UNI-VIBE UV1 faint effect

[tedsorvino]

Hi there. I'm trying to realise where to start from in order to debug this pretty complicated effect pcb. The problem is that the sound when the effect is engaged is alright, but there is no real vibe effect there. I checked the soldering and all the other connections and everything seem fine (at least there is no obvious problem).
I ve got no info regarding correct voltage values around the chips and transistors (I've found some schematic info and other layouts), but I don't know how to work on it.
Should I audio probe it (but it's a matter of effect quality and not signal loss)?
Any idea or info it would be really valuable.

[brejna]

Hi, post few pics.. Also first see if lamp is working properly..

[tedsorvino]

What do you mean by lamp Brejna? The leds? Tomorrow I will post a couple of close up pictures.

[tedsorvino]

Here are some images (just in case)

[lolbou]

The light bulb is under the chrome box (hold with wire). Its pads are in the very center, so you can measure the voltage it gets, as well a its DC resistance (when off).

I'd suggest to take a look at the schem (posted here) and check Q (buld driver), as well as the ribbon cable going to pots PCB from the main PCB (the modulating signal goes through it), and U as well.

Keep in mind that these PCBs are dual side, and are a bitch to desolder (add some leaded one to make it wetter and lower the melting temp, and just be sure of your diagnosis before any surgery)...

Keep us posted!

[tedsorvino]

Thank you lolbou for the reply.
Any idea what voltages I'm looking for around the buld,the Qs and Us.
The ribbon cable looks in perfect condition. Actually I only have voltages and signal only on the volume pot pins.
What goes on with the ring on top of the speed pot? I guess it's ground ...or not?

[tedsorvino]

The bulb voltage seems correct. B+. Around 15V. Which Qs and Us should i measure?