Yamaha GE-60 Equalizer Troubleshooting Help

[kermit_xc]

I recently acquired a GE-60 and a T-60 that came as part of a M-60 and C-60 collateral in a Craigslist deal. T-60 has been collecting dust in the garage since. But the GE-60 greatly intrigues me - I never had a thing for EQs - but this one on paper appears to have virtually no distortion at 0.005% THD and it came with a calibration mic - oh why the hell not, let's try this fancy pants thing

and that's where I have been pulling my hair for the last week ... when I engage the EQ mode, the left/rights faders LEDs light up ... but that's about IT, going up and down with those pots (mostly down as I worry about my EMITs with +15dB slips) makes absolutely no difference. The tricky part is that the output level pots very much work ... I'm just baffled, so baffled I even read the manual !!!

I tried the following connections:
- CD => GE-60 => AMP the line in/out loop as well as the tape pb/rec loop
- source => C-60 => GE-60 => M-60 (line in/out)
- source => C-60 => GE-60 (tape loop) => C-60 (pre-out) => M-60

in all cases above - it sounds great, just no freaking EQ difference

does anybody here have any experience dealing with these ? I have a feeling I am missing something trivial here. The mic and pink nose generator work - just no way for me to correct the response curve



EDIT: And yes, I just finished the complete disassembly / cleaning. All switches / fader pots have been treated with deoxit.

 

[timblade68]

try this test: preamp out to EQ in - EQ out to main amp in - on the GE60 - tape 1 & 2 off - defeat off - EQ on - REC off - then try your sliders.
I have seen the same symptom you describe, it was a GE60 made to be used in Japan at 100 volts that was plugged into USA voltage.. It lit up like a holiday tree, but the sliders had no effect.
Sorry, but I do not know much else about repairing the issue.

 

[kermit_xc]

it's the 110/120 and 220/240 switch model - that being said. I noticed just now when messing with it after work that it makes a significant pop when turning engaging the EQ function (EQ on) - once I cycle the defeat / EQ on - the subsequent pops are not as bad - would this indicate some caps going bad ?

also - what is the VR104 trim pot for ?

 

[timblade68]

I have no idea what VR104 adjustment would do. You could always inspect the solder side of the main board (and mini board) to make sure the capacitors and heat sinked transistors have good solder joints. I would think the pop you hear is because your main amp is on before the GE60 is powered up.

 

[avionic]

I would think the pop you hear is because your main amp is on before the GE60 is powered up.

Key !

 

[avionic]

Likely takes a second or two for the EQ amplifiers DC offset to stabilize.