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Hacked up Pioneer SA-9100 restoration

S

SansuiSushi

Active Member
A friend decided to buy a SA-9100 unseen and having no amp restoration experience, and me having a few sucesses under my belt, he passed it to me to fix for him.

Now of all the amps that have sat upon my work bench in its various forms, I have never seen an amplifier with this degree of unprofessional cowboy repairs. I hope that some of you find these pictures entertaining.

Ouch, who did the work Edward Sissorhands?! This is after I cleaned it up see below as it looked basically the same as board 2
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Too many things happening here!
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A cheap speaker wire to join the the broken solder connection
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I think "Series and paralel were mixed up here"
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Spot the missing corner? How does that even happen? Perhaps the 'tech', (or unqualified 'soldering iron holder' in this case) dropped it and wheeled his chair over it as he turned to find it or pick it up.

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What ideas can you come up with as to what might have happened there? Write them below!



While I dont feel "out of my depth" with this one per say, its new to me certainly, and transistor replacement advice would ve MOST hepful. So I would like to consult and confer with others, who maybe know of devices, products, or techniques that I may not yet be aware of, that could help solve the issues with this amplifer as I go through it.

As it stands now both amp boards have been removed from the amplifier, THANKFULLY to the amplifier gods, the preamp section with it's complex switching remains untouched, and aside drom a few broken wires, likely works. Now yes, I did check the amplifier powered up before starting on it and it did even went out of protection, this was on a very limited current via a DBT as is standard proceedure.

Now I must admit, I did forego the initial internal visual inspection, my friend was there and wanted to know if it even powered up, and its his amp his choice, this is absolutely an error on my part, you should ALWAYS do a visual inspection of this equipment before it seen any plug juice.

Its a nicely made amplifier which is somewhat of a bugger to work on due essentially a powerful TOTL amplifier being crammed into a standard amplifier size, lots of wire runs, lots of mechanical switching with large 4 gang rotary switches, some of you may be familiar with it.

Now the difference between the two boards is stark, I have stripped, cleaned and removed loose tracks,

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I dislike my "repair here", I can be better, thoughts? How would you appoach this corner?
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I've somewhat started rebuilding one of them, pending what to do with the other, I made a repair rough, but to see how it would turn out, ideally I want to remake the entire board, but I'm not sure how to go about that or if it's worth it vs the work involved to repair the tracks etc. I have half the tools for that those I dont have I ordered, some self adhesive copper tape UV light for curing the green solder mask.


Would also like to replace the pins perhaps with some sort of socket system so the boards can more easily be removed to be work on in the future, given how weak the traces are that may or may not be a good thing.

Looking forward to your thoughts, its a lovely amp thats been treated badly.. lets fix it up.
 

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A closer comparison of the boards

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Heres another fun find...

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Main fuse, "aww man the fuse" "what?" its blown and I don't have a replacement.. oh well!" "i'll just solder some wire to one end and and call it good!" To think it may have actually tried to be used like that is bonkers.

Dont do drugs and work on amplifiers.. :biggrin:
 
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A few things to be checking with those that are wiser, C3, C6 with 47uf 25V Nichicon Bipolar UES?

D6 is a 1S2471, research tentitively suggests a 1N4148 as a replacement, can anyone confirm?

1.2V (Q5 Collector) on the anode of D6
 
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Great work there. I'm working on an SA9100 myself too. Transistor list for the power boards is:

Q1, Q2 2SA774A 512-KSA992FBU
Q3, Q4 2SC869 512-KSC1845FTA
Q5 2SA628 512-KSA992FBU
Q6, Q7 2SC1451 512-KSC3503DSTU
Q8 2SD358 512-KSC2073TU
Q9 2SB528 512-KSA940TU
Q10 2SC1079 863-MJ21194G
Q11 2SA679 863-MJ21193G
 
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Thanks so much, saved me a heap of time, I'd lost steam a bit there, so thanks for the boost.

Cant find those MJ21193G and 94G in stock, shame, those are kinda crucial to the whole thing.
 
Yeah those 93 and 94 are a bit of a pain. And I actually fried one when I made a snafu... :')

Also, you want to give C3 a slight bump. In the BOM it states a 33uF 16V, put a 33uF 25V in there. I'm currently on to the control amp assembly (AWG-018-A) putting together a parts list.
 
Hello @SansuiSushi, I noticed that some of the boards in your pictures appear to be in a similar condition to those in my SX-1250, which I'm currently in the process of restoring. Instead of attempting repairs, I opted to replace them entirely with new PCBs. Recreating them in KiCad and having them printed turned out to be a relatively straightforward process—I've successfully done this for two of them so far.

I understand that some enthusiasts might prefer to restore the original boards to maintain authenticity. However, in my perspective, having a device with new boards offers several advantages. Not only can it ensure reliable functionality, but it's likely to have a longer lifespan and be easier to maintain in the future.
 
That would be amazing to do, what was the cost of the boards from the manufacturer? Do you still have the files? I looked into it but seemed too expensive to be a viable option.
 
Zender said:
Yeah those 93 and 94 are a bit of a pain. And I actually fried one when I made a snafu... :')

Also, you want to give C3 a slight bump. In the BOM it states a 33uF 16V, put a 33uF 25V in there. I'm currently on to the control amp assembly (AWG-018-A) putting together a parts list.
Click to expand...

Good tips, I'd always bump a cap up to the next voltage rating, recently did a Sansui AU-222 which had a 470 35V cap on a 34.8v rail... Put a 50V in there. Keep us up-to-date with your project, would like to know how you get on.

MarkyM said:
Try ebay seller Affinity for Artifacts (the store of AK's peace.love.and.music). He should have them in stock.
Click to expand...
Thank you, I'll will check out his store, lets hope he has some.. shipping might be costly though I'm in the UK :)
 
SansuiSushi said:
That would be amazing to do, what was the cost of the boards from the manufacturer? Do you still have the files? I looked into it but seemed too expensive to be a viable option.
Click to expand...
The PCBs I did were for the Pioneer SX-1250 receiver. So far I've done the AWG-042 Flat Amp board and the AWR-106 Power Supply board, which cost less than $70 each to have printed. The minimum quantity per order was 5 pieces for each board, so 5 pieces for less than $70, shipped. Check out my SX-1250 restoration thread, where I've posted pictures of the new boards. I used KiCad to create the design files and used PCBway to get them printed. It was a bit of a learning curve to learn KiCad, but the time spent on that was well worth it.
 
barrakkuda said:
The PCBs I did were for the Pioneer SX-1250 receiver. So far I've done the AWG-042 Flat Amp board and the AWR-106 Power Supply board, which cost less than $70 each to have printed. The minimum quantity per order was 5 pieces for each board, so 5 pieces for less than $70, shipped. Check out my SX-1250 restoration thread, where I've posted pictures of the new boards. I used KiCad to create the design files and used PCBway to get them printed. It was a bit of a learning curve to learn KiCad, but the time spent on that was well worth it.
Click to expand...
Yes that's about what i was getting, I'm not sure the owner wants to spend that much, first order of buisness is to get it operational :) definitely look into learning that KiCad though for some other projects and ideas I've had in the past.
 
barrakkuda said:
I opted to replace them entirely with new PCBs. Recreating them in KiCad and having them printed turned out to be a relatively straightforward process—I've successfully done this for two of them so far.
Click to expand...
I've considered this route myself and was wondering if we should set up a library of sorts with these files. Those old pioneer traces are a bit sensitive to damage and lifting, having the option to get a new board would be awesome. And not everyone here is skilled enough with KiCad.

Maybe even put some of the basic improvements in as well and multilayer pcbs can make things much much tidier and logically layed out than the old single layer ones.
 
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Been a while, but here's a little update, one of the power amplifier boards has been reworked, it has yet to be idiot checked and tested, however I must first overcome the other issues in the protection board, now I'm not certain, and perhaps someone can confirm, is it necessary for these boards to be installed for the relay to engage?
 
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