Mad Bean Pork Barrel - MN3007 how do I know if it is working?

Started by FastEdTex, March 19, 2017, 05:12:35 PM

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FastEdTex

OK, so I'm building a second Pork Barrel by Mad Bean. 1st one is working well, so well I have an order build another for my Brother.

I got a lot of 3007/3101 ic's from seller on Ebay. One set is in my #1 PB Chorus and working well.
In my down time, I build an audio probe so I could be more efficient at resolving issue with my builds.

So I have the PCB populated except the 2 pots. I have inserted the pots without soldering to test the PCB. "Rock it before you box it"

I'm getting good voltages compared to the #1 PB pedal.
I'm getting sound from pin 3 of the BBD but nothing from pin 7 or 8 which is the output of the BBD.

I'm getting dry sound from the 4558 on pin 1 and 7 - the outputs - no chorus effect.

Should you hear the signal/sound on the BBD on pin 7 and 8?

1. bypass and effect both produce sound, no chorus effect
2.Name of the circuit = PorkBarrel Chorus from Madbean
3.Source of the circuit (URL of schematic or project) = http://www.madbeanpedals.com/projects/PorkBarrel/docs/PorkBarrel.pdf
4.Any modifications to the circuit? Y or N= No
5.Any parts substitutions? If yes, list them= No
6.Positive ground to negative ground conversion? Y or N= NO
7. What is the out of circuit battery voltage? = 9.1 V from Godlyke
Voltage at the circuit board end of the red battery lead = 9.1 V
Voltage at the circuit board end of the black battery lead = 0 V


FastEdTex

Quote from: thermionix on March 19, 2017, 06:12:24 PM
Didja socket?
Yes, both PB#1 and PB#2 are socketed.

Just finished testing, again.

I was afraid of blowing the only functioning 3007 I had but, I pulled it from the pedal and inserted each of the 9 3007's I had.
None worked.
Put the only working 3007 in the new PCB and it works as well as it does in it's original PCB in the pedal.

Did a check with a signal probe while I had it working in the PCB #2 and there is audible signal from pin 7 & 8. None of the other 3007's produced a audible signal.

Lesson: When you buy MN3007 from Ebay, you get what you pay for. Pot luck. :-[
Could have gotten 2 working sets of MN3007/MN3101 from Small Bear for the same Money.  :icon_cry:

thermionix

Sorry to hear about the bogus chips, but good you got it figured out I reckon.

anotherjim

If you need a lot of expensive parts that are only available as NOS or unsoldered pulls, it would be wise to keep at least one good example in a working board at your workshop. You can always prove your purchases that way, and indeed, sell them on as "tested" if you get a surplus.

I'm curious to know if the bad chips were supplied in proper packaging - anti-static or not?
How come the BBD's are often bad, but the clock generators are usually ok?