EH4800 Small Stone (original) Not Phasing (No LFO?)

[Rocket Roll]

Hi, I've acquired an EH4800 Small Stone (which is the same as the "Issue J").

Complete project: http://www.generalguitargadgets.com/index.php?option=com_content&task=view&id=51&Itemid=26
Schematics: http://www.generalguitargadgets.com/pdf/ggg_smallstj_sc.pdf
Layout: http://www.generalguitargadgets.com/pdf/ggg_smallstj_lo2.pdf

I've converted its DC jack to a standard Boss-type jack using Lumberg isolated DC jack.

I've also done the UniVibe mod as described here: http://www.lynx.bc.ca/~jc/pedalsSmallStone.html

The unit was working before the mods, but now there's no phasing. It passes the sound in working mode (sound gets a bit duller and quieter) and the "Color" switch is EQing (lower position-brighter sound).

Here are my voltages:



Could anybody direct me to a possible error, please? Thanks in advance!

[Rocket Roll]

Right, I've got the phasing back - reflowed a few connections, replaced those two 100nF caps near (or in) the LFO section, but the main problem seemed to be the "Color" switch: the wires going from it are not soldered but mechanically secured to it.

Now the speed changes randomly - the worst kind of problem, if you ask me... I'll replace the pot. I hope the caps involved in the mod (which I've mounted on switches) have no effect on phasing speed, because I wouldn't like to have to resolder those four switches...

[R.G.]

If the unit was working OK before the mods, then quit when the mods were done, it's pretty certain that the mods were the problem.

This can come in two flavors: mods which would work if done properly, and mods which are themselves incorrect, and will not work if executed perfectly.

I have not run through the mods to see if they're plausible; could be, maybe not.

But as you say, there should have been no change to the LFO. However, the Color switch *is* involved in the LFO, it changes the sweep as I remember from decades ago. My best guess is that you have accidentally changed the wiring to the Color switch, or by soldering error made a solder open or short in the LFO part of the circuit. Get out the magnifying glass and ohmmeter and start tracing out what you actually did versus what you thought you did.

[Rocket Roll]

Thanks a lot, R.G! Your guess was right:

My best guess is that you have accidentally changed the wiring to the Color switch, or by soldering error made a solder open or short in the LFO part of the circuit.

One of the wires that go to "Color" switch was loose. I've removed the... what's the word? clamp?... that secured the wire to the switch and soldered the wire directly.

Here's an example of the mods:

->EHX Small Stone: UniVibe Mod<-

First part (00:00-00:34) is the "standard" Small Stone, the other is the UniVibe mod. Does it now sound like a UniVibe? I guess not... but it's a nice option nevertheless.