Pioneer SX-636.....rushing sound on left channel

Hey Guys,

I bought this receiver new circa 1976. Had a tech look it over once. He said he replaced some bad caps in the power supply and tuner sections (turns out the shop wasn't too reputable, so who knows if he actually did).

In the post below, @MarktheFixer mentions the need to replace "two round cased shiny transistors (dreaded 2sc1451s)" and "any little sky blue capacitors".

http://www.audiokarma.org/forums/showpost.php?p=4688557&postcount=5

In the pictures of my receivers power supply board (see below), I don't see any round shiny transistors, but do see light blue nichicon caps. Does it look like any of the transistors or caps are new to you guys?

It is time I start giving my first receiver some TLC. So, will post updates and questions in this thread as I proceed.

The 2sc1451's will be on the amplifier board.

The power supply has been worked on. The ELNA's are original. The Nichicons are later. I'd replace all of them. Nichicon UPW Series.

At minimum replace the 2sa726's (Q1 & Q2 on the AWK-035-1/2 AF AMP (Tone Control ) Board, and the 2sc1451's (Q5&Q6) on the AWH-034 Main Amp board.

Watch your speaker connections. The 636 only has fuses for protection. No Protection board or relay.

The "SKY BLUE" caps Mark is referenceing are the 4.7uf and smaller "SANYO" caps on the amplifier, Toner Control. and equalizer boards. KLUDGE!!!


Larry

Thanks for the clarification Larry. I'll start putting together a cap and transistor order later this week.

I'm amazed how much less this SX-636 weighs compared to a Sansui 7000 I have...and the Sansui has a smaller footprint, but 2X the power output.

Most of that weight is in the Transformer. Sansui historically used larger iron than anyone else. Take my 800C and my 1000A and put them together. The outputs on the 1000A are larger than the power transformer on the 800-C. And they both run 7591's.

Larry

The power supply caps are 6800uF 35 V. Any suggestions on what these should be replaced with? Hopefully with some about the same size and same soldered connector type.

I got all the small caps in a saved cart at Mouser right now.

Have also found all the problematic transistors:

Two 2SC1451
Two 2SA725
Six 2SA726

Am not sure what to replace these with from Mouser. Any recommendations on these would also be greatly appreciated.

don't I have lists out there for recapping and retransistoring it?

parts list checked and updated for oos or obs...
edit - parts list FIXED awh-034 q1,q2,q3,q4 wrong polarity (said c1845, MEANT a992)!!!

eq amp
awf-014 c1 3.3 10 csza 3.3 50 647-UKL1H3R3MDDANA
awf-014 c2 3.3 10 csza 3.3 50 647-UKL1H3R3MDDANA
awf-014 c3 0.47 50 cea 0.47 100 667-ECQ-E1474KF
awf-014 c4 0.47 50 cea 0.47 100 667-ECQ-E1474KF
awf-014 c5 100 35 cea 100 35 647-UPW1V101MPD1TD
awf-014 c6 100 35 cea 100 35 647-UPW1V101MPD1TD
awf-014 c11 22 10 cea 22 50 647-UPW1H220MDD
awf-014 c12 22 10 cea 22 50 647-UPW1H220MDD
awf-014 c13 0.47 35 csza 0.47 100 667-ECQ-E1474KF
awf-014 c14 0.47 35 csza 0.47 100 667-ECQ-E1474KF
awf-014 q1 2sc1344 x x x x 512-KSC1845FTA
awf-014 q2 2sc1344 x x x x 512-KSC1845FTA
awf-014 q3 2sc1344 x x x x 512-KSC1845FTA
awf-014 q4 2sc1344 x x x x 512-KSC1845FTA

af amp
awk-035 c5 1 25 csza 1 50 647-UKL1H010KDDANA
awk-035 c6 1 25 csza 1 50 647-UKL1H010KDDANA
awk-035 c9 100 16 cea 100 35 647-UPW1V101MPD1TD
awk-035 c10 100 16 cea 100 35 647-UPW1V101MPD1TD
awk-035 c13 4.7 25 cea 4.7 50 647-UPW1H4R7MDD
awk-035 c14 4.7 25 cea 4.7 50 647-UPW1H4R7MDD
awk-035 c21 4.7 25 cea 4.7 50 647-UPW1H4R7MDD
awk-035 c22 4.7 25 cea 4.7 50 647-UPW1H4R7MDD
awk-035 c23 4.7 25 cea 4.7 50 647-UPW1H4R7MDD
awk-035 c24 4.7 25 cea 4.7 50 647-UPW1H4R7MDD
awk-035 c25 2.2 25 cssa 2.2 50 647-UKL1H2R2KDDANA
awk-035 c26 2.2 25 cssa 2.2 50 647-UKL1H2R2KDDANA
awk-035 c27 47 10 cea 47 35 647-UPW1V470MED1TD
awk-035 c28 47 10 cea 47 35 647-UPW1V470MED1TD
awk-035 c31 100 35 cea 100 35 647-UPW1V101MPD1TD
awk-035 q1 2sa726 x x x x 512-KSA992FBU
awk-035 q2 2sa726 x x x x 512-KSA992FBU
awk-035 q3 2sc1344 x x x x 512-KSC1845FTA
awk-035 q4 2sc1344 x x x x 512-KSC1845FTA
awk-035 q5 2sc1344 x x x x 512-KSC1845FTA
awk-035 q6 2sc1344 x x x x 512-KSC1845FTA

power amp
awh-034 c1 0.33 25 cssa 0.33 50 598-DSF050J334
awh-034 c2 0.33 25 cssa 0.33 50 598-DSF050J334
awh-034 c7 220 6 cea 220 10 647-UPW1A221MED
awh-034 c8 220 6 cea 220 10 647-UPW1A221MED
awh-034 c9 47 35 cea 47 35 647-UPW1V470MED1TD
awh-034 c10 47 35 cea 47 35 647-UPW1V470MED1TD
awh-034 q1 2sa726 x x x x 512-KSA992FBU
awh-034 q2 2sa726 x x x x 512-KSA992FBU
awh-034 q3 2sa726 x x x x 512-KSA992FBU
awh-034 q4 2sa726 x x x x 512-KSA992FBU
awh-034 q5 2sc1451 x x x x 512-KSC3503dstu
awh-034 q6 2sc1451 x x x x 512-KSC3503dstu

power supply
awr-060/61 c6 470 50 cea 470 50 647-UPW1H471MHD
awr-060/61 c7 220 50 cea 220 50 647-UPW1H221MPD
awr-060/61 c8 220 50 cea 220 50 647-UPW1H221MPD
awr-060/61 c9 100 50 cea 100 50 647-UPW1j101MPD
awr-060/61 c11 100 16 cea 100 35 647-UPW1V101MPD1TD
awr-060/61 c12 10 16 cea 10 50 647-UPW1H100MDD
awr-060/61 c13 10 35 cea 10 50 647-UPW1H100MDD
awr-060/61 c14 220 50 cea 220 50 647-UPW1H221MPD
awr-060/61 c16 100 16 cea 100 35 647-UPW1V101MPD1TD
awr-060/61 q1 2sd234 x x x x 512-KSC2073TU
awr-060/61 q2 2sc945 x x x x 512-KSC2383Yta
awr-060/61 q3 2sd313 x x x x 512-KSC2073TU
awr-060/61 d8 wz-140 x x x x 512-1N5244B


misc c3 6800 35
misc c4 6800 35
misc c8 100 6 cea 100 35 647-UPW1V101MPD1TD



tuner tuner
awe-046 c18 4.7 25
awe-046 c20 10 16
awe-046 c21 0.47 50
awe-046 c25 1 50
awe-046 c28 100 16
awe-046 c32 4.7 25
awe-046 c33 47 6
awe-046 c36 0.1 25
awe-046 c39 10 16
awe-046 c44 10 16
awe-046 c48 0.33 10
awe-046 c49 1 10
awe-046 c50 0.47 10
awe-046 c59 0.33 25
awe-046 c60 0.33 25
awe-046 c61 220 16


list :
647-UKL1H3R3MDDANA
647-UKL1H3R3MDDANA
667-ECQ-E1474KF
667-ECQ-E1474KF
647-UPW1V101MPD1TD
647-UPW1V101MPD1TD
647-UPW1H220MDD
647-UPW1H220MDD
667-ECQ-E1474KF
667-ECQ-E1474KF
512-KSC1845FTA
512-KSC1845FTA
512-KSC1845FTA
512-KSC1845FTA


647-UKL1H010KDDANA
647-UKL1H010KDDANA
647-UPW1V101MPD1TD
647-UPW1V101MPD1TD
647-UPW1H4R7MDD
647-UPW1H4R7MDD
647-UPW1H4R7MDD
647-UPW1H4R7MDD
647-UPW1H4R7MDD
647-UPW1H4R7MDD
647-UKL1H2R2KDDANA
647-UKL1H2R2KDDANA
647-UPW1V470MED1TD
647-UPW1V470MED1TD
647-UPW1V101MPD1TD
512-KSA992FBU
512-KSA992FBU
512-KSC1845FTA
512-KSC1845FTA
512-KSC1845FTA
512-KSC1845FTA


598-DSF050J334
598-DSF050J334
647-UPW1A221MED
647-UPW1A221MED
647-UPW1V470MED1TD
647-UPW1V470MED1TD
512-KSA992FBU
512-KSA992FBU
512-KSA992FBU
512-KSA992FBU
512-KSC3503dstu
512-KSC3503dstu


647-UPW1H471MHD
647-UPW1H221MPD
647-UPW1H221MPD
647-UPW1j101MPD
647-UPW1V101MPD1TD
647-UPW1H100MDD
647-UPW1H100MDD
647-UPW1H221MPD
647-UPW1V101MPD1TD
512-KSC2073TU
512-KSC2383Yta
512-KSC2073TU
512-1N5244B




647-UPW1V101MPD1TD

edit april 5, 2018 I fixed C12 in the power supply, 220uf was way too much for a voltage divider bridge in the voltage feedback regulator section. another 10uf 50v is appropriate.

6800uf 50V Nichicon. Straight leaded termnals. Stuff in original cans.
647-UVR1H682MRD

Unless Mark has a better choice. Increases the capacitance slightly and gives you some headroom in voltage.

To get the same size You'd have to go with something around 18,000uf and 100V and it would still be slightly smaller. that's why I stuff the cans' in mine. Keep the capacitance at a reasonable level and increase the voltage overhead a bit.


Larry

Thanks Mark and Larry!!

Caps and transistors on order from Mouser.

Transistor orientation??

I'm ready to replace the problematic 2sc1451 on the amp board. Want to make sure I install the new KSC3503dstu oriented correctly. Is there an identifying mark on the new transistor that tells me how to install it? Would rather be safe than sorry, so am asking. :scratch2:

That's a KSC3503, right?
The pinout is in the data sheet.
http://www.mouser.com/ds/2/149/KSC3503-90028.pdf

Those are ECB (Emitter, Collector, Base) arrangement.

The lettering is on the "front", so looking at it so you can see the lettering, the pins are ECB from left to right.

On your board, the base is the hole on the left (makes the short "T" shape).
The Emitter is the top hole (the ARROW one).
The collector is the bottom hole (the angled line).

If you google transistors and look at the wiki it talks about whats what.

Just bend the legs to get them to go into the holes and solder away.

Data sheet shows it as "ECB" which is from left to right with the numbers face up, pins down.

http://www.mouser.com/ds/2/149/KSC3503-90028.pdf

Hope this helps!

Edit: the mad scientist above beat me to it! :smshot:

from the picture, letters facing about 10:30

emitter (closest to the "C" found in the "C3503-D" transistor labeling) into hole at 2:00 with arrow
(center lead on transistor) collector into hole at 5:00 with NO arrow (bend it back)
base (closest to the "D" in the "C3503-D" transistor labeling) into hole at 9:00

and you will have to clean out the holes (or heat them) to get the leads to actually fit into the holes.

I also hope you got TWO, one for the OTHER channel

Thanks guys!! I replace transistors once in a blue moon and forget the convention every time.

Power supply and power amp boards are now recapped and the two 2sc1451 replaced with KSC3503s.

She sounded good at first. But after about 10-15 minutes of playing some noise started to creep in.

Time to replace the 2SA725s and 2SA726s now I guess. Still need to recap the EQ and AF amp boards too. That will have to wait until another day. Got to take Grandma out to dinner for Mother's day.

I had briefly considered asking about the other transistors...

note: 2as725 and 726's are BCE layout

and
the ksa992 replacements are ECB, opposite that.

Thanks for the heads-up Mark on the 2as725 and 726's are BCE layout.

I'd have probably messed that up otherwise.

Finished recapping and replacing problematic transistors on the Power Amp board. Also recapped the EQ amp board.

Been running her for 15 minutes. No noise this time.

Still need to recap replaced 725/726 transistors in the AF board and Tuner board. Also need to restuff the power supply caps.

Just contacted @dgwojo for a set of new lamps.

Power supply caps restuffed and reinstalled. Some caps and all problematic transistors replaced on AF amp board. Wow!! This board is hard to work on while still installed in the receiver. Some of the caps may just have to wait.

I'm still amazed what one small missing dab of solder will do to the sound......as in no sound at all out of the left channel after the aforementioned work completed. Glad I was test playing it as I went after working on each board. This helped me know the last work I did was the culprit. Found one solder pad I forgot to resolder and another that might not have flowed good.

Both channels playing again!!

Contacted @dgwojo for a new set of lamps. One fuse lamp is burned out and 2-3 others are dim.

I've got the Tuner board left to mess with. It has a bunch of 726 transistors on it and a bunch of little bitty caps too. :sigh:

When you get tired of that 636, let me know. Collecting the whole series and short a 535, 636, 838, 1010 (wish I had kept the one I had!!).