REL Q50 problem

[tobsco]

Hi I have a rel q50 that has developed a fault, my best guess is that it is a problem with the set-safe function. It will play fine when first switched on but as soon as it is pushed a little to the point where the set-safe would come in it starts making a popping noise every second or so, it is like it is stuck in a loop with some noise being amplified, it reaching the point of clipping and the gain being cut by the set-safe then building back up again until it clips and round we go again.
Once it starts doing this there is nothing you can do to stop it except switch it off for a couple of minutes, a quicker off and on will just have it going back into a loop.
I'm thinking that this sounds like the behaviour of a capacitor in some way, but I don't know a huge amount about electronics so any help would be much appreciated as I want to fix it myself.

Thanks.


Also this is the manual http://www.rel.net/q-operating-instructions.pdf

[serjan]

Just wanted to say I have exactly the same problem with my Q50 and I'm woking on it.

It works fine on low levels, when I turn up the volume it begins to "click" and starts over again as you described. I saw there are few cheap *** capacitors in the amplifier, first I will try to replace all electrolytic capacitors, totaly 6 of them including the two big ones (dunno English name) from Nichicon (good cap).

I'll keep you updated.

[serjan]

I replaced all caps exept the big Nichicon (buffer?) caps. It's not a capacitor problem, stupid of me to think it was. Because the problem started directly and didn't go from bad to worse. (sorry for my bad English)

Seems one of the ICs isn't working as it should? If anyone knows more about this problem, please let us know. I can make some pics of the amp if necessary.