in and plugged them in, fully expecting success. It turned out to be anything but, said opto isolators were a different type, and not a direct swap.
The long and short of it was I had to modify the bases again.
Well tonight I had all the lamps pulsing at the right frequency, at the same voltage. I guess I should put a scope across them to make sure all is well, we'll see tomorrow. Closer than I've been to date....
Emptied to go for it.
Huw

You're making this stuff up, right?

im an electrician and i caught most of that as english. what are you Huw an erectrical gingerbeer?

Yeh, long time ago did an mod apprenticeship in electronics, plus some other qualifications. A little rusty now though.
Scoped all the driver signals out, looks good, 4v square waves all around. Fingers crossed will have it running later.
Huw

Sort of qualified success!
Had the inverter running, went in for tea doing cartwheels, came out later it had stopped...
So, fed up with sitting on the floor (the inverter is wall mounted, quite low), I decided to switch my attentions to an identical, but lower powered unit which runs my lift. This is much easier to work on, uses identical circuit boards, but lower power thyristors and less capacitors.
After much testing and repairing of driver and the analogue board, I had the lift running. Then it failed, then I changed another driver FET , and today, success - lift motor runs!
So, transferred the circuit boards to the big inverter - still no good. Another blown thyristor.
So now I'm out of thyristors. however, these are dual units, built together in one block. tonight I've mounted two units, one with failed cathode, one with failed anode side by side, using the good half of each one.
Tomorrow I'll know if this has worked...
I'm getting pretty peed off with this faring about, but it has its plus points - if I can locate suitable replacement (modern) gate turnoff thyristors, I'll allways be able to fix these. If I go and spend a thousand pounds on a new one and it fails a year later I'm stuffed.
Wish me luck
Huw

Huh?

As you well know Mr. M, gate turnoff thyristors are SCR's that can be switched off, as well as on, therefore.....................come to think of it Mr. M, and by your own admission re. the complexities of wiring such items as hazard lights, maybe not.. ;D ;D ;D ;D ;D, ho, hum, what about steam power, now theres the future,alright, I'm on my way.......

What he said!    ;D

I looked it up for you Manky, here y'go - it's as clear as mud!

http://en.wikipedia.org/wiki/Thyristor (http://en.wikipedia.org/wiki/Thyristor)

 :)

I'm with MM on all this trickery stuff. I know what a few of the items that were mentioned are, but have absolutely no idea what some are, what they do or how they do it .  If I can't actually see how something works then as far as I'm concerned it's either magic or voodoo.

Had some success with the inverter, miller actually ran for a minute before stopping, suspect one of the thyristors blown again. Worse, I can't find equivalents/replacements, so this might be the end of the line.
Huw

Well I had a blown thyristor, with no spare. So, since they are effectively two in one, one for the positive half cycle, one for the negative, I figured using the good half of two separate ones, and as luck would have it I still had one of each.
Wired it all up, switched on, and it ran - for 30 secs.
Anyway, another driver board fault, that was 3 weeks ago. In all the testing I managed to blow a 4010 chip.
Tonight it all went back together for the umpteenth time, switched on, and I nearly did a jig. Running like a dream! I even made a little video, which I'll try to upload.
Now, I'd like to say that it all ended happily, but it didn't, 10 minutes or so later one of the snubbers started spraying smoke out like it was going out of fashion. So it's in bits again, I'm hoping this snubber has been the root of the original problem, so I'll try another in its place. Should know by Sunday afternoon ( I'm off up north tomorrow with work, back Friday evening, hopefully in time for the rugby.
All the best,
Huw

Damnit, can't copy and pase with this useless tabet, bring back laptops.
Huw

Well I had it working, test started three or four times, even started to believe.  It didn't last, blew my last thyristor, so chucked it under the bench and dragged another one, of a different type, that must have been there at least 10 years out.
That was three, maybe four weeks ago.
I spent a couple of nights working out the control wiring and fired it up.
Initially it filled the wkshop with smoke, from some previously overheated connections and the dc charging relay.
I fixed these one by one, and lo - it just sat there...
Anyway, some dc (low voltage) guesswork - I mean fault finding, showed the two positive supply regulators weren't giving anything out. Tracing the circuit by holding the Pcb up to the light, removing and testing the regulators drew a blank, so I cut some tracks to isolate various parts of the circuit.
Bear in mind every time I do this I have to remove the Pcb, do the soldering,refit and test, and it takes some time.
Fast forward to tonight , I'd pinned it down to a tantalum bead capacitor, which I replaced with something pretty close. Switched on and bugger all happened...
So back to the drawing board and work logically, which led me to the capacitor I'd just replaced, tested it, and sure enough it was duff.
Replaced it again ( but with a tested one this time) and damn it all, it worked, I had a dc supply.
Linked the start relay, and away it went, like a good un!
To say I'm a happy bunny is an understatement, it's only taken 3 months, which I should have spent on my trike. So now to mount this on the wall, wire it up and enjoy a long and happy relationship with my "new" inverter.
All the best from west wales

happy endings!
well done sir