petehall347
the brandy coffee man
lift one end off d5 see if relay clicks .
SX-950 In Protection ... maybe more issues SOLVED
- Thread starter Johnny_Law
- Start date
Nope.
However, connecting Q7 C to E directly does immediately cause the relay to click. (Per http://audiokarma.org/forums/index.php?threads/sx-950-protection-issue.776253/#post-10645656) But Q7 is (the second) new KSC2690AYS I've tried, and tests good.
However, connecting Q7 C to E directly does immediately cause the relay to click. (Per http://audiokarma.org/forums/index.php?threads/sx-950-protection-issue.776253/#post-10645656) But Q7 is (the second) new KSC2690AYS I've tried, and tests good.
petehall347
the brandy coffee man
q3 and q4 collector voltages ?
they need to match each other .
q5 base needs to be higher than emitter . i see they are both very low .
they need to match each other .
q5 base needs to be higher than emitter . i see they are both very low .
Last edited:
Double triple quadrouple checked the orientation - all good.
Re-measured Q3 and Q4 collector voltages. Maybe I was too many drinks in last night - but now they're both around 16V and change. About 0.3V apart.
And Q5's B is in fact lower than E. 1.2V compared to 2.7V which are both an order of magnitude off anyway ...
Re-measured Q3 and Q4 collector voltages. Maybe I was too many drinks in last night - but now they're both around 16V and change. About 0.3V apart.
And Q5's B is in fact lower than E. 1.2V compared to 2.7V which are both an order of magnitude off anyway ...
petehall347
the brandy coffee man
is d5 still lifted ?
No, I put it back in.
(Note that I also have added the recommended diode between pins 9 and 10, cathode on 10.)
(Note that I also have added the recommended diode between pins 9 and 10, cathode on 10.)
petehall347
the brandy coffee man
get q5 voltages again with d5 lifted
if it looks no better also lift d6 and d7 .
if it looks no better also lift d6 and d7 .
petehall347
the brandy coffee man
also see what voltages are at each end of r25
Q5 voltages don't change even with all 3 diodes lifted.
R25 is -5.3 from D8 and -3.9 into C5.
R18 measures 146K (in circuit).
R25 is -5.3 from D8 and -3.9 into C5.
R18 measures 146K (in circuit).
petehall347
the brandy coffee man
try a new q5 if you have one .
thinking about it relay should click if q5 is removed . or its base lifted
thinking about it relay should click if q5 is removed . or its base lifted
Put in my other KSC2690AYS in the Q5 spot, no click.
Lifted B, no click.
Note, D5, D6, and D7 are still lifted.
Lifted B, no click.
Note, D5, D6, and D7 are still lifted.
petehall347
the brandy coffee man
q5 is PNP 2SA733 .
KSC2690AYS is NPN ... so there is the problem .
best go through any transistors you changed to be sure they are correct subs .
KSC2690AYS is NPN ... so there is the problem .
best go through any transistors you changed to be sure they are correct subs .
Replaced with a KSA992 ... CLICK! I must have gotten my Q5s confused between the power supply and the protection boards.
... Still have the dim lights issue. And haven't even attempted to see if it actually makes sound through the speakers. Nor have I measured any new pin voltages. BUT IT CLICKS!
... Still have the dim lights issue. And haven't even attempted to see if it actually makes sound through the speakers. Nor have I measured any new pin voltages. BUT IT CLICKS!
petehall347
the brandy coffee man
did you put the other parts back ?
i knew q5 was reading a bit oddly . it doesn't make it easy from here when incorrect parts are installed .
i knew q5 was reading a bit oddly . it doesn't make it easy from here when incorrect parts are installed .
Yeah, other parts back in. (And 13V Zener still in the 14V spot.) Lesson learned on my part - slow down and pay attention when making parts lists. Very nice work on your part figuring that out from afar.
Reminds me of the proctologist who went to auto mechanic school ... after he finished his final test, an engine rebuild, his instructor couldn't believe it. "Nice work," the instructor said, "and even more impressive ... you did the whole thing through the tail pipe!"
I just verified that it does pass sound to the speakers - tuned into an FM station, came in clear and strong through my bench Minimus 7s. In addition to the dimming indicator lights, it has a slight hum through the speakers when no inputs are selected and volume at minimum. It's currently turned on, Aux input, vol min, awaiting a solid DC offset reading.
Edit: DC offset is -26mV in R, -31mV in L. Jumps to -50mV when AUX input is de-selected (leaving no inputs selected).
Reminds me of the proctologist who went to auto mechanic school ... after he finished his final test, an engine rebuild, his instructor couldn't believe it. "Nice work," the instructor said, "and even more impressive ... you did the whole thing through the tail pipe!"
I just verified that it does pass sound to the speakers - tuned into an FM station, came in clear and strong through my bench Minimus 7s. In addition to the dimming indicator lights, it has a slight hum through the speakers when no inputs are selected and volume at minimum. It's currently turned on, Aux input, vol min, awaiting a solid DC offset reading.
Edit: DC offset is -26mV in R, -31mV in L. Jumps to -50mV when AUX input is de-selected (leaving no inputs selected).
Last edited:
Well, for the bright / dim light issue, I found a thread directly on the subject, and the following was the solution as suggested by @kramden so I too will give it a shot.
For reference, here's my transistor BOM for the two circuit boards I have rebuilt (Power Supply AWR-101 and Protection Circuit AW-062):
For reference, here's my transistor BOM for the two circuit boards I have rebuilt (Power Supply AWR-101 and Protection Circuit AW-062):
Solved it - didn't have a 2N551 on hand, but I did have a spare KSC3503, so in it went. Lights now behave, and no more hum when no inputs are selected nor through headphones.
Probably time to take that KSC2383 out of the BOM at Q10 in the power supply.
So here's the final BOM so as not to confuse:
Probably time to take that KSC2383 out of the BOM at Q10 in the power supply.
So here's the final BOM so as not to confuse:
petehall347
the brandy coffee man
well done 
another thing to note . some have had troubles subbing q3 q4 on protect board . i seem to remember 2sc945 work properly . and are original numbers .KSC1845FTA might not work properly .
another thing to note . some have had troubles subbing q3 q4 on protect board . i seem to remember 2sc945 work properly . and are original numbers .KSC1845FTA might not work properly .
petehall347
the brandy coffee man
if i remember right they should be about 20v each .. may have been q5 pulling yours low