tire car balancer

[tonytiger]

hi guys,a client just brought me this power board,and since the ceramic capacitor is all burn im not sur what i could install there to replace it.....any ideal out there....it is red and big like a 5 cents and there is nothing written on it(burn and gone) i know it is on a 230vac and it is j2.any help will be very appreciated,thank you

[Evil Lurker]

Re: tire car balancer

That is a Metal Oxide Varistor, not a capacitor. It is used for transient surge suppression.

[R_J]

Re: tire car balancer

I agree, it is a MOV, likely 275vac 20mm something like a littlefuse V20E275P or V20H275P I would check the transistors on that board (mounted to the heatsinks) The circuit should work (without protection of course) with the mov out of circuit.

[PeteS in CA]

Re: tire car balancer

An MOV is normally across the AC line to absorb transient surges. Two things I noticed are the reasons for my comments that follow: that device is over 15 years old; that RJ-45 socket and the nearby PCB show heat damage that probably occurred over some time, not quickly.

MOVs are fast, can absorb a lot of surge energy, and are cheap. All good characteristics. What is less good is that every time it clamps a surge, a little bit of damage is done. Over time and lots of surges, the voltage at which it will clamp deteriorates until it starts conducting at normal line voltage. The device then starts to overheat and self-destruct.

I think it is possible that is what happened, a known wear-out mechanism failure. IOW, there is a good chance that if you replace the MOV and any fuse that might have blown, that tire balancer might work OK. You could simply remove it to test it, but leaving it off permanently is probably not a good idea in a repair shop light industrial environment.

[redwire]

Re: tire car balancer

Crydom PF480D25 SSR is rated 660VAC operating and 1200V transients. PCB is labelled 230VAC.
So that burned MOV should protect just below that, it looks like a 20mm dia. size.
I would put in EPCOS S20K250 for a 250VAC nominal line.

Put in a new RJ-45 jack and maybe the green connectors because carbon and soot from the flames are conductive and the board has high voltage present.

[tonytiger]

Re: tire car balancer

thank you very much for all these info,will check all of this and let you guys know.very good info you gave me,thank you very much all of you.

[stj]

Re: tire car balancer

dont use a 250v rated part - it will fail very fast!

[redwire]

Re: tire car balancer

What do you suggest for mains in Europe?

B72220S0251K101 (250) starts to turn on at min. 350V-390V typ.-429V max. (1mA) so 250VRMS min. I thought the data said operating voltage.
If mains is higher than that then go up to say 300VAC (470VDC) ?

[stj]

Re: tire car balancer

275v parts are commonly used

[budm]

Re: tire car balancer

275v parts are commonly used

+1

[sam_sam_sam]

Re: tire car balancer

If you can check these Crydom PF480D25 SSR individually it is rare that they fail but they fail at least DC volts in DC volts out version in our magnets fail and when they it will parlay still work but not correctly

But they are easily checked but you have to remove them from the board

[R_J]

Re: tire car balancer

I did'nt look at all the pictures, and missed the fact they were ss relays.