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 Post subject: Zenith Royal 500D (early) project...
PostPosted: Feb Fri 07, 2014 3:43 am 
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Joined: Oct Mon 26, 2009 10:02 pm
Posts: 5738
Location: Indianapolis, IN
Hello All,

I'd been looking for one of these since it was the first of the "500" series with an RF amp stage and still had the simple, "durable" early styling which is my favorite. Finally found this one at a reasonable "Buy It Now" price (with an "instant" 10 % off coupon from Ebay !)---and it was actually in better shape than I thought from listing pics ! Several areas which looked scratched & scuffed were actually oily finger smudges---nylon very shiny after cleaning ! The back side does have several scuffs which I don't think will polish out, however... Scratches on aluminum "control panel" which looked really bad from flash are just slightly noticeable in person... One battery contact appeared almost "eaten away" by corrosion in pic, but piece itself was fine after removing leakage residue with Q-tip & Windex as were all others... And the kickstand looks new ! It came with its original case & shoulder strap which looks good and feels like real leather, though somewhat stiff...

Was shocked, though, on how thin the nylon case is on this radio---guess Zenith was trying other cost cutting measures at this time ! Looks about half the thickness of my 500B and later model 500E's. And the tension of the kickstand arms had actually deformed case back by pushing the sides in noticeably---wonder if our resident Zenith expert, Brett Buck, has seen this before and knows if it could be repaired by carefully spreading sides back to normal position and applying heat (hairdryer) ???

After cleaning battery compartment (rest of interior appears very clean & untouched), installed batteries and turned on---volume control a bit noisy as is tuner, but radio very sensitive/selective as expected. But the audio is terrible---plenty of it, but very tinny ! Doesn't even sound as good as the "B" & "E"'s... Hopefully just an electrolytic cap issue...

Had almost made it through entire month of January without acquiring another radio---then three right at the end ! Oh boy...

Will post pics & more when able...

EDIT: After five years, finally ran across a pic of an owner's booklet for the "early" 500D which proves that this is indeed that model---so modified subject line...
John


Last edited by xrhonda91 on Feb Sun 10, 2019 6:11 pm, edited 1 time in total.

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 Post subject: Re: Zenith Royal 500C project...
PostPosted: Feb Sat 08, 2014 3:08 am 
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Joined: Oct Mon 26, 2009 10:02 pm
Posts: 5738
Location: Indianapolis, IN
Below are a few Ebay pics...

Hoping to get this radio back in "shape" this weekend...

John


Attachments:
ARF 500C BAT CONT EBAY.jpg
ARF 500C BAT CONT EBAY.jpg [ 140.86 KiB | Viewed 4246 times ]
ARF 500C EBAY BK.jpg
ARF 500C EBAY BK.jpg [ 116.83 KiB | Viewed 4247 times ]
ARF 500c EBAY FRT.jpg
ARF 500c EBAY FRT.jpg [ 142.34 KiB | Viewed 4247 times ]
ARF 500C W-CASE EBAY.jpg
ARF 500C W-CASE EBAY.jpg [ 147.17 KiB | Viewed 4247 times ]
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 Post subject: Re: Zenith Royal 500C project...
PostPosted: Feb Sat 08, 2014 7:06 pm 
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Joined: Sep Sat 29, 2012 6:32 pm
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I was not aware that Zenith made a model 500C and I can't seem to find anything about it. I have a white Zenith 500D (chassis 8AT40Z2) that I recapped but it still doesn't sound very good unfortunately, although that may be due to the speaker cone being warped. Your set looks like it should clean up very well, mine is very beat up, so I have put as much time into it as I intend too (I am on the lookout for a better example).


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 Post subject: Re: Zenith Royal 500C project...
PostPosted: Feb Sun 09, 2014 2:50 am 
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Joined: Oct Mon 26, 2009 10:02 pm
Posts: 5738
Location: Indianapolis, IN
From what I've read, the "C" designation has been "unofficially" applied to the first RF amp equipped set introduced just prior to the 500D---the chassis is identical. Guess I should have mentioned this earlier... Is yours an actual "D" with script on front below crest ? If so, does it have the "inverted cone" speaker ?

Spent a little time this evening trying to disassemble in preparation for recapping, but could not remove the tuning knobs ! Since they are recessed and the clear one is fairly fragile, couldn't figure a way to get enough leverage on opposite sides to pop 'em off... Any "safe" ideas ???

Injected some Faderlube into volume control and cleaned tuning cap plates with folded paper and Isopropyl alcohol and they're both fine now...

Can't do anymore until I remove those tuning knobs ! And still wonder if heat from a hairdryer would be enough to help reform the kickstand tension "depressed" back cover sides ???

John


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 Post subject: Re: Zenith Royal 500C project...
PostPosted: Feb Sun 09, 2014 3:24 am 
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Joined: Jan Sun 06, 2008 3:28 am
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Location: Richmond, VA
It's also called the 500RD. Does it have chassis 8AT40Z2? SAMs lists it as the RD in Set 422, Folder 17.

It's my understanding all RD's had chassis 8AT40Z2 and preceded the actual 500D. It's a transitional model between the B and D.

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 Post subject: Re: Zenith Royal 500C project...
PostPosted: Feb Sun 09, 2014 4:14 am 
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Joined: Oct Mon 26, 2009 10:02 pm
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Location: Indianapolis, IN
Hello Ed,

Yes, it does have that chassis---and the service info for the actual "D" model also lists that number.
Think I remember you mentioning that "RD" before in an earlier thread...

Do you have any "tricks" for removing the tuning knobs safely? These just won't budge...

John


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 Post subject: Re: Zenith Royal 500C project...
PostPosted: Feb Sun 09, 2014 4:53 am 
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Location: Richmond, VA
I do have an RD, although I thought it was a D when I got it. True 500D's have a smaller Zenith badge in the center and the logo "500D".

For stubborn knobs, if space permits, I use a stiff bladed scraper/putty knife with cardboard or something similar under the blade to protect the case. On the 500RD, you have vernier tuning, so the small knob is just on the round splined end of the tuning shaft, and should pull right off. The clear plastic knob with the station frequencies is on the larger part of the shaft, which is a D shaft, but it should pull straight off once the smaller knob is removed.

If you pry it loose with something like a putty knife, just work slowly and carefully as it would be easy to damage the finish or break the clear knob beneath it. But both should come straight off in time.

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 Post subject: Re: Zenith Royal 500C project...
PostPosted: Feb Sun 09, 2014 5:23 am 
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Location: Indianapolis, IN
Thanks Ed---but as you know, the clear knob is dished and there is no way to get anything safely between it and the black outer one except fingernails. And I can get a finger on each side, but knob is so tight that I can actually pull tuning cap up in attempt ! Will try again tomorrow---maybe make a puller from two very thin strips of steel with bent ends and place a couple small pieces of thin plastic beneath to protect lower knob's surface...

By the way---how's the sound quality on your "RD" ?

John


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 Post subject: Re: Zenith Royal 500C project...
PostPosted: Feb Sun 09, 2014 6:20 am 
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Location: Richmond, VA
It is clearly the best of my three, a 1st generation hand-wired, second generation PCB, and the 500RD. There is a clear progression in sound quality from model to model. I think it is quite good, but I'm sure the later models were even better.

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 Post subject: Re: Zenith Royal 500C project...
PostPosted: Feb Sun 09, 2014 10:25 am 
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Joined: Feb Fri 27, 2009 11:43 am
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Location: Tucson Az
I don't know if this will work but maybe you can pull the chassis without removing the knobs first. With luck the case will push the knobs off as you pull the chassis back.

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 Post subject: Re: Zenith Royal 500C project...
PostPosted: Feb Sun 09, 2014 3:03 pm 
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Maybe a few seconds with a hair dryer (not a heat gun) will expand it and loosen gunk enough for it to pull off. I don't think the nylon cases are rigid enough to try and pull the chassis out wihout getting the knobs off first. If your wife has one of those thin rubber grippers for twisting off jar lids, you could try gripping the knob with it and rocking it as you pull.

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 Post subject: Re: Zenith Royal 500C project...
PostPosted: Feb Tue 11, 2014 3:02 am 
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Joined: Oct Mon 26, 2009 10:02 pm
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Location: Indianapolis, IN
Thanks Guys...

No luck again with fingertips---and was pulling so hard that the tuning cap was flexing PCB which is not a good thing !

But, got an idea to make a "puller" from some thin steel strips and found some strong, but thin & small strain-relief inserts in junk-drawer at work which looked promising. They had holes in both rounded ends for #4 screws---so thought that a threaded stand-off would make a good handle while the rounded ends would be less likely to damage inner knob during insertion. Found a 3/4" stainless stand-off in another junk stash and it looked like just the "thing"...

Got home tonight and bent one end of each insert to fit under knob and attached both to the standoff with 4-40 screws. Cut and folded two small strips from a polyethylene bag to protect inner knob's surface and inserted beneath outer knob using a piece of stiff paper between folds to slide them in. Then carefully put both bent ends of "puller" below lip of outer knob---they slid right in on top of slick poly "protectors"... Tightened screws after centering puller on knob, then pulled center of "standoff handle" with a very gentle "rocking" motion and knob popped right off !!! The lower knob then came off easily with fingertips...

Below is a pic of the simple, but safe & effective home-made "tool"---think it would help many others in same situation...


Attachments:
ARF KNOB PULLER 2-10-2014.jpg
ARF KNOB PULLER 2-10-2014.jpg [ 217.68 KiB | Viewed 4149 times ]
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 Post subject: Re: Zenith Royal 500C project...
PostPosted: Feb Tue 11, 2014 4:45 am 
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Location: Richmond, VA
Great innovation! Glad you were able to get the knob off without any damage. Could you tell why it was so hard to get off?

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 Post subject: Re: Zenith Royal 500C project...
PostPosted: Feb Tue 11, 2014 10:21 am 
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Joined: Jan Thu 01, 1970 1:00 am
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Location: SoCal, 91387
xrhonda91 wrote:
found some strong, but thin & small strain-relief inserts in junk-drawer at work

Goofing off at work, are we? :wink:

Very innovative knob puller; contact AES and see if they would be interested in carrying them...

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 Post subject: Re: Zenith Royal 500C project...
PostPosted: Feb Tue 11, 2014 3:39 pm 
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Joined: Oct Mon 26, 2009 10:02 pm
Posts: 5738
Location: Indianapolis, IN
Thanks Guys !

Sometimes necessity is truly the "Mother of invention"...

Ed---couldn't see any reason visibly. It was very clean beneath and didn't appear that the knob had ever been removed. The radio is from Arizona, however, and maybe it was stored in a very hot environment which caused the plastic to bond somewhat with shaft ? The case itself is sure "warped" inward on both sides where the kickstand mounts !

Fifties---it is very slow right now at work as we wait for the customer to provide parts & info required for project & deal with the poor data they've already provided... Think maybe that puller idea should be in our "Hints & Kinks" forum ? The basic idea could be adapted to many knob types...

Have the day off, so am hoping to complete recap...

John


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 Post subject: Re: Zenith Royal 500C project...
PostPosted: Feb Tue 11, 2014 4:02 pm 
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Very ingenious John!

Colin


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 Post subject: Re: Zenith Royal 500C project...
PostPosted: Feb Tue 11, 2014 4:04 pm 
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Location: Richmond, VA
That warping at the waist of the radio seems to be very common. I have it on two of my 500's and the same problem on an Emerson 888. I think the pressure of the stand over the years gradually the deforms soft "Nevabreak" plastic. They never claimed it was "Nevabend." :roll:

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 Post subject: Re: Zenith Royal 500C project...
PostPosted: Feb Wed 12, 2014 1:44 am 
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Joined: Oct Mon 26, 2009 10:02 pm
Posts: 5738
Location: Indianapolis, IN
Thanks Guys...

Sure hope I can straighten out the sides somehow---wish it had been "unbendable" as well as unbreakable Nylon, Ed !

Got the new caps installed today... Since replacements were so small, relocated them on PCB and used the yellow sleeving from old cap leads to help new parts "blend in" a bit. Radio now working great ! Excellent performer with decent audio and more volume than speaker can handle. C50 (50 uf) driver bypass cap and C5 (3 uF) AVC filter were completely open and C18 (50 uf) main supply filter as well as C16 (3 uF) audio coupling cap were "almost gone"... Also "gone" with cap replacement are the subtle "oscillations" and noise across entire band as well as the slightly distorted, very "tinny" audio...

Just need to finish cleaning case, knobs (and hopefully straighten case back sides !) and reassemble. Found while cleaning the knobs on my 500"B" that even dilute dishwashing liquid attacked the black plastic, so will simply use a toothbrush and water on these.

Put chassis back into case temporarily without knobs for "testing" and am listening to Zoomer 740 right now---just couldn't wait !

Here are a couple pics of completed chassis---notice that the battery contacts look nearly new after cleaning, thankfully:


Attachments:
ARF 500 CHS CMP BOT.jpg
ARF 500 CHS CMP BOT.jpg [ 202.89 KiB | Viewed 4108 times ]
ARF CHS CMP TOP.jpg
ARF CHS CMP TOP.jpg [ 194.45 KiB | Viewed 4108 times ]
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 Post subject: Re: Zenith Royal 500C project...
PostPosted: Feb Wed 12, 2014 1:58 am 
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Joined: Jan Sun 06, 2008 3:28 am
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Location: Richmond, VA
I hope you come up with a way to straighten the sides. I bet a few of us would be interested in that!

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 Post subject: Re: Zenith Royal 500C project...
PostPosted: Feb Wed 12, 2014 3:38 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 550
Location: N.E. Florida
I'll sign up for one of those pullers!!

I have a 500D that I never opened. Maybe it's time.


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