Chorus weirdness.....

[Gtr_tech]

Subject: Crate G-130CXL

This thing came in a few days ago with some broken pot shafts. Replaced the pots...everything seemed OK on the bench. Put it back together, played through it for a few mins, turned on the chorus and things got strange. What seems to be happening is the LFO is dropping out as signal decays. Works fine otherwise, but hit a chord and let it decay and the LFO stops...LED and all. Doesn't sound like its stuck at a delay time, but almost like a gated type of thing where it bypasses the delay chip and routes signal around it.

I think I may have the schematic for this chassis somewhere. Just seems strange to me. The LFO should run all the time.

I'll dig into it more and try'n see whats goin' on.

[Enzo]

Keep us posted

[David Schwab]

I have a little Crate with 2X5" and stereo chorus and distortion, and I have to constantly open it up and re solder the connections where the pots connect to the circuit board. They keep breaking which makes the chorus and distortion stop working.

The amp just sits in my living room, not like I take it on the road!

[Enzo]

Well yeah, but you're in New Jersey.

[Gtr_tech]

Originally Posted by Gtr_tech

Subject: Crate G-130CXL

I think I may have the schematic for this chassis somewhere. Just seems strange to me. The LFO should run all the time.

I'll dig into it more and try'n see whats goin' on.

Got it sorted out. The LFO was actually stopping. After finding the schematic (and near worthless layout) I found a transistor in the LFO section was toggling a line high/low. A high would kill the oscillator, low started it back up again. Why they did this I don't have a clue. I didn't spend alot of time pouring over documentation since it was a rush job, but they were taking feedback off the output section and that ended up causing the gate effect. I don't know if it was intentional, but if so what were they thinking. Only thing I can think of is maybe they were trying to reduce noise at a no signal condition with the chorus on, but there's certainly more elegant ways of doing that. I ended up just putting in a pull down resistor in that kept the LFO operational full time.

Another one for the WTF files.....