SA-8100 transistors... confused!

[guest111]

Thanks to you guys on ak, I finally restored my pioneer sa-8100 to working condition. However, there're a few issues; it's very hissy, and the dc offset drifts considerably and will not stay put no matter what I do. I'm asuming this is down to the known faulty transistors.

I've read all the threads I can find on this amp, and several mention various transistors and various different replacements. I'm new to this (I've never replaced a transistor), and all these 2sc numbers are confusing me!

Has anyone done a complete restoration of this amp, including transistor replacement? If so, exactly what do I need to buy, how many, and which way round do I put them in?

Sorry if this is an extremely stupid newbie question; this amp restoration is never ending, I just want the thing to be working so I never have to see the insides again!
Thanks for any and all help

 

[Marty Socal]

If you have the factory service manual, in the parts lists for the various boards, the transistors are listed by the manufacturers part number. Get together a list of them, compare them to the ones on your boards to verify the actual parts Pioneer installed. You might find that a magnifier will help inspecting the small numbering on them.

Once you have a list, take each part number, and search the Pioneer forum, more than likely you will find the modern replacement part number for it. Usually, the difference, if any, in the terminal layout is noted in the posts that pop up.

As a newb, I use a thinline marker to draw the flat side of the old transistor onto the board BEFORE I remove it. Then I verify the old transistor layout using my cheap Harbor Freight multimeter that tests transistors. Now you can verify the marking on the board as related to the old transistor. I then check the replacement using the meter to verify that the listed layout is correct, then install it per the verified board marking. When done, Isopropyl Alcohol removes the marking pen markings easily with a q-tip.

If you get a complete verified transistor list, we can add it into the recap list for the SA-8100!

Hope this helps!

 

[markthefixer]

when you have the raw list, post it so I can get the replacements figured out - save me a lot of typing.
(hopefully in the
aaa-nnn q1 2sa725
format)
I'll take a look for quick replacements

BECAUSE

sometimes the replacements are not straightforward replacements - it depends upon what it is being asked to do, the capabilities of the ORIGINAL, and the capabilities of the replacement, AND THEN I take into account the Pioneer tendency to run things too close to the edge, which is why now we have "problematic" transistors....

 

[guest111]

Thanks both for your responses; I'll get the list from the factory service manual when I have a spare moment and post them here.

 

[guest111]

Sorry it's taken so long - here's the list from the service manual! Hope this was what you wanted


aaa-nnn q1 2sa72


AWG-017-0 Q1 2SC1478 t or s
Q2 2SC1478
Q3 2SC1478
Q4 2SC1478
Q5 2SA726 g or f
Q6 2SA726
Q7 2SC1345 d or e
Q8 2SC1345


AWH-022-A Q1 2SA726 g or f
Q2 2SA726
Q3 2SA726
Q4 2SA726
Q5 2SC869 c or d
Q6 2SC869
Q7 2SA628A c or d
Q8 2SA628A
Q9 2SC1451 v or b
Q10 2SC1451
Q11 2SD357 c or d
Q12 2SD357
Q13 2SB527 c or d
Q14 2SB527
Q15 2SD370 r or o
Q16 2SD370
Q17 2SB530 r or o
Q18 2SB530


AWF-006-0 Q1 2SA774 t or s
Q2 2SA774
Q3 2SA774
Q4 2SA774
Q5 2SC1345 d or e
Q6 2SC1345
Q7 2SC1345
Q8 2SC1345


AWM-027-A Q1 2SC857K-A
Q2 2SC857K-A
Q3 2SC945 r or q
Q4 2SC945
Q5 2SA73
Q6 2SC945


AWK-020-0 Q1 2SC1345 e or d
Q2 2SC1345

AWR-030-0 Q1 2SD313 d or e
Q2 2SB507
Q3 2SC945 r or q
Q4 2SA733

AWS-036-0 Q1 2SC1345 g or f
Q2 2SC1345

 

[Marty Socal]

List was figured out by searching posts for the original number to Mouser part number interchange.

I have not vetted the list as to fit or actual compatability with this unit! Usually when changing to a larger transistor body (TO-92 to a TO-126, etc) it will require a slight opening of the holes through the board. Please verify that there is room above and near the smaller original transistors for a larger style to fit. You will also need to verify the lead arrangement, old vs. new, if you don't understand this, ASK! Also, please check the actual parts used on your unit before ordering, sometimes, Pioneer substituted, removed or added in extra parts with revisions. If you find something different, please note the board number and suffix on the board and post the differences! Usually, Pioneer changed the suffix number on a board when they revised them.

All are current numbers, in stock at this time at Mouser, total cost for all of them is $24.90 USD + shipping, good til June 26th, 2013! if you remove the prefix, they are the original part number, ie.: 512-KSC1845FTA Mouser part number is KSC1845FTA Fairchild part number, in case you are using a different parts supplier.

AWG-017-0
Q1, Q2, Q3, Q4 2SC1478 t or s
512-KSC1845FTA (ln)to-92 ecb 120v .05a .5w 100mhz 150-800hfe

Q5, Q6 2SA726 g or f
512-KSA992FBU (ln)to-92 ecb 120v .05a .5w 100mhz 150-800hfe

Q7, Q8 2SC1345 d or e
512-KSC1845FTA (ln)to-92 ecb 120v .05a .5w 100mhz 150-800hfe


AWH-022-A
Q1, Q2, Q3, Q4 2SA726 g or f
512-KSA992FBU (ln)to-92 ecb 120v .05a .5w 100mhz 150-800hfe

Q5, Q6 2SC869 c or d
512-KSC2383YTA to-92L ecb 160v 1a .9w 50mhz 160-320hfe

Q7, Q8 2SA628A c or d
512-KSA992FBU (ln)to-92 ecb 120v .05a .5w 100mhz 150-800hfe

Q9, Q10 2SC1451 v or b
512-KSC3503DSTU to-126 ecb 300v .1a 1.2/7w 150mhz 40-320hfe

Q11, Q12 2SD357 c or d
512-KSC2073TU to-220 bce 150v 1.5a 25w 4mhz 40-140hfe

Q13, Q14 2SB527 c or d
512-KSA1220AYS to-126 ecb 120/a160 1.2a 20w 155mhz 35-320hfe

Q15, Q16 2SD370 r or o
863-MJ21194G npn to-3 250v 16/30A 250W 8-75hfe 4mhz

Q17, Q18 2SB530 r or o
863-MJ21193G pnp to-3 250v 16/30A 250W 8-75hfe 4mhz


AWF-006-0
Q1, Q2, Q3, Q4 2SA774 t or s
512-KSA992FBU (ln)to-92 ecb 120v .05a .5w 100mhz 150-800hfe

Q5, Q6, Q7, Q8 2SC1345 d or e
512-KSC1845FTA (ln)to-92 ecb 120v .05a .5w 100mhz 150-800hfe


AWM-027-A
Q1, Q2 2SC857K-A
512-KSC1845FTA (ln)to-92 ecb 120v .05a .5w 100mhz 150-800hfe

Q3, Q4 2SC945 r or q
512-KSC2383YTA to-92L ecb 160v 1a .9w 50mhz 160-320hfe

Q5 2SA73 (ASSUMING this is a 2SA733)
512-KSA992FBU (ln)to-92 ecb 120v .05a .5w 100mhz 150-800hfe

Q6 2SC945
512-KSC2383YTA to-92L ecb 160v 1a .9w 50mhz 160-320hfe


AWK-020-0
Q1, Q2 2SC1345 e or d
512-KSC1845FTA (ln)to-92 ecb 120v .05a .5w 100mhz 150-800hfe

AWR-030-0
Q1 2SD313 d or e
512-KSC2073TU npn to-220 bce 150v 1.5a 25w 4mhz 40-140hfe

Q2 2SB507
512-KSA940TU pnp to-220 bce 150v 1.5a 25w 4mhz 40-140hfe

Q3 2SC945 r or q
512-KSC2383YTA to-92L ecb 160v 1a .9w 50mhz 160-320hfe

Q4 2SA733
512-KSA992FBU (ln)to-92 ecb 120v .05a .5w 100mhz 150-800hfe

AWS-036-0
Q1, Q2 2SC1345 g or f
512-KSC1845FTA (ln)to-92 ecb 120v .05a .5w 100mhz 150-800hfe

BOM:
512-KSC1845FTA 16
512-KSA992FBU 14
512-KSC2383YTA 6
512-KSC3503DSTU 2
512-KSC2073TU 3
512-KSA1220AYS 2
512-KSA940TU 1
863-MJ21194G 2
863-MJ21193G 2

Note: The number after the part number is = Qty. in the above BOM. You should be able to import it directly into Mouser's website for ordering or stock/price checks.

Hope this helps!

 

[guest111]

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!

 

[Marty Socal]

The service manual will give the original orientation of the original transistor, often with a picture/drawing of the transistor with the leads marked besides it. The boards are usually marked with the Transistor lead orientation symbol. The list of transistors above shows the orientation of the replacement part in the description. (ie. ECB)

Check out this thread posted by Echowars too, it's very helpful:
http://www.audiokarma.org/forums/showthread.php?t=43186

One more hint: Since I'm a relative noob that sometimes suffers from CRS (Cant Remember S&^t! ), I found it helpful to draw a line on the board below the flat side of the old transistor with a fine tip permanent marker. This helped me remember the original orientation. Some units have improperly marked boards or schematics that are incorrect in the manual, so it's good to check! I then would test the old and new transistor with my cheap Harbor Frieght multimeter, which has a transistor tester, to verify the leads (The meter will only give a HFE reading if the leads are inserted in the proper orientation) Once I was sure it was installed properly, I soldered them in. The markings are easily removed from the board when you are done by using a q-tip soaked in 91% isopropyl alcohol.

Harbor Freight meter, currently on sale for $19.95!:
http://www.harborfreight.com/ac-dc-digital-multimeter-37772.html
It also tests capacitors below 20 uf :thmbsp:

 

[guest111]

sorry if I'm being really thick here (the coffee's still kicking in), but I asume the 'bom' is the final order?

 

[guest111]

ah, I asumed right... answered my own question haha. I will get there, some day...

 

[markthefixer]

transistor orientation installation

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

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?:

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.

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

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....

and two transistor layouts, ebc and ecb with the same triangular target hole arrangement

well, you do need to get the parts, first....

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...

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

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