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 Post subject: Royal 500E-1 "freebie" project...
PostPosted: Aug Fri 27, 2021 8:37 pm 
Member

Joined: Oct Mon 26, 2009 10:02 pm
Posts: 7095
Location: Indianapolis, IN
Hello All,

An ARF friend kindly sent me some parts for a project recently and said he was including a "freebie" which turned out to be dirty, complete, very well used Zenith Royal 500E-1 from 1964. Had paint splatters and smears (as well as a couple of small "globs" of dried tar) and back is badly scraped/scratched from being slid around on rough surfaces. But the inside was amazingly clean including the battery compartment which didn't have a trace of battery leakage residue, only a bit of dust. Apparently an earlier owner kept an eye on their batteries ! The biggest mess was from the sticky, "decomposing" battery-pull ribbon which left residue on plastic in areas that had to be scrubbed off with isopropyl alcohol. When ribbon removed, it also ripped out a section of the battery cover label which it had "glued" itself to...

Installed batteries to see what it would do, and all I got was a "pop" when turned-on---at least speaker good ! Tapped on PCB and would intermittently get very poor reception at top end of dial as well as squealing and distortion. Seems these PCB's are prone to cracking at tuning cap mounting plate ground tab due to stress and symptoms indicated this issue. Temporarily grounded connection and radio worked well with very good sound ! Installed two lead-clipping jumpers (see pic below) and radio worked great until PCB flexed and erratic squealing and distortion returned. After carefully inspecting PCB for other cracks, gently tapped & slightly moved all components and discovered that just touching top of AGC filter cap would cause the problem. Looked at solder connections and found that the positive lead (which was also used by factory as a ground jumper) had a cold solder joint and was loose at that land ! Quick resolder and radio worked great without issue ! IF alignment was nearly dead-on as it was and performance very good, but dial uniformly off across band. A small tweak of the OSC trimmer brought it back where it should have been and all stations now back on their "marks". After readjusting ANT trimmer (screw nearly all the way out), performance now excellent across entire band ! And the sound quality was amazing for one of these sets, even though speaker has some slight warpage and with chassis out of cabinet ! The volume control is also amazingly "noise-free" ! Carefully brushed the light dust off of chassis with soft, dry toothbrush and blew off with compressed air. Even though battery compartment clean, went over contacts and all with Windex and Q-tips to remove light film of dust.

The "E-1" chassis is basically a "cheaper" version of the "E" with OTL (no audio output transformer) and "soldered-in" transistors. It also uses the Zenith "Integnets" to replace many discreet components.

Spent hours detail cleaning "cosmetics". The paint spots/smears (and tar) came off cabinet with some effort using isopropyl alcohol. The finish is so fragile on the escutcheon that I just carefully cleaned it with soft-toothbrush and cold dish-soap solution. Was able to very carefully remove paint spots from knobs with fingernail and thin, flexible piece of plastic. Had to go over them many times with Novus-2 to restore clearness. The inner aluminum volume knob plate was loose, so after removal for cleaning, reattached from back-side with small bead of hot-glue.

When I'd first seen the convex speaker grille on this model, I thought someone had "pushed it in" until others were seen online. Had no idea then that it was a "feature" of the "E-1" version. This one had a few minor dings that I was able to carefully press out against finger from behind using the flat end of X-acto knife handle. The grille was also loose in retaining ring, so rotated it to proper position (notched at top) and pressed all ring tabs tight against cabinet.

After reassembly, was still amazed at the sound quality of this model---best of any of my Royal 500 collection other than the "H" which uses that special, large elliptical speaker. Very clean & clear with good fidelity---guessing the OTL output and specific speaker type used in this set ? All electrolytic caps are original and since the radio performs & sounds so good, decided to leave 'em in ! My Royal 280 uses similar, but newer chassis and it definitely doesn't have as good of sound...

Glad that Henry posted on one of these awhile back as I'd never had or seen one in person until now and it is an impressive radio other than that poorly wearing escutcheon---though this one is much better after cleaning than either of the two "E's" I've had since childhood.

Am listening to favorite oldies station on it now...

Pics below... Thanks again, R. K. T. !

John


Attachments:
01ARF 500E-1 PCB CRACKED TRACE REPAIR  8-26-21.jpg
01ARF 500E-1 PCB CRACKED TRACE REPAIR 8-26-21.jpg [ 355.16 KiB | Viewed 532 times ]
02ARF 500E-1 AGC CAP +LEAD  COLD SOLDER 8-26-21.jpg
02ARF 500E-1 AGC CAP +LEAD COLD SOLDER 8-26-21.jpg [ 310.74 KiB | Viewed 532 times ]
03ARF 500E-1 CHS CLN BOT 8-26-21.jpg
03ARF 500E-1 CHS CLN BOT 8-26-21.jpg [ 560.6 KiB | Viewed 532 times ]
04ARF 500E-1 PCB CMPLT BOT 8-26-21.jpg
04ARF 500E-1 PCB CMPLT BOT 8-26-21.jpg [ 805.63 KiB | Viewed 532 times ]
05ARF 500E-1 CAB PRTS CLN IN 8-26-21.jpg
05ARF 500E-1 CAB PRTS CLN IN 8-26-21.jpg [ 940.77 KiB | Viewed 532 times ]
06ARF 500E-1 CAB PRTS CLN OUT 8-26-21.jpg
06ARF 500E-1 CAB PRTS CLN OUT 8-26-21.jpg [ 1007.75 KiB | Viewed 532 times ]
07ARF 500E-1 CMPLT INS 8-26-21.jpg
07ARF 500E-1 CMPLT INS 8-26-21.jpg [ 521.05 KiB | Viewed 532 times ]
08ARF 500E-1 BATT CVR LBL 8-27-21.jpg
08ARF 500E-1 BATT CVR LBL 8-27-21.jpg [ 636.71 KiB | Viewed 532 times ]
09ARF 500E-1 CMPLT FRT 8-27-21.jpg
09ARF 500E-1 CMPLT FRT 8-27-21.jpg [ 612.64 KiB | Viewed 532 times ]
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 Post subject: Re: Royal 500E-1 "freebie" project...
PostPosted: Sep Wed 01, 2021 1:18 am 
Member

Joined: Nov Wed 14, 2007 11:37 pm
Posts: 1498
I've got one of those in slightly worse condition with surface corrosion on the faceplate. If I remember correctly this model was from early 60s and used the same chassis as the royal 285 from 1964. Replaced the agc cap all others original. Used as beater breakfast radio for whmp on top of the frig. The royal 80 is up there too set at wtic. No more changing stations in the morning!


Last edited by metzman on Sep Wed 01, 2021 7:14 pm, edited 1 time in total.

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 Post subject: Re: Royal 500E-1 "freebie" project...
PostPosted: Sep Wed 01, 2021 5:09 pm 
Member

Joined: Oct Mon 26, 2009 10:02 pm
Posts: 7095
Location: Indianapolis, IN
Metzman---this one has a 1964 date code on tuning cap, so they must have made both models around the same time. Still amazes me that they used this cabinet that late as it really looked "old" then---must have made way too many of them back in '59-'60 !

Maybe you can rig up a switching system so you can simply flip a toggle for desired radio ? Then you wouldn't need to adjust volume either ! Oh boy...

John


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 Post subject: Re: Royal 500E-1 "freebie" project...
PostPosted: Sep Fri 24, 2021 3:36 am 
Member

Joined: Feb Fri 01, 2019 11:35 pm
Posts: 712
Location: Riverside Ca. 92504
I have a 500 E and the transistor varies between the early and later chassis. There is chassis 8CT40 thru 8CT40Z7. That is a lot of changes. I am working on the last Z7 now. Tom


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