Bottlehead Forum
Bottlehead Kits => Eros Phono => Topic started by: arri on January 20, 2017, 06:23:47 PM
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Just finished a new Eros I'm building for a friend. Everything seemed like it was checking out (with some exceptions noted below) but when I replaced my old faithful Seduction with the Eros to feed a Crack amp from a Goldring G012 moving magnet cartridge the gain just wasn't there and what little sound there was had a kind of distortion. On the other hand, with no vinyl spinning, the noise floor was extremely low ;)
Voltages:
Terminal A B
Kreg 4.1 4.6
breg 136 140
OA 142 145
IA 223 223
bA 0 0
OB 137 140
Resistance Check (only listing where things were potentially out of bounds and all of the C socket):
TS Read Target
T2 85k 71k
T4 75k 60k
T9 47k 39k
T10 47k 39k
T12 75k 60k
T14 86k 71k
A4 620Ω *
A6 75k 60k
B4 620Ω *
B6 75k 60k
C1 47k 39k
C2 75k 60k
C3 falling *
C4 620Ω inf
C6 47k 39k
C7 75k 60k
C8 falling *
C9 0 0
The Kreg, breg, OA and OB all seem high but I can't figure out why. The power supply voltages all measured correctly. All of the LED's are lit although it takes a few seconds for the shunt regulator board to light up. Any electrolytics are facing the correct direction. I have gone back over everything and am not seeing anything glaring; frankly, I was pretty pleased with the quality of my assembly and soldering.
Any suggestions or requests for more info?
arri
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Looking over the C4S's again (for the n'th time) I think I located the problem. I installed the 2N2222A transistors on the A side instead of the B side of the board on both. Amazing because I deliberately told myself to (and did) build each board separately following the instructions each time so that I wouldn't replicate any mistakes. And yet I still apparently read it wrong both times!
Now to move the little bastards.
arri
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Yup. That was it, Kreg came down to 1.8v. OA up to 164, and OB down to 96v. And now they sound good too!
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Good job sorting it! This is one of those cases that explains why we suggest posting photos in these queries. More eyes on can usually spot misplaced parts pretty quickly.