Should I recap my G9000 myself?

[djbono]

Hi all Sansui lovers,
I know you can't possibly answer this - but let's have an opened discussions on what it takes to "restore" a G9000. [I don't like the term restore as it implies of some current issues, which, to my untrained ear, my G9k doesn't seem to have, really].

Short preamble:
When I was 10 yo, I was always in awe when I went down my best friend's basement, as the G9000 sat there with original decks, in all its majesty. Later in the youth, it powered some quite impressive parties, and had the police come on knocking almost every time. (back then power was valued over quality).

F-FWD a few years and when moving out of his house, my friend's dad gave me the chance to buy it. That was roughly 10 years ago. Back then , the left channel never came op, and lots of static noise whenever playing with any knobs.

I deoxied it - and even embarked on a recap of it (I was in engineering school back then , and was full of hopes and motivation). Motivation faded away at the complexity (electrical eng. classes nowadays are more centered towards UC chips & already built raspberry pies and the likes.), and so I closed it up after characterizing its curve, which wasn't bad. Left channel came back as well with the cleaning/deoxit.

Current status:
Plays remarkebly well, gets between 6 to 12 hours of listening every day (oh and - hit me for this - I never shut it off. It gets off only when the power's out, which, doens't happen often.) It's cosmectically flawless.

BUT... having said that it does have some finicky particularities.
1) If input volume is too low, left channel will shut off. However, if it's in the -6dB to 0dB range, it's all good. It generally never cuts off while listening to music, only when it's been muted for a few hours but kicks back in easily.

2) VERY RARE. Like once every two or three months. Left channel will be significantly lower than the right channel. (-12 or even less dB). Toggling the pre-amp CONNECTED/SEPARATED swithc brings it back in a jiffy.

3) Constantly: The VU meters for both channel clearly never peak at the same level , given the same input; and it varies with the music. (So I'm guessing the curve / freq response is different for both channels. Probably means it needs a recap). Or could it be just the VU meters not being super reliable?

I just notice balance know is a 2 towards left, but stereo image is perfect. Yeah, it clearly needs to be restored!

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Now, onto my abilities:
I'm an electrical engineer - but that means I've passed that class. I've never worked in electronics or anything (I'm in the VoIP field), but I do have a good dad who taught me about electronics when I was a wee kid. I have no issues with soldering irons or replacing parts on PCBs.

My worries come more from the fact that I don't rememebr sh*t regarding capacitor values, how to recognize amplifier circuit patterns, calculate values, different kinds of resistors or Caps to use, etc.
So I'm worried I won't order the correct type of caps, or won't know if a value is critical or not.

I'm also worried I'll worsen things. or worse - I'll just end-up with a dead amp, because I'll have done a half-ass job.

I do have (very bad photocopy of) the service manual, somewhere, but looking at it just increases my worries.

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So should "i bring it in" somwhere? I called an audio repair shop nearby, and w/o looking at it, he said it *could* go as high as 1.5k$ to have it recapped, but would need to bring it in for a proper evaluation... which I'm tempted to do. (But rest assure, I absolutely have no intentions of giving them 1500$ for it, let alone 500$....)

I also doubt that the guys at the repair shop share our love for sansui, and I believe that in the multiple threads here, there are gems of infos and DO's & DON'TS which they prolly won't follow. (i.e. double capping ala Kevzep for the oval ones)

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So the real question,
on average, how hard / complex / long / needs years of audio repair experience - is it to recap a G9?
Also, would I need to change resistors (I saw Kevzep has done it.) ?

Which ones to change, which ones to keep - how to know?

Thanks!

 

[djbono]

I should add, I'd aslo need a pastime away from work and kids, late night basement kinda-gig. So this sounds ideal. But again, I love this unit too much to f* it up...

 

[JOMARK911]

djbono , take your precious G9000 to a qualified and well known restorer for this kind of work. You'll never get it right. You'll probably f...t it up. It's a shame.
Take it to an AK member , and give him sometime. He'll work miracles. None of it's flaws will be there afterwards. They really know what to do and how and when .
Don't worry.
As for the time of operation leave it on 24/7 , there's no problem with this. The shock an electronic device is imposed at is on the start up , not later on while stabilized and running normally.

 

[jheu02]

I recommend putting it on the back burner for now and go to a thrift shop/garage sale/etc and find a cheap vintage receiver to practice on. You may have no problems with soldering new boards, but these older ones can be brittle, traces can be lifted somewhat easily, wire wraps broken, etc. Practice on one while getting familiar with all the other disassembly and specifics associated with doing a restoration. Then, revisit the idea. If things go really smoothly with the cheapie, go for it with the G9000.

 

[tybrad]

My experience was a positive one on my 9000. I replaced all of the caps (and the known fail-prone components) except on the pre-board and the twin towers. It was easy for me and this was my first recap- I started big. There were a couple of foil lifts, but I repaired them as they appeared. The important points for me were to
1. inventory the replacements.
2. the standard advice is to take pics before doing anything. I did not.
3. go methodically, one-by-one; removal, then replacement before moving on.
4. BE SURE on polarity.
5. Re-check polarities.
6. Check 'em again.
7. Bring the unit up on a variac and a dim bulb- just to not "fry on first juice".

I'd say, go for it if you are confident in your abilities.

 

[LBPete]

The G-9000 is not a good first project. There is a lot in there that could get messed up. As has been already stated, find a simpler receiver for practice before tackling this one.

Where are you located? There may be someone nearby that can help with it.

- Pete

 

[59volvo]

FYI - ConradH is near Rochester NY - might talk to him

 

[djbono]

Thanks for the replies;
a very good friend of mine who knows me too well also mentioned I should practice on something "easier" (or less valuable to say the least.) I might have toned down my abilities a bit here; but yeah - I think I'll start with the old pioneer that powers the shed's speakers. It truly needs a revamp! (And it doesn't get any use during winter so.. perfect timing!)

@tybrad - thanks , I WILL over-document every step. And yes, with my ADD, I absolutely need to do parts one by one. I can't afford to remove all and then hope to fill the gaps afterwards. It'll just be a mess!

@LBPete / 59Volve - I'm in a suburb of Montreal. While Rochester is indeed quite close, I wouldn't cross the border with such a thing, for fear of having to pay humongous duties (they won't believe it's mine on the way back.)

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I did something foolish this morning - I brought it up to a (supposedly) reknown audio repair shop. We'll see what they say. Briefly chatting with the guy, he said "never replace those big caps - they're good". Not sure what to think of this... they're over 40 years old... and when yous ee the state of them in some of you guy's pictures... I doubt they're still good. Plus there's this huge volume & freq response discrepancy between L & R channels, it can't be in the good of a shape.

The guy mostly talked about replacing relays, switches & bulbs. He even suggested hard-wiring the speaker toggle switches, cause "they usually cause issues". Which isn't the case for me, and I truly don't want to do that. I almost immediately walked out of there when he mentioned that, but one can't quickly "walk out" with a G9 plus I had already paid for the evaluation, which should be non-intrusive.

It's now been a few hours that it's gone and I already feel the void in my life.


will keep you posted on any of the decisions, I really appreciate you guys taking the time to respond.

Pierre

 

[Hyperion]

You are right to think that hard wiring the speaker toggle switches is not a good idea - they don't seem to cause problems, judging by the traffic here about them (nil?)

He could well be right about the big caps - if he means the main PSU capacitors. You can't get direct replacements now, so it's quite a lot of work to recondition the old ones.

 

[djbono]

See - those big ones, I actually would have no problem doing the same thing Kevzep did (two 10,000uF panasonic caps in each). To me that (sounds/looks like) the easiest of them all to do... But is it worth it to do only just that?

 

[Hyperion]

See - those big ones, I actually would have no problem doing the same thing Kevzep did (two 10,000uF panasonic caps in each). To me that (sounds/looks like) the easiest of them all to do... But is it worth it to do only just that?

No, it won't cure your channel imbalance issues if that's what you mean. There are at least 2 ways to test those capacitors, if they need to be changed/reconditioned (as per Kevzep) it will be quite obvious.

Assuming they test 'ok' (but are not necessarily in the peak of condition) When everything else is done and you want to just add that last bit of icing on the cake - that's the time to think about it.

I did the 4 in my AU-919 and I can assure you it is quite a job.

My personal recomendation is for you not to try and tackle the whole job yourself, but it shouldn't cost you $1500 or maybe even $500 to get it done. If you can persuade a good AK'er to do it for you (for a price - usually) this is the best method. Remember this will probably need to include a tuner re-alignment, not many high street electronics repair 'shops' can offer this service.

 

[djbono]

Yeah, thanks - I'll definitely not embark on that endeavour myself.

I'll see what the guys at the shop say. On the phone the "junior" dude with a nice shirt trying to push "hi fi" gears to snob folks mentioned the 1.5k repair cost;
while the gray-haired calmed down tech mentioned something like 400$, at which point the other guys' face went red and he left. 400$ seems quite steep, but I still love the unit enough to cough it up - UNLESS you guys think it's a rip-off and doubt the guy's abilities. (Ateliers Brosseau, in st-hubert,qc).

I'd be very inclined to give the same amount to any of you guys - but I fear the shipping & duty costs will ruin me in the end...!
Unless it's in the northern USA, not too far, and I can justify a visit to my friends in NYC... I could drop it , but still, not ideal.


Pierre

 

[djbono]

djbono , take your precious G9000 to a qualified and well known restorer for this kind of work. You'll never get it right. You'll probably f...t it up. It's a shame.
Take it to an AK member , and give him sometime. He'll work miracles. None of it's flaws will be there afterwards. They really know what to do and how and when .
Don't worry.
As for the time of operation leave it on 24/7 , there's no problem with this. The shock an electronic device is imposed at is on the start up , not later on while stabilized and running normally.

that was my thoughts as well. Transitive states always suck !