Breaking MX-1000 out of long term storage

[Millspec96ss]

I have been reading alot of posts and have learned a ton by reading. Thanks for all of the education. I have a Yamaha MX-1000 that I purchased new when I was stationed in Japan in the early 90's. It's been in the box and always stored indoors since about 1998 or so. I unboxed it and it appears to be in excellent condition just like when I put it away. I want to make sure that I take all the precautions in order to (hopefully) power it up without a meltdown. I was an electronics tech in the military, so I have at least a basic electronics background. I believe I can tackle simple inspection steps and some meter measurements.

Any suggestions would be appreciated.

George

 

[avionic]

I was an electronics tech in the military,

Welcome to AK.. What branch ? Thank you for your service. As well. MX-1000 is a real nice piece of gear.

 

[Millspec96ss]

I was USAF as well. 1981-2006. Thank you for your service as well. I figure I can remove the cover and give it a basic visual inspection and clean some of the dust out, but what I have read about the tendency of the caps going south has me a bit nervous.

 

[avionic]

That amplifier has some unique ,near impossible to find, large smoothing caps.

 

[avionic]

That amplifier has some unique ,near impossible to find, large smoothing caps.

Saving the originals is the best option.

 

[rottalpha]

Welcome to AK and thank you for your service!

That is a really nice amp you have. This amp was for export only. It never sold to the Japanese market. Is rarely that we got something nice and the Japan didn't.

Avionic is our Yamaha resident expert, so you are in good hands.
A couple of suggestions I would make:
If you purchased in Japan, your amp has a voltage selector. Make sure it is set to 120v and not 115v.
Bring the amp up with a variac. The main caps are one of the two sets of components that are unobtanium in these amps. Luckily, they are really good quality and rarely go bad. But do not take any chances, so start the amp with a variac and allow ample time to reform those caps.

 

[avionic]

Might be handy. Lets hope not.
http://sportsbil.com/yamaha/mx-1000-sm.pdf

 

[avionic]

As well as...
http://sportsbil.com/yamaha/mx-1000-s.pdf

 

[avionic]

Closely inspect the solder connections of the TO-126 transistors (Q511 - 516)... These transistors in the voltage amplifier circuit. Normally run pretty warm and tend to develop annular cracks in the solder around the components lead. I wiggle the transistors while observing the solder connections under magnification. A cracked connection stands out , like a sore thumb.

 

[avionic]

As preventative maintenance. I definitely always reflow the soldered connection for those transistors. And any other iffy looking connection.