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Here's what happened yesterday with my Mac
#4

This story has the second part to it.
I was playing my Nakamichi ZX-9 when it all happened.

When old tubes went back in, I heard only one channel working, so the crap was scared out of me.
I though "there go my Klipsches".
Switched the channels....no, Klipsches worked.

Then I swapped the output tubes...nope, same thing. The crap loudly complained about being scared, I literally had to cheer it up. He thought it was the output transformer.

And then....I noticed that just one channel of my Nak was having the indicator running. The other was dead.
I decided to play with the cable....no, the Nak was outputting just the right channel. Plus, there was a problem with one of the RCA outs GND. It wasn't there.

So today I put my Nak on the bench, opened it up....The Devil would break a leg inside it.
But first things first - the GND.
The Nak's 4 RCA jacks have their GND coming to them from a shiny metal plate to which they are fastened by staple-like brackets, and then the plate gets the GND from the cables coming from inside, by wire-wrap. three connectors were OK, one had intermittent or no GND. One bracket got just a little loose from reinserting the cables, but it was not noticed as the other channels provided the GND. But when I tested one jack at a time I discovered this.
I simply soldered the brackets to the plate - both were solderable.
One down, one to go.

Put the Nak to the stand, play a tape.....for a few seconds the other channel appeared, and then went away.
So, before I dug into it, I though - what if it is the head azimuth?
So I took a blank cassette and performed azimuth alignment.

After that all my cassettes played fine, I played several songs from various tapes, all was OK.

So what I think happened was, due to the voltage surge, the uProcessor screwed the azimuth data. What threw me off, one channel played OK, so I thought it was the signal path of the other channel. Good thing I tried the simple theories first!

Now I filed the case with eBay; I am not accusing the guy of anything but two of his tubes that he promised would test as NOS were simply weak, one was 1/4 value and less than 2/3 into "replace" on the English scale with the second triode in it testing as new. I photographed it and sent to eBay.
Not an awful lot of money but I think these tubes are iffy. Even if they work in fully AC-coupled circuit (which is likely how he tested it) it does not mean they work in mine.

Well, I am done troubleshooting for today. It's the bourbon time!

People who do not drink, do not smoke, do not eat red meat will one day feel really stupid lying there and dying from nothing.


Messages In This Thread
RE: Here's what happened yesterday with my Mac - by morzh - 11-13-2016, 09:00 PM



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