Pioneer SX-850 No relay click

yes, fresh eyes,

Q4: 512-KSA1013YBU
e: -23.3v
c: -13.7v
b: -14.3v

makes more sense as:
Q4: 512-KSA1013YBU
e: -13.7v *** because of the zener D12
c: -23.3v
b: -14.3v

but -23.3 is still low. use a new q4 if NOT installed correctly. lettering facing you, leads pointing down, q4 is ecb.

Q2: 512-KSA940
b: -23.3v
c: -67.5v
e: -22.8v

is doing what it's told (b -23.3v) so (e -22.8v)
 
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Do not reinstall, 6 way diode test them for gross faults first, any time there's more than 5 volts base to emitter the transistor is toast.
 
clean the pot,

re q4, q6: go buy a lottery ticket, you are riding on a wave of luck... :D

in other words, they are behaving, and thus hopefully didn't suffer damage.
 
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happy ending.

thanks for the perfect schematic of the 850 950 power supply. its in the file for my use at a later date.
 
I hope that by this point you have downloaded a service manual.

You are doing nicely, most likely Q5 has died, it is a common occurrence - the transistor is overworked for it's size. The replacement I have specified in other threads is a larger cased transistor that will shed the extra heat more effectively - at a price of maybe having to enlarge the holes the transistor leads fit into slightly to get them to fit.

The MOST IMPORTANT thing is to get the correct lead into the correct hole - there are six possible combinations of which only one is correct. The guys should find and link to my explanations of the transistor symbol printed on the board.

edit: this will help a little, read at least the first page of posts, there are useful diagrams:
http://www.audiokarma.org/forums/showthread.php?t=43186
this is a load of reading, especially with the links, but is does cover a lot:
http://www.audiokarma.org/forums/showthread.php?t=331932&highlight=symbol&page=5


Q5 is (the larger packaged):
AWR-101: Q5 2SC1318 ecb
512-KSC2690AYS to-126 ecb 120/a160 1.2a 20w 155mhz 35-320hfe $0.40

or it could be (the SMALLER packaged):
512-KSC2383YBU to-92L ecb 160v 1a .9w 50mhz 160-320hfe $0.17

both numbers are from mouser.com, and the extra data is to assist if you try to obtain the transistor or an equivalent locally. Preferably NOT NTE (long story).

You will notice they both are ECB layout. the guys should explain... that is with the lettering facing you, leads pointing down, going left to right. The original 2sc1318 is also ecb, but we can't trust that blindly. We use the symbol on the board to designate which lead goes into which hole.

Now, there is a small chance that Q5 won't get it going (don't worry about pin 11's 28v, that 28v depends upon 8.9,10's +36.5 volts being present. That 28v only runs the phono amplifier section). Then either R6 or C18 is at fault. The big parts list (costing under $15 iiac) does list C18, but not R6. But I can come back with a part number for R6, if needed.

(You could rebuild the board from that list, ensuring a higher level of reliability.)

Upon the chance that Q5 replacement does not restore the +36.5v (+/- 10 percent) then voltage reading from the three Q5 leads will be needed to locate less probable reasons for the failure.
I have a defective SX-850 (no sound/no relay click). I've separately tested the relay and it is working fine (coil energizes and contacts make with low contact resistance). My power supply pcb is a -101 variety rather than the -102 I see in the manual schematic I've downloaded. R5 is 56k, not 150 Ohms. R6 is a 150 Ohm resistor though..is that the resistor referred to as R5 in the thread above? I tested the pin voltages and all are per the manual for the -102 pcb other than pin 11 which is 19 Volts and not 28 Volts as stated on the -102 schematic. Do you think the problem still resided with Q5 (or Q7)?
 
Eamon - It is probably best to start a new thread for your particular problem. While it is good to search through the archives for information about similar problems, adding to this thread could likely only become more confusing when diagnosing the specific issues in your unit.
 
Eamon - It is probably best to start a new thread for your particular problem. While it is good to search through the archives for information about similar problems, adding to this thread could likely only become more confusing when diagnosing the specific issues in your unit.
Sorry for the long delay in responding. Thanks for the tip!
 
A bit off topic but, my curiosity is piqued regarding this thread. What happened to all of the responses by JohnDoe99? They're all deleted. Thanks.
 
This thread just saved my day. Friend dropped off his SX850 for repair as it had the same issue and matched the voltages by the OP exactly. Went right for Q5 and I had voltage on the Base and Collector nothing going out to pins 8,9 and 10 that sends power to the Protection Relay. Followed the Gurus advice and ordered a couple beefier transistors to replace Q5 but since the ones it feeds are unchecked at this time I'll pop in nee ones ass well while the board is lifted.

Man I am impressed with this beastie. Can't wait to hear it rattle the rafters when it's done. He's plan info on running a set of Advents on it I believe. I'll be resting with my 901s. I'll have to find one of these of it makes my 901s sing.


Also replacing the 15000uf 50v filter caps and bleed resistors and replacing the indicator lights as a few are out with a few dial lamps. Nice kits from eBay available. Thanks to the Gurus on this thread. I was fearing a total power supply rebuild and may still in the future.


*Note is the tool Pioneer used to make these awesome wire wraps available? What is it called. I thought they were all soldered I couldn't believe when I see it's just rightly wrapped on the post. *

-Dan
 
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