mxr analog delay problem

[pinkjimiphoton]

hi, my friend asked me to look at his old green mxr analog delay. it had no echo on the high e string at all...

i opened it up, cleaned it, re-seated the chips and played with the three pots that weren't soldered to be un-adjustable.

now it's working...kinda...you can hear echo all the way up to about the 17th fret of the high e string, but it's kinda faint...the bass notes are MUCH more effected than the treble. but it's a definite improvement.

anybody else run into this kind of problem? any ideas, or tricks that could help me fix this thing right?

i used to have one of these, it was muddy, but not like this thing is.

as always...thanks in advance!!

peace
jimi

[theehman]

There's a tantalum cap on the output.  I've seen them go bad and cause faint echo.

[pinkjimiphoton]

i can hear a faint buzzing with the box open, so i'm guessing there's a cap problem. i'll try replacing it.
does it have to be tantalum, or will something else do? does it matter?

thanks for the tip!!

[theehman]

I just use regular electrolytics.

[Mark Hammer]

The M-118 uses a tracking filter that adjusts the high-frequency cutoff, depending on the delay time set.  It uses a switched resistor filter that employs the same master clock as the BBD.  Slow the clock rate to get a longer delay time and the filter cutoff goes lower to keep that clock signal out of the audio path.

The filter employs the eight CMOS switches used in two 4016 chips.    The thing is, if those switches are left closed, because the chip is either dead or a section or two are dead, or because the clock pulse that turns the switch on is having continuity problems, the filter will be set quite low, making it difficult to hear the repeats.

Consequently, I suggest you check the 4016 chips.  Reseat them first to make sure there is simply no continuity issue and maybe swap them for others, just to be sure.