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Pioneer SA-9100 electric checkup walkthrough

santashooter

santashooter

Active Member
Pioneer SA-9100 electric restoration walkthrough

Hi there, I have recently bought a Pioneer SA-9100 after years of wanting one.
The seller told me it worked, that he had it turned on shortly, before storing it.
I took the amplifier and cleaned it thoroughly yesterday, with focus on all contacts and the PCBs. I have read a lot of problems regarding the SA-9100, but also that it is worth the trouble, I am an electrical rookie, I know how to handle my multimeter, but i doesn't hope it comes to anything more than that.
I have not had the amplifier turned on at all, yet. and everything inside is original. I am strongly against changing components, just for the heck of it, but faulty components, and components known to fail is of course alright.
Is there anybody(Markthefixer?) out there, who could help me through the electrical checkup of this amplifier?
What should i do?

I read in another thread, that it was unwise to buy from the old lists of components posted in other threads, but I am not even sure if the amp has trouble other than the protection circuit needs attention.

best regards
Soren from Denmark

I am very active on a danish hifi forum as well, So for pictures of the unit please go to; http://vintagehifi.dk/forum/viewtopic.php?f=556&t=684&p=5261#p5261
 
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Without anything connected to it and the volume all the way down and all switches in the off or "normal" positions, turn it on and see if the protection circuit works correctly (a click a few seconds after power on). If so, leave it on for a while. Maybe 5-10 minutes. Then turn it off and connect a set of speakers to it, and take a listen and see how all the switches and pots sound. If everything works, your in great shape.

If not, then troubleshooting will commence. I would have done this BEFORE even starting any cleaning. That way I would know if I had done something to it while in the cleaning process. It's all about steps of progression. See what you have right off the bat, then go in steps from there.

Deoxit, board cleanup, etc. Then if it has not been re-capped, that would be a great time to get the CORRECT parts list going. Some other components may or may not need to be replaced as well (trim pots, transistors, resistors, etc).

You're in great hands on AK though.
 
I'm a newby, but just went through this. And I have an SA-9100 in everyday use.

1. Check the unit for absent screws and tool marks on the case bottom, knobs and faces. This will give you some indication of the unit's problem history. Download the manual (although many threads complain about the production quality of the SA-9100 document). Turn the speaker selector to "Off."

2. Don't plug it in. Get or make a dim bulb tester. Plug it into the dim bulb tester. Turn it on. If the bulb dims, there are no shorts. If the bulb remains bright, turn it off, and post a description of the problem. Listen to see how quickly the protection circuit clicks. If it clicks immediately, post the problem. There should be a couple of seconds delay. If the relay clicks, use your multimeter, set to DC current, to check the offset. Turn the speaker selector to "A" and place the + and - meter probes into the corresponding speaker "A" outlets. Check both L and R. If the readings are 0 to .050 V DC + or minus, connect to speakers, connect to source appliances--TT, CD, etc, and test the source inputs and tone/balance controls. If not within the offset tolerance, post the problem.

3. If there is static, crackling, or imbalance in volume between the channels when the controls are turned, read up on cleaning the controls, get Deoxit and Faderlube, and clean the unit. If problems persist after cleaning, post the symptoms.

This isn't complete, but should get you started. This may sound involved, but if there are major issues with the amp, this will prevent immediate catastrophic damage to the amp or your speakers.
 
I should have mentioned, as did the previous poster, before you turn the unit on, make sure the level set ring on the volume control is set to "0", volume is set to minimum, tone controls set to "0", Function set to "Aux", Tuner/Phono 1 switch defeated (in full down position), all loudness switches in the up position ("Off" or "Defeat"), filter "Off", Balance in neutral position (marker centered vertically), Tape switches centered, Stereo to "Normal".
 
Thank you all for your posts, The reason i would like to make an electric overhaul, even though there might not be anything wrong, is that; according to my understanding the Protection circuit can make all kinds of trouble, and if there is components known to be faulty, i could just as well replace these and avoid further havoc, caused by these components?

I will go on, replying to your posts!

thank you
Soren Iversen
 
Nortonrider said:
I'm a newby, but just went through this. And I have an SA-9100 in everyday use.

1. Check the unit for absent screws and tool marks on the case bottom, knobs and faces. This will give you some indication of the unit's problem history. Download the manual (although many threads complain about the production quality of the SA-9100 document). Turn the speaker selector to "Off."
Click to expand...
- there is no screws missing, nor do they seem to have been worked(no sign of wear) all screws are of the same type, color and size, according to the ones around them. (Cabinet screws are alike, front facia screws etc. etc.)
- The manual has been downloaded in Hi-res pdf.
- The speaker selector is set to "OFF"
Nortonrider said:
2. Don't plug it in. Get or make a dim bulb tester. Plug it into the dim bulb tester. Turn it on. If the bulb dims, there are no shorts. If the bulb remains bright, turn it off, and post a description of the problem. Listen to see how quickly the protection circuit clicks. If it clicks immediately, post the problem. There should be a couple of seconds delay. If the relay clicks, use your multimeter, set to DC current, to check the offset. Turn the speaker selector to "A" and place the + and - meter probes into the corresponding speaker "A" outlets. Check both L and R. If the readings are 0 to .050 V DC + or minus, connect to speakers, connect to source appliances--TT, CD, etc, and test the source inputs and tone/balance controls. If not within the offset tolerance, post the problem.
Click to expand...
- I made a dim bulb tester, nothing wrong, the bulb dimmed as it should, the relay clicked out, after precisely 3.3 seconds.
- I took my multimeter and checked the offset with the speaker selector in the "A" position. the source selector moved to "function" and "aux 1"
The right channel measured after 10 minutes of being plugged in: 0.045 V DC
The left channel measured after 10 minutes of being plugged in: -0.004 V DC
- I connected one speaker to the R channel A, and tested:
"Aux 1" nice sound without distortion; all switches works according to function, unless Tone defeat, which makes it louder and makes it distort; probably just needs further cleaning!
moving on to "aux 2" The same diagnose as with "Aux 1".
The same goes for "Tuner", also.
Testing the phono stage now; "phono 1" works as the other channels, without a fuss. the same goes for "Phono 2".
Now testing the Left Channel.
"Aux 1", "Aux 2", "Tuner" and both tape sources works great and the same goes for both phono stages.
No notable problems with the amp this far!

- Tested both channel in level for imbalance;
Nothing notable, but it seemed that the left channel sounded a little different than the right channel.
I moved the selector switch to mono, and it is an almost unnoticeable problem, maybe it is just in my head?

Nortonrider said:
3. If there is static, crackling, or imbalance in volume between the channels when the controls are turned, read up on cleaning the controls, get Deoxit and Faderlube, and clean the unit. If problems persist after cleaning, post the symptoms.
Click to expand...
- small problems in the Filter department in the preamp, sounds like the contacts needs cleaning.

Nortonrider said:
This isn't complete, but should get you started. This may sound involved, but if there are major issues with the amp, this will prevent immediate catastrophic damage to the amp or your speakers.
Click to expand...
Thank you! - it seems as though my steps now involve cleaning the filter section, adjust DC offset and I am still indecisive whether the Protection circuit in the amp needs attention, due to the risk of problems.

edit: The speakers "plop" when the amp is turned off, if the speaker selector is not turned to "off"
also, my bass speakers move very much, even though the "subsonic" filter is attached - i assume this is because this switch needs cleaning, and thus there is feedback going through my speakers and TT.
It is not present when using an auxiliary input, or when i apply the "30 hz" filter.
Thank you!
 
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Ok, as far as "havoc" inducing components:
There is a pair of 2sc1451 transistors in each power amp
512-KSC3503estu to-126 ecb 300v .1a 1.2/7w 150mhz 40-320hfe $0.28 ea

and a low probability problem 2sa726 in the phono amp (no 2sa725's)
512-KSA992FBU (ln)to-92 ecb 120v .05a .5w 100mhz 150-800hfe $0.05 ea


and more general purposes replacements

the 2sc1318 and 2sa720 transistors in the power supply with to-126 cased transistors for better heat dissipation
512-KSA1220AYS to-126 ecb 120/a160 1.2a 20w 155mhz 35-320hfe $0.39 (R=60-120, O=100/200, Y=160/320)
512-KSC2690AYS to-126 ecb 120/a160 1.2a 20w 155mhz 35-320hfe $0.40

the protect relay driver Q7 2sc1384
512-KSC2690AYS to-126 ecb 120/a160 1.2a 20w 155mhz 35-320hfe $0.40

and protect's current dump transistor Q6 2sc945
512-KSD1616AGBU to-92 ecb 60v 1a 0.75w 160mhz 135-400hfe $0.09

and add the 1n4004 diode across the relay coil (pin 9 anode, pin 10 cathode)
512-1n4004
 
markthefixer said:
Ok, as far as "havoc" inducing components:
There is a pair of 2sc1451 transistors in each power amp
512-KSC3503estu to-126 ecb 300v .1a 1.2/7w 150mhz 40-320hfe $0.28 ea

and a low probability problem 2sa726 in the phono amp (no 2sa725's)
512-KSA992FBU (ln)to-92 ecb 120v .05a .5w 100mhz 150-800hfe $0.05 ea


and more general purposes replacements

the 2sc1318 and 2sa720 transistors in the power supply with to-126 cased transistors for better heat dissipation
512-KSA1220AYS to-126 ecb 120/a160 1.2a 20w 155mhz 35-320hfe $0.39 (R=60-120, O=100/200, Y=160/320)
512-KSC2690AYS to-126 ecb 120/a160 1.2a 20w 155mhz 35-320hfe $0.40

the protect relay driver Q7 2sc1384
512-KSC2690AYS to-126 ecb 120/a160 1.2a 20w 155mhz 35-320hfe $0.40

and protect's current dump transistor Q6 2sc945
512-KSD1616AGBU to-92 ecb 60v 1a 0.75w 160mhz 135-400hfe $0.09

and add the 1n4004 diode across the relay coil (pin 9 anode, pin 10 cathode)
512-1n4004
Click to expand...
I guess those part numbers are from mouser? I am living in denmark, so it is exciting to see what the total cost for me is.
The shipping might be the biggest expense, so is there anything other than the things listed, which could be clever to get as well?
and btw. thanks for your participation, you are highly regarded when it comes to Pioneer, and I feel in good hands, when the advice comes from you!
- not that I doubt other's opinion and help, but sometimes advice can be contradictory. :thmbsp:

best regards
Soren
 
That is why I include the specifications of the transistors, so that local sources can find a reasonable substitute.

If you want to make a big order of everything, then do the work in stages as you increase your comfort level, we can do that - as you assemble the lists from around karma where the are posted, I'll vet them, make suggestions etc for a big master list that will eventually be ordered.

Perhaps not as contradictory as different in focus, others relate to their experiences and emphasize different things.
 
I just don't know, if i need anything else than what you posted. It is quite funny, in Denmark, from most of our suppliers one of the transistors you list with a cost of $0.40 cost around $2.8
So actually, the whole shipments is cheaper than local suppliers, but it still seems weird using 4.48 euros, and then 20 euros on shipping.

You are absolutely right! and i appreciate the different perspectives in restoring and rescuing an amp!

Edit; And on top of that, i can't seem to find equivalents - so i quess i'm just going to order from Mouser!
 
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I have placed an order now, for the transistors and the diode you recommended, along with new caps for the power supply board, should it be necessary in the future.
I would like to measure and adjust Idle current and neutral potential on the amp (this is the brilliant names given in the manual)
I suspect it is a Typo with the VR3 thing right?
I have always been able to acess the pins from the top, when I adjusted offset and Bias before, But here, the pins are only accessible from underneath the machine, so i just want to make sure, that i should indeed measure between pin 9 and pin 13, and it is not also a typo?
and for the neutral potential the manual tells me to measure terminal no 23. but that doesn't seem to be present on the amplifier PCB?
am i missing something here?

best regards
Soren
 
1. Can't answer your questions on which pins to meter for idle current and neutral potential adjustments--MKT will have to do that.

2. Looks like V3 is a misprint, but will defer to MKT on that one, too.

3. Looking at the foil side schematic in the manual--(Section 11.5, AWH-023B power amp assembly) it looks like pin 23 is inboard from pin 18, on the inboard side of the 5th trace from the edge, sitting between resistors R-34 and R-33. Looks to be about 25mm from the edge. I'd have to pull mine apart to verify--but you might look on yours--since you've got the bonnet pulled. The manual doesn't show any difference between the 120V and the general export multivoltage versions of the 9100 in this regard.

Haven't done the adjustments on mine, either, but did do them on an Pioneer SX-980 a few days ago. The center current measurement (what they're calling neutral potential for the 9100) for the 980 was also on the bottom of the board, requiring access from the bottom of the unit on one of the two power amp boards. In that regard it doesn't look like Pioneer is using a strict 'from the top" protocol in setting up the boards for adjustment. For that reason, could not use a shielded probe to do the measurements--had to get a minigrabber lead. Echowars has a Pomona Electronics reference for that (see his sticky "So you want to repair audio gear, Eh!" in the AudioKarma DIY Forum. Mouser carries these leads. The Mouser parts numbers are 565-3782-48-2 and 565-3782-48-0 for red and black leads, $5.78 US for each.
 
Checked the Mouser site for availability on the leads--they are in stock--if Mouser hasn't shipped your order yet, they might be able to add them.
 
When I did the adjustment on the 980, I was able to feed the lead down through the heat sinks and get the attachment that way--so could do the process with the unit sitting upright on the bench.
 
I've already got a pair of those (in denmark we call them Daddy long legs) and i have just adjusted my amp, everything went as it should, and i found answers to my question regarding the manual in other threads.
Now i am just awaiting my order from Mouser sweden - I have also ordered parts, so that i would be able to recap the entire powersupply board.
I will post my measurements soon, just to see if they are up to spec.

best regards
Soren
 
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Here is my measurement of the power supply voltages:
Pin number [measured voltage] (should-be voltage)
#1 [0.00] (0.00)
#2 [-17.1] (-16.0)
#3 [-26.3] (-24.0)
#4 [-13.8] (-13.0)
#5 [-45.0] (-42.0)
#6 [-64.6] (-56.5)
#7 [63.7] (-56.0)
#8 [45.3] (42.0)
#9 [37.6] (35.0)
#10 [26.1] (24.0)
#11 [16.9] (16.0)

I don't know very much, but i think, that since all the voltages are a bit high, maybe it seems to be high, all over - would a recap do anything positive to this? or should i just leave it as it is?

A further note; i found that my machine is a 220 volt model (without the possibility to chose between 110,130,220 or 240) and in Denmark we have 230 Volt 50 Hz.
Could this higher mains voltage be the reason for my highter PSU voltages?
and should i do anything to change this?
Normally i always change equipment to work on 240 instead of 220, since it makes bulbs last longer, and no significant difference in performance.

best regards
Soren
 
Leave the voltages alone. They are fine.

The zener diodes control the regulated voltages, not the primary voltage.

13.8 versus 13.0 is a more significant number, but like I said, it's fine.
 
Hi again, the parts i have ordered has just arrived and I am ready to replace the old components. I have used a soldering iron, desoldering gun many times before, also on other vintage equipment, But is there any good advice on freeing the board for easy access? I just don't want to break any wirewraps and cause even more trouble.
That said, if there is anything I should be aware off, before jumping in?
I know there might be threads out there with this information, i just can't seem to find it?

best regards
Soren
 
Hi again, after spending hours just looking at the amp. i started and replaced everything, triple checking that everything went in and out the way it should. all the transistors where put in the right way, and The two output transistors in each channel, where taken off in order to replace thermal compound and isolation disks.
When i finished the entire workover, I put the machine on the Dim Bulb tester, and the bulb kept glowing, and the two indicators on my machine went on, and grew in brightness, until they both blew after about 5 seconds.:tears::sigh:
I quickly took the machine of, and desperately started thinking about what could be wrong.
I thought that it might be with one of the output transistors, because as I remembered, on the little ducts in where the screws that holds the TO-3 transistors goes, one of these ducts, broke off. And i forgot to repair it, which means that the Base might have been shorting to ground. I took of the screw and tested on the dim bulb tester again; it went on and dimmed as it should. But is this a sign that there is hope for my little amp? or is all hell loose?
I guess i need new bulbs for the indicator and the protection circuit before I should try firing up the machine again.
Maybe test the output transistors somehow?
Test the power supply?

I hope there is something to be done!
At least my amp go up in smoke!

Best Regards
Soren
 
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