My Sharp system 7700 amplifier has started blowing internal fuse, 3amp, have taken a look and the transformer seem's to be working ok, so it look's like a fault somewhere on the board, is there any wiring diagram's any where out there, or any good repairer's in the midland's area, any help at all would be appreciated.
Does it have a mains transformer? If so check in this order.. Main smoothing can (big black or blue can) bridge rectifier.. black square thing with 4 wires standing up off the board or 4 diodes (black tubes with a silver band round one end) Output transistors/mosfets.. usually on the back of the case or fixed to a heatsink.. output coupling capacitors.. a pair of blue or black cans near the speaker terminals.. You will need a multimeter with an ohms range to do power off short circuit tests. It should be pretty straight forward as the fault is on the main power rails. I would go for main smoothers or output trannys. I can't find that model listed anywhere, the closest I can get is here http://www.eserviceinfo.com/equipment_mfg/Sharp_5.html .. maybe it is in there, or you can work out exactly what model it is.. most sharp gear has a number starting with 2 letters for audio kit. (sc-7000 etc) Failing that you need to find a competent repairer. Yellow pages is your best bet.. they don't tend to advertise on t'internet, or a local independent tv/hifi shop will usually know somebody.
Thank's for that speedy reply Varnull, will try your component checkto eliminate item's, have already proved the transformer and bridge rectifier, will test the rest now. The only information I could find was mainly from German site's, but not being able to translate does'nt help, this is a picture of the amp in question and once again thank's for your help.http://www.expressz.hu/szorakoztatoelektronika/hifi/erosito/showAdvert9610123.html
Here you are.. after much hunting and some guesswork (thanks to manuals.ru) the downloads of the service manuals http://www.nodevice.in/manual/Sharp/page67.html They want money.. swines.. I wouldn't personally pay them as there must be other sources out there.. Firstly as it is just a big power amp it should be easy to trace out the necessary bits of the circuit.. I find that googling the semiconductor data sheets gives lots of information about the expected circuit conditions. Seems there are 2 models, I think yours will be the HMK2 variant.. but they should be very similar.
