Vintage Ibanez FL9 problem - TECHS PLEASE READ

[qb]

My FL9 now has a quite noticible noise either when it's on or off.
With a battery, the noise very weak and acceptable but with DC power
supply, it is much stronger. The noise has a hint of a signal like
tone and, when it's on, i can even hear a hint of flange jet tone.

Is there anybody who can direct me where to look at?

thank you very much.

[Jim]

Post by qb
My FL9 now has a quite noticible noise either when it's on or off.
With a battery, the noise very weak and acceptable but with DC power
supply, it is much stronger. The noise has a hint of a signal like
tone and, when it's on, i can even hear a hint of flange jet tone.
Is there anybody who can direct me where to look at?
thank you very much.

What I can say is don't get tempted to play around with the trim pots.
I bought one off of ebay, and it sometimes wouldn't even flange. I had
to get a service manual, then do my best with a frequency generator and
a scope. It is now adjusted so that it works properly whenever I step
on it. But previous owner screwed it up, then dumped it on ebay.

[D***@DeerInTheTraffic.com]

As Jim says "don't play around with the trim pots."

Sounds, to me, like you've got leakage in the switching circuit.

The circuit around Q103, a 2SA445P FET, is the likely cause.

Try temporarily shorting the two outside legs of this FET
(which will effectively switch the Flanger ON)
then playing through it.


If doing this cures the problem, replace the FET.


If the resulting sound is STILL weak,
you've got problems elsewhere.

Elmo' 7#9

Post by qb
My FL9 now has a quite noticible noise either when it's on or off.
With a battery, the noise very weak and acceptable but with DC power
supply, it is much stronger. The noise has a hint of a signal like
tone and, when it's on, i can even hear a hint of flange jet tone.
Is there anybody who can direct me where to look at?
thank you very much.

What I can say is don't get tempted to play around with the trim pots. I
bought one off of ebay, and it sometimes wouldn't even flange. I had to
get a service manual, then do my best with a frequency generator and a
scope. It is now adjusted so that it works properly whenever I step on
it. But previous owner screwed it up, then dumped it on ebay.

[qb]

Post by D***@DeerInTheTraffic.com
As Jim says "don't play around with the trim pots."
Sounds, to me, like you've got leakage in the switching circuit.
The circuit around Q103, a 2SA445P FET, is the likely cause.
Try temporarily shorting the two outside legs of this FET
(which will effectively switch the Flanger ON)
then playing through it.
If doing this cures the problem, replace the FET.
If the resulting sound is STILL weak,
you've got problems elsewhere.
Elmo' 7#9

Post by qb
My FL9 now has a quite noticible noise either when it's on or off.
With a battery, the noise very weak and acceptable but with DC power
supply, it is much stronger. The noise has a hint of a signal like
tone and, when it's on, i can even hear a hint of flange jet tone.
Is there anybody who can direct me where to look at?
thank you very much.

What I can say is don't get tempted to play around with the trim pots. I
bought one off of ebay, and it sometimes wouldn't even flange.  I had to
get a service manual, then do my best with a frequency generator and a
scope.  It is now adjusted so that it works properly whenever I step on
it.  But previous owner screwed it up, then dumped it on ebay.

[qb]

Here is the update. I chaged some (larger ones) of Electrylic caps.
But unfortunately the noise (boom like noise) is still the same....
Should I still continue to change all other smaller caps?

Regards