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Yamaha newbie A-700 resto thread

analogwisdom said:
I'm assuming you're being facetious but don't encourage me... LOL

I've actually had the idea to get very intimately familiar with an amplifier then replace every single component for a modern one just to see what happens... Probably something marginally perceptible and an emptier wallet. :D
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Don't laugh. :biggrin:

I routinely replace all carbon film resistors with 1% metal film. Usually Vishay SFR, CMF and RN depending on the position. I buy them in bulk, sort test and channel match. Tiny improvements add up.

Your work looks good. :thumbsup:

Cheers,
James
 
analogwisdom said:
Well, the new faceplate came today. This is what it was shipped in. The seller threw it in a cheap-ass bubble mailer with no other protection. Not even tape. What a dumbass. I can't stand when people are lazy with shipping.

Naturally, there are some snapped off plastic pieces in the envelope with it. I think I can superglue them back on, but I'm still annoyed as f@#k.
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I hope the pieces you need are still salvageable. Plus, I hope you give the seller some well-deserved feedback!
 
Since no one chimed in on the xfmr top cushion. I was thinking about two solutions and I haven't tried these yet. Two acoustic dampening products come to mind.
No-res
Dynamat

Not sure they come in red though, there's always rattle can paint, ha

Random ideas
 
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Soundscape said:
Alot of people overlook where it all starts, the plug. Good call. I was cleaning my cord and found a big sheath cut waiting to torch my cats and carpet.
Check this out... They hold the prongs tight and should satisfy your fetish:

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This is the way that one of my Marantz monoblocks arrived. I guess that you just have to keep it within 1 foot of an outlet. :biggrin:

DSC02055.JPG

Cheers,
James
 
Bratwurst7s said:
This is the way that one of my Marantz monoblocks arrived. I guess that you just have to keep it within 1 foot of an outlet. :biggrin:

View attachment 3135447

Cheers,
James
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Lol...omg looks like a lamp cord. Can't trip over that one. Unreal.

Sidenote:
I gotta ask you something about your Avatar sir. While many people display dogs & cats, you have 7 big weiners. I'm German too, and like brats. Is it like a Bob Carver silver 7 reference with a side of sausage? Kinda makes me hungry every time I see it. What's the origin?
Respectfully
SS
Edit: I counted 5 weiners in the pan after posting this and more curious now.
 
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Soundscape said:
Lol...omg looks like a lamp cord. Can't trip over that one. Unreal.

Sidenote:
I gotta ask you something about your Avatar sir. While many people display dogs & cats, you have 7 big weiners. I'm German too, and like brats. Is it like a Bob Carver silver 7 reference with a side of sausage? Kinda makes me hungry every time I see it. What's the origin?
Respectfully
SS
Edit: I counted 5 weiners in the pan after posting this and more curious now.
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The background on my Avatar:
I am a longtime Speakerlab fan and when I first joined AK I used a username that reflected that. Shortly after I saw that there was another longtime member with a very similar username. To avoid confusion I changed my name, and at the deciding moment my wife was making those bratwurst in the pan. Sadly there were only 5 and not 7, but that's life. :biggrin:

Cheers,
James
 
Trying to stay a bit on topic, analogwisdom, in my opinion what you are doing concerning replacing small value elcos with film caps is quite simply good maintenance. I do it regularly.

You are buying reliability. They will stay stable for the life of the amp now. In general they have a higher than required voltage rating so that no longer plays a factor in their lifespan. And they are rated at 125°c, also a good thing. Low ESR and lower noise than an elco also.
And well, yes, they do look nice.

4.7µF and below it will almost always be possible to fit a Wima. 6.8µF and 10µF are space and budget constrained but where possible I use them there also. For caps in the signal path consider Panasonic ECW polypropylene types. They are large and space will be a deciding factor, but they are the best choice imho for signal path coupling caps where possible.

Amusingly even though Wima are a German product I can buy them cheaper and usually quicker from Mouser.

Cheers,
James
 
Bratwurst7s said:
Trying to stay a bit on topic, analogwisdom, in my opinion what you are doing concerning replacing small value elcos with film caps is quite simply good maintenance. I do it regularly.

You are buying reliability. They will stay stable for the life of the amp now. In general they have a higher than required voltage rating so that no longer plays a factor in their lifespan. And they are rated at 125°c, also a good thing. Low ESR and lower noise than an elco also.
And well, yes, they do look nice.

4.7µF and below it will almost always be possible to fit a Wima. 6.8µF and 10µF are space and budget constrained but where possible I use them there also. For caps in the signal path consider Panasonic ECW polypropylene types. They are large and space will be a deciding factor, but they are the best choice imho for signal path coupling caps where possible.

Amusingly even though Wima are a German product I can buy them cheaper and usually quicker from Mouser.

Cheers,
James
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I appreciate the advice. I'm still learning about the types of capacitors so I hadn't read about Panasonic ones yet. I will do so!

I'm also still trying to wrap my head around what the signal path truly is. I know you can track it through the schematic and I think I've done this before... But it's usually a single straight line. I like to use tone controls, once you start using them do more caps become in the "signal path"? I need to do more reading...

Your comment about the caps being cheaper on Mouser is funny. It reminds me of my other hobby. I shoot film and love Fujifilm E6 slide film, which is only made in Japan now. A box of it is about 3 times cheaper over here than it is in Japan.
 
Not all ECW caps have tinned copper leads. Some have tinned steel.

Here are links to ones that I know for a fact have tinned copper leads:
https://www.mouser.de/ProductDetail...2BdvILcjJFJLrFVbsOG0AanJ4eg4pEcrBpNEzZAVRTQ==
https://www.mouser.de/ProductDetail/Panasonic/ECW-F2105JA?qs=GoZnPdyRfjZScBQE8XcRvw==
https://www.mouser.de/ProductDetail/Panasonic/ECW-F2224JAQ?qs=1CGoW/3pMwq/DEfUrK9bpA==
https://www.mouser.de/ProductDetail/Panasonic/ECW-F2225JA?qs=GoZnPdyRfjaMv23tZi287A==
https://www.mouser.de/ProductDetail...H5WLeE/ZAQV5zYfvGH8IahfdYhAV4FJ%2BM74xf3EoQ==
https://www.mouser.de/ProductDetail...HntbszIh3IVVpVwMRDxpluFHf92YrnK/Ia7%2BBvFYQ==
https://www.mouser.de/ProductDetail/Panasonic/ECW-H8103RHV/?qs=GoZnPdyRfjZLBdoBmljywg==
https://www.mouser.de/ProductDetail...nb%2BR%2Beb4uKeBgyIqkD4KZ23Xs32p3SFWeRug40A==
https://www.mouser.de/ProductDetail/Panasonic/ECW-F2475JA?qs=GoZnPdyRfjbTFkwsw7ZE%2Bg==

Obviously you won't need all of those links for this project, perhaps none. But I am sure that there will be other projects.
I have purchased all of the above caps and stripped the tinning from a lead and checked them under a usb microscope and with a magnet and they are copper.

Cheers,
James
 
analogwisdom said:
I appreciate the advice. I'm still learning about the types of capacitors so I hadn't read about Panasonic ones yet. I will do so!

I'm also still trying to wrap my head around what the signal path truly is. I know you can track it through the schematic and I think I've done this before... But it's usually a single straight line. I like to use tone controls, once you start using them do more caps become in the "signal path"? I need to do more reading...

Your comment about the caps being cheaper on Mouser is funny. It reminds me of my other hobby. I shoot film and love Fujifilm E6 slide film, which is only made in Japan now. A box of it is about 3 times cheaper over here than it is in Japan.
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I am still working on being able to reliably trace the signal path through areas where it is not documented on the schematic. I'm only a few years down the road from where you are now.

Yamaha is usually pretty good about showing the signal path through one channel on the schematic. But they don't always show it through the Tone section. You are correct tho that if Pure Direct or Tone Bypass is not engaged then the signal path is much longer as it goes through the tone section.
The A-1000 is considerably different than the A-700 but the schematic at least shows the signal path through one channel of the tone section and can give you a better idea of what to look for.

I'm thinking that the signal path in your tone section goes through (left) R161, C125, IC103, C133, then I get a bit confused as to exactly which resistors it goes through next as it goes through the tone pots before getting to C143 and R(indecipherable on the schematic from HiFi Engine, looks like 185 or 186?).

In any case C125 (4.7µF) and C133 (2.2µF) I would at the very least replace with Wima MKS2. If you have enough room to get creative with lead bending and make them fit go with ECW.

I would simply deal with that area by replacing all of the resistors in the entire tone control section that are not specifically called for 1/4w fusible with Vishay SFR25 400mW. I don't see any resistors there that are marked as 1/4W fusible. If there are, 1/4w metal film fusible are getting hard to find. Where I don't have 1/4W metal fusible on hand I use Vishay CMF or RN flame proof. But I tend to a bit over the top concerning replacing carbon film with metal film.

SFR25 and SFR16 (small body) are pretty cheap, especially when you buy in quantity.
https://www.mouser.de/c/passive-com...resistors-through-hole/?m=Vishay&series=SFR25

Cheers,
James
 
analogwisdom said:
View attachment 3134216

The foam on top of the transformer was disgusting and kinda just crumbled away when I tried adjusting it so I got the rest off, still need to clean up what's left. Any suggestions on what to replace it with?
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Soundscape said:
Same problem on my M-80...**** canned it. The things a sponge waiting to rot the xfmr IMO. If it hums later on I just turn up the volume F it. Anxiously awaiting chime time from the pro's on this one before I chop up my gardening knee pad and stick it up there.
I imagine Yamaha chose non-torroidal xmfr types to keep hi-fi pieces at a mid-fi cost. Is what it is, some hum will result cushion or not. Strongly recommend tightening the xfmr bolts on the chassis bottom to minimize this. Don't overtighten though due to the rubber bolt washers, just snug bro.

Disclaimer: I rarely offer these technical advisements for free. I accept payment via BeerPal, BeerMo, BeerCoin. Thank you
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I've been using copper foil lately. Strip all that old foam and adhesive from the transformers with a single edge blade. Wipe 'em down with acetone. And apply ......

 
@Bratwurst7s, thanks for all the great advice on parts + signal path. I think I need to be done buying parts for this project right now, but I will definitely keep the things you presented in mind for the future, especially the Panasonic caps tip. The Schematic on HFE is awful, but I bought a paper copy before the amp came and it's a lot better. I'll need to make a good scan of it and get it uploaded for everyone else to use. It's 2024 and data storage is cheap... No reason to not have full-color, full-resolution scans these days!

avionic said:
I've been using copper foil lately. Strip all that old foam and adhesive from the transformers with a single edge blade. Wipe 'em down with acetone. And apply ......

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Thank you for the tip! I appreciate you replying to the thread, I have seen your name a lot searching around the Yamaha forums :D If you have a photo of how you've done it, would you mind sharing? I really don't wanna accidentally screw something up or create conductivity where I shouldn't.
 
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