crackling phaser, need some HELP

[FuzzAldrin]

Ok,... I rehoused an old EH Small Stone Issue J Phaser for a friend.
(When turned on, NOT bypassed) it occasionally has a very prominent crackling sound that is needless to say, not cool.
It goes away for awhile, then out of nowhere it comes back and can last for seconds to a full minute. Sounds like some dwarf is in my amp crumpling up papers!!! I checked and nope, no dwarf.

I added a True Bypass switch, fixed volume drop, and added a standard red LED.
I also replaced all Electrolytic caps, 1M Pot with small bear replacement, and replaced the slide DPDT switch with a new equivalent.
I also replaceed the jacks with new switchcraft.
I ALSO (lol) replaced all wires, and removed all of the old solder and applied fresh solder to the joints on the wires.
Went over every joint with a jewelers loupe and all joints look very good.
All wire connections are heatshrunk (to adaptor, switches and jacks)
I wired it using the STAR input ground.
Sounds BEAUTIFUL until the crackling comes...
Does not matter if using battery or adaptor.
It appears nothing is touching anything that shouldnt be touching...
Not much comes up when I searched the forum on this matter.
He doesnt know if it has been "crackling" cause he hasnt used it in about 3 years because of the tone coloration when in bypassed...

I need to fix this ASAP so I can give it back to my friend.
Can anyone help me out? How to I debug this?
Thanks in advance.

[R.G.]

You've already done most of what I'd tell you to do. You're down to following the audio path with a probe and finding which section is crackling.

It's almost certainly one of the semiconductors. The audio probe is to let you find out where in the chain it starts. What you want is for it to be the input transistors, not one of the CA3094's. If it were mine, I would arbitrarily replace the two input transistors, then if it still had problems, go looking down the chain for a bad 3094. I think Small Bear still has some of those.

[FuzzAldrin]

R.G., Thank you for the quick reply! I will make an audio probe and get on the debugging path. I will also replace those transistors. Hopefully those are the problem and not the IC's. But, if so that is cool.
I will reply back once this matter is resolved.
Thanks agin!

[Mark Hammer]

Though not a huge board, it is big enough to bend and crack under strain.  So consider the outside possibility that it could be a crack in a trace.

[FuzzAldrin]

Though not a huge board, it is big enough to bend and crack under strain.  So consider the outside possibility that it could be a crack in a trace.

I checked with a high powered micro, and no crakcs in the board.

What you want is for it to be the input transistors, not one of the CA3094's. If it were mine, I would arbitrarily replace the two input transistors, then if it still had problems, go looking down the chain for a bad 3094. I think Small Bear still has some of those.

Ok, I replaced the first 2. No more crackling .... BUT, now the phaser effect is not as pronounced as before. Not deep and the knob really only reacts to the last 3/4 turn before it goes all warbly. Could the trannies be too high gain? I believe I replaced them with 5088 or 5087 like the schemo calls for. Any advice?

[FuzzAldrin]

Anyone have an idea why the trannies seemed to drastically weakened the sound?

[FuzzAldrin]

also, my pot is wired backwards, but that shouldnt be why there is very little phase in the pots rotation.

BUMP! anyone? ....about to give up on this.

[FuzzAldrin]

Power Supply = 9.15v

Q1 (2N5088)  replaced original
C = 8.35v
B = 3.40
E = 3.00

Q2 (2N5087) replaced original
C= 5.70
B= 8.40
E= 9.00

Q3 (Original BC309)

C= 5-6.20 (climbs)
B= 4.45
E= 4.20 – 7.02  (climbs)

Q4 (BC309)

C= 3-6
B= 4.00-7
E= 4.20 – 7.5


Now, for the IC's. They are original and are marked "EH1048 274 7801", EXCEPT Q5 is "EH1048 274 7806"

IC1
4.8v
3.6
3.6
0.7

0.6
3.6
8.9
8.9

IC2
4.65
3.62
3.60
0.2

0.65
3.6
9.0
9.0

IC3
4.8
3.6
3.6
0.1

0.65
3.6
8.9
9.0

IC4
4.75
3.6
3.6
0.1

0.5
3.6
9.0
9.0

IC5
1.8
6.5
7.00
0.1

0.5
0.65
9.0
7.2

Like I said earlier, phaser worked, then was true bypassed and modded with the volume mod. Worked fantastic, but was crackling. Replaced Q1 and Q2 and now it still works, But only in the last 1/2 of the knob. Has a ridiculously slooooooowwwww sweep until towards the end and then it just warbles.

[FuzzAldrin]

looks similar to this members working russian small stone from another thread...
"Ok. Incidentally I've got a russian small stone disassembled and I just pulled it out and lended a battery from the
fire alarm     :-)
This machine has the original 3094 ic's. What voltages do you want?

Vbat unloaded 8.84
Vbat in circuit 8.81

IC 1-4 ( filter )
pin
1     4.2 - 4.6
2     3.51
3     3.49
4     0
5     0.60 - 0.65 ( changing while sweaping )
6     ~3.5
7     8.6
8     8.6 ( pin 7 and 8 connected )

IC 5 ( LFO )
1     1.7 -1.9
2     4.5 - 7.0
3     4.5 - 7.0
4     0     
6     0.54 - 0.65
6     0.6 - 0.7
7     4.5 - 7.0
8     8.6

divider feeding rate potentiometer 1.8V"