a question about some amplifier components

[davey_duck_breath]

Not a standard UK household electrics question so forgive me if this doesn't interest you. Someone out there may have some experience with this sort of thing.
I have an amp as photod below, that doesn't work. I suspect that the problem lies with the 2 units at the front (circled in red) I just wondered is anyone able to confirm what these are. I think they are voltage converters but I'm not 100% positive.
The fuses are all ok btw.

[/img]

 

[toasty]

They are transformers, however it's highly unlikely that these are at fault.
They are just large coils of wire so there is very little to go wrong (except that some have a thermal fuse embedded in them)

If you have a multimeter/continuity tester try measuring the resistance of the windings, they should be reasonably low (even the primary) expect to see < 1000 ohms or so.

My money would be on the output devices (mounted on the heatsinks)

Can you measure any voltages on the circuit board? If so then the transformers can't be at fault.

It looks like a simple dual mono power amp, so if both channels aren't working then it's probably more likely to be something common to both channels, perhaps the plug fuse or mains cable?

 

[davey_duck_breath]

thanks toasty.
all the fuses are ok. i have tested with a multimeter. voltage is getting to the switch and on to the transformers however there is no voltage boyond the transformers i.e. where they connect to the pins on the board (see photo) and the power led (fed from the board) is not coming on so thats why i was thinking it was the transformers.
i will test the resistance of these tonight as you suggest and let you know.
thanks again.

 

[Lectrician]

Rare for 2 trannies to go. Check N as well??

 

[davey_duck_breath]

well the wires from one had been cut and you can see where i have reconected it with chock blox (blue circle). I have no idea why it had been disconnected but perhaps if the amp was running using just one transformer then that would have blown the remaining one? i dunno im just guessing here.

 

[Lectrician]

Usually, one tranny is for left and the other for right.

 

[supersparks]

thanks toasty.
all the fuses are ok. i have tested with a multimeter. voltage is getting to the switch and on to the transformers however there is no voltage boyond the transformers i.e. where they connect to the pins on the board (see photo) and the power led (fed from the board) is not coming on so thats why i was thinking it was the transformers.
i will test the resistance of these tonight as you suggest and let you know.
thanks again.

maybe theres an inverter built in or something...
try measuring the output using the dc function on the transformers

 

[davey_duck_breath]

I have tested the continuity between the input and output of the transformers. There is none! The input is obviously 240 volts and it says 120 volts next to the pins on the board so these transformers are presumably converting down to 120 volts, not sure why there is 2 of them or why there is no continuity through them? hmmm

 

[Lectrician]

There wouldnt be any continuity from primary to secondary.

Measure from L to N on primary, and L to N on secondary.

120V?? Is this not the centre tap of the incomming primary?? Secondary on most amps is geared for 50ish volts.