Technics amp SU-CH9 no power ..possible repair?????

[rabbit@]

Hi,

Had lots of help on this forum with a delay pedal once upon a time. Thought I would try an amp from an integrated bi-wired sound system.

There are four modules to this system and the receiver , cd and tapes all power up and plays through the speakers but the sound is tinny and low volume without the power amp which has no lights and looks dead to me.
I have power coming into the transformer but I am not sure how to test it's output as there are about eight contacts there. There are three fuses inside and they all tested ok.

Any ideas on how to proceed folks.

Thanks
Paul

here's a pic of the unit like mine

http://i.ebayimg.com/images/g/LjsAAO...Tl/s-l1600.jpg

[nickb]

If you can post a schematic then someone will be able to help.

[rabbit@]

wish I had a schematic to post but I don't have looked on the net but could'nt find one. sorry . can take pics of the innards if that would help

[nickb]

It'll cost ya: Technics SU-CH9 service manual, schematics, circuit diagram, parts list

[g1]

Also here:
TECHNICS SUCH9 - Service Manual Immediate Download

[olddawg]

Are you sure you don't have some thing like the "tape monitor switch" engaged or main/pre jumpers removed?

[olddawg]

Are you sure you don't have some thing like the "tape monitor switch" engaged or main/pre jumpers removed?

Sorry.. Misread your post. If it is dead, check for DC voltage on the positive side of the main filter caps. If nothing is there work backwards to the transformer. You say you have AC on the primaries. What is on the secondaries? Hard to do much more without a schematic. Power switching might be microprocessor controlled.

[rabbit@]

Also here:
TECHNICS SUCH9 - Service Manual Immediate Download

Hey G1 . thanks alot for the manual . nice one.

[rabbit@]

Hiya,

well I'm not sure of much old dawg.
I'm hooking the amp up without the other modules . there is a ac cord that goes inot the receiver and then out and into the amp. I am just going staight into the amp. It's got a power switch on the back and I 've pushed all the buttons on the front. It was working a few days ago. then one day the amp says no.

[rabbit@]

I think it has a protector on it . will do checks asap. and am working on getting that schemtaic up. bare with me and thanks

[rabbit@]

do you think that this amp needs to be hooked up the tuner module to work . the tuner has an ac input that says 'switched' 300 watts max. then an ac out which goes to the amp. I have just hooked the amp up to the wall socket. check out the pic. it's of the back of the unit.


https://pics.ricardostatic.ch/ImgUse...5772_6_Big.jpg

[J M Fahey]

Just in case, fully assemble it, maybe no power gets to the amp if used alone.

Besides that, it must certainly have a fuse protecting just the amp, check it.
If you downloaded a schematic, check what it shows as mains connection.

Just in case, build a lamp bulb limiter and use it, if it blew a fuse once, it will blow others.

[rabbit@]

ok. thanks for input JM. got to retrieve the tuner . I only took the amp with me . it's a friends unit that I'm attempting to fix .
all fuses are good . have tested them .

[olddawg]

ok. thanks for input JM. got to retrieve the tuner . I only took the amp with me . it's a friends unit that I'm attempting to fix .
all fuses are good . have tested them .

You really do need a schematic to do/understand anything without a ton of experience and training. Can you take a picture with the case off? I was a Panasonic/Technics authorized for tech for 25 years. When I see a newer unit like this with a big fan I immediately suspect it has a PMPS. If it doesn't have a big PT with multiple secondaries and weighs nothing, it probably is. Maybe not, but usually. IMHE... Most power amp units will work stand alone. (But that does mean this one does.) Especially if it has a power switch. And you my be right about protection. If your friend shorted some speaker wires and fried an output device, it may not power up. BUT it would try to quickly before it detected the over current condition.

[nickb]

Hey G1 . thanks alot for the manual . nice one.

So have you bought it yet at the lower price of $4.99 from that site? I think you can only see the first few non-schematic pages for nothing.