Nak 670ZX

J!m

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#1
So, I pulled this out of the Drumgeon the other day.

Those with longer memories than mine, recall this is in good working order other than the meter being stuck. I seem to recall it was a "mechanical" fix- something needs bending/tweaking and then they will swing freely again. I can't find that thread/post, so I'm starting this to try and lure in the relevant people (@nakdoc perhaps?). "Tape path cleaned, and head demagnetized. Belts good and fully functional other than the meters, which are stuck."

I popped the hood and can see the back of the meters. The front needs to come off to do anything more, but before I start losing screws, I figured I'd pause and ask (unusual for me). I also checked the tires and belt, and all looks to be in good order. I have not applied power yet. I'll probably clean it again before I put the cover back on anyway. (Found a used q-tip in there from the last guy...)

Observations: I can't see anything wrong mechanically. I don't see the needles in contact with the scale anywhere. They do have an odd bend at their base (coming off the coil/rotor) but they both seem to be bent the same, so I guess that's "correct". I'm wondering if they got magnetized somehow. Tapping the back of the meter case (where the rotor is) doesn't do diddly.

There is a seller on ebay with a digitial "upgrade" meter set that drops in. Maybe if I was keeping it, I'd go that route. No, I'd want the mechanical meters working properly.

It does have an enviable build quality. Fair bit of steel along with the plastic. I like the compound action of the tape door too. I see why people like them.
 

J!m

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#2
Thinking on this... is it possible for the pivots of the meter rotor to come out of their settings? Maybe from a HARD jolt?
 

J!m

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#4
Hairsprings are attached at both ends on both meters. I’m wondering if adjusting the slotted screw (holding the pivot I assume) is the right thing to do?

IMG_2132.jpeg IMG_2133.jpeg
Bulbs do not appear to be putting pressure on the pivot mount.
 

J!m

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#6
Why do you think that? I can regulate a wrist watch I think I can deal with these massive things. I’m just not going to bother if that won’t help whatever the problem is.
 

George S.

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#7
I'd pull the meters and try to separate the meter case with safety razor blades. It'll probably pop right open with a little work as the meter bulbs should be a serviceable item.
If the springs look good, then the pivots are probably tight.
Perhaps the prior "mechanic" overtightened the mounts or put too much pressure on them, squeezing them.
A slight turn of the adjusting screw while watching the mechanism may gain you insight on the issue.
 

J!m

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So, I opened her up and applied a bit of leverage on the outer meter pivot mounts, and they fell toward -40.

So, I need to lift one side of the bulbs for access to the adjustment screw and back it off a hair. That seems to be the fix.

I’ll clean all the lenses while it’s apart too.

IMG_2134.jpeg IMG_2135.jpeg
 

Vintage 700b

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#10
So, I opened her up and applied a bit of leverage on the outer meter pivot mounts, and they fell toward -40.

So, I need to lift one side of the bulbs for access to the adjustment screw and back it off a hair. That seems to be the fix.

I’ll clean all the lenses while it’s apart too.

View attachment 85518 View attachment 85519
Thats got to feel good Jim.
Knew you'd get it.
Nice work.
 

Hexis22

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#11
So, I opened her up and applied a bit of leverage on the outer meter pivot mounts, and they fell toward -40.

So, I need to lift one side of the bulbs for access to the adjustment screw and back it off a hair. That seems to be the fix.

I’ll clean all the lenses while it’s apart too.

View attachment 85518 View attachment 85519
Nice no cost fix.

I don’t find many of those.
 

J!m

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#12
All set. Doing a full detail while the front is off. All the switch openings have dust/nicotine in them. This thing is in nice cosmetic shape…

IMG_2136.jpeg IMG_2137.jpeg IMG_2138.jpeg
The right meter is not coming all the way down but if I manually bring it up to full and let it fall that’s where it rests.

Left one is pretty close to the bottom.

Cleaned all the lenses on the inside while it’s open.
 
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#13
Why do you think that? I can regulate a wrist watch I think I can deal with these massive things. I’m just not going to bother if that won’t help whatever the problem is.
You must have steady hands. Me, not so much with things that small.
Glad all is now well.
 

J!m

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#18
I put together a pile of recorded and blank cassettes this morning... and left them on my desk at home.

I did bring in the headphone amp and headphones at least, but o testing today.
 
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