It makes sweet music but I need a little help

Karl5150 · 2042

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Offline Karl5150

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on: February 07, 2014, 08:29:30 PM
My S.E.X. is up and running with my Reduction and sounds sweet.
I have some resistance and voltage numbers that are way off of the manual, Rev 1.1.
In all cases both channels are virtually identical and I have a fresh battery in my digital meter.
Resistance: a6/b6, manual says 1.27 kOhms but I get 8.15 kOhms
Voltage: a6/b6, manual says 2.5 but I get 10.7
             a5/b5, manual says 75  I get 215.
a7/b7; a8/b8; c1/c2 & c4/c5 all the neg. read about 0.6 high(-3.75) and positives read about 0.6 low(2.55)
Every thing else checks out very, very close. I wouldn't have fired it up except like I said both channels are identical.
It worked in the down and dirty hook-up with 8ohm garage speakers (wired for 4s) and cables of dubious lineage so I moved it into the rack and promptly lost the right channel.
I took it out and ran all the checks again and got identical results. Turns out my AQ 0.6m got tired of being stretched between the Reduction's RCA outs. Cheap cables back on and it sings.
Thanks in advance for any help with these numbers.
Karl
« Last Edit: February 07, 2014, 08:31:56 PM by Karl5150 »

Karl
Downstairs: Planar3>PH-16>Stereomour II>OB Betsy+
Upstairs: RP1>Eros/CD5004>Seductor (2x Monoblocks)>FH3
Office: Modi Uber 2/Sirius>SEX2.1.1>µFonken FF85WK + DC160 subs
BR: FiiO M6>SEX3.0.1>ScanSpeak 10F + TangBand W6 (Mono)/DT770Pro
Garage: X12 streamer>Quicksand>Minimus 77


Offline mcandmar

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Reply #1 on: February 08, 2014, 06:22:36 AM
Resistance: a6/b6, manual says 1.27 kOhms but I get 8.15 kOhms
Voltage: a6/b6, manual says 2.5 but I get 10.7
             a5/b5, manual says 75  I get 215.

That makes me nervous.  There are two sets of resistors, 1.27k for the cathode (post 12 to A6, and post 22 to B6), and 8.2k in the power supply section, (post 6 to 11, and 16 to 21).  Double check you haven't got those resistors the wrong way around, i'm willing to bet you have.

Please dont run the amp until you do confirm the above as your putting way too much power through the driver section if they are the wrong way around.
« Last Edit: February 08, 2014, 10:38:24 AM by mcandmar »

M.McCandless


Offline Karl5150

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Reply #2 on: February 08, 2014, 07:20:23 AM
Thanks for the save MC, even with cheaters they look the same. Crappy laptop display doesn't help. I will try to source locally and swap.
Thanks again,
Karl

Karl
Downstairs: Planar3>PH-16>Stereomour II>OB Betsy+
Upstairs: RP1>Eros/CD5004>Seductor (2x Monoblocks)>FH3
Office: Modi Uber 2/Sirius>SEX2.1.1>µFonken FF85WK + DC160 subs
BR: FiiO M6>SEX3.0.1>ScanSpeak 10F + TangBand W6 (Mono)/DT770Pro
Garage: X12 streamer>Quicksand>Minimus 77


Offline mcandmar

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Reply #3 on: February 08, 2014, 10:43:17 AM
You should be able to move the 1.27k in ok, but i expect the 8.2k will be too short.  You could add an offcut to the 8.2k to make it fit but i would advise against it, should it break free the end will contact the chassis plate making it live, best to source a replacement pair for safety.  They are listed as 8.2k 1/4w metal film in the parts list however they see ~400-450 volts dc in normal operation so make sure whatever you source is rated for that voltage.  Its probably best if you source them direct from Bottlehead to be honest.

M.McCandless


Offline Karl5150

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Reply #4 on: February 08, 2014, 10:56:20 AM
Mc, I  went to an almost local electronics place. The wall o' resistors had just what the doctor ordered, US made, 2%. I swapped 'em out and all the #s are good. Thanks again for the catch.
It developed quite a full time hum and scratchiness when adjusting the volume, must have lifted a ground as it was dead quiet before, even with my resistor lysdexia.

Karl
Downstairs: Planar3>PH-16>Stereomour II>OB Betsy+
Upstairs: RP1>Eros/CD5004>Seductor (2x Monoblocks)>FH3
Office: Modi Uber 2/Sirius>SEX2.1.1>µFonken FF85WK + DC160 subs
BR: FiiO M6>SEX3.0.1>ScanSpeak 10F + TangBand W6 (Mono)/DT770Pro
Garage: X12 streamer>Quicksand>Minimus 77