Hello Guys.
I need help. Problem-No Loudness effect in GF-777Z.Only super minimal diference can hear beetwen loudnes on/off.I check a loudness switch( and bypass this) and all resistors and caps around switch with schematic and for 99% OK. All other function in this 777Z working good. Please help me find this problem. Where search ? Maybe somebody have any suggestions. 777Z without loudness is junk.
I have a hope you guys help me.
Regards

Maybe a dirty switch? Have you cleaned all the switches?

Clean and everything else checked out OK?

Hmmm... maybe Fuzzyduck can help. She's pretty good with the GF-777. Calling Fuzzyduck!!

the loudness function is typically attached as a resistive element in the volume knob between 0-40% of the range of value to disengage as volume increases. Try cleaning the volume knob to see if that helps

quote:

Originally posted by Fatdog:
Clean and everything else checked out OK?

Hmmm... maybe Fuzzyduck can help. She's pretty good with the GF-777. Calling Fuzzyduck!!

Hi.
Maybe not everything else because i no have now idea what do.I looking in service manual and replace capacitors conected around to this loudness switch..check resistors around this.Looking ok.Zero loudness.Only extra minimal effect can be hear but nothing similar to loudness effect.I have second full working 777Z and this have extra loudness.Im sorry but my english language is not to ok but i have a hope you understund me.
Fuzzyduck..!!! Help!

quote:

Originally posted by kittmaster:
the loudness function is typically attached as a resistive element in the volume knob between 0-40% of the range of value to disengage as volume increases. Try cleaning the volume knob to see if that helps

I complete open carrefully this volume knob and clean this inside .And looking nice.Zero effect. Maybe capacitors or resistors..but C541,C542 is OK,R541,R542 is OK.Conectors check and looking OK. Its possible failure chip IC-351(LM 13600N) (low pass filter) ?Or maybe wrong is in other board ..maybe on P.W. BOARD? Im lost

I'll look at the schematic when i get home tonight and get back to you.

Chris

Nice. Very thanks

Sorry I can't help with this issue Megablast, I don't have much knowledge regarding the electronics side of BBXs unfortunately.

If the switch is working S501 A/B, then the signal process comes from the following circled components. You should check them out to see if there is damage or bad grounds to damaged traces.

Thanks for help. So...i check this all RC elements and Treble/Bass knobs again today...or maybe replace all this what you mark on schematic.I let you know..

Hello Guys!
I have a problem with this two C539,C 540. What is this? On schematic value .0033. This is capacitors? Or jumper? I want buy this and people in shops never seen this. In service manual "Replacement parts" i no see this.Please help...i thing this two C539,C540 make loudness problem

Ok first .....yes those are capacitors. It looks like the capacitors are be stated in microfarads, so .0033uF OR 3300pF (pico).

You can get these from an electronics supply house.

BUUUUT.....HOW do you know these are bad? Are you using an oscilloscope to measure the signal on both side of the capacitor to see if the signal comes across the component?

If your using a digital meter, then your results will be completely wrong and you'll be replacing components for nothing and still have an issue.

I would use your digital meter to verify the switch is "really" working.

these are capacitors, the value is 0,0033 microfarad or 3,3 nanofarad. Often these capacitors are marked with a 332, the first two digits are in real the two leading digits, the third is the number of zeros and the unit is picofarad: this means here 3300 picofarad or 3,3 nanofarad
Such capacitors in this application never go defective, I guess, the pin at the pot for this
capacitor has an interrupt to the carbon film (inside the volumepot)

quote:

the pin at the pot for this
capacitor has an interrupt to the carbon film (inside the volumepot)

If he has volume at the speakers and the volume knob controls the volume, then this would be an in correct diagnostic since the POT is working as it should. I would suspect the trace from the caps to the POT wiper arm may be cracked or damaged......assuming my beginning statements are true.