RCA R-8 Chassis Rebuild - Printable Version
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RCA R-8 Chassis Rebuild - Phlogiston - 07-15-2016
If anyone is interested, I just posted a pictorial of this much despised chassis being rebuilt on my blog:
http://www.russoldradios.com/blog
Most people hate it. Not because it works poorly but because it is very difficult to work on. I have done several of these since they were used with a few changes for 2 years in many RCA and GE (Westinghouse?) radios. The same chassis was used in consoles and table models with the same speaker. There were also 7 and 9 tube versions.
Russ
RE: RCA R-8 Chassis Rebuild - KCMike - 07-15-2016
Very nice job Russ.
That is a fine looking cabinet also.I almost bought one similar awhile back but was out bid at the local club auction. Good to see what all is involved if ever I get one.
RE: RCA R-8 Chassis Rebuild - Eliot Ness - 07-15-2016
Nice job Russ! Those tips will come in handy when I finally tackle a G.E. J100 cathedral I've been putting off for years.
RE: RCA R-8 Chassis Rebuild - klondike98 - 07-15-2016
Another A++ job Russ!
RE: RCA R-8 Chassis Rebuild - Paul Philco322 - 07-15-2016
With the tuning condensor underneath it is busy under there, many of those RCA are toughies, RCA 28P is loved and hated too.
Nice work kid.
Paul
RE: RCA R-8 Chassis Rebuild - Arran - 07-16-2016
They aren't that bad, I've worked on a couple of these, and will work on a couple more that are in the restoration docket. One was a C.G.E J-82 and the other a Canadian Westinghouse 801 Columaire which uses similar circuitry and components but in a Westinghouse built chassis, the next two will be another J-82, and an S-42A. The biggest nuisance isn't the tuning condenser it's the IF cans and the oscillator coil, which you may or may not have to remove to get at some things. These sets are good performers though, which probably explains why there are so many survivors as they were probably good sellers.
Regards
Arran
RE: RCA R-8 Chassis Rebuild - palegreenthumb - 07-16-2016
Wow Russ, hard to believe that's the same radio!
What's your take on casting 2W resistors into dogbone molds? Are they still able to dissipate 2W, or are they derated a bit?
RE: RCA R-8 Chassis Rebuild - Phlogiston - 07-16-2016
(07-16-2016, 04:28 AM)palegreenthumb Wrote: Wow Russ, hard to believe that's the same radio!
What's your take on casting 2W resistors into dogbone molds? Are they still able to dissipate 2W, or are they derated a bit?
I have been doing this for years now. I have only had one get hot enough to damage the molded material and it was the result of another failure. The idea is that you replace a 1/2w with a 2W or larger to better dissipate any heating, most of which leaves by way of the leads anyway.
But, yes. I would not run them at 2w. I have used 3.8w wire-wound when I thought heat would be a problem. This increases the cost by about 10X. These resistors (the ww) are the same size as a 2w metal (blue) so are sized to cast into a 1/2w dogbone or larger.
RE: RCA R-8 Chassis Rebuild - Phlogiston - 07-16-2016
(07-16-2016, 04:22 AM)Arran Wrote: They aren't that bad, I've worked on a couple of these, and will work on a couple more that are in the restoration docket. One was a C.G.E J-82 and the other a Canadian Westinghouse 801 Columaire which uses similar circuitry and components but in a Westinghouse built chassis, the next two will be another J-82, and an S-42A. The biggest nuisance isn't the tuning condenser it's the IF cans and the oscillator coil, which you may or may not have to remove to get at some things. These sets are good performers though, which probably explains why there are so many survivors as they were probably good sellers.
Regards
Arran
Removing the tuning cap allows access to the IF cans. One IF can cap can be removed by slightly distorting the front and back flanges of the chassis to get it past the coil. This also allows access to the tabs at the base of the cap can which must be bent to remove the can.
Another tip: When removing the cap can also remove or loosen the mount for the ceramic padder cap or you will break it with one of the tabs.
RE: RCA R-8 Chassis Rebuild - Arran - 07-18-2016
Russ;
Just a thought on that wire wound that's on the resistor board, I looked up the set and found out that there was a 3 Watt carbon resistor in that position according to the parts list. It may have been replaced by a service man or it may have been a production change since it looks like they shrouded it in fish paper, either way putting a 5 Watt wire wound in it's place was a smart move.
Regards
Arran
RE: RCA R-8 Chassis Rebuild - Phlogiston - 07-18-2016
(07-18-2016, 03:13 AM)Arran Wrote: Russ;
Just a thought on that wire wound that's on the resistor board, I looked up the set and found out that there was a 3 Watt carbon resistor in that position according to the parts list. It may have been replaced by a service man or it may have been a production change since it looks like they shrouded it in fish paper, either way putting a 5 Watt wire wound in it's place was a smart move.
Regards
Arran
Yes, I believe all of that is true. The fish paper is factory installed.