Vintage Ehx Frequency Analizer not working properly

[Jonny toetags]

A buddy dropped off this old Ehx Frequency Analizer for a tune up.
It basically sounds like a very light Flanger right now (nothing at all like the YouTube videos)
I tried looking for some stock board pictures online since this one looks like it has been worked on before.
Any insight is greatly appreciated.

[Jazz P Bass]

This looks like the proper schematic.
http://experimentalistsanonymous.com...alyzer%203.gif

Start with the power supply.
Are both +15 & -15 voltages present on the output of the SG4501?

[Jonny toetags]

This looks like the proper schematic.
http://experimentalistsanonymous.com...alyzer%203.gif

Start with the power supply.
Are both +15 & -15 voltages present on the output of the SG4501?

I checked the voltage around all the chips, I have +15 and -15 on every one.

[Jazz P Bass]

Time to signal trace it.
Half of the battle is won.
You have a working schematic.
The thing I would like to know is what's up with the snipped out resistor.

[Jonny toetags]

Time to signal trace it.
Half of the battle is won.
You have a working schematic.
The thing I would like to know is what's up with the snipped out resistor.

It looks like the resistor was taken out, then another was re-attached on the other side.
Any guidelines for signal tracing an effect like this?

[Jazz P Bass]

The best way is to use a signal generator & a scope.

The first ic is an opamp.
Look for a signal at the output pin #2.

[Jonny toetags]

The best way is to use a signal generator & a scope.

ugh..I have neither

[52 Bill]

Look at the schematic and figure out what each section does and see if it is working or not. You said that it is passing signal, correct? Does it pass signal in both modes on and off? If it does, then the input buffer chip (741) is working.

Turn the effect on and sweep the blend control. One end of the rotation is all straight signal the other all effect. The straight signal should be the same as the bypass mode signal. Do you hear any effected signal?

Try switching the top slide switch (filter) on and off. Do you hear any change in the effected signal? If you do than the filter chip (4558) is probably working.

Listen to the effected signal and sweep the Shift and Fine controls do they do anything to the signal? Try listening to the output of the function generator chip (8038) at pin #2. Use a small cap to connect the input of your listening amp to pin 2 and see if you hear the sine wave signal. Sweep the shift and fine controls and see if the frequency of the signal changes.

Finally look up the data sheet on the balanced modulator chip. Find out what the trim pots are doing in the circuit. My guess would be to null out the carrier signal and to set the levels for lowest distortion. This a guess on my part, as I didn't look up the data sheet. Once you know what the trim pots are doing, be sure to adjust them for the best effect.

[doctor]

Look at the schematic and figure out what each section does and see if it is working or not. You said that it is passing signal, correct? Does it pass signal in both modes on and off? If it does, then the input buffer chip (741) is working.

Turn the effect on and sweep the blend control. One end of the rotation is all straight signal the other all effect. The straight signal should be the same as the bypass mode signal. Do you hear any effected signal?

Try switching the top slide switch (filter) on and off. Do you hear any change in the effected signal? If you do than the filter chip (4558) is probably working.

Listen to the effected signal and sweep the Shift and Fine controls do they do anything to the signal? Try listening to the output of the function generator chip (8038) at pin #2. Use a small cap to connect the input of your listening amp to pin 2 and see if you hear the sine wave signal. Sweep the shift and fine controls and see if the frequency of the signal changes.

at the trim pots are doing in the circuit. My guess would be to null out the carrier signal and to set the levels for lowest distortion. This a guess on my part, as I didn't look up the data sheet. Once you know what the trim pots are doing, be sure to adjust them for the best effect.

Attached schematic may be more suitable.