Arvin 552N - Printable Version
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Arvin 552N - klondike98 - 11-22-2025
The Arvin 552N that I just picked up had a stuck knob which I was eventually able to get off. I first tried the rubber glove technique seen in this youTube video by RestoreOldRadios https://www.youtube.com/watch?v=GUUJDrS3V4g and after that failed, I used the two pry technique seen in a number of videos on youTube. Some folks use two spoons, some fashion "L" shaped pry bars. I used two thin screw drivers and some wood as a fulcrum (and to protect the radio). The key is to get the screw driver right up to the metal shaft of the radio and under the plastic or bakelite base of the knob. If you pry on the outer edges of the knob it will surely damage the knob. Here's a photo of the set up, although its after the knob was off and I could only put one screw driver in place while I photographed. Its important to use both screw drivers and lift both sides of the base at the same time. Now hopefully I can find a second knob.
RE: Arvin 552N - Arran - 11-22-2025
Bob;
I was going to suggest that if you have a stuck knob that squirting some penetrating oil, like WD40, on the shaft, and allowing it to soak in sometimes helps. I had an Eaton's "Viking" radio (Electrohome) that had the same problem, also stuck on a spline shaft, and my late uncle suggested that. What I did after was to wrap a string or cord behind the knob, and kept wrapping it around until it was forced off by the multiple turns wedged behind it. The reason it was stuck is that the tuning shaft was steel, and some rust formed between the inside of the knob, and the spines on the shaft, the volume control didn't have this problem as it was brass.
Regards
Arran
RE: Arvin 552N - klondike98 - 11-22-2025
Thanks Arran. I was almost ready to apply some WD40 but the knob popped off just before I took pressure off the screw drivers to do that. I’ve also read that gently warming the knob sometimes helps.
RE: Arvin 552N - radiorich - 11-23-2025
Hello Bob,
I have Kit with tiny prybars and spugers for working on computers I have used the tiny prybar and I also have tiny metal prybar that I'ved used.
Glad you got the knob off with out any damage .
Sincerely Richard
RE: Arvin 552N - klondike98 - 11-25-2025
I opened up this Arvin radio today. For those who are interested, here is the schematic LINK.
I love this part of the restoration. Looking the radio over in detail, getting to understand what's wrong with it, what you might be able to do to fix it, what you are going to need to order and the best part...finding the surprises inside the radio. On the bottom of this radio there was a name that was probably written by a repair tech at some point in the past. In this case it was: "Mrs Luis Gilbrick".
Also on one of the tubes, the tech has put in grease pencil, OK 1-3-52.
I bought the radio at one of the many antique shops nearby in Aurora, Oregon. One of my pastimes is genealogy so just for fun I thought I'd see if Mrs. Gilbrick was in the area in the 1950s.
Lo and behold, the 1950 Federal Census revealed a Louis C. Gelbrich age 55 and his wife Lucile D. Gelbrich age 50 living on Lone Elder Road between Aurora and Macksburg Oregon. Louis was a conveyer operator at a sawmill as well as a farmer. The 1950 census also had a selective sampling of people who were asked extra questions and Lucile was selected for those questions which revealed her mother was born in Germany, her father in Ireland; she had gotten through 8th grade, worked for 4 weeks in 1949 earning $90. It turns out that the Gelbrich's lived in Bend Oregon during the 30's and 40's (about a 3 hour drive southeast from Aurora on today's road) but in the 1920's, Louis and Lucile, at the ages of 25 and 20, were living with Louis's parents on the family farm somewhere near the very same Lone Elder Road.
I think I have Lucile's radio! Thanks Lucile.
For a bit of closure...Louis died in 1977 and Lucile in 1982. Virginia, their daughter, married Henry Masterson in 1942 and she passed away in 2013. It turns out there is still a Masterson family member owning the property along Lone Elder Road! Sometimes these radios come along with stories.
RE: Arvin 552N - klondike98 - 11-26-2025
I did get to test the tubes in the 552N and had a puzzling test result. The 50L6GT showed a short. If I understand things right it would be between the cathode and the filament. I tested two other 50L6GT tubes that I had and one tested fine, no shorts, and the other seemed to indicate a possible short between the cathode and filament depending on where I set the leakage resistance on the tester. I have a Jackson 648R tube tester.
I figured that the tube testing with the strong short signal should be able to be checked with a multimeter but when I did that I did not detect any short.
RE: Arvin 552N - MrFixr55 - 11-26-2025
Hi Bob,
Is it possible that you have a screen to grid, screen to suppressor or beam forming plates or screen to plate short? If the output transformer is open, the screen will absorb all tube current, in some cases, causing the screen to overheat to the point of incandescence, melt and short to another element. I had this occur once to a 6K6 in a GE set with an open output transformer primary and in another case, almost destroyed a globe 42 on a Philco 80.
462ron - 462ron - 11-26-2025
Bob, that’s a great genealogy story on your radio, if only they could talk! This renews my interest in a name I found scribbled on the back arch of my Philco 70 cathedral I got several years ago at Kutztown. I think all I did was Google the name and found nothing, I should try Ancestry.com. I did find a sticker on one of the tubes from a repair shop in Detroit. Makes me wonder how that radio made its way from Detroit to Kutztown, PA!
Ron
RE: Arvin 552N - RodB - 11-26-2025
I found a message from an assembly line guy flirting with another. I was restoring a Zenith TO and had removed the chassis to find written in pencil on the inside of the cabinet: "Hi Ciel how ya doing?" Is this better than texting?
RE: Arvin 552N - klondike98 - 11-26-2025
Thx MrF, I’m just going to toss the tube that tests shorted. Yes its possible the tube overheated as you suggest, there is a little evidence in the bottom of the chassis that something got hot enough to melt some wax and that may have also affected the tube. Time will tell if there is something else amiss.
Rod, I guess Ciel never got the note or just left it there.
Ron, I got a bit lucky in that the set was still local and that the name, although misspelled, was a bit unusual.
I was once restoring a Radiola 60 for a museum in Bandon Oregon and the set had a repair sticker from a shop in Detroit Michigan called, Reno Radio. Maybe we should have a thread for “Strange finds in your radio”
RE: Arvin 552N - Paul Philco322 - 11-26-2025
I have sets with repair shop stickers, hand written names on backs. Occasionally a tube test sticker. Always makes you wonder. Paul
RE: Arvin 552N - radiorich - 11-27-2025
Hello Bob,
That is really cool ""Mrs Luis Gilbrick"
One thing I thought was strange on those sets is the bottom and that piece that like a arm .
I have a very similar chassis but my cabinet is different and one our late ARF members Peter had his guy paint it for me my set used one those christmas tree light bulbs .
Sincerely Richard
RE: Arvin 552N - Arran - 11-27-2025
A heater to cathode short, if it really is shorted, will cause the radio to hum loudly, I have not seen this on a 50L6 but have on a 50B5
I would confirm it actually is defective before tossing it, some testers show phantom defects that really aren't there, I have a Triplett that does that on some tubes, but won't show it on another tester.
Regards
Arran
462ron - 462ron - 11-27-2025
Bob I like your idea of a thread dedicated to things found in our radios although I can’t think of any off hand. Now that you mentioned Reno Radio, that repair shop in Detroit, my curiosity is wanting me to get my 70 down and have a look at the name on it and the repair shop sticker on a tube! Only thing now is it sits up on a top shelf and I don’t know if my rotator cuff problem will allow me to take it down
Ron
RE: Arvin 552N - MrFixr55 - 11-27-2025
Hi Rob,
The overheating is not due to lack of ventilation, the specific issue that I described was caused by an open output transformer. In these sets, the same B+ that connects to the output transformer connects to the screen grid of the output tube. If the transformer is open, all cathode current (and in a Class A amp, the current at no signal is almost as much as the current with max signal) will pass through (Let me reword this) be conducted by the screen grid, causing it to overheat and melt. Therefore, you may want to verify that the output transformer does not have an open primary or open wiring.
The first sets with the '47 pentode had warning stickers to not operate the set without a load on the plate because of this issue.