schematics help

[Richard.]

Right ok! Well I'm no sparky in fact far from it so I certainly would not be sticking my mittens in a machine so whether it's high voltage/amperage or not. I would still be giving it a wide birth. I'm very good at using them but completely useless at fixing them.

 

[wheresmejumper]

Caps first, then the bridge.
After that clock/firing pattern on the inverter.
Diagram is too blurry to help much with TBH.

Hi,caps have to be removed from circuit and be tested one by one is that right?

 

[Jim Davey]

That's right, make sure they are discharged! And that you get them the right way (polarity) when you re-fit them.

 

[wheresmejumper]

I hate soldering,especially desoldering.i was hoping that you could measure the capacitance of the lot and do maths to work out if its adding up right

 

[Jim Davey]

Have you got a nice hot iron and a solder sucker?

 

[wheresmejumper]

Yeah but 15 yr old solder,and its big lumps on the ends of these mofo caps,doesnt like shifting.i tried the trick of adding a little new solder to the mix.it helps but it still takes an age and its messy.

 

[Jim Davey]

Cut the worst off near flush, was going to say add new solder but you already know that one. Get them hot fast, you don't want the thru-board ferrules giving up because they overheated.

 

[Sidewinder]

Are the ends of the caps bulging, (convex), or are they/have they leaked?
You would need to check both the capacitance and the ESR to prove they are OK.
If you are going to go to the trouble of removing them, just replace them.

 

[wheresmejumper]

I have a 40w and an older 80w iron.i have a sacrificial board that it took out one cap from today.id say 2 hrs for the real board to get 8 out tested and back in.
cheap ass meter takes about 25 seconds to read the caps,ill have to buy another fluke

 

[wheresmejumper]

Are the ends of the caps bulging, (convex), or are they/have they leaked?
You would need to check both the capacitance and the ESR to prove they are OK.
If you are going to go to the trouble of removing them, just replace them.

No,they look good,no bulges.2 are missing small bits of plastic cover but i think just aged
how do you check esr?

 

[Sidewinder]

Don't bother with a Fluke for caps!
Get a Peak Electronics one if you are serious about measuring components.
See here, http://www.peakelec.co.uk/acatalog/jz_instruments.html
These are what quite a few of my friends who regularly do component level stuff use.
Very good velue for money £/performance wise.

 

[Sidewinder]

If the caps are not leaking or bulging then likely fine.
ESR with an ESR meter!

 

[wheresmejumper]

If the caps are not ling or bulging then likely fine.
ESR with an ESR meter!

Ah,i see!
you mentioned earlier check the firing order.how would i do that?

 

[Sidewinder]

Ok, if you are going to check the firing pattern that is an oscilloscope job on the output of the firing board onto the inout of the power board.

 

[wheresmejumper]

Ok, if you are going to check the firing pattern that is an oscilloscope job on the output of the firing board onto the inout of the power board.

Thats beyond me unfortunately.i dont think theres much hope for me and my meter.
Ill have to try harder to find a repairer i think

 

[wheresmejumper]

Found some damage to a board.
its behind what ever the two black cylindrical components linked together with glue at the base

 

[Wedg1e]

Still LV though.

You're right, it is. Some of the high-voltage x-ray generators I've repaired generate up to 225. kV, that is

 

[Wedg1e]

Found some damage to a board.
its behind what ever the two black cylindrical components linked together with glue at the base
View attachment 61621

Looks like a couple of resistors to me...

This might come in useful:

http://www.onsemi.com/pub_link/Collateral/MUR6040-D.PDF

 

[Wedg1e]

Well? Fixed it yet?

 

[wheresmejumper]

Its back together cos ive shed loads to weld with it!
i got given a contact number for a kind of mad scientist fella and he'll have a look at it in a fortnight.crazy as a bucket of frogs but seems to know his stuff.more than me anyway!