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

[jbeckva]

Just recieved a couple of these a week or so ago.From Parts Connexion. For another DIY project.

MUNDORF-70414 QTY ADD
47000uf / 80VDC, MLytic® HC, 90mm x 75mm, 5 ESR (mOhm)
$99.26 $99.26 pcX USD Price

yow!!.. see? lol

Those 'r too wide for the '80 tho. The one's I have my eyes on are 63.5mm which is the same as the originals. Thing is they are also 108 tall, hence the necessity to bust out the back panel and have 'em stick out a little bit. I do think it'll look pretty darn "neat" when it's done.

 

[laatsch55]

nOTHIN CHEAP ABOUT YOU!! Mr. Dave!!!!

 

[avionic]

Just have to refurb another M-80 to cover the costs.

 

[laatsch55]

Just have to refurb another M-80 to cover the costs.

No shortage of those????

 

[jbeckva]

Ok, back to it methinks...

Since it's not going to be possible to get the caps with the exact dimensions, and I'm thinking too that punching holes in the back side probably isn't too good either...

I'm thinking now of standing all 4 caps up in front of the PCB with standoffs and clamps, then running heavy guage jumpers with terminals on the cap end from the PCB to the caps...

So to visualize it... look at the cavity between the two heat sinks, and visualize 4 big caps standing up and running the length of it. Run heavy buss bars between each "pair" for the common connections, then heavy cables going to the PCB in the back end. For the standoffs I am thinking of rods that span the entire front to back space.

Hmmmm... we'll see when the caps come in! But one way or another, those caps are going.. to.. FIT!

 

[stuwee]

Ok 'lil Cookie, you do that, just make sure you test fit, before you franken weld the bussbars or you'll be sorry

 

[jbeckva]

I'll superglue the things to the top if I haveta

 

[orange]

Don't they have clamps at the bottom? Are these larger or smaller?

If smaller, can't you stuff the old cans like an antique radio?

 

[avionic]

Get yourself a ESR meter.Check the condition of the other 3 bigass caps. Find a M-80/M-85 parts unit.

 

[jbeckva]

Get yourself a ESR meter.Check the condition of the other 3 bigass caps. Find a M-80/M-85 parts unit.

Actually both 47's are leaking.

Nah, I got the caps today... this M80 is going to be one bad mofo tho, because the 47's (well, 48's actually) are the SIZE OF FOSTERS BEER CANS!!

Heheh... I got "idears"... but nothing quite yet. What I might do is build an external enclosure and hook it up via heavy duty molex's...

pics later.. ya gotta see the size of these caps!

 

[avionic]

Get yourself a ESR meter.Check the condition of the other 3 bigass caps. Find a M-80/M-85 parts unit.

Actually both 47's are leaking.

Nah, I got the caps today... this M80 is going to be one bad mofo tho, because the 47's (well, 48's actually) are the SIZE OF FOSTERS BEER CANS!!

Heheh... I got "idears"... but nothing quite yet. What I might do is build an external enclosure and hook it up via heavy duty molex's...

pics later.. ya gotta see the size of these caps!

As in a "stand-alone" filter bank..

 

[jbeckva]

Yuh huh, yup. I don't think I can fit these godzilla-sized caps in there, anywhere..

 

[avionic]

Ok, so finally... getting to the task of rebuilding the M80. Here's the "before" pics..

Overall. Yeah, it can use some work...

Seems either it has been worked on before, or someone at the factory needed to learn how to use the alcohol and kimwipes afterwards... yuck.. all of these will be reflowed (8 of 'em per channel)

Gotta do some corrosion control on these here..

And this here? That's the main input that goes into a nasty ribbon. I think that will be replaced by some decent shielded cable.

Another wider view. I think I"m going to do some rewiring all around to make it look (and probably sound) better.. and not a rat's nest..

Then I have some caps to take care off. Here are the big bama-jama's. Looks like a blowtorch will be required to unsolder.. heheh... There are four total, and encapsulated in a plastic case of some sort. Sooo.. whatever I do get to replace should be pretty darn close to the same dimensions.

And then on the main PCB there are a few more to take care of.

I'm going to take my time and do 'er right. More coming as progress is made!

I have one of these--Basket cases.. LOL

 

[jbeckva]

I have one of these--Basket cases.. LOL

NOPE.. not at all. It will be rebuilt, with the godzilla caps, and it'll kick the crap outta anything when it does. I don't have all the parts yet or the time, but I'm far from throwing it out in the trash...

LOL.. or you'll hear a BIG BOOM all the way from VA the first time I power it up again. And THEN .. yeah.. probably...

 

[avionic]

I take it this piece was aquired DOA..Have you checked all the Sanken outputs yet?
Suitable Sanken MT-200 style outputs are available from BDEnterprise. Bdent.com

 

[jbeckva]

No, not DOA.. had it running for a good year or so, but it seemed to be lacking in a few ways. Hence this thread on rebuilding 'er. Lack of bass was a gradual thing, I think. Just enough left in the caps to deteriorate over the year.

 

[avionic]

Lack of bass was a gradual thing

Most likely the main filter caps was the root cause.

 

[avionic]

Well should you or anyone else need them..
The OEM outputs are...
2SA1169 & 2SC2773's 15 amp devices.----Replace with these 17 amp outputs
2SA1494 & 2SC3857's

 

[jbeckva]

Lack of bass was a gradual thing

Most likely the main filter caps was the root cause.

Yep, but they sure won't be when it's all done...

Here's what's "going to fit, come hell or high water".. Next to it is a typical 10K 80V cap...

But daaayum.. as you can see, two of them have a very slim chance of staying inside the amp... let alone the two 33K's when I find what I want there...

 

[avionic]

Just a wee bit to large...
How much did those set you back ?