speaker protection relay trouble

[lordy]

hi
I have a warrior kt600 p.a amp but when I turn it on the speaker protection relay comes in straight away (instead of waiting 4 or 5 seconds ) causing a loud speaker pop , any ideas why this could be happening. I dont have the schematics for this amp and it would be usefull if someone could point me in the right general direction as to why this is happening ? I have searched the web and havent been able to find n e thing.

[Jan Dupont]

Without knowing the exact speaker relay circuit in your amp, I would say that the inrush delay cap in the protction circuits fails, - either because of a bad soldering or because it's "dead"

[lordy]

hi

thanks for the reply but i am having trouble locating the capacitor non appear to b blown and the circuit isnt that easy to trace with my limited knowlege of electronics, would sombody be able to help if I posted a picture of the circuit board ?

[Jan Dupont]

Depending on the layout of the circiuts, a photo could be useful....
Normally you will be able to narrow in the protection by following the PCB traces back from the relay coil.....

[lordy]

Here's a pic of the relay on the pcb if that if any help?

[AndrewT]

There are two electrolytics on the board.
The green thingy and further right the blue one in the middle of the group of transistors.
Have you got any way to test them after you get them off the board?
regards
Andrew T.

[MikeB]

Hi lordy !
Is it me or does D17 look a bit cooked ?

Mike

[lordy]

Hi
I have a basic multimeter to test the capacitors resistance i think if its working the resistane should read from low to high one way and high to low the other am i right ? Can i test them on the board ?
MikeB, d17 does look a bit burnt but i think that is the (stuff) from a blown mains smoothing capacitor on the far right of the pic.
I replace the mains smoothing cap a while ago and didnt really clean the board up properly.

[Jan Dupont]

MikeB:
Yes! D17 seems a bit "cooked" however it doesn't means that it's "blown". However it could be a good idea to check it

AndrewT:
Yes! One of them are almost for sure the timing cap.

Lordy:
If you can´t test the caps outside the circuit, you could try to apply supply power to the board, while meassuring the voltage across each cap. It should rise slowly when power is applied.
If the voltage across the cap rises instantly, the cap cut be defect or there is a bad soldering

[phase_accurate]

Don't forget the possibility that some semiconductor (i.e. transistor) could be burnt as well and therefore the circuit be in a totally nonworking condition (i.e. it would not even detect DC at the amp's output).

Regards

Charles