MN3102 drawing too much current

[Stevpo]

As the subject suggests, I have an MN3102 that might be drawing too much current for some reason. The circuit is a homebrew layout for a CE-2 chorus, using the 3207/3102 chips rather than 3007/3101 set. Only other modification to the circuit is it is true bypass. The effect powers on. Signal gets through in bypass. Signal gets through when switched on - which means my op amp stages are working fine, but no chorus.

I have scoped the signal path, and everything seems operational until it gets to the 3207. Audio signal is present at pin 3, but nothing comes out from pin 7/8. I've scoped the clock pulses from the 3102, and my LFO. Both working. In fact, I can see the modulation of the clock pulses change as I adjust the depth and speed controls. This can be seen on pins 2 and 4 of the 3102, as well as 2 and 6 of the 3207 - so I know my BBD is getting clock pulses.

However, weird things start to show up when I take voltage measurements. Here are my voltage measurements:

Supply: 9.6

3102:
1 - 8.07
2 - 1.94(?!)
3 - 0
4 - 2.24(?!)
5 - 7.5
6 - 4.07
7 - 4.43
8 - 3.19

3207:
1 - 0
2 - 2.24
3 - 3.72
4 - 7.5
5 - 9.12
6 - 9.12
7 - 1.94
8 - 8.12

Referring to: https://el34world.com/charts/Schematics/files/Effects/Boss_ce2_chorus.pdf the voltage drop after R52 (verified 33R) on my circuit is 1.4 volts! By my calculation, that's over 40mA! If I pull the clock and BBD chips, supply voltage normalizes. With just the 3102 in the circuit, I get the crazy voltage drop. So my 3102 alone seems to be pulling 40mA?! That's weird, right? Does anyone have any ideas? Am I powering it wrong?

Thanks in advance

[ElectricDruid]

If the circuit was *designed for* the MN3007 chip and you're using it for the MN3207, then yes, you're definitely powering it wrong. There are variants of the circuit that have been modified for the other chipset.

The lower voltage is not the only difference. They also use opposite polarities, so it's not a surprise that it would draw a big current if it was powered in reverse.

[Stevpo]

Yeah. I get that. I was pretty sure I got it right, though. Should have mentioned, my layout took polarity of the chips into account. Pin 1 on my 3207 is ground, while pin 5 is connected to my positive supply voltage - through that 33R resistor.

[ElectricDruid]

Yeah. I get that. I was pretty sure I got it right, though. Should have mentioned, my layout took polarity of the chips into account. Pin 1 on my 3207 is ground, while pin 5 is connected to my positive supply voltage - through that 33R resistor.

Ok, that sounds alright. Could there be a short somewhere on the clock's socket or the surrounding connections? I'm thinking that when the clock is plugged in, something at a high level finishes up shorted to ground causing the high current draw. It's possible the chip is fried, and the test for that is to plug a different one in and see if the same thing happens, but that's (a) risky, since it could be something on the circuit that's frying them, and (b) expensive, if you don't have a few of these things kicking around already.

[Stevpo]

Well, I tried other clocks and BBDs in the circuit, with the exact same results. Rather than try to debug my layout, I ordered a Pork Barrel pcb from Madbean. Hopefully this is all that's needed, and I didn't fry any clocks or BBDs...