Jamie t wrote in message
...
N_Cook wrote:

What can go wrong with a triac control cct , visual and cold component
test
of these comps shows nothing obviously amiss
TIC2360, BC214C,2x 1N4005,5V.1W zener, 2 thermal switches, 2x 100R w/w,
2K7,47R, 2.2uF 400V polyester and 2x 220uF,10V electros
I will have to draw it out as a schema


Triacs can develop latching issues and thus, depending on what you're
doing with them, they may take out a protection circuit (fuse), or
if used to select +/- outputs to generate a selective DC polarity, could
hang up on one side and this cause erratic behavior to the device
connected to it.

The transistor BC214, is a PNP type, know to open in the BASE/EMITTER
how ever, you've stated that you have done the cold test on that. The
other problem is, they lose gain and thus, what ever function they have,
they'll have no gain to perform it. This normally happens to a poorly
designed circuit or one that got over voltage, unexpectedly.

I would check the Zener to make sure it does have 5 volts across it
when power is on.

And also, Are you sure that is a zener? by the looks of the parts
list, I would say this may be a simple phase control device? Maybe you
have a failing DIAC/SIAC which can be past off as a diode? That 2.2 uf
Cap at 400V, is leading me towards that direction. Since that is a
common value for the trigger pulse on the gate which gets generated by
the DIAC.







The overlay next to the zener says Z1 and I can read 5V1 on the body but not
anything else. Its a bit difficult to do "diode" checks because of the 47
and 100Rs around, but I suspect failed C-E of the transistor if anything.
But I will sketch out cct first tomorrow , rather than start replacing parts
on hunches.
Does not actually knock out fuses, mains transformer runs hot .