Hello, yes those are the ones. The replacements that i found seem to be the same (they have the same characteristics), but the product numbers have a few extra characters (and slight price difference).
SA-6500 II restoration
- Thread starter Livin4
- Start date
Hello, yes those are the ones. The replacements that i found seem to be the same (they have the same characteristics), but the product numbers have a few extra characters (and slight price difference).
Thanks for your help - that is also what i thought. Did you also replace the transistors (the ones with Q)? While at it i wanted to replace all that i can, to be sure that the amp will have a long and joyfull life.
Also does it make sense to order an extra capacitor / transistor (for each type), for safety, or just the needed amount(i am pretty handy, but have never done this before)?
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Hopefully others with more experience are watching and will chime in if I give you bad advice.
Yours is a working amplifier. Right? With respect to transistors (Q's), there is a list on here that was put together by dlucy of naughty transistors. Ones that are known to fail or become troublesome in one way or another. It is universally accepted that if you have any of these in your amplifier you should get them out of there and substitute with suitable replacements. There are substitutes on the dlucy list -- or you can advanced-google-search with keyword (name of transistor), and put site or domain or whatever Audiokarma -- is another way to look.
If you get into this sport after a while you may learn to find and read the datasheet for the old transistor and see if data sheet for substitute matches up on key characteristics to your satisfaction. Mainly follow what others who know much more than we do have done / recommend.
https://audiokarma.org/forums/index...ilure-prone-whatever-and-replacements.731653/
Otherwise I say leave all other transistors in there. With any luck you or whoever has the machine next will be pushing up daisys before the amplifier has transistor woes.*
My 6500 was my first project and I was brand new to the game. It was not a working amplifier. I "shotgunned" the transistors. Replaced them all. This is considered 'bad form' as a repair method. Among other things it means higher risk of damage to PCB / solder pads. You want to avoid lifted, torn or otherwise damaged solder pads and traces.
Shotgunning worked in my case. And probably the transistors that went in were better than the originals. Did it make a difference? I doubt anyone could tell in a blind listening test.
My policy is to only replace transistors when broken; known lousy performers; or known hazard for poor performance or potential catastrophic failure.
No need to order extras, assuming decent tools and soldering skills. If you've never done this before practice beforehand on a junk PCB soldering and desoldering. Watch some videos. Read Conrad Hoffman's white paper on touble shooting without tears. He's a good egg. One thing you may not see is a recommendation to get some cheap acrylic headstrap magnifiers. Only recently got me some. They make a world of difference in doing inspection of original solder work throughout the machine (fairly important), and doing the new soldering work.
Later when you become hopelessly addicted and begin to think a reasonable amount of gear means one unit for every room in your house including bathrooms and closets, you can begin strategic ordering of extra parts.
*there are exception for example transistors in certain roles experience unusual wear and tear but even then some would say if it aint broke...
Stock Photo
Yours is a working amplifier. Right? With respect to transistors (Q's), there is a list on here that was put together by dlucy of naughty transistors. Ones that are known to fail or become troublesome in one way or another. It is universally accepted that if you have any of these in your amplifier you should get them out of there and substitute with suitable replacements. There are substitutes on the dlucy list -- or you can advanced-google-search with keyword (name of transistor), and put site or domain or whatever Audiokarma -- is another way to look.
If you get into this sport after a while you may learn to find and read the datasheet for the old transistor and see if data sheet for substitute matches up on key characteristics to your satisfaction. Mainly follow what others who know much more than we do have done / recommend.
https://audiokarma.org/forums/index...ilure-prone-whatever-and-replacements.731653/
Otherwise I say leave all other transistors in there. With any luck you or whoever has the machine next will be pushing up daisys before the amplifier has transistor woes.*
My 6500 was my first project and I was brand new to the game. It was not a working amplifier. I "shotgunned" the transistors. Replaced them all. This is considered 'bad form' as a repair method. Among other things it means higher risk of damage to PCB / solder pads. You want to avoid lifted, torn or otherwise damaged solder pads and traces.
Shotgunning worked in my case. And probably the transistors that went in were better than the originals. Did it make a difference? I doubt anyone could tell in a blind listening test.
My policy is to only replace transistors when broken; known lousy performers; or known hazard for poor performance or potential catastrophic failure.
No need to order extras, assuming decent tools and soldering skills. If you've never done this before practice beforehand on a junk PCB soldering and desoldering. Watch some videos. Read Conrad Hoffman's white paper on touble shooting without tears. He's a good egg. One thing you may not see is a recommendation to get some cheap acrylic headstrap magnifiers. Only recently got me some. They make a world of difference in doing inspection of original solder work throughout the machine (fairly important), and doing the new soldering work.
Later when you become hopelessly addicted and begin to think a reasonable amount of gear means one unit for every room in your house including bathrooms and closets, you can begin strategic ordering of extra parts.
*there are exception for example transistors in certain roles experience unusual wear and tear but even then some would say if it aint broke...
Stock Photo
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I'm not sure if you were asking if there were components other than certain electrolytic capacitors and transistors that you might want to consider replacing.
IF the 6500 has open frame variable resistors (potentiometers), for setting bias, it is common pratice to replace these with Bourns brand mutli-turn sealed ones. The old ones can become faulty which can lead to problems. Recently another fellow from Germany allerted me that Vishay also makes a nice multi-turn potentiometer. When you take the old ones out you can measure them and adjust the new ones before you put them in so they are close. Then fine tune once they are in there.
All this is probably more than you ever wanted to know.
You should probably also become familiar with and possibly check DC offset -- which is different that bias / idle.
https://audiokarma.org/forums/index.php?threads/offset-bias-idle-current.347566/
IF the 6500 has open frame variable resistors (potentiometers), for setting bias, it is common pratice to replace these with Bourns brand mutli-turn sealed ones. The old ones can become faulty which can lead to problems. Recently another fellow from Germany allerted me that Vishay also makes a nice multi-turn potentiometer. When you take the old ones out you can measure them and adjust the new ones before you put them in so they are close. Then fine tune once they are in there.
All this is probably more than you ever wanted to know.
You should probably also become familiar with and possibly check DC offset -- which is different that bias / idle.
https://audiokarma.org/forums/index.php?threads/offset-bias-idle-current.347566/
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Wow, thanks man, that is a lot of usefull information. Already checked the bad transistor list and found a couple that are on the list, so i guess i will try to change them too.
It will take some time until i digest all the information, but i should be about done and ready to start when the replacements arrive.
I was mostly reffering to capacitors transistors and such, but i will, this time at least, only change the caps and troublesome transistors, and see how it all goes. I will have to gather some more knowledge before starting more complex operations.
One last questin, that may seem stupid is, do you take the amp apart, and unmound the PCB from the frame, or only remove the cover and work on it while the PCB is still on the frame?
Thank you for all the help, and if you're ever in Frankfurt drop me a line i will buy you all the beer you can drink.
It will take some time until i digest all the information, but i should be about done and ready to start when the replacements arrive.
I was mostly reffering to capacitors transistors and such, but i will, this time at least, only change the caps and troublesome transistors, and see how it all goes. I will have to gather some more knowledge before starting more complex operations.
One last questin, that may seem stupid is, do you take the amp apart, and unmound the PCB from the frame, or only remove the cover and work on it while the PCB is still on the frame?
Thank you for all the help, and if you're ever in Frankfurt drop me a line i will buy you all the beer you can drink.
Glad to help. Giving back -- as AK people here have helped me -- possible help to others who may look on this in future, as well.
Good plan. Probably do not remove PCB if you can access everything well enough. If I remember correctly the Pio 6500II is pretty open accessible. Not sure.
Thanks for your kind offer. One of my daughters and her Russian husband (cellists), put on symphony masters classes in Germany and Italy. Their organization is InterHarmony. Maybe one day if I ever make it there that would be nice. Thanks.
https://en.wikipedia.org/wiki/InterHarmony_International_Music_Festival
Good plan. Probably do not remove PCB if you can access everything well enough. If I remember correctly the Pio 6500II is pretty open accessible. Not sure.
Thanks for your kind offer. One of my daughters and her Russian husband (cellists), put on symphony masters classes in Germany and Italy. Their organization is InterHarmony. Maybe one day if I ever make it there that would be nice. Thanks.
https://en.wikipedia.org/wiki/InterHarmony_International_Music_Festival
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Back again with an update. I just finished recaping, and at the last round (changed them in groups of 5 caps at a time) i soldere a capacitor (c69) the wrong way (i cannot understand how, because i always double checked them before soldering). I discovered my error because i tried the amp, and it did not make any sounds, so i started searching for the culprit. Now after changing it back, the right way, the amp has sound, but it is distorted, and just bad. I am really dissapointed in me because i thought i can do it, but it seems like i rushed tings.
Tried with both the new and the old capacitor, instaled the right way, and the results are the same, distorted sound.
Now the question ist what can i do to make thing right, and have it functional again? I double checked all caps again, and all are soldered correctly, and with the right polarity. Can a capacitor that is oppositely installed ruin other things on the board?
Tried with both the new and the old capacitor, instaled the right way, and the results are the same, distorted sound.
Now the question ist what can i do to make thing right, and have it functional again? I double checked all caps again, and all are soldered correctly, and with the right polarity. Can a capacitor that is oppositely installed ruin other things on the board?
Hey thanks for getting back on here with this status report. Was hoping to hear back. After last exchange I felt I fell short on focusing on what you are working on accomplishing and words of encouragement.
So here goes.You're doing fantastic! Keep up the good work. I finally got off my ass just now and pulled the file. While I'm looking it over here, can you please offer for the studio audience here what does the distortion sound like. Were you firing it up and doing sound checks all along every five components or so and everything's going swimmingly and then awe poop. One channel or both.
So here goes.You're doing fantastic! Keep up the good work. I finally got off my ass just now and pulled the file. While I'm looking it over here, can you please offer for the studio audience here what does the distortion sound like. Were you firing it up and doing sound checks all along every five components or so and everything's going swimmingly and then awe poop. One channel or both.
Thank you for the encouraging words. Actually i did not try the amp every steo, juat fired it up to see if smoke comes out (read on the web that badly installed caps blow with a bang and a lot of smoke), but it never did. Distortion is actually more like a lot of static and bass seems too strong, and volume is lower than before - and it is the same on both chanels as far as i can tell.
I visually compared the instaled components with a photo i made before beginning, and all the components seem ar the right place and orientation - maybe except the small blue ones, that have no polarity marking on the body of the original cap.
As i do not have any measuring devides, all the checks i can do are visual, and comparing the installed caps to the scheme in the service manual can be a pain, as it is a view from under.
Also double checked that all the solders are clean, and with no unwanted bridges and such... looks like i should start looking for a replacement until i get this one fixed....
One more question - the big caps (57 and 58) originally had 4 pins soldered to the board, but the new ones only have 2, so i only soldered those (2 holes each were left open, but they did not seem to be connected to anything)
Thank you again for your help.
I visually compared the instaled components with a photo i made before beginning, and all the components seem ar the right place and orientation - maybe except the small blue ones, that have no polarity marking on the body of the original cap.
As i do not have any measuring devides, all the checks i can do are visual, and comparing the installed caps to the scheme in the service manual can be a pain, as it is a view from under.
Also double checked that all the solders are clean, and with no unwanted bridges and such... looks like i should start looking for a replacement until i get this one fixed....
One more question - the big caps (57 and 58) originally had 4 pins soldered to the board, but the new ones only have 2, so i only soldered those (2 holes each were left open, but they did not seem to be connected to anything)
Thank you again for your help.
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OK well this is how we learn. Don't kill me or get discouraged. Here's some meanderings.
It was really good that you stopped every five or so parts and checked. With a sound check or something like it performed at each pause, you have much more chance of having an idea where things started to go wrong. I know you know this now. No. You are not permitted smoke or explosions. Hahaha.
To do this work you really need at minimum a DVM. The first thing to do might have done first or now is measure the "idle" (bias), for a preliminary read on the amplifier's health. Next perhaps you would go on to check voltages at key points in the power supply identified in the schematic. Just a first couple things a DVM would enable you do beforehand or now. I'm linking Conrad Hoffman's No Tears below.
If you don't have an original -or- high definition color pdf of the schematic, you're probably not going to see key voltages, because you are probably looking at a not-so-good black and white copy the voltages are in red ink. You mentioned frustrations withe PCB diagram. I just looked at the original. Wow. It's gorgeous. The traces are all in a beautiful green color. IIRC Messr. Hoffman uses a trick where he flips it on his computer when the diagram is the wrong way so you don't have to do it in your mind. Me I for some reason still relish torturing myself.
In any event, as far as where to go with diagnosis and repair, if you decide you want to do the work yourself, we probably need to bring in another AK member with a LOT more experience than me to help you figure it out and fix it. I'm sure you can do it if you want to.
Here's my SWAG:
There's 34V on the one leg of C69 when the amplifier is powered up in a normal state. Wild guess. Change in voltage and or current might have damaged the transistors that make up what is called the "long tailed pairs" Q7,9 and Q8,10 or possibly messed with Q11,12 which may be involved in idle (bias is same thing). These six all play key roles in neutralizing distortion.
http://conradhoffman.com/troubleshoottut.htm
-Matt aka Spenser
It was really good that you stopped every five or so parts and checked. With a sound check or something like it performed at each pause, you have much more chance of having an idea where things started to go wrong. I know you know this now. No. You are not permitted smoke or explosions. Hahaha.
To do this work you really need at minimum a DVM. The first thing to do might have done first or now is measure the "idle" (bias), for a preliminary read on the amplifier's health. Next perhaps you would go on to check voltages at key points in the power supply identified in the schematic. Just a first couple things a DVM would enable you do beforehand or now. I'm linking Conrad Hoffman's No Tears below.
If you don't have an original -or- high definition color pdf of the schematic, you're probably not going to see key voltages, because you are probably looking at a not-so-good black and white copy the voltages are in red ink. You mentioned frustrations withe PCB diagram. I just looked at the original. Wow. It's gorgeous. The traces are all in a beautiful green color. IIRC Messr. Hoffman uses a trick where he flips it on his computer when the diagram is the wrong way so you don't have to do it in your mind. Me I for some reason still relish torturing myself.
In any event, as far as where to go with diagnosis and repair, if you decide you want to do the work yourself, we probably need to bring in another AK member with a LOT more experience than me to help you figure it out and fix it. I'm sure you can do it if you want to.
Here's my SWAG:
Reversal in polarity of C69.
Crackling - hints of possible bad transistors.
Distortion now where before there seemed none.
Distortion now where before there seemed none.
When disaster strikes electrons take the path of least resistance.
There's 34V on the one leg of C69 when the amplifier is powered up in a normal state. Wild guess. Change in voltage and or current might have damaged the transistors that make up what is called the "long tailed pairs" Q7,9 and Q8,10 or possibly messed with Q11,12 which may be involved in idle (bias is same thing). These six all play key roles in neutralizing distortion.
Disclaimer: I have not been at this long and could be entirely full of you know what. This is only a SWAG.
http://conradhoffman.com/troubleshoottut.htm
-Matt aka Spenser
Considering that C69 was changed in the last round, sound checks would not have influenced the fact that i am an idiot and would nevertheless taken place. As i am going on a holiday soon, i will put the whole project on ice for a few weeks, and will start with purchasing a multimeter (and probably a new amp) and start measuring - only need to figure out how to do it without more damage caused. The next problem will be ordering parts, as i need to order for 50€ to get free shipping from Mouser - last order had a lot of stuff i may need sometime in the future.
I will probably start a new thread soon, to get more exposure to more knowledgeable users.
The schematics i used are actualy not that bad, i had them all printed out on A2 paper, and all is readable. This looked like a nice project to get started with the basics, but was also looking to upgrade my amp to a higher model. Considering what it is worth, it makes sense to try and repair it myself - especially as i like to take stuff apart, and try to fix them (not alway succesfull).
Thank you for your help, and the great tips you gave me.
I will probably start a new thread soon, to get more exposure to more knowledgeable users.
The schematics i used are actualy not that bad, i had them all printed out on A2 paper, and all is readable. This looked like a nice project to get started with the basics, but was also looking to upgrade my amp to a higher model. Considering what it is worth, it makes sense to try and repair it myself - especially as i like to take stuff apart, and try to fix them (not alway succesfull).
Thank you for your help, and the great tips you gave me.
Ha that's funny. The most important thing of all is know how to discharge capacitors; unplug the equipment when you're working on it; all the other important safe practices. This is dangerous work. Know and follow them. Sorry. I should have said that at the outset. It's ME who is the idiot.
Get an autoranging one. Multimeter. You don't need an expensive one. I got mine at Home Depot. Works great.
When the time comes look into the little Chinese TC-1 multi-function testers. Origins in a electrical engineering student's college project. I think. Great stuff. There are are others.
I wonder if Digikey's shipping policy extends to there. If you send them a written order including calculation for tax and a check including that they will not charge shipping. Don't quote me and that may only be for here in the U.S. It's supposed to be in their fine print somewhere. Sometimes one has things the other does not.
Glad to hear of your plans. You're most welcome. Thank YOU.
Get an autoranging one. Multimeter. You don't need an expensive one. I got mine at Home Depot. Works great.
When the time comes look into the little Chinese TC-1 multi-function testers. Origins in a electrical engineering student's college project. I think. Great stuff. There are are others.
I wonder if Digikey's shipping policy extends to there. If you send them a written order including calculation for tax and a check including that they will not charge shipping. Don't quote me and that may only be for here in the U.S. It's supposed to be in their fine print somewhere. Sometimes one has things the other does not.
Glad to hear of your plans. You're most welcome. Thank YOU.
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Sorry for asking question after question, but here is another, most probably stupid question: i have looked over all the schematics, and all the key voltages (in red) are visible, and am pretty sure i can locate them on the board. Now i know that to measure something, you need to connect your measuring device to (at least most of the time) 2 points - one of them is marked on the schematic, but where should i connect the other probe (of the multimeter)?
edit: just read that the black probe should be connected to the chassis - is that the correct way to read voltages? (i assume the amp should NOT be plugged in)
Also how does one measure the idle current, is it somewhere marked on the schematic? I habe combed the internet in search of information, but have not found anything relevant until now (i am in the process of reading "no Tears") - something with pictures would be more helpfull.
Would apreciate if you could guide me in the right direction - maybe a few links that i need to bookmark, or anything really.
I already looked for testing equipment and i found all i need locally and for more than decent prices - will see about the replacement parts when and if i identify the problem.
Thank you in advance.
edit: just read that the black probe should be connected to the chassis - is that the correct way to read voltages? (i assume the amp should NOT be plugged in)
Also how does one measure the idle current, is it somewhere marked on the schematic? I habe combed the internet in search of information, but have not found anything relevant until now (i am in the process of reading "no Tears") - something with pictures would be more helpfull.
Would apreciate if you could guide me in the right direction - maybe a few links that i need to bookmark, or anything really.
I already looked for testing equipment and i found all i need locally and for more than decent prices - will see about the replacement parts when and if i identify the problem.
Thank you in advance.
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No no. Good questions. Also raising other important points.
1. Yes. Connect to chassis as your 'reference ground.'
2. Amp will be plugged in and running when you are taking voltages. Read some basic electronics. DO NOT go sticking your hands on, in or around live voltages without good understanding of how electricity works. It CAN kill you. Learn and understand why there is a "one hand behind you back" technique.
3.. You need to get a set of Pomona Electronics mini-grabber test leads. Helps keep you avoid damaging the machine during testing because if you short between two points with your other (positive), probe when reaching in to get a reading bad things can happen.
I will be offline at work for a few hours.
https://www.digikey.com/product-detail/en/pomona-electronics/3782-24-02/501-1458-ND/736648?utm_adgroup=Test Leads - Banana, Meter Interface&utm_source=google&utm_medium=cpc&utm_campaign=Shopping_Product_Test and Measurement&utm_term=&utm_content=Test Leads - Banana, Meter Interface&gclid=CjwKCAjwjLD4BRAiEiwAg5NBFrpFgP6MxaHRQ51Rf3U1BughHiItatAmscGrJfe_EDOpXzo7NoFqBRoCbl0QAvD_BwE
1. Yes. Connect to chassis as your 'reference ground.'
2. Amp will be plugged in and running when you are taking voltages. Read some basic electronics. DO NOT go sticking your hands on, in or around live voltages without good understanding of how electricity works. It CAN kill you. Learn and understand why there is a "one hand behind you back" technique.
3.. You need to get a set of Pomona Electronics mini-grabber test leads. Helps keep you avoid damaging the machine during testing because if you short between two points with your other (positive), probe when reaching in to get a reading bad things can happen.
I will be offline at work for a few hours.
https://www.digikey.com/product-detail/en/pomona-electronics/3782-24-02/501-1458-ND/736648?utm_adgroup=Test Leads - Banana, Meter Interface&utm_source=google&utm_medium=cpc&utm_campaign=Shopping_Product_Test and Measurement&utm_term=&utm_content=Test Leads - Banana, Meter Interface&gclid=CjwKCAjwjLD4BRAiEiwAg5NBFrpFgP6MxaHRQ51Rf3U1BughHiItatAmscGrJfe_EDOpXzo7NoFqBRoCbl0QAvD_BwE
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Wow, another helpfull post, thanks a lot.
Regarding electricity i have a basic knowledge of how it works (my father is an electrical engineer in the construction industry), and know the danger involved. Will take it slow and carefull.
I also looked at a few multimeters, and found this one for a decent price (especially considering the use it will get): https://lygte-info.dk/review/DMMAnengAN8008 UK.html
To this i would have 2 questions:
1. do you think it has all the needed functions and range
2. do those leads have a safety switch somewhere, or only the shape of the tip make them special? (hard to find those exact ones in germany, and would hold off buying from the us until i can also ordere the broken parts, if ever identified).
I will start to diagnose it in about 3 weeks, as i will be away visiting the family, and hopefully will have all the info i need untill then.
Thank you again for all the help, you have been really helpfull.
Regarding electricity i have a basic knowledge of how it works (my father is an electrical engineer in the construction industry), and know the danger involved. Will take it slow and carefull.
I also looked at a few multimeters, and found this one for a decent price (especially considering the use it will get): https://lygte-info.dk/review/DMMAnengAN8008 UK.html
To this i would have 2 questions:
1. do you think it has all the needed functions and range
2. do those leads have a safety switch somewhere, or only the shape of the tip make them special? (hard to find those exact ones in germany, and would hold off buying from the us until i can also ordere the broken parts, if ever identified).
I will start to diagnose it in about 3 weeks, as i will be away visiting the family, and hopefully will have all the info i need untill then.
Thank you again for all the help, you have been really helpfull.
OK. Thank you. Good to know. Sorry I must assume no knowledge for others who may come after us; read this thread; possibly make a mistake and put a powerful electrical current from say right hand 'hot' across chest/heart to left hand 'ground' = CARDIAC ARREST. Pushing up daisys before completed repair.
OK that DMM looks like it will work. (Later can advance to one with 'auto ranging' feature if stay in this sport.)
No the leads do not have a safety switch. It's the shape and the mechanics. Stiff wire with tiny hook in the end encased in an insulated sleeve. Spring loaded. Depress plunger once the probe is placed in close where you are going to attach, and the hook sneaks out and grabs the component lead. Minimizes potential of short-circuit with other component leads. No safety is fast enough to prevent damage from that.
Handy also for attaching negative to chassis while you use a regular probe on the positive end. You can use your alligator clip or spade end to attach to chassis reference ground.
Sounds good. Safe and successful travels.
OK that DMM looks like it will work. (Later can advance to one with 'auto ranging' feature if stay in this sport.)
Two tips: You might stick a piece of tape over the "AmA Fused 10A Max" red input. Beginner- and highly-experienced people alike will absentmindedly put a jack in there. Look up where you are going to get fuses and the cost just so you know what you are looking at. There are two and they are different from each other I'm guessing.
No the leads do not have a safety switch. It's the shape and the mechanics. Stiff wire with tiny hook in the end encased in an insulated sleeve. Spring loaded. Depress plunger once the probe is placed in close where you are going to attach, and the hook sneaks out and grabs the component lead. Minimizes potential of short-circuit with other component leads. No safety is fast enough to prevent damage from that.
Handy also for attaching negative to chassis while you use a regular probe on the positive end. You can use your alligator clip or spade end to attach to chassis reference ground.
Sounds good. Safe and successful travels.
I'm currently going through some old amps with a variety of issues.
I have a sa-6500 (2) which has an issue in the phono stage,i suspect that it's one of the transistors so i would like to change them but the markings on them are unclear and i can't make any sense of the schematic vs their location on the pcb.
any advice/help would be welcomed.
Many thanks
I have a sa-6500 (2) which has an issue in the phono stage,i suspect that it's one of the transistors so i would like to change them but the markings on them are unclear and i can't make any sense of the schematic vs their location on the pcb.
any advice/help would be welcomed.
Many thanks
First most likely failure point switches and connections. Work the function switch 50 times. Clean the switches and potentiometers up first if you haven't already. If that's not it let me know and I'll try and located my file because I thought I had the service manual.
hifiengine (free registration) has the SA-6500ii service manual: https://www.hifiengine.com/hfe_downloads/index.php?pioneer/pioneer_sa-6500_mk2_service.pdf
The phono stage is not transistors, it is one integrated circuit : TA7136P1 per channel. Behind the tape monitor jacks.
Runs off of +21, -16v resistor derived from the Zener regulated + & - 24v power supplies
There is only one set of phono jacks, so they run directly (unswitched) INTO the phono preamp stage.
AWK-083 pins 3(L) & 4(R) are the Phono INPUT, while phono output is at AWK-083 pins 13(L) & 14(R)
Output is switched by function select ( PHONO, TUNER< AUX) rotary switch.
C1, C7, C21 left channel
C2, C8, C22 right channel
C1, C2 are tantalum, replaced with Nichicon UKL
Rest were low noise, also replaced by Nichicon UKL.
Not much to fail .
The phono stage is not transistors, it is one integrated circuit : TA7136P1 per channel. Behind the tape monitor jacks.
Runs off of +21, -16v resistor derived from the Zener regulated + & - 24v power supplies
There is only one set of phono jacks, so they run directly (unswitched) INTO the phono preamp stage.
AWK-083 pins 3(L) & 4(R) are the Phono INPUT, while phono output is at AWK-083 pins 13(L) & 14(R)
Output is switched by function select ( PHONO, TUNER< AUX) rotary switch.
C1, C7, C21 left channel
C2, C8, C22 right channel
C1, C2 are tantalum, replaced with Nichicon UKL
Rest were low noise, also replaced by Nichicon UKL.
Not much to fail .
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