SX-980 Project

zaskarx

Active Member
About a year ago I bought a somewhat haggard but complete and functional SX-980 at a yard sale. I've been busy with grad school so it has sat neglected until now!

I'm by no means an expert so advice and corrections are much appreciated, especially since this is the first Pioneer I have tackled. Being a hobbyist and not a pro, I find that slow, methodical, and well-researched work has led to good results in the past so that's what I plan to do.

My plan is to perform the following:

1. Thorough cleaning and de-ox (complete)
2. Replace broken bulb sockets and bulbs, repair broken acrylic lamp holder
3. Replace electrolytic and tantalum capacitors
4. Replace larger power supply board transistors due to heat issues
5. Upgrade/replace power supply board transistor heatsinks
6. Very carefully clean and re-grease output transistors
7. Replace any other suspect components as they are found
8. Repair and possibly re-stain damaged wooden case, polish faceplate

I am working up a capacitor/component list and will post it this week. As per Mark the Fixer's recommendations I am planning to use Nichicon UKL to replace the CEANL, CSSA, and CSZA caps and UPW for CEA.

I have a few questions before I begin:

1. Is it worth it to replace the caps on the tuner board? They seem to be in decent shape and the FM function works well. Just trying to do a cost/benefit analysis since it may need an alignment afterwards.

2. Are there any other "while it is apart" components I should replace? I am considering replacing the diodes and resistors that are in the discolored area on the power supply board but am not sure if it is strictly necessary. See attached picture for details.
 

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Wow, that's not an easy post. Essentially it is rebuild instructions for the whole unit.

this thread: http://www.audiokarma.org/forums/showthread.php?t=180603 will give you a head start.

edit when I say caps, I mean e-caps (cea, ceanl, cssa, csza)

the tuner, many caps can be changed IF the board is not physically moved to access the solder side, there are a few caps to avoid, to not affect the audio/stereo part of the alignment. Those caps will just total up to a few bucks, but alignments are 60 - 100 bucks (w/o shipping).
The funny thing is that while we don't want to disturb the alignment, there are some caps in the final audio sections that I am suspicious of, that MAY have something to do with the irreplaceable pa1002a chips dying. They might disturb the separation adjustment if changed.

phono amp is integrated circuits, so no transistors there to swap, just caps.
2sa726's in the flat amp, and caps
MAYBE ksc1845's in the tone amp and caps
power amps, just caps and trimpots
speaker switch assy, just caps
protection assy, caps and relay driver transistor q2, maybe q1 protect
power supply: r3, r8, r9, all electrolytic caps, transistors and zeners, and maybe the power rectifiers...

you come up with the Pioneer end of the list, and we (I?) will come up with the mouser replacement parts numbers...
 
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Component List

Thanks for jumping in to help Mark! I took the cap lists that bisonguy put together and updated it with the additional components you mentioned.

I have a good start on the Mouser part numbers but could use some help filling in the gaps.

As far as the tuner goes I don't mind paying for an alignment if replacing the suspect parts means increasing the longevity/reliability of the unit. There is a guy here in town who did a good (if not cheap) job aligning my Marantz 2240; I could always take it to him.
 
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with everything that's going on, I see the list, but I cannot vet it for a few days. bump this thread every day or two if it languishes.

pretty good!!
I HOPE you checked that list against the service manual's bill of materials, searching out any missing electrolytic caps, etc


from my notes:

652-3296P-1-104LF 100Kohms 3296P Multi Turn : 12 3/8" Sealed parallel to pcb
sx-980 offset adjust

-----------------------

652-3386H-1-101LF 100ohms 3386H Single Turn 3/8" ? 10% parallel to pcb, triangle of pins ccw min#1 triangle
Non Switching Amp 56mV setting
NSA sx-3800, sx-3900
NSA sx-D5000, sx-D7000
sx-1280 idle current adjust
sx-1980 idle current adjust
sx-838 idle current adjust
sx-737 idle current adjust uh oh, FACING UP from pcb , need a different letter!!
sx-980 idle current

-----protect------------------------
Q2 2sc1438
512-KSC2690AYS to-126 ecb 120/a160 1.2a 20w 155mhz 35-320hfe $0.40


------power supply------------

q1 2sd712 100v 4a 30w 55-300hfe 8mhz
512-KSC2073TU npn to-220 bce 150v 1.5a 25w 4mhz 40-140hfe $0.54
q4 2sb682 100v 4a 30w 55-300hfe 8mhz
512-KSA940TU_Q pnp to-220 bce 150v 1.5a 25w 4mhz 40-140hfe $0.54
neither side is going to come close to an amp of current, no less 4 amps


q2 2sc1735 100v 0.5a 0.8w 55-300hfe 130mhz
512-KSC2383YBU to-92L ecb 160v 1a .9w 50mhz 160-320hfe $0.17
q3 2sa850 100v 0.5a 0.8w 55-300hfe 130mhz
512-KSA1013YBU to-92L ecb 160v 1a .9w 50mhz 160-320hfe $0.17 (R=60-120, O=100/200, Y=160/320)


Q5 2sd712 512-KSC2073TU
q6 2sc945a eCb 50v .15a .25w 300mhz 40-700hfe
512-KSC2383YBU to-92L ecb 160v 1a .9w 50mhz 160-320hfe $0.17

d8 mz-140 512-1N5244B Fairchild 14 V, 0.5W Zener
d9 mz-130 512-1N5243B Fairchild 13 V, 0.5W Zener
d10 LZ230 512-1N4748A Fairchild 22 V, 1.0W Zener
d11 LZ230 512-1N4748A Fairchild 22 V, 1.0W Zener

awr-164
c19,c20 4.7uf 50v 647-UPW2A4R7MDD 4.7uf 100v $0.14
c17,c18 47uf 16v 647-UPW1V470MED 47uf 35v $0.16
c24,c25 47uf 25v 647-UPW1V470MED 47uf 35v $0.16
c11,c12,c15,c16 220uf 80v 647-UPM2A221MHD 220uf 100v $1.02 ea
c13 220uf 35v 647-UPW1V221MPD 220uf 35v $0.28
c23 2200uf 35v 647-UPW1H222MHD 2200uf 50v $1.49 ea

----------------------------------

But:
512-KSA940TU pnp to-220 bce 150v 1.5a 25w 4mhz 40-140hfe
512-KSC2073TU npn to-220 bce 150v 1.5a 25w 4mhz 40-140hfe
these tolerate power supply heat better:
863-MJE15033G pnp to-220 bce 250v 8a 50w 30mhz 70hfe
863-MJE15032G npn to-220 bce 250v 8a 50w 30mhz 70hfe
 
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Ok, we are getting really close, I did double check the Pioneer service guide and added in the caps missing from the original list I had downloaded from AK.

I attached the latest revision of the list updated with your recommendations. There are a few transistors that are now considered obsolete, here they are along with the updated parts:

Power supply AWR-156

Q2 & Q6 - 512-KSC2383YBU (obsolete & out of stock) ---> 512-KSC2383YTA
Q4 - 512-KSA940TU_Q (obsolete & out of stock) ---> 512-KSA940TU
 

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  • SX-980 Component List.zip
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Parts have arrived!

The remainder of the parts arrived today, I should have everything I need to start. I am going to start with the power supply board, I will take before and after pics for each board. Any last advice or caveats before I begin?

Mark- I know you are a busy guy but when you have a few minutes could you tell me which caps on the tuner board are safe and useful to replace?
 
It's my second complete restore, first Pioneer. I restored a Marantz 2240 and it turned out pretty good. I've done repairs on quite a few other electronics but am by no means an expert so any advice is appreciated!

I think the main things to keep in mind are transistor pinouts which I've printed from the Pioneer manual and making sure to use a DBT. Is there anything unusual about setting offset and idle current or should I just follow the instructions in the service manual?
 
You sound like you know what you are doing and I didn't want to imply or jump to conclusions. What a great hobby, I wish I started earlier!
 
Thanks for checking in, it is a great hobby! I have very fond memories as a kid of listening to records with my dad on his '70's hifi so this era of gear holds a special place for me.
 
It's my second complete restore, first Pioneer. I restored a Marantz 2240 and it turned out pretty good. I've done repairs on quite a few other electronics but am by no means an expert so any advice is appreciated!

I think the main things to keep in mind are transistor pinouts which I've printed from the Pioneer manual and making sure to use a DBT. Is there anything unusual about setting offset and idle current or should I just follow the instructions in the service manual?

DO NOT USE THE PIONEER MANUAL FOR THE REPLACEMENT TRANSISTOR PINOUTS!!!! BTW, the manuals have significant mistakes in transistor pinouts, while the silk screened symbolls on the board have been proved to be accurate.

The replacement transistors WILL NOT have the same pinouts, if they DO, it's an ACCIDENT that they are the same.

Use the silk screened symbols on the pc board to identify the lead holes, and download the data sheets from Mouser, OR if my data shows it.

like:

q1 2sd712 100v 4a 30w 55-300hfe 8mhz
512-KSC2073TU npn to-220 bce 150v 1.5a 25w 4mhz 40-140hfe $0.54
q4 2sb682 100v 4a 30w 55-300hfe 8mhz
512-KSA940TU_Q pnp to-220 bce 150v 1.5a 25w 4mhz 40-140hfe $0.54
neither side is going to come close to an amp of current, no less 4 amps


q2 2sc1735 100v 0.5a 0.8w 55-300hfe 130mhz
512-KSC2383YBU to-92L ecb 160v 1a .9w 50mhz 160-320hfe $0.17
q3 2sa850 100v 0.5a 0.8w 55-300hfe 130mhz
512-KSA1013YBU to-92L ecb 160v 1a .9w 50mhz 160-320hfe $0.17 (R=60-120, O=100/200, Y=160/320)


Q5 2sd712 512-KSC2073TU
q6 2sc945a eCb 50v .15a .25w 300mhz 40-700hfe
512-KSC2383YBU to-92L ecb 160v 1a .9w 50mhz 160-320hfe $0.17

************************************************************************

Thanks for your reply and amazing work! You mentioned orientation... how do I varify (once I've ordered them) that I'm orienting them properly?
Thanks once again, your help is much appreciated!

you have to READ the symbol on the board (before you pull the old transistor to be sure the symbol is correct) then look up the replacement transistor (mouser always has links to data sheets you can download) lead orientation, and adjust accordingly.

This should help...

I have now done the cleaning. So I guess next thing is to desolder and resolder the new parts. All the old smaller caps have the polarity marked on them but I don't seem to find the markings on the biggest ones. And now I need help with the orientation of the new transistors.

every Mouser transistor has a data sheet available for download.... download them and look them up. then install as per the symbol printed on the pc board at that location.
never ever use the original transistor to determine how the replacement will go in.

from an earlier post:



First you need to learn about what the three transistor leads are about, and identifying which is which and where it goes according to the symbol. Then you will see that my parts list include lead arrangements - which assume the transistor lettering (and flat) are facing you and the leads are facing down, then go left to right.

Q13 2sc938 150v 0.05a 0.6w
512-KSC2383YTA to-92L ecb 160v 1a .9w 50mhz 160-320hfe $0.17


attachment.php


The big TO-220's with the metal mounting plate are hard to reverse, but the smaller ones are, but my specified replacements are usually E C B as a rule of thumb BUT we ALWAYS CHECK...

But you really should start here and follow ALL the links...

http://www.audiokarma.org/forums/showthread.php?t=331932&page=5

here's a preview, DO YOU SEE these symbols on the boards you are working on?:


80px-BJT_PNP_symbol.svg.png


80px-BJT_NPN_symbol.svg.png


e is always the arrow on one angled line (direction can be out (npn) or in (pnp) towards the base)
b is always the flat line the other two lines come out if at an angle
c is always the angled line without the arrow

letters can be smudged or illegible, while the symbols are hard to mistake and pretty language independent
pioneer doesn't use letters, if there is a symbol. sometimes in a linear hole arrangement, there is only an 'e'.... with no room for a symbol.



attachment.php



-----------------------------------------------------

now a quick lesson on installing a small transistor in a traditional triangular hole arrangement with a symbol printed in the center of the triangle

1. find the LEFTmost lead on the package and identify it's designation (emitter? base? collector?)
2. look at the symbol on the board, find the corresponding hole
3. insert that lead into that hole
4. find the RIGHTmost lead on the package and identify it's designation (emitter? base? collector?)
5. look at the symbol on the board, find the corresponding hole
6. insert that lead into that hole
7. the center lead will now need to bent forward or back to go into the leftover hole.

DON'T THINK "WHERE IS THE FLAT FACING"
think
"outside leads" and THEIR holes...

this one's ecb....
attachment.php


and two transistor layouts, ebc and ecb with the same triangular target hole arrangement
attachment.php
well, you do need to get the parts, first.... :D

and when ordering the transistors, mouser has links to the transistor's data sheets, DOWNLOAD the data sheets!!! THEY are your BEST guide as to the correct lead connections for THAT particular transistor.

Do you understand the transistor symbol? enough to identify the emitter, base and collector from it? Because most boards (Pioneer) have the symbol printed on it, with holes around it, and it is orientated so there is an emitter hole, a base hole and a collector hole. And obviously, only the transistor's emitter goes into the emitter hole, the base into the base's hole and the collector into the collector's hole. IF you want it to work... :D

oh, and by the way, the symbol usually DOESN'T have the E, C and B letters ON on it... :stupid:
there are two flavors,
pnp: arrow pointing in, 2sa,2sb, ksa, ksb part number prefixes
npn: arrow pointing out, 2sc,2sd,ksc,ksd part number prefixes

attachment.php


hint: if "rotating" it in your mind is a puzzler, orient it in the hole this way(transistor hole arrangements are usually triangular):

choose the leftmost lead, use the data sheet to identify it... for example it is the emitter
put it in the emitter hole

choose the rightmost lead, use the data sheet to identify it... for example it is the base
find the base hole, rotate the transistor line of leads around the inserted leftmost lead to point at the base hole
put the rightmost (base) lead in the base hole.

the THIRD hole is now either in front of or behind the transistor, in this example the collector is "left over"
bend the center lead forward or back to go into the hole.

easy...

notice that this example had the lead order of emitter, collector, base which is a common lead arrangement

that means that:

looking at the transistor, with the leads pointing DOWN, and the flat part (or lettering in the case of some zetex transistors) FACING YOU
going from left to right has the lead order of emitter, collector, base


attachment.php
 
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Great info, thanks Mark. I finished the caps on the power supply last night, cleaning up all of the glue took more time than anything. Will start on the rest of the components today.

What are your thoughts on replacing the rectifiers? In a previous post you had said that they should maybe be replaced, I went ahead and ordered them since they were fairly cheap.
 
Great info, thanks Mark. I finished the caps on the power supply last night, cleaning up all of the glue took more time than anything. Will start on the rest of the components today.

What are your thoughts on replacing the rectifiers? In a previous post you had said that they should maybe be replaced, I went ahead and ordered them since they were fairly cheap.

D8, D9, D10, D11 ? They are zener diodes, Yes, but keep track of the old ones just in case the replacement's voltage is too different.

If you got power rectifiers (d1-d4, d6, d7, d12-d15) we need to talk a bit first.
 
I have the zener diodes and plan on replacing those (part number listed below), I have the rectifiers too. Since everything is working I only want to replace components that I have to in order to increase reliability of the unit; I'll defer to your judgement on the rectifiers.

D8 - 512-1N5244B
D9 - 512-1N5243B
D10 - 512-1N4748A
D11 - 512-1N4748A

Also, I got a little overzealous with the Dremel and chopped up the plastic sleeve on one of the new caps while I was cleaning up glue around the heatsinks, will have to order a replacement as I don't have a spare on hand :sigh: If you think of anything else I should replace I can add it to the next order.
 
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do d8 - d11.

rectifiers fall in the possible overkill category.
what are the rectifier numbers you got? include target location and original part number, and replacement number.
 
D1 10E2 512-1N4004
D2 ""
D3 ""
D4 ""
D6 ""
D7 ""

D12 SR3AM-8 512-1N5404
D13 ""
D14 ""
D15 ""

I noticed that you mentioned a few years back that the SR3AM-8 diodes may be a bit undersized...
 
Power Supply Complete

Finally have the power supply board complete! Caps, rectifiers, transistors, various resistors, and zener diodes have been replaced! The toughest, most time consuming part was cleaning off the caked on glue around the larger caps and heatsinks.

I added mica insulators to the TO220 transistors and additional heatsinks; hopefully this will keep them cool for the next 30+ years.

The unit passes the dim bulb test so on to the next board.

sx980psu.jpg
 
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