bobtheninja
Active member
- Joined
- Sep 5, 2010
- Messages
- 31
Hi,
I've taken it upon me to fix the 1176 LN rev d that lives at the studio I work in. I'm not the worlds greatest repairman, but I have built compressors and preamps and had success, and I really enjoy the process.
The symptoms are:
I can only get it to reduce gain by 5 or so dB on the 4:1 setting. I think this has to do with the pre-amplification stage of the compressor, that I can't amplify the signal high enough above the threshold to increase the gain reduction beyond 5 dB.
Also - the positive rail on the power supply is giving only giving me 27.68 VDC when measured on R80. My negative rail is -9.99 VDC when measured at CR9.
I've also measured voltages at each transistor (except for the FETs). See below for the results.
Let me know if you see anywhere I should be taking a closer look. And also feel free to hurl insults at me for being stupid and overlooking something - I know that I'm not very experienced at this, but I'm eager to learn.
Thanks in advance
I've taken it upon me to fix the 1176 LN rev d that lives at the studio I work in. I'm not the worlds greatest repairman, but I have built compressors and preamps and had success, and I really enjoy the process.
The symptoms are:
I can only get it to reduce gain by 5 or so dB on the 4:1 setting. I think this has to do with the pre-amplification stage of the compressor, that I can't amplify the signal high enough above the threshold to increase the gain reduction beyond 5 dB.
Also - the positive rail on the power supply is giving only giving me 27.68 VDC when measured on R80. My negative rail is -9.99 VDC when measured at CR9.
I've also measured voltages at each transistor (except for the FETs). See below for the results.
Component | C | E | B | Voltage |
R80 | 27.68 | |||
CR9 | -9.99 | |||
Q1 | ||||
Q2 | 1,66 | 0,50 | 0,977 | VDC |
Q3 | 10,43 | 1,09 | 1,65 | VDC |
Q4 | 3,64 | 0,37 | 0,92 | VDC |
Q5 | 21,53 | 2,46 | 3,04 | VDC |
Q6 | 25,04 | 1,85 | 2,47 | VDC |
Q7 | 13,66 | 3,52 | 4,05 | VDC |
Q8 | 27,43 | 13,06 | 13,66 | VDC |
Q9 | 14,94 | 2,80 | 3,35 | VDC |
Q10 | 27,41 | 14,32 | 14,95 | VDC |
Q11 | ||||
Q12 | 14,06 | -1,60 | -2,49 | VDC |
Q13 | 13,30 | -1,51 | -0,94 | VDC |
Q14 | 27,41 | 9,88 | 10,43 | VDC |
Let me know if you see anywhere I should be taking a closer look. And also feel free to hurl insults at me for being stupid and overlooking something - I know that I'm not very experienced at this, but I'm eager to learn.
Thanks in advance