Kingslayer 2 weird gain knob

[Alaboogie]

I just built a kingslayer 2 and the gain knob is doing something weird. I understand that since it is a dual gang pot, it blends the clean and dirty signal. My KS is doing something weird that none of the other 4 or so klones I've made have done.

When the gain is all the way down its clean and when it's all the way up, there is a distorted signal. But the weird thing is when halfway it's almost as if the signal drops out, and loses db's.

So say it's at 0db when gain is all the way down and when you turn it up it goes to -10db and is still really clean and seems like the sound sort of disappears and then when a little past halfway the db level comes back up. When gain is dimed the db level is back to 0db and is dirty, although the distorted signal that is present isn't what I imagined it to sound like. Obviously something is wrong so the dimed gain sound probably isn't what it's supposed to sound like.

I perused tech help for KS posts and found one that Bean gave voltages for the tl074 (I swapped it in instead of the tl274 that he said might be better). My voltages seemed low to me, especially since there's a pump, on pin 1 of the 1044 I think I was getting somewhere around 5.7V. Shouldn't that be the input V which would be around 9V? So because pin 1 was 5.7V, pin 4 on the tl074 was 5.7V as well.

What could I possibly be missing? I'm in class right now so I can't post pics or voltages for all pins but if anyone wants me to when I get home I can.

😞

[Alaboogie]

So I looked at the schem and r28 was changed to 150R which I put in but it brought my voltage down to the 5.7V. I put in a 100R resistor and it was still low, like 6.x volts. I'm assuming that was intentional? So pin 1 of tc1044 is supposed to be low? 5.x volts low?

[Alaboogie]

I have to mention I bypassed the resistor in r28 to see what 9V would do for the gain (nothing haha). What you see is a temporary bridge, it's not actually soldered down but still passes voltage (so I can fix it in case someone has a solution)

[Alaboogie]

Anyone?

[mgwhit]

Yeah, you've got a low VC voltage for some reason.  Measure your voltage on either side of D5.  You should really only drop less than a half a volt across that 1n5817.  If it's really off post D5, I would recommend jumpering or swapping that diode with a known-good 1n5817.  If the voltage is low pre- and post-D5, first test your power supply isolated from the board.  If that's good, try removing D6 completely.

[Alaboogie]

Yeah the voltage was fine on both sides of D5, ~9.45V pre and ~9.15V post D5, but I switched it out anyway and same voltage readings. So i switched out D6 for another 1n4742A and same thing. The only thing I see in the schematic in between the V input and pin 1 of the IC is the 150N resistor...I put a 100N in there and still nothing

Anyone else have any suggestions? Any other info you guys might need to help me out?

[mgwhit]

You said earlier that you were getting ~5-6V on pin 1 of your TC1044, but it sounds like you're getting ~9V now.  Is that with R28 jumpered, or is there a resistor in there?

I suspect you had a 150K resistor in there earlier when you were getting ~5.7V and a 100K in there when you were getting around 6V.  You were saying R (rather than K) earlier, but if you're getting 9V now with that resistor jumpered it's the only good explanation.  You're saying N now, which makes me suspect you might not understand the resistance annotation values.  150R is 150 Ohms, 150K is 150,000 Ohms.

[Alaboogie]

My bad, I meant 150R on my last post. So i switched it out for a 100R resistor. I have always had the 150R in the R28, i even measured it at 150R on my voltmeter. I shouldn't have put 100N (It's not a capacitor )

I am getting 6.4V on pin 1 of my TC1044 with the 100R resistor in R28.

When I jumpered R28 I was getting the correct 9V on pin 1 of my TC1044, it seems depending on the value of R28, the input voltage gets limited accordingly.

[mgwhit]

My bad, I meant 150R on my last post. So i switched it out for a 100R resistor. I have always had the 150R in the R28, i even measured it at 150R on my voltmeter.

Okay, cool.  Just trying to make sure you knew the difference.  It's a common mistake.

I am getting 6.4V on pin 1 of my TC1044 with the 100R resistor in R28.

When I jumpered R28 I was getting the correct 9V on pin 1 of my TC1044, it seems depending on the value of R28, the input voltage gets limited accordingly.

Yep, that how it works, but 3V seems like a large drop across a 100R resistor.  I think something is pulling too much current.  I would just remove D6 if I were you.  That part is not necessary and bad Zeners have been causing a lot of problems in that configuration lately.

Just for giggles, are you getting about -6.4V on pin 5 of your TC1044, and are you getting those voltages on pins 4 and 11 of your quad op amp IC?