PTL-Pioneer
Super Member
I don't know to be honest but I gave them a reflow there to be sure. No change in voltage at pin 41
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SX-690 - No Output - Repair Thread - Help & Guidance Requested-Please
- Thread starter PTL-Pioneer
- Start date
petehall347
the brandy coffee man
q402 is what supplies the 45v that is missing .
2sc1384
2sc1384
PTL-Pioneer
Super Member
Ok I popped out 2sc1384 and replaced with ksc2690, just because I have a bunch. Will I take voltages of that?
E= -0.56v
C= 350mv
B= 122mv
That's DMM positive to test point and negative to chassis
E= -0.56v
C= 350mv
B= 122mv
That's DMM positive to test point and negative to chassis
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petehall347
the brandy coffee man
make sure of pinouts
petehall347
the brandy coffee man
if it still doesn't work check voltages each side of r401 ..
PTL-Pioneer
Super Member
One side is 44.5 v the other 0.826v : R401
petehall347
the brandy coffee man
power off check ohms r401 .. 33 ohms ..
PTL-Pioneer
Super Member
It was open circuit!! I had to wire 3x 100 ohm resistors together, now there is music. Thanks Pete! The volume rises and falls though and crackles like crazy. I'll get the stk voltages again now?
Pin41 is now at 38.69v
Pin41 is now at 38.69v
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petehall347
the brandy coffee man
are you running it off full mains voltage ?
it looked a little low at r401 .
it looked a little low at r401 .
PTL-Pioneer
Super Member
I have it on DBT only, will I check voltages again without the dbt?
Check pin 41 without dbt, and it was 50v
Check pin 41 without dbt, and it was 50v
petehall347
the brandy coffee man
music will maybe most likely play fine now on full mains ... on dbt the voltage will drop lots when turning up the volume .
petehall347
the brandy coffee man
to be sure everything ok in relation to the resistor going bad measure voltage right across it ..it should measure about 1.4v if all good .
PTL-Pioneer
Super Member
Thank you so much for all your help Pete, i will check that tomorrow as you have asked and i will post the results, including those at the stk's.
I have to leave the unit for the night now. I will order that replacement resistor too.
I have to leave the unit for the night now. I will order that replacement resistor too.
Awesomeaudio
Super Member
Just wondering how you went. So the issue was a faulty resistor then ?
Q402 was ok, but you decided to replace while you had it out ?
You think your STKs are still the originals?
I will be doing a re cap of my 690 soon.
I'll post up my measurements before and after as I proceed.
As I mentioned before, one of my STKs are toast and have purchased aftermarket units.
The unit plays fine but only on one Channel for now.
Q402 was ok, but you decided to replace while you had it out ?
You think your STKs are still the originals?
I will be doing a re cap of my 690 soon.
I'll post up my measurements before and after as I proceed.
As I mentioned before, one of my STKs are toast and have purchased aftermarket units.
The unit plays fine but only on one Channel for now.
Telegraph-H
New Member
Hi There, had one SX690 in my workshop today. Failure: No Sound on both channels. All Fuses OK, STK's did not have short outputs. 1. 24V was not feed into Power amp due to a burned Resistor. (easy to find with Schematics.) After recovering 24V big hum at outputs on all 2 Amps. Switched off. 2. Found defective 100Ohms Resistors (2 on each STK) green in colour. All 4 no Ohm readings. Had problems with green Resistors 1/2W in the past. After replacing 4x100Ohm and one 27?Ohm for 24 control Voltage all OK. Hope this helps. Cheers, Oliver