Pork Barrel

[Vtguy22]

Hello,

  I'm trying to figure out the Pork Barrel and not having much luck.  I've reflowed everything.  I get a strong clean signal with the effect on or off.  Attached are my pics, and here are the voltages I'm getting

4558
4.65
4.65
4.65
0
4.65
4.65
4.65
9.45

MN3101
7
3.13
0
3.8
Varies
6.18
Varies
1.50

MN30007
7.1
3.89
3.14
1.45
0
3.14
1.42
1.42

TL062
Varies
4.67
Varies
0
4.07
4.8
Varies
9.45

Thanks in advance,
Paul.

[madbean]

You supply voltages on both the MN3101 and MN3007 are looking quite low. I see you do have a 33R resistor there to create the VD supply. How about that D4 zener? Are you sure it is a 9.1v? You can actually clip it out with no adverse effect on the circuit.

Also, you can try pulling out both the MN3101 and MN3007 and then measure the supply voltages in their sockets (pins1). That would tell you if either chip if sinking current. Does either chip get hot under power? 

[Vtguy22]

Thanks!  It'll be a week or so before I can try those ideas.  Just had my oil tank replaced, so half my basement is in my work area...  They tore up my floor paint dragging the tanks around, so need to wait for the touchups to dry before unburying my bench.

[Scruffie]

Where'd you get your chips? Your 3101 voltages even at the low supply look suspicious.

[Vtguy22]

Okay, dug out my bench.  I removed D4, and the voltages didn't change.   Pin 1 on the sockets is 9.4 for each chip. 

Not sure where I got the 3101 from, I thought Smallbear, but very likely I'm mis- remembering that...

[Scruffie]

So you say it's 9.4V on the socket, have you seen if it's one chip or the other that's pulling things down when in place?

[Vtguy22]

I'm not sure how I would tell.  They are both around 7V with the chips in place.

[Scruffie]

Put the MN3007 in but leave the MN3101 out, measure pin 1, take the MN3007 out and put the MN3101 in, measure pin 1.

Is it 7V in both cases?

[Vtguy22]

Thanks.

With 3007 removed, both are 7.4v
With 3101 removed, both are 9.4v

Is that sounding like a problem with the 3101?

[Scruffie]

Yup!

[Vtguy22]

Thanks, I'll order a couple when Small Bear opens back up.