Alpha Dog Debug Help

[jjjimi84]

Yesterday the triplet was assembly with no issues, today is not going well at all.

When I plug in the Alpha Dog, the led lights up and does not go off. All audio goes through it but it never actually goes to the circuit, it is just clean.

I have checked all values and double checked wiring and solder joints, before mess around with removing the relay and the transistors is there anywhere i should start looking?

Surprisingly I was able to drill two enclosures with no issues, so at least there is a high point.

[jimilee]

Got pictures?


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[jjjimi84]

Did what I should have done before posting, took a break and came at it with fresh eyes. Also spent way too much time reading the build docs again. Replaced the BS170 and reflowed a few solder joints and now we are good to go.

[jjjimi84]

Kinda rehashing an old topic but this thing is driving me crazy. I got it to work and everything was going well......

Then it stopped working, when plugged in, the led never shuts off and the switch is unresponsive. I then removed the switching board and all components, replaced the relay, put sockets in at all of the transistors. Same problem and I dont know what to do.

Any ideas would be super helpful.

[fair.child]

Check your SPST switch. I've found cheap SPST Momentary switch created several issues. You should use 110-PM-OFF from Smallbear. If this happens to me, I'd check the power supply section first (9V to 5V) the LP2950 I mean. Check the voltage in and out. You should hear a click when you first run the switching board. Next, check your LED as well. I had an issue using low light Blue LED/ Color LED. The clear LED tends to work better.

Really, I think to increase chance of success building all the VFE's, you need to follow Peter specs. 

Hope this helps!

[gordo]

I had a few bad LP2950's that would turn the LED on and off but not the relay.  Might be worth checking.

[jjjimi84]

I am actually thinking it is the inductor, tracing the voltage there is nothing coming off the end of the inductor where it connects to c1 and d2. I am going to try that in the morning and see if that fixes it.

[jjjimi84]

It was the inductor, I jumpered it and everything worked. Swapped it out and it is all good to go, nice learning experience and such a cool sounding pedal.

[zgrav]

good to know the inductor is a part to check if VFE switching fails.  I've had bad relays when building them, but never had a good one go bad.