Pioneer SX-990 receiver problems/questions

[Jimbob3416]

I found a note in a spreadsheet I made that I think I had gathered from another thread or forum on the SX-990 for that filter cap...
Here's what I had typed n there:
"2200/80 -> 4700/100 BCComponents/Vishay series 052, paralleled with 3 themself paralleled 1.0/100 MKP"

I don't think I replaced that filter cap or the two big output caps mounted just off the amp boardbecause I didn't have those in my list of parts installed. The only big caps were the (2( 1000uf/35V on the main amp board which I replaced with: 647-UKA1V102MHD1TO 1000uf/35V.

I basically replaced most of the components on the main amp board and then tested it and it worked great. It was a gift to a friend so I figured if it ever failed on him I could always go back in and replace those at a later date.

Here's what I had listed in my spreadsheet as installed:
The two different voltage numbers on there were the original value and then what I could find and ordered.
And as you can see I never ordered anything for the control amp board and only replaced the 100uf on that board that I had left over...

Main Amp Board (W15-060)
C1 3.3uF 647-UPW1H3R3MDD 10V 50V Electrolytic
C2 3.3uF 647-UPW1H3R3MDD 10V 50V Electrolytic
C3 100uF 647-UPW1H101MPD 50V Electrolytic
C4 100uF 647-UPW1H101MPD 50V Electrolytic
C5 3.3uF 647-UPW1H3R3MDD 25V 50V Electrolytic
C6 3.3uF 647-UPW1H3R3MDD 25V 50V Electrolytic
C7 100uF 647-UPW1H101MPD 50V Electrolytic
C8 100uF 647-UPW1H101MPD 50V Electrolytic
C9 100pF 140-50N5-101J-RC 50V Ceramic
C10 100pF 140-50N5-101J-RC 50V Ceramic
C11 100uF 647-UPW1H101MPD 3V 50V Electrolytic
C12 100uF 647-UPW1H101MPD 3V 50V Electrolytic
C13 1000uF 647-UKA1V102MHD1TO 35V Electrolytic
C14 1000uF 647-UKA1V102MHD1TO 35V Electrolytic
C15 47pF 140-50N5-470J-RC 50V Ceramic
C16 47pF 140-50N5-470J-RC 50V Ceramic
C17 0.02uF 667-ECQ-V1H223JL 50V Mylar
C18 0.02uF 667-ECQ-V1H223JL 50V Mylar
C19 100pF 140-50N5-101J-RC 50V Ceramic
C20 100pF 140-50N5-101J-RC 50V Ceramic

R31 0.5Ω 588-WHCR50FET 2W Wirewound
R32 0.5Ω 588-WHCR50FET 2W Wirewound
R33 0.5Ω 588-WHCR50FET 2W Wirewound
R34 0.5Ω 588-WHCR50FET 2W Wirewound

VR1 30KΩ 652-3386H-1-503LF 50k Trim Pot
VR2 30KΩ 652-3386H-1-503LF 50k Trim Pot
VR3 50Ω 652-3386H-1-500LF Trim Pot
VR4 50Ω 652-3386H-1-500LF Trim Pot

Q1 2SC732 512-KSC1845FTA NPN
Q2 2SC732 512-KSC1845FTA NPN
Q3 2SC497-O 512-KSC2383YTA NPN
Q4 2SC497-O 512-KSC2383YTA NPN
Q5 2SA497 512-KSA1013YBU PNP
Q6 2SA497 512-KSA1013YBU PNP
Q7 2SC497-O 512-KSC2383YTA NPN
Q8 2SC497-O 512-KSC2383YTA NPN
Q9 2SC793-Y 863-MJ21194G NPN Output
Q10 2SC793-Y 863-MJ21194G NPN Output
Q11 2SC793-Y 863-MJ21194G NPN Output
Q12 2SC793-Y 863-MJ21194G NPN Output

Control Amp Board (W15-079)
C1 .47uF 25V 50V Electrolytic
C2 .47uF 25V 50V Electrolytic
C3 10pF 50V Ceramic
C4 10pF 50V Ceramic
C5 .22uF 25V 50V Electrolytic
C6 .22uF 25V 50V Electrolytic
C7 100uF 35V 50V Electrolytic
C8 100uF 35V 50V Electrolytic
C9 1uF 16V 50V Electrolytic
C10 1uF 16V 50V Electrolytic
C11 .0047uF 50V Mylar
C12 .0047uF 50V Mylar
C13 .0047uF 50V Mylar
C14 .0047uF 50V Mylar
C15 33uF 6.3V 25V Electrolytic
C16 33uF 6.3V 25V Electrolytic
C17 50uF 47uF 25V Electrolytic
C18 50uF 47uF 25V Electrolytic

Indicator Lamps 8V 0.25A 560-46
Dial Fuse Lamps 8V 0.3A GF680

Thermal grease (pack of 5) NTE303
TO-3 Mica washers 534-4667

Here's some other notes I had accumulated from someone else either on here or elsewhere:

Power Amp parts:
2SC793 TO-3 npn 100v 7a 60w 30-200hfe 9mhz
863-MJ21194G npn to-3 250v 16/30A 250W 8-75hfe 4mhz $4.23
2sa497 100v 0.8a 0.6w 40-240hfe 50mhz
512-KSA1013YBU to-92L ecb 160v 1a .9w 50mhz 160-320hfe $0.17
2sc497 100v 0.8a 0.6w 40-240hfe 50mhz
512-KSC2383YBU to-92L ecb 160v 1a .9w 50mhz 160-320hfe $0.17
2sc732 60v 0.15a 0.4w 150mhz 200hfe
512-KSC1845FTA (ln)to-92 ecb 120v .05a .5w 100mhz 150-800hfe $0.05 ea

W18-026 (muting unit)
designation, old µF/V -> new µF/V, type
C1, 4.7/16 -> 4.7/50, UKL
C2, 2.2/35 -> 2.2/50, UKL

W15-049 (head amp unit)
C1, C2, 10/10 -> 10/50, UKL, each paralleled with 0.47/63 MKS-2
C15, C16, 10/25 -> 10/50, UKL, each paralleled with 0.47/63 MKS-2
C17, 50/25 -> 47/63, UKL

W15-079 (control amp unit)
C1,C2, 0.47/25 -> 0.47/63 MKS-2
C5,C6, 0.22/25 -> 0.22/100 MKS-4
C9, C10, 1.0/16 -> 1.0/63 MKS-2
C15, C16, 33/6.3 -> 33/50 UKL
C17, C18, 50/25 -> 47/35 UKL, each paralleled with 1.0/63 MKS-2

W15-080 (control unit)
C1, C2, 3.3/50 -> 3.3/50 UKL, each paralleled with 0.1/63 MKS-4
C5, C6, 0.01/? -> 0.01/63 ECQ

W15-081 (push switch unit)
C3, C4, 0.01/? -> 0.01/63 ECQ

W15-082 (push switch unit)
C1, C2, 0.039/? -> 0.01/63 ECQ (0.039 was too strong IMO)

W16-022 (power supply unit)
C8, 220/35 -> 220/50 UPW
(here more could have been done...)

W15-060 (power amp unit)
C1, C2, 3.3/10 -> 2.2/50 UKL, each paralleled with 1.0/63 MKS-2
C4, C5, 3.3/25 -> 2.2/50 UKL, each paralleled with 1.0/63 MKS-2
C11, C12, 100/6.3 -> 100/25 UKL
C13, C14, 1000/35 -> 3300/63 BCComponents/Vishay series 056,
each paralleled with themself paralleled 1.0/63 CD DME and 1.5/50 MKS-4

main filter cap:
2200/80 -> 4700/100 BCComponents/Vishay series 052, paralleled with 3 themself paralleled 1.0/100 MKP

STV3H
Forward Reference Diode - VF 1.60V-1.80V at 7.0mA,Tstg -60 to 100C.
Sanken Electric
Diodes
I(FSM) Max.(A) Pk.Fwd.Sur.Cur.=10
V(FM) Max.(V) Forward Voltage=1.8
@I(FM) (A) (Test Condition)=7.0m
I(RM) Max.(A) Reverse Current=10u
@V(R) (V)(Test Condition)=50
Semiconductor Material=Silicon
Status=Discontinued
Package=TO-92

I believe those were from someone elses BOM.
So maybe all that will help you out with more detailed reference info and substitutions. Those additional paralleled MKP and MKS film caps I'm thinking were suggestions from Markthefixer.
As you may know there is some "mod tweakin" going on with using small value film caps in parallel with the big ecaps that block and shunt high frequency oscillations components. That might be something you can look into
Again I didn't get into any of that serious tweak mods as it ended up being a gift fix and I was only trying to repair it cheaply.....so YMMV.
I'm sure there could be other performance tweaks or mods out there too....

Sir, Is this the most recent BOM for the SX-990? If not, where could I find one? Thanks.

 

[tribaker]

Just broke into my 990. Had amp fuses blowing 2-3 seconds after turning on...could still get sound out of RCA jacks in back. Have 4 0.5 wire resistors and 4 output transistors in a mail! will update!

 

[PioneerPro]

Can someone give me the all the transistors of the Power Amp Board and where they go and which way they point without overcomplicating it with a ton of information that I can not understand or use?

Please do not send the info like the following. The following info just confuses the hell out of me. Please keep it simple. There are only 8 transistors in my Pioneer SX 990 Power Amp board not including the large output transistors. Once again the location and which way the center lead points and the transistor KSC numbers only

Thank You Very Much, Ray


2SC793
+ - 1A 1B 2A 2B
B - E .325 .521 .395 .512
E - B OL OL OL OL
B - C .457 .526 .393 .488
C - B OL OL OL OL
E - C OL OL Short OL
C - E OL OL Short OL

Markthefixer listed the other transistors:
512-KSA1013YBU (2SA497)
512-KSC2383YBU (2SC497)
512-KSC1845FTA (2SC732)
Amp Board
Q1 2SC732 512-KSC1845FTA
Q2 2SC732 512-KSC1845FTA
Q3 2SC497-O 512-KSC2383YTA
Q4 2SC497-O 512-KSC2383YTA
Q5 2SA497 512-KSA1013YBU
Q6 2SA497 512-KSA1013YBU
Q7 2SC497-O 512-KSC2383YTA
Q8 2SC497-O 512-KSC2383YTA
Q9 2SC793-Y 863-MJ21194G
Q10 2SC793-Y 863-MJ21194G
Q11 2SC793-Y 863-MJ21194G
Q12 2SC793-Y 863-MJ21194G

R31 0.5 588-WHCR50FET 2W Wirewound
R32 0.5 588-WHCR50FET 2W Wirewound
R33 0.5 588-WHCR50FET 2W Wirewound
R34 0.5 588-WHCR50FET 2W Wirewound
C1 3.3uF 10V 35V? Electrolytic
C2 3.3uF 10V 35V? Electrolytic
C3 100uF 50V Electrolytic
C4 100uF 50V Electrolytic
C5 3.3uF 25V 35V? Electrolytic
C6 3.3uF 25V 35V? Electrolytic
C7 100uF 50V Electrolytic
C8 100uF 50V Electrolytic
C9 100pF 50V Ceramic
C10 100pF 50V Ceramic
C11 100uF 3V 6.3V? Electrolytic
C12 100uF 3V 6.3V? Electrolytic
C13 1000uF 35V Electrolytic
C14 1000uF 35V Electrolytic
C15 47pF 50V Ceramic
C16 47pF 50V Ceramic
C17 0.002uF 50V Mylar
C18 0.002uF 50V Mylar
C19 100pF 50V Ceramic
C20 100pF 50V Ceramic
Main Amp Board (W15-060)

C1 3.3uF 647-UPW1H3R3MDD 10V 50V Electrolytic
C2 3.3uF 647-UPW1H3R3MDD 10V 50V Electrolytic
C3 100uF 647-UPW1H101MPD 50V Electrolytic
C4 100uF 647-UPW1H101MPD 50V Electrolytic
C5 3.3uF 647-UPW1H3R3MDD 25V 50V Electrolytic
C6 3.3uF 647-UPW1H3R3MDD 25V 50V Electrolytic
C7 100uF 647-UPW1H101MPD 50V Electrolytic
C8 100uF 647-UPW1H101MPD 50V Electrolytic
C9 100pF 140-50N5-101J-RC 50V Ceramic
C10 100pF 140-50N5-101J-RC 50V Ceramic
C11 100uF 647-UPW1H101MPD 3V 50V Electrolytic
C12 100uF 647-UPW1H101MPD 3V 50V Electrolytic
C13 1000uF 647-UKA1V102MHD1TO 35V Electrolytic
C14 1000uF 647-UKA1V102MHD1TO 35V Electrolytic
C15 47pF 140-50N5-470J-RC 50V Ceramic
C16 47pF 140-50N5-470J-RC 50V Ceramic
C17 0.02uF 667-ECQ-V1H223JL 50V Mylar
C18 0.02uF 667-ECQ-V1H223JL 50V Mylar
C19 100pF 140-50N5-101J-RC 50V Ceramic
C20 100pF 140-50N5-101J-RC 50V Ceramic

R31 0.5Ω 588-WHCR50FET 2W Wirewound
R32 0.5Ω 588-WHCR50FET 2W Wirewound
R33 0.5Ω 588-WHCR50FET 2W Wirewound
R34 0.5Ω 588-WHCR50FET 2W Wirewound

VR1 30KΩ 652-3386H-1-503LF 50K Trim Pot
VR2 30KΩ 652-3386H-1-503LF 50K Trim Pot
VR3 50Ω 652-3386H-1-500LF Trim Pot
VR4 50Ω 652-3386H-1-500LF Trim Pot

Q1 2SC732 512-KSC1845FTA NPN
Q2 2SC732 512-KSC1845FTA NPN
Q3 2SC497-O 512-KSC2383YTA NPN
Q4 2SC497-O 512-KSC2383YTA NPN
Q5 2SA497 512-KSA1013YBU PNP
Q6 2SA497 512-KSA1013YBU PNP
Q7 2SC497-O 512-KSC2383YTA NPN
Q8 2SC497-O 512-KSC2383YTA NPN
Q9 2SC793-Y 863-MJ21194G NPN
Q10 2SC793-Y 863-MJ21194G NPN
Q11 2SC793-Y 863-MJ21194G NPN
Q12 2SC793-Y 863-MJ21194G NPN

Some miscellaneous parts:

Indicator Lamps 8V 0.25A 560-46 (6.3V 0.25A)
Dial Fuse Lamps 8V 0.3A GF680 (8V 0.30A)
TO-3 Mica washers 534-4667
Thermal grease (pack of 5) NTE303

 

[PioneerPro]

Come on People, someone has to know the correct schematic here. This info is from a Youtube video on the restoration of the SX 990 and from this Post. There is confliction info here. Which one is correct???

 

[kwayde]

 

[kwayde]

Come on People, someone has to know the correct schematic here. This info is from a Youtube video on the restoration of the SX 990 and from this Post. There is confliction info here. Which one is correct???

The third pic is wrong. The last pic looks right but I'd use ksc1845 (also ECB) for Q1 & Q2.


In the pic I posted above, this is a pic of the trace side, not the component side. The transistor legs are as follows:



Using this you should be able to figure out how to place the new transistors since they are all ECB.

 

[PioneerPro]

Thank You kwayde, that's the same crappy schematic that I have been seeing on Hifi Engine. I can barely read it.

I honestly need someone to draw a schematic like I did so I can read it. Some people say KSC1815 others say KSC1845.

 

[Bruno Primas]

Just broke into my 990. Had amp fuses blowing 2-3 seconds after turning on...could still get sound out of RCA jacks in back. Have 4 0.5 wire resistors and 4 output transistors in a mail! will update!

There is more than a chance that one of your 50 ohm bias trimmers has gone bad. With the power off, measure in ohms across the two outside leads. Anything more than 50 ohms means that it's defective. (VR3 and VR4)

 

[kwayde]

Thank You kwayde, that's the same crappy schematic that I have been seeing on Hifi Engine. I can barely read it.

I honestly need someone to draw a schematic like I did so I can read it. Some people say KSC1815 others say KSC1845.

That's a fine schematic, very readable.

Does this help?

 

[PioneerPro]

Still hard to read but better. I zoom out, put my readers on and use a magnifying glass to read the Q numbers and that works. So my Picture #1 is the correct schematic reference however I may have the left and right wrong, they are still in the correct orientation for which transistor goes with each apposing set.

Thanks Again

 

[kwayde]

Remember, that image is the bottom of the board with the traces. The top will be reversed so your first pic is backwards.
Give me a minute....

 

[kwayde]

Here's your pic corrected. This view is from the top of the board as you look at the parts. I placed the emitters, collectors, and bases as they're pictured on the board scheme.



There are stencil marks under the xstrs showing pin placement. Compare them to mine and let me know if any are wrong.

 

[PioneerPro]

Good Lord, thats what I needed. Thank You So So much.

 

[kwayde]

Good Lord, thats what I needed. Thank You So So much.

It's damn easy to put them in wrong. I replaced 8 transistors in an SX-636 today and found I placed the first one wrong, but I double checked before I soldered.

So triple check everything. Pin placement, correct transistor, etc. Clean flux off between contacts when finished soldering. And I always check continuity between all contacts near every solder joint I make, even to the surrounding contacts to be sure there are no shorts.

 

[kwayde]

And after I finish working on boards I always fire it up using a dim bulb tester. If you don't have one you should make one.

Here's a link to DBT's. The first post is very informative and towards the end of the post there are links to building one.

dlucy's guide to Dim bulb testers, Variacs and autotransformers

 

[gadget73]

It's damn easy to put them in wrong.

Would you like to take a guess why I didn't change any transistors in mine that weren't bad?

 

[kwayde]

Would you like to take a guess why I didn't change any transistors in mine that weren't bad?

Was wondering why he wants them changed....

 

[PioneerPro]

Well, I am starting to learn my lesson. Every time I touch the transistors it turns into a ****ing mess and a lot of research. Up until a few months ago I had no idea the you can change two pins in a transistor around to go from EBC to ECB. Ironically I could not find a Youtube video on this either. The only reason I have changed transistor in the past is because something was still not working after I changed all the Capacitors or because the Transistors were famous for failing. This board was working fine after I changed the caps and I should of stopped right there. Live and Learn.

 

[PioneerPro]

Here is the finished Power Amp Board #W15-060 verified by many people on Audiokarma and Youtube. If you see any problem please let me know asap because others will be using this in the future and its important to be 100% right. This is not from the trace side, this is from the component side. Please notice the orientation of the screws holding the output transistor in.

Thank You, Ray

 

[kwayde]

Here is the finished Power Amp Board #W15-060 verified by many people on Audiokarma and Youtube. If you see any problem please let me know asap because others will be using this in the future and its important to be 100% right. This is not from the trace side, this is from the component side. Please notice the orientation of the screws holding the output transistor in.

Thank You, Ray

That pic looks right, but before you publish it replace the transistors on your board and compare it to the stenciled diagram on the circuit board that are under the transistors. Or if you can see the stenciling without removing the transistors, compare all transistors to the diagram.

Want to be sure the diagram matches what's printed on the board and how the transistors are mounted since I don't have a SX-990 to see if the transistors are placed as shown in the service manual diagram and the way I drew it up.

Changes are made all the time without the revisions being addressed in the service manuals.