This is my next project.
I have the sch from Nostalgia Air.
This, of course, is no service manual.
Overall condition is very clean, but the battery connector (the one hanging out) has some wires frayed, and so I want first to take the chassis out of the case.
This is where I am trying to be gentle. I see two screws at the sides that hold the chassis, but I am afraid this is not it.
So, if someone has experience taking it apart, please let me know how I should be taking the chassis out.
Mike.
Update:
Well, I took it out.
Was a snap: the two screws and knobs were almost; the only other thing was disconnecting the antenna from the tuning cap.
Now the fun begins.
Not easy to work on. Good luck!!!
Yeah, this is a weird animal, a 5-tuber, with serialized filaments and direct rectifying of the main power, no transformer.
Well, as one English person put it, I will keep my pecker up (the English don't really care of how it sounds in AE).
Q1: Another question:
I have the volume control pot that seems to work half-a**, that is it changes from 0 to 350kOhms between the wiper and one end, practically does not change between the wiper and another end (from 1M to 900kOhm) and has 1M between the two ends.
But the worst of all, I cannot work the power switch on it. Once it comes to the switching position, it does not move any further, and I tried a pair of pliers (I did not want to apply so much effort so to destroy it, of course, but the effort was sizeable and way more than it is usually required). I made sure the mechanics that closes the tuning dial when the volume is off did not interfere, so it is inside the pot.
The power switch seems to have a gap between it and the front (volume) section so I sprayed a little of the DeoxIT lube inside; no effect.
The pot does not seem to easily lend itself to disassembling.
Q2:
The main filter electrolytic cap (four of them inside, 20, 2x40 and 200uF, I think). Obviously it will need replacement. I pulled the paper sleeve off, and the aluminum can remains. It's base is riveted to the chassis, but the can itself seems to have to twist-tabs that go through the base. I untwisted them and tried to pull the cap off, but so far it is resisting.
Anyone has experience with these?
Try contacting Bob Timms (Joybird) either here or on that other site. He is currently doing a Transoceanic himself and is one of the best radio guys I know.
Thanks TA,
If I could only find his profile to click and send the mail. I'll see if he's there.
Another question:
While at it, I disconnected few caps and measured them (they look really good). All of them so far right on the money. Well within tolerance. I am not sure I want to change them (let alone this being a real pain in the Zenith - very tight assembly and rubber wires). And there is a lot of them too.
Anyone has a good luck with not really throwing the caps out?
Also interesting, the electrolytic cap (4 caps assembly) looks good too. 40uF measure at 56uF, 20uf - at 28uF, 200uF - at 400uF (well, yeah, this one is a bit out there, but then the voltage is low - it is a 10V rated cap).
(04-19-2012, 06:00 PM)morzh Wrote: [ -> ]Another question:
While at it, I disconnected few caps and measured them (they look really good). All of them so far right on the money. Well within tolerance. I am not sure I want to change them (let alone this being a real pain in the Zenith - very tight assembly and rubber wires). And there is a lot of them too.
Anyone has a good luck with not really throwing the caps out?
Also interesting, the electrolytic cap (4 caps assembly) looks good too. 40uF measure at 56uF, 20uf - at 28uF, 200uF - at 400uF (well, yeah, this one is a bit out there, but then the voltage is low - it is a 10V rated cap).
Up to you. Ya got time bombs. If you want the set to play 20 years from now, change 'em all. If you don't care, just listen with pleasure.
Bob's email is deleted per Joybirds request
Mod Note: Email removed - Ipwizard
Thanks TA, I will write him.
(04-20-2012, 11:45 AM)morzh Wrote: [ -> ]Thanks TA, I will write him.
TA Please remove my e-mail address from the post
Thanks
Morzh
Contact mar mopatt , he will fix you up with a new Volume Control Sw assembly
The sw are a weak part on all of the TO radios.
Mine too was bad. Repalced with one from a parts radio for $10
http://www.oldradioparts.net/
Joybird,
Thanks.
I was actually able to disassemble and fix the pot; it was stuck due to the rear half (the switch) getting loose and jamming the shaft. Hence the bad resistance reading - the wiper would not travel to the far end of the element.
I took it apart, DeoxITed it, put a dab of Lithium/WD40, assembled back - the regulator works just fine and the switch works too.
The worst part was the desoldering it - the Zenit companion uses very tight assembly. Had to remove the dial.
Now to restoring the electrolythic - you convinced me.
I have some good 56uF 400V ones, with a high ripple; this can be used in place of 40uF ones, and two in series - for 20uF. Have a very hi-ripple cap for 1000uF/25V, but I have to see if this one can be used for 200uF one.
I fixed the quad electrolytic, and after some doubts and misunderstanding of some power-up behavior (well, the tubes are a bit unusual) I connected the antenna, and the thingy sings like a bird, loud and very clear.
There are of course quite a few paper caps; I am not sure all of them need to be changed, only those exposed to high voltages, I will do this later, plus tuning, of course. The way these radios assembled does not inspire changing a lot. Too tight.
The resistors are within except one of a different type, a 2.2M, which I changed (in series with volume pot).
Thanks everyone.
Re-visiting this one after almost 7 years.
The power cord that at the time seemed ok now has fully crumbled.
While at it I decided to recap which should be easy as the twistlock was fixed back then.
Also tubes will need the pins scraped, as I remember.
And will realign.
Waiting on the cords to arrive while recapping.