VintageKustom.com: Repairing Kustom Amps » K150-6 pumps out DC voltage when powered on.

Re: K150-6 pumps out DC voltage when powered on. [message #27716 is a reply to message #23707]

Sun, 08 March 2020 21:41

corybrown
Messages: 51
Registered: August 2015

Member

Well that's a good call. I've been out there working on it this evening and realized that Q4 was an NPN and I had replaced it with a PNP. That's on me. Stevem recommended nte128 and like an idiot I bought nte129. My old Q4 tested fine now that I have it out of the board so I put it back in and checked all of my measurements again.

Measurements that make me scratch my head are the collector of Q4. The schematic shows -3.7 at Q4s collector but I'm getting -33V. There is a node at that point between Q4 collector, C7 and R18. Should it be -33V on both sides of C7 or could it be a typo on the schematic?

The other one is CR4 where it goes into the collector of Q7. All of the other diodes have the same voltage on both sides but CR4 has -25V on one side and -256mV on the other side and that -256mV is going into the collector of Q7. Should it be like that?

I'll try the Q6 swap tomorrow evening.

Here are my measurements after putting Q4 back

Component In Out
R1 47K 169mV .6V
R2 47K 193mV .6V
R3 82.5K 1% .6V 5.7V
R4 221K 1% .6V -8.5V
R5 2200 5.7V 8.5V
R6 4700 5.7V 5.6V
R7 33K 38mV 0V
R8 39K 42.85V 20.67V
R9 39K 20.68V .6V
R10 4700 -33V -33V
R11 3900 -34V -34V
R12 1820 1% -1.9V -2.2V
R13 33K -1.9V -26V
R14 2200 42V 11.4V
R15 2700 11.4V -19V
R16 97.6K 1% -2.3V -26V
R17 4700 -26V -33V
R18 470 -33V -27V
R19 470 -33V -33V
R20 470 -34V -42V
R21 1K -26V -26V
R22 100 -25V -26V
R23 1K -25V -26V
R24 100 -42V -42V
R25 820 5% -26V -26V
R26 .5 5W -26V -26V
R27 267 1% -26V -26V
R28 .5 5W -26V -26V
R29 267 1% -26V -26V
R30 820 5% -26V -26V
R31 100K -26V 109mV
R32 18K 43V 9.7V
R33 1200 7.6V 8V
R34 4700 8.5V 7.6V
R35 10K 7.6V 0V
R36 1K 9.1V 8.6V
R37 4.7 8.6V 8.5V
R38 10K 1% 8.5V -.6V
R39 8.25K 1% -8.5V -.6V
R40 18K -42V -9V
R41 1K -42V -42V
R42 4.7 -8.5V -8.5V
R43 510 109mV 109mV
C1 0.005 5.7V 0V
C2 0.33 5.7V 38mV
C3 1.0 35V 20.6V 0V
C4 33 15V -1.9V 0V
C5 27 35V 11.4V -26V
C6 27 35V -26V -33V
C7 47 PF -33V -33V
C8 0.005 -33V 0V
C9 47 PF 42V 9.7V
C10 47 PF 9.7V 7V
C11 33 15V 7V 0V
C12 33 15V 8.5V 0V
C13 47 PF -9.2V -.6V
C14 47 PF -9.2V -42V
C15 10 15V -.6V -8.5V
C16 33 15V -8.5V 0V
CR1 1N3193 -25V -25V
CR2 1N3193 -25V -26V
CR3 1N3754 -26V -26V
CR4 FD111 -25V -256mV
CR5 FD111 -26V -27V
Q1 PET8002 B .6V C5.7V E 0V
Q2 2N4249 B 38mV C-33V E .6V
Q3 2N4249 B -2.3V C -34V E .6V
Q4 38735 B -33V C -33V E -34V
Q5 38736 B-25V C 42V E -25V
Q6 38737 B -26V C -42V -26V
Q7 2N3567 B -26V C -256mV -26V
Q8 2N3638 B -26V C -26V E -26V
Q9 PET8002 B 7.6V C 9.2V E 7.5V
Q10 CR10 SZ51218 7V 0V
Q11 2N3567 B -9.7V C 43V E 9.1V
Q12 36892 B 9.1V C 43V E 8.6V
Q13 PET8002 B 8.6V C 9.7V E 8.5V
Q14 2N3638 B .6V C 0V E -9.2V
Q15 2N3638 B -9.2V C -42V E -8.6V
Q16 36892 B -42V C -8.6V E -42V
Q17 2N3638 B -8.6V C -9.2V E -8.5V
Q18 36892 B -20V C 42V E -20V
Q19 36892 B -21V C -42V E -43V

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