Mitsubishi p.c.b.

[SUBCONTRACTOR]

Doing an install of wall mount Mitsubishi ,i was replacing existing system which was faulty.I left the existing supply and interconnecting cables which were armoured ones( nothing wrong) but this is exactly how i fu**** up,i mixed up the supply with the interconnecting one and of course blew the p.c.b. Question is how do i measure a varistor ,what range on the meter and if i change them is it going to cure the problem.Or can i start doing troubleshooting on air conditioning p.c.b. There is a lot of electronics info on Google but i need to know exactly what i shall look for in order to self -teach that stuff.i tried a few times and only how to build radio pops up...

[a/c.king]

mate i have some second hand mitsubishe pcb send me ur unit modell number to see if my pcb will suite ur unit thin ill sen it to u.
king

[nike123]

Doing an install of wall mount Mitsubishi ,i was replacing existing system which was faulty.I left the existing supply and interconnecting cables which were armoured ones( nothing wrong) but this is exactly how i fu**** up,i mixed up the supply with the interconnecting one and of course blew the p.c.b. Question is how do i measure a varistor ,what range on the meter and if i change them is it going to cure the problem.Or can i start doing troubleshooting on air conditioning p.c.b. There is a lot of electronics info on Google but i need to know exactly what i shall look for in order to self -teach that stuff.i tried a few times and only how to build radio pops up...

Cut the varistors with pliers from pcb replace fuse and try to start unit. If works, you only need to change that varistors with new ones, and if not, you need new pcb or, someone who knows how to service electronic pcb and schematic diagram of that PCB. Good luck!

[Brian_UK]

Subcontractor, Email sent.

[paul_h]

Varistors should be open circuit, they cross the active and neutral. If there's a power surge they short, causing the fuse to blow.
If the fuse isn't blown, the problem may not be a faulty varistor anyway. Check the varistors for continuity, there shouldn't be any.
But if the fuse is blown, like nike123 said cut the varistor/s out, replace the fuse and retest. If all is good, replace the varistors with a 470V one available at any electronics shop.
If it doesn't work, check for component scorch marks, capacitors for bulging/blown, and for burnt tracks on the underside of the PCB etc.