sick amp please help

[richa]

hi everyone, new here , hope i'm in the right place. i'll start with my first problem....., not a hi fi amp but a chip amp all the same, i have an indie sky 10 guitar amp (please don't laugh, i know it's a bit rubbish , all the same it does suit my purposes very well at the moment, problem is it's given up the ghost.., guitarist friend used it on a jam session a while back and it was used very hard all day,,, it then just stopped. he gave it to me (if i could fix it!!!!) to use in my home studio. even though its not great the overdrive channel sounded ...goood.
this is the problem.
1. it doesn't power up, no pilot light, no switch on thump or anything
2. there is no evidence of blown components, no burning at all and no damage to any components
3.i have checked the transformer, there appears to be no voltage at all from the power transformer, or any voltage anywhere on the board. (it did say .03 volts (ac at the transformer)?,
could it simply be power supply problem?
brief rundown
the amp is rated at 10 watts output, it uses tda 2050A chip
the power diodes are 1n4002 ( 4 of)
the transformer siply gives 4TZ-10, TY0603, cant find any info on this at all,.... i assume it is split rail ( red black red on the output side, any idea on voltages (for replacement)
Please help!!!! the photos give you an idea of layout.
i have built ("from kits") a pair of maplin 50 watt mono blocks with uprated power supplies,(individual to each channel,) and a pre amp, they are rather goood, these are kit amps and i merely followed the instructions but when it comes to troubleshooting i'm a bit lost. could anyone give any help on the indie repair, there is no point buying anything else as i'm sure it must be a simple repair, anyway thanks in advance for any help you can give,, 

[techno-rachit]

A 12-0-12 vac/1 amp transformer should work...but if u have transformer re-winders in your locality, then its better to rewind it for exact output...i have never seen a tda2050 used for a 10 watt amp as it is rated at 32w.....the most common one used is the tda2030a....also check the fuse maybe it has died without showing any cases of burning...all the best! And welcome to the forum! Even i'm new :-P

[joecool85]

Start with checking the fuse.  Then try checking the transformer.  To do this you will need to desolder the red, black and red wires coming from the output side of the transformer.  Turn it on again and see if you have any voltage out of the transformer.  I'd imagine you should see at least 12v on each red lead when grounded on the black lead.

[J M Fahey]

As stated above, the first suspect is the power fuse.
It seems to be the one labelled F2 on the board itself, close to the power transformer. The picture is somewhat fuzzy.
BEWARE THAT THIS FUSE HAS LIVE LINE VOLTAGE (110/220v) APPLIED TO IT, DO NOT TOUCH IT.
First unplug the amp and then pull it and measure continuity , or replace it with another one SAME TYPE AND RATING.
Maybe it blows again, in that case we can give you further instructions, but let's go step by step.
Good luck.

[Enzo]

When there is no voltage coming from the transformer, then the first thing to look for is voltage going TO the transformer.  Your mains voltage in this case.  If the transformer primary gets no mains voltage, it certainly can't make any voltages on its secondary.

And follow the above advice from others.  Checking fuses and stuff.   And for that matter even your power cord could be defective itself.

[joecool85]

And for that matter even your power cord could be defective itself.

That's a good point and I've actually had that happen once before.

[Enzo]

I've had about a half dozen of them over the last 25 years.  But then I fix amps for a living every day.