Micro Vibe Issue (and general vibe question)

[palelight]

Hey all,

Not so much of an issue as a general query. Picked up a Micro Vibe and set to tweaking it to make it sound like my Chicken Salad. Added a light-box and tweaked the trim pot. I'd say they sound about 99% the same now. BUT, the trim pot had to get tweaked pretty hard clock-wise from the factory setting. Everything sounds great until the depth and speed increase over 3 o'clock(ish). If the speed is below 3'oclock the depth can be cranked, and vice-versa, but if they both go over 3'oclock the vibe sound fades out over about a 2 second period. Decreasing either makes the effect come back. Looking at the bulb when this happens the light goes quite dim with no pulse/throb.

Now I don't run both knobs cranked ever, but I was wondering if a) this configuration is stressing either the bulb or the driver transistor, or b) if this can be fixed. I tried strapping various resistors to the depth pot, and while it does decrease the depth, when it's maxed the same thing happens.

Thanks!

[PRR]

If the bulb goes dim, it seems "unlikely" the bulb or driver is stressed.

However real thinking demands a link to the schematic.

[pinkjimiphoton]

Hey all,

Not so much of an issue as a general query. Picked up a Micro Vibe and set to tweaking it to make it sound like my Chicken Salad. Added a light-box and tweaked the trim pot. I'd say they sound about 99% the same now. BUT, the trim pot had to get tweaked pretty hard clock-wise from the factory setting. Everything sounds great until the depth and speed increase over 3 o'clock(ish). If the speed is below 3'oclock the depth can be cranked, and vice-versa, but if they both go over 3'oclock the vibe sound fades out over about a 2 second period. Decreasing either makes the effect come back. Looking at the bulb when this happens the light goes quite dim with no pulse/throb.

Now I don't run both knobs cranked ever, but I was wondering if a) this configuration is stressing either the bulb or the driver transistor, or b) if this can be fixed. I tried strapping various resistors to the depth pot, and while it does decrease the depth, when it's maxed the same thing happens.

Thanks!

sounds to me like the trimmer controls the oscillator's phase shift stages not the light. try turning the knobs up all the way and then tweaking it.
if it will work, it will work.

odds are for the circuit in question it was tweaked for optimal performance as set up stock. when you change that, you need to take into account that it will likely throw other parts of the circuit out of balance.

google up scruffie's celeste chorus building guide.. he gives some good ideas as to how to get these things set up by ear.

but that said, try diming the control pots before messing with the trimmer. i know it sounds counterintuitive, but that way you MAY be able to tweak it til it sounds "good" to you AND still keep the pots working.

oscillators are weird things. when you upset their balance, all kindsa weird stuff can happen.

not saying i'm right... ever. (seriously) but that would be all i can think of unless as paul suggested you supply a schematic.