gf 777 prob

my 777 only has 1 woofer working both the mid range are ok, tried cleanig all pots and switches, can anyone help, thanks

How did you clean the pots? Did you include the "super woofer" pots?

cleaned with contact cleaner, yes did the super woofer pots.
that balance didnot work at all, cleaned pot . then it worked
but not the left woofer

check if the other speakers on that channel are working...

if so, maybe easy,

something disconnected inside.

its wires.

i bet its not cross over troubl.

geoffhartwell said:

cleaned with contact cleaner, yes did the super woofer pots.
that balance didnot work at all, cleaned pot . then it worked
but not the left woofer

Click to expand...

Don't forget your external speaker plugs, if they aren't making good contact inside you will lose an entire channel.

There's always the possibility that one woofer or one side of the amp is blown. Are you getting a peep at all?

geoffhartwell said:

cleaned with contact cleaner, yes did the super woofer pots.
that balance didnot work at all, cleaned pot . then it worked
but not the left woofer

Click to expand...

I'm guessing you removed the knobs before spraying the pots. I would say that if you are getting faint or muffled sound from the woofer, it would be a dirty super woofer pot. I had that problem with mine and it took several sprays and wiggling over a period of time.

If you have no sound at all, I would check the internals. Maybe a wire like John suggested. Hopefully, it's not the amp like Norm mentioned.

im getting nothing from the left woofer, but i do get sound from the left mid range, could this still be the ic chip ?

I was thinking that the GF-777 just had two amps (L & R). If that's the case, I would definitely check speaker connections. Even if the woofer had a bad voice coil, you should still get some sort of noise coming out of it.

Just had a thought...

Open up the case and hook up the left woofer to the right woofer connections and see if you get sound then.

no i wouldnt say its IC.

if you have some out on the same channel.

should be some wiring.

!!!

or maybe in the worst chance,

something in the CROSSOVER.

good luck.

( just info

im still battling over my Boombox,

because when i want to turn it louds the sound gets all muffled.

me and my technician are guessing a shorted capacitor,

or maybe a small transitor burned out.

all the big capacitors are tested OK,

and so are the OUT AMP tsistors. )

tried the speaker change trick and still no joy. all the connections are good, the only connection i havent checked is the super woofer vol knob, as i cant get to it with out taking every thing out

geoffhartwell said:

im getting nothing from the left woofer, but i do get sound from the left mid range, could this still be the ic chip ?

Click to expand...

Yes. The GF-777 has 4 amps via (2) x stereo amps. Each amp module powers either the midrange/tweeters or the super-woofers. Each one of the amp modules can blow a channel separately as well. Try blipping the speaker terminals with a small penlight battery (unhook the wires first). You should get a crackling sound from the speaker. If you get nothing, then it's almost certainly the speaker. If yes, then sounds like the woofer is OK and it could be the amp, provided you've already checked all the obvious such as loose or disconnected connectors, etc.

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Wait, just went back and re-read your previous post. You said you tried the speaker test and still no joy. Can you be more specific about what exactly did you do? You say you swapped speaker wires around and its still not working but which speaker is not working now? The same speaker or a the other speaker? 'It's important.

ok i patch a wire to speaker, then touched it to the ext super woofer and it worked, is this safe, then i tracked back on the pcb touching every point, then i got to a transister i think (big fat thing), then after that all the way back to the ic chip all i got was one click on every point i touched. dose the ext super woofer have its own amp

i might have a spare amp board for the gf 777, i wont be able to look for it till this saturday.i'll let you know if i find it.

gf777 has only 2 ic 2 channels per ic so one ic would control 2 speakers the outside left and right the other ic controls the subwoofer in the middle left and right i think thats how the amp section is if i am not mistaken as i remember that as i was looking for the num to the ic which is a hitachi part num and there were only 2 ic

Hi. The IC's are HA1392's and yes, there are 2 of them. Each amp module is a stereo amp so it will run 2 channels per amp for a total of 4. The tweeters run in parallel with the outside speakers. The inside speakers have their own amp. You might have blown 1 side but what I was asking you to do is confirm or rule out whether the woofer is bad. Don't probe around with a wire -- you could damage something. That really isn't what Fatdog or I envisioned asking you to do. Fatdog was asking you to swap the wiring for the left and right woofers and see what happens. If the dead channel switches to the other side, then it's possible, even likely that you have an amp problem. If the dead channel remains on the same side with the speaker swapped, then it's almost certain that your speaker is blown since you are putting a good known output to the dead side.

As for probing around, what I was really asking you to do is take a small 1.5v battery and run leads to the dead speaker (with the wiring disconnected). merely scratching or swiping the speaker terminals should cause a crackling sound to be emitted. If you hear absolutely nothing then the speaker is blown.