[philpeel]

vtech... i registered in this name. just didn't have password with me at work.

i'll have a look at it when i can and i'm sure i'll be back with more questions

btw.. i got a broken lcd tv at home.. so i'll be here for a while yet


thanks

Phil

[vtech]

OK,

It would be a lot better to pick out a name, use it to register & login for further postings and picture posting if you had to.
Since you mentioned that using headphone is ok, you will need to concentrate
on final amp stage & power supply. Do a basic DC reading & compare to what is printed on schematic on various points in final stage (with/volume set to zero).

[Guest]

ok... it's really hard to discourage me

i have some basic electronics knowledge and some test equipment. i've managed to get hold of a service manual for this now so going to have a good look through and see if i can understand any of it... i'm more interested in learning as opposed to actually getting this working, but if i can get it working too that's a bonus.

thanks again for the help so far..

[vtech]

Not to sound discouraging but, the cheap cap testers are not going to help. While it may be a cap, it is still a guess. It is likely a simple device causing the problem but Without any circuit information, it would be like working with blinders on.

Depending on the type/design, there are certain voltage measurements that can be used to help pinpoint the problem. At least if there was some sort of circuit diagram, I could give you certain points to check.---way too many variables; There could also be a problem in any of these; Rails? drivers? biasing? coupling etc.

[Guest]

ok... thanks for all your help! much appreciated..

this amp is part of a separates system - but it all contects using non standard ribbon cables. it was given to me free... but if i can't get the amp to work it's all going in the bin. i'm not too bothered therefore if my messing with it results in it being irreperably damaged. I don't think it's worth paying for a professional repair - as similar systems can be picked up 2nd hand off ebay for probably less than the repair cost.

was mainly interested in trying to learn a bit more about repair etc.. and if i get it working that's a bonus. i'm fairly skilled at soldering.. so not a problem to de-solder the caps and put them back. they have capacitance meters on ebay for around US$20.00 - are these worth the money in your opinion? or are they just chinese junk? i know you don't have much to go on.. but you think old / dried up capacitors is the most likely problem? have seen ways of testing caps using a multimeter.. but not sure how accurate this would be.

thanks again

phil

[vtech]

As far as testing caps, there is no reliable way without a tester and it should be pulled from the circuit. Again, this is not the only way to attack the problem or something for the average user & best not to get involved if you are not equipped.

[Guest]

ok.. thanks v much.

is there a way to test the caps without a capacitance meter?

and can i do this without removing them from the board?

Phil

[vtech]

More likely, excess heat has caused cap(s) to dry out which again w/out further diagnostics may in fact not be worthed.

[Guest]

i think continued use without the fan may have caused the probem - but the fault is there before the heatsink has warmed so dont think replacing this alone will solve the problem.
i was thinking of bridging the relay as a temp measure to see if the problem goes away - and measure the voltage at the speaker terminals. if it does it suggests to me the power supply is ok..maybe.
i'm going to measure the voltage supply to the relay and see how much this fluctuates while the problem occurs.
note that everything works ok through headphones.
i think the fault is likely to be the amp module is faulty in which case it's probably not worth repairing.

[vtech]

If the fan is definitely bad, why not just replace it with a similar rating & see if it has any effect?