troubles with dod fx 96

[EdJ]

Hi,
i have the older version of the fx 96(the purple one with the tape on the outside and without the trimmer on the inside).
I changed c 19 from 22 to 100p and the delaytime is fine,however i have a few problems i need help with.

The bypassed signal has signifficant less highs then the signal has without the pedal.
Is there a cure for this,without true bypassing the pedal?

The dry/tape pot is only usable in the first 10 %(approx)of the pot,after 10% the delayed signal is much stronger then the dry signal.
A humm(about 60 hz)is introduced by turning the pot and becomes noticable when the delayed signal is heard.

More humm comes from the echo pot,the higher the more humm.

I`d like to get rid of the humm,have a more workable range in the dry/tape pot and have the bypassed signal more like the original,is this possible?
Schematic http://www.diystompboxes.com/pedals/schemsc/fx96schem.pdf
Any help is greatly appriciated!

greetings,Ed

[Mark Hammer]

There is a .0015uf cap to ground on the input (C44), but technically its treble-cutting action on the input should only start well above the range of most pickups and speakers (10khz or so), so that doesn't seem to be the major source of your difficulties, even though one tends not to see other pedals with similar input buffers using that sort of arrangement.  Similarly, C3 and C42 are always shaving top end off the signal i both bypass and effect mode, but again that doesn't really begin until around 15khz or so, which ought not to be audible in the average guitar amp.

You might try just lifting one leg of C44 and see if it makes an audible difference.  It certainly wouldn't hurt much to reduce it to 1000pf from 1500.

It is possible (though not that probable) that something is amiss with C4.

As for the dry/tape pot, that may be a matter of taper.

[EdJ]

Thanks Mark,
i`ll start with c44 and see what happens.
The treble cutting is very audiable when the pedal is placed between the guitar and amp,almost like a brightswitch on a Fender amp.
Not nessecery bad sounding,just darker.
If the caps don`t workout i can allways bypass the pedal by putting it in a loop, but that leaves the humm issue.
I tried 2 different transformers but the pedal humms with both of them.
My guess is that it is 50 Hz humm because it sounds somewhere between A and B(notes).
as it is an old pedal;could it be (some of the)elco`s?
The echo,as such,is nice.

Ed

[EdJ]

Checked the electrolitics and there are bad ones indeed.
I am replacing them and try to find .22uF ones for C8 and C41.
I have .47uF but no .22.See if i can find something that fits..

[EdJ]

I replaced all the electrolitics and the humm is gone.
The dark sound,however,is not.
Even with the echo bypassed,the sound is much to dark for my liking.
It seems like i am losing unprocessed guitar sound far to much.
Is there a cure?
Thanks in advance,Ed