I am trying to diagnose why the left speaker has no sound. I done the basics using a signal tracer to check if there is a signal at the speaker but there is nothing. Trying to locate the left speaker inputs/outputs of the poweramp is prooving difficult without schematic. There is quite a few manuals for sale online in America, but due to price and trasit time I was hoping for a pdf. For now Ill try to figure out from a different but smillilar models manual, gf-7500
Sorry, I don't see any using my searches, you might want to try some of these websites. https://stereo2go.com/forums/thread...lkman-free-service-owner-manual-thread.10086/ I always start with the FUNCTION selector switch and it looks like this has mono/stereo amoung others and give them a good cleaning. This tends to fix 90% of my sonic issues. Is the problem also with headphones?
I've deduced the problem to be todo with the headphone board. Pin 5 - L channel output from power amp Pin 4 - L channel signal to speaker Pin 3 - GND Pin 2 - R channel output from power amp Pin 1 - R channel signal to speaker So normally the pair Pin 5 to Pin 4 (left) and the pair Pin 2 to Pin 1 (Right) should be 0 ohm with a spring mechenism inside the headphone jack keeping them closed. This will feed all the signal to the speaker. When you plug in the headphone the plug forces the spring to disconnect from the speaker path and send the signal to the headphone jack (through a resistor) My issue is Pin 5 to Pin 4 (left) is open circuit. And after spraying liberally with contact cleaner and inserting a headphone plug about 20 times now Pin 2 to 1 (right) is also open circuit with the headphone jack not inserted. So both pairs are not open circuit with no plug in. My question now would be, what would be the best way to try to repair the headphone jack. When I got the boombox it was completely caked with dirt so i suspect thats the problem. I have also read online you can try to bend the clips to retensio them but I dont see how that would be possible as I cant see anything. My idea at this point is to make a warm soapy water bath and bath the switch in trying to remove the debree as much as possible by moving it back and forth. maybe use a small brush. Then insert headphone plug and move it around in water to try dislodge debree. I dont unfortunenly have an ultrasonic cleaner by the way. Then allow it to dry out. When dried out enough conduct another ohms test. Any advise? Edit: I fixed the headphone jack by using the method I described above it now has continuity. To my supprise there was no sound though! On further investigation I've deduced the actual speaker is also faulty. Very Annoying
Hello TP86, Yes , ultrasonic cleaners are amazing tools . Have you tried bypassing the switch . I will have to look I might have the service manual I was a Sharp warranty repairshop . Sincerely Richard
Hi Richard. I managed to fix the switch by giving it a good clean in soapy water but now my problem is the left speaker has open circuit in its coil. I am trying to source the best I can find
Hello TP86, first thing I would do is to take out that speaker so you can meassure it did you meassure across the speaker leads to see if the voice coil is open ? if So try them they sell tons of raw woofers I use a lot Visaton speakers in my restoration they are great german built woofer that does not take a lot power I use them even in my tube radios for replacements https://www.parts-express.com/. Sincerely Richard
Hi Richard. Thanks for the resource website. In Australia we have a shop called Alltronics that seems to have a few options. www.altronics.com.au/p/c0616-100mm-5w-4-8-ohm-paper-cone-speaker/ - this one is only 5W max whereas the existing is 8W but it has a 8ohm tap that i could use so not too much power is delivered. It will attenuate the volume but would work at least
