bad transistor? [solved]

Karl5150 · 2204

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Offline Karl5150

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on: March 17, 2014, 06:16:28 PM
After enjoying about four hours of uninterrupted music Sunday I figured all was well with the c4s equipped SEX.
I fired it up after work today and after about 10 min warm up all h*ll broke loose, thought it was going to blow out my little fostex OBs
On the bench I noticed that while all 4 LEDs light at first the D2 on the B side goes out after about 40 seconds. I reflowed the LED and transistor solder joints but the same thing happens.
There are no bridges but powered off I get a 500 ohm reading between the b and c legs on that transistor. The A side transistor gives no such reading.
« Last Edit: March 26, 2014, 06:36:41 PM by Caucasian Blackplate »

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 Paul Birkeland

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Reply #1 on: March 18, 2014, 09:17:56 AM
Voltages?

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline Karl5150

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Reply #2 on: March 18, 2014, 01:04:12 PM
10 & 20 - 424V
0A - 74 V when lit, constant.
0B - 400+ before the LEDs light, drops to 220s when the LEDs light then creeps up and stops at 311 when the D2 LED goes out.
Yesterday I went through the original resistance and voltage checks and everything was good through A5.
B5 showed 311 and that's when I noticed the LED was out.
A6 - 2.35
B6 - 10.4
All the + & -3.15 were as they were on the orig. build: the +s reading 2.5 and the negatives reading -3.8

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 Paul Birkeland

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Reply #3 on: March 18, 2014, 01:45:02 PM
I'd replace both transistors on that side.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline Karl5150

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Reply #4 on: March 19, 2014, 01:29:42 AM
Thanks Paul,
Guess I'll be ordering a care package.

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 Karl5150

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Reply #5 on: March 26, 2014, 05:39:35 PM
Did as you suggested, 4 LEDs glow full time, voltages normal. 4 hours of run time and nothing but music.
Thanks

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