Blown pcb's

[newcomers]

Hi,

when I was working with an older fella, we had a few jobs where the pcb was blown. He changed the pcb, switched boiler on and bang, it blew again straight away. On this particular job, he went through about 6 pcb's before he found the actual fault.........the lead going from the pcb to the gas valve.

So far I havent encountered a blown pcb but would like to prepare myself for when I do. Ive had a couple where the fuses have blown, replaced fuses and they have worked fine.

What I'd like to know is, before you guys replace pcb's, do you firstly consider that it could be the gas valve / pump / fan / leads that couldve blown the pcb? If so, how would you go about it so that you dont keep blowing pcb's before finding the actual fault?

Thanks

 

[cross thread]

prob normaly is a component rather than pcb . try component for resistance readings when working on boilers pumps etc test the resistance reading to get a idea of what you should expect so you build up your knowlage

 

[ChrisR]

Always coinsider the pcb LAST unless it's a puma or a suprima!
Even then, you can measure the resistances of things especially where you know they aren't connected through relays.
Can you drive a multimeter?

 

[newcomers]

Always coinsider the pcb LAST unless it's a puma or a suprima!
Even then, you can measure the resistances of things especially where you know they aren't connected through relays.
Can you drive a multimeter?

Not really!! But how can you test for these things when the pcb is blown and there is no power to any components?

 

[Agile]

Er... you measure their resistance!

Many of the Potty PCB designs have fusible resistors designed to blow if the fan, pump or gas valve has failed. Thats a nice way of selling some more new PCBs.

Now I have to take issue with your statement "when working with an older guy". Age is no pointer towards incompetence !!! Many older prople would even say that its the younger guys who display the most !

Tony

 

[pannierstan]

Good grief I think you need some serious electrical training mister!

By the way was the boiler you were working on a Baxi

And what the heck is someone teaching for when they have to fit 6 PCBs before finding a fault. Hope they didnt charge the customer for all those.

I have heard of putting fuses in to look for the flash , but PCBs

 

[nickso]

thats shocking....i wouldnt bother paying any attention to that "older guy" anymore.

even common sense tells you to check every set of leads coming in and out of the pcb.....pump,fan,gasvalve at a very minimum.

no wonder you have a thousand questions if those are the sort of guys showing you the ropes

 

[geoff@cetltd]

CORGIs ...

always good for a bit of entertainment

 

[Slugbabydotcom]

6 PCB's!

Dear Moderator,
I wish to re-iterate my call for a shaking head with disbelief emoticon.

yours faithfully

Slugbabydotcom

 

[newcomers]

To be fair, I think the only reason he did it was because

1) It wasnt a private job so neither he or the tenant was paying

and

2) He had about 10 of the pcb's on his van anyway!!

Wheres the best place for me to learn about this type of testing?

I know how to check for correct power at gas valve, continuity on pressure switches etc etc but not how to check if components are faulty

Thanks

 

[Agile]

"""Wheres the best place for me to learn about this type of testing?"""

To be working or training with someone who knows what they are doing.

I would also have serious reservations about a firm which has to employ such an incompetent person !

Tony

 

[doyle]

happen we should get this guy a job with the alqaeda, trainer in improvised explosive devices kill two birds with one stone
i think i would have stopped after the fith one and im a nobody

 

[geoff@cetltd]

To be fair, I think the only reason he did it was because
1) It wasnt a private job so neither he or the tenant was paying
and
2) He had about 10 of the pcb's on his van anyway!!
Wheres the best place for me to learn about this type of testing?
I know how to check for correct power at gas valve, continuity on pressure switches etc etc but not how to check if components are faulty
Thanks

So, does he have a "source"

a dent somewhere on the corner perhaps?

 

[newcomers]

To be fair, I think the only reason he did it was because
1) It wasnt a private job so neither he or the tenant was paying
and
2) He had about 10 of the pcb's on his van anyway!!
Wheres the best place for me to learn about this type of testing?
I know how to check for correct power at gas valve, continuity on pressure switches etc etc but not how to check if components are faulty
Thanks

So, does he have a "source"

a dent somewhere on the corner perhaps?

As always, thanks for the all the help, ive really learned a lot from this