Jerry's Gotten-off-butt Yamaha M80 Rebuild Thread

[jbeckva]

So just an update...

Still looking high and low on the sources for the caps. I can get the 33's without too much trouble (more about that below), but all I can really find for the 47's are with 50 wvdc ratings. Anything bigger requires a larger diameter cap, which probably is a no-can-do with the cap clamp that the M-80 has.

But as far as having taller caps, I think I'm going to go a little bit "radical". I can't make up room on the inside (towards the main PCB), and right now I can't go the other way (towards the back) since the stock caps are already butting up against the back panel.

But.. ok... what IF I eliminate that restriction on the back end? And actually put a hole in the back panel so that the caps can poke out the back end a little? Then make a cover so that it all looks "nice"?

I think that'll be what I end up doing. But unfortunately, paycheck's already "spoken for" this pay period (we gotta eat... damn that slight "problem"!)

More after next payday, mehopes...

 

[avionic]

OK Jerry. on my M-80 the actual voltage measured on the main caps are as follows..
The 33K @ 50 vdc actually have 40vdc on them.
The 47K @ 56 vdc actually have 52vdc on them.

 

[jbeckva]

Owch!...thanks for checking tho!

That means I can't go with 50 volts on the 47's. Hmmmm... so what if I went any lower than that as far as capacitance? Yeah... never want to go lower in capacitance - that's the rule. But how much does this beastie really need?

 

[avionic]

Owch!...thanks for checking tho!

That means I can't go with 50 volts on the 47's. Hmmmm... so what if I went any lower than that as far as capacitance? Yeah... never want to go lower in capacitance - that's the rule. But how much does this beastie really need?

But how much does this beastie really need

Yamaha engineers seem to think...The 33K @ 50 vdc &
The 47K @ 56 vdc

 

[jbeckva]

Damn.. aint gonna "enable" me eh?

Need to go dumpster divin' in a old mainframe surplus shop or somethin...

 

[Fast Forward]

I,m starting to get a Woodrow

 

[jbeckva]

Well, looks like these here are going to be what I go with (oww... $66.00 apiece!)

http://www.newark.com/epcos/b41560a8479 ... dp/13J5284


Still going to need to mod the back end tho.

 

[avionic]

Well, looks like these here are going to be what I go with (oww... $66.00 apiece!)

http://www.newark.com/epcos/b41560a8479 ... dp/13J5284" onclick="window.open(this.href);return false;


Still going to need to mod the back end tho.

See that $20 handling charge as well from Farnell..

 

[laatsch55]

Did you check Apex Jr????

 

[Web Police]

Still going to need to mod the back end tho.

Sacrilege.

 

[jbeckva]

Sacrilege.

Nah, I don't see it like that. I think it's going to look pretty cool when it's all done.

Can't find the "exact" caps nomo! So adapt n overcome.

 

[jbeckva]

Did you check Apex Jr????

Yeah, highest they had >50wvdc were 22K's

 

[stuwee]

Well, looks like these here are going to be what I go with (oww... $66.00 apiece!)

http://www.newark.com/epcos/b41560a8479 ... dp/13J5284" onclick="window.open(this.href);return false;" onclick="window.open(this.href);return false;


Still going to need to mod the back end tho.

See that $20 handling charge as well from Farnell..

And they place all the dohickey accessories in there, like the grocery stores, impulse items near the check-out, bastids

Do you expect and sound diffs with all these changes??

 

[jbeckva]

Since the caps I pulled have leaked electrolyte, yup.

 

[avionic]

So..Whats the plan? How about a "stand alone " capacitor bank? Just thinking outside the box here..

 

[laatsch55]

Wit amphenol 4 prong connectors, MS 3106 style.

 

[jbeckva]

So..Whats the plan? How about a "stand alone " capacitor bank? Just thinking outside the box here..

Didn't I say above? Heh.. yep, this does involve "outside the box" thinking.

THE ISSUE - Caps I can find are too "tall" i.e. they are the right diameter, but since they are laying on their sides, one end against the back metal plate, the other hindered by the circuit boards (above and below), then they have to be 63.5mm or less in length. The only ones I can find are 105mm in length.

THE SOLUTION - I can't go in the direction of the circuit boards, as that would mean sawing off said circuit boards and probably losing "valuable components" in the process.

BUT... I can go the other direction i.e. towards the back panel/metal plate. But peeps will say "the back metal plate is there.. what will do you do about it??". Well... I'm going to put a big ole hole in the back panel so the extra 2 inches of cap can "protrude" out the back end of the amp. If I can get fancy enough (and with the right tools), I'd like to make the hole actually 4 "holes" - each to just clear the caps, and circular. If not, then one big square will do it. I have the square cap clamp to use as a guide.

BUT (but number two.. and most important)... I can't do anything until next Friday, or maybe longer than that, because these daggone caps cost a small fortune.

 

[Fast Forward]

I amire you guys who have the knowledge and patience to tackle these re-builds,,,

 

[Web Police]

You can mount the caps sideways or up and down? Or maybe hollow out the original caps and make a higher rated cap out of a some of smaller ones? I saw a Sansui or a Pioneer receiver where they did this.

 

[laatsch55]

Marantz I think it was Web. On ak, couple guys did it, are we talking about the same thing?