I've been attempting to cure a persistent problem with the left speaker of my Sharp GF-8989 ever since it arrived. On tape mode, both speakers work perfectly and unit sounds very good. On radio mode however, the left speaker is at a very low level. When the function selector is switched from tape to radio, the sound comes out at a reasonable level for a second, then gradually loses volume until I have to put my ear right up to the grille to hear any noise. As described above, both speakers work fine on tape, so the speaker isn't blown. The problem seems to be with the power (or function) selector. I've had the unit open, the tape deck unplugged and removed from the PCB, and the whole of the circuitry removed from the case for greater access for me to undertake cleaning. The unit was full of sawdust when I first opened it, so I'm guessing it must have been used for music in a place where they work with wood. I cleaned it all out and sprayed the best part of quarter of a can of contact cleaner into all of the switches on the unit and gave them some 'good exercise'. I put the unit back together again and let the insides dry off. Still the speaker problem remains. Could the problem be the selector? I need the insides of another 8989 to put straight into my case. I've already become an expert at taking one apart since the start of the 'project'. It must be the easiest box I've ever worked on. Can anyone help me with some replacement 'guts' so I can sort this thing once and for all? Is anyone parting out a fully working one due to a badly damaged case, for example? I don't need the deck or power supply, or speakers. Hopefully someone can help me, and thanks for reading.

the only real way to find that type of problem is to use an oscillscope if you have access to one.

quote:

Originally posted by kittmaster:
the only real way to find that type of problem is to use an oscillscope if you have access to one.

Oscilloscope


I've never come across one of those before. I wouldn't know how to use one. Plus, I don't have a soldering iron supposing a component needs replacing. Thanks anyway. 'pacwestuk' just PM'd me and suggested I try pressing record a few times quickly. I'll have a go.

I have a GF-9191 with very similar problem. Tapes play perfectly fine and sound great, but when I play the radio it has issues on the right side about 80% of the time. I can play with the stereo/wide switch and sometimes it will then work okay for a few moments and then drop out again. I also noticed that when I grab the box firmly on both sides and torque it just a bit, the radio sounds great from both speakers until I let go.

I think its obviously a loose contact or weak solder point inside the box, but without a scope, schematic and some learning on my part, I don't think I'll ever figure out which one...

quote:

Originally posted by JT:
I have a GF-9191 with very similar problem. Tapes play perfectly fine and sound great, but when I play the radio it has issues on the right side about 80% of the time. I can play with the stereo/wide switch and sometimes it will then work okay for a few moments and then drop out again. I also noticed that when I grab the box firmly on both sides and torque it just a bit, the radio sounds great from both speakers until I let go.

I think its obviously a loose contact or weak solder point inside the box, but without a scope, schematic and some learning on my part, I don't think I'll ever figure out which one...

Interesting, JT. But what are we to do with the boxes while they're still like that? My GF-8989's currently in my way.

quote:

Originally posted by JT:
I have a GF-9191 with very similar problem. Tapes play perfectly fine and sound great, but when I play the radio it has issues on the right side about 80% of the time. I can play with the stereo/wide switch and sometimes it will then work okay for a few moments and then drop out again. I also noticed that when I grab the box firmly on both sides and torque it just a bit, the radio sounds great from both speakers until I let go.

I think its obviously a loose contact or weak solder point inside the box, but without a scope, schematic and some learning on my part, I don't think I'll ever figure out which one...

Sometimes its not a bad solder joint, the box I'm working on for appleknocker has a cracked board.......even worse!.....you just never know due to the age and the boxes history. I've been chasing a phantom on the one I'm doing.....very labor intensive......

Hi-I've had 2 GF-8989II's.
Luckilly the first one I bought new and the second one is working fine.
I'd say do the obvious again to make sure-switch the switches back & forth really well.Try the back Line-in switch back & forth if it has it phono switch(II only)
Could it be a bad capacitor heating up? Only if it works in the beginning then goes weak-could be?
Need testing equipment if this doesn't work i'm figuring.
Good luck-gheettoboom777.