Sovtek green small stone not phasing

[Mark Hammer]

The 47R resistor will be power-supply related. If there are heat marks around it, that does not bode well. Drawing that much current to produce burn marks might be a harbinger of damage elsewhere.

[mictester]

i have exactly the same problem with a old small stone (around 1980).

No phasing, just a loose of volume. Color switch and rate pot do nothing.

All the traces are ok (checked with multimeter)

All the resistors are ok (checked on board with multimeter). The 47 ohms on the +9v input was burned but sill fonctionnal. I changed it anyway.

The 4 transistors are OK (unsoldered and test with the diode test of my multimeter).

All the condensators seem OK :tested ONBOARD with an softare oscilloscope : I injetct an audio signal (sine 440 hz) in input and i "see" it in output.

I think that the UC5 (wich "drives" the LFO isn'it ?) is dead.
How can i test it ?

"Poke and Hope" won't fix it. If you don't know what you're doing, and you have no idea how it's meant to work, you'll just break it further. Send it to someone who understands these things, has the right instruments to track the problems, and the spares to repair it. Otherwise, you're just wasting your (and our) time.

[Lee_ranaldo]

i have the same phaser
but the black issue (it has the same board anyways)

The rate pot is 1M reverse log.

The LFO might be not oscillating.
There is a cap in the circuit that when get's bad or unsoldered
the pedal doesn't have the LFO working that controls the CA3094.

Check Pot, LFO section for any shorts. Replace CA3094 in LFO section.

[mictester]

You also have No Idea!

i have the same phaser
but the black issue (it has the same board anyways)

The rate pot is 1M reverse log.

The LFO might be not oscillating.
There is a cap in the circuit that when get's bad or unsoldered
the pedal doesn't have the LFO working that controls the CA3094.

Check Pot, LFO section for any shorts. Replace CA3094 in LFO section.

I have NEVER had any of the ICs fail in a Small Stone, and I've mended dozens of them. The ICs don't even fail if the wrong supply is connected!

Please stop wasting our time with silly, uninformed conjecture. If you can't actually suggest what's wrong with the thing, don't bother replying.

Don't waste your time and money just randomly replacing components - you might get lucky and find a faulty component, but it's very unlikely. I'll say it again, but louder this time:

"POKE AND HOPE" WILL NOT MEND THIS UNIT. If you don't know what you're doing, ship it to somebody who mends equipment like this and get it fixed. It will be cheaper for you in the long run, and will save the world's components for the rest of us who know how to use them!

[Lee_ranaldo]

Check the 33uf Capacitor is it's properly soldered and it's ok.
If now measure with a scope if u're getting an LFO signal. Check the components in the red square.

The LFO IC is next to a couple of Transistors.





PD:Posting some info against any kind of help we are trying to give
sound like a fantastic strategy. either u're a part of the solution or part of the problem, cheers!

[52 Bill]

I've fixed a few of the Sovtek versions, and none have needed a new chip. I have also fixed a lot of the older original EH versions and many have needed new CA3094 chips.

I thought that we were all here to help one another. If someone asks a reasonable question, then I think that it deserves a reasonable answer.

The generic answer to the question regarding chip testing is to read the voltages on the pins of the ICs. Get a copy of the data sheet or the schematic and look at the pinout of the chip in question. Check the voltages and see if there are voltages where they should and shouldn't be.

[Steve Conner]

Please stop wasting our time with silly, uninformed conjecture. If you can't actually suggest what's wrong with the thing, don't bother replying.

Chill out, Mr. Grumpy 3 Posts. The entire Internet is a mass of silly, uninformed conjecture designed to waste the time of most of the Western world, you're not going to make a difference.