Another RCA CT-100 discovery B8001599

[Popester]

Great results it appears in the tester. I have a question about the background of your photo on the shelf. Are those 78 records? I can make out Rachmaninoff on the back of the spine on one of them.

[Penthode]

Originally Posted by Popester

Great results it appears in the tester. I have a question about the background of your photo on the shelf. Are those 78 records? I can make out Rachmaninoff on the back of the spine on one of them.

Yes I am an inveterate 78 collector. The Rachmaninoff is the 1929 recording with Stokowski and the Philadelphia Orchestra and Sergei Rachmaninoff at the piano.

"Rachmaninoff Plays Piano Concerto No 2 (1929)" on YouTube
https://youtu.be/X_7O09ucelM

[Penthode]

With the 15GP22 showing life and promise, I am now proceeding to the chassis.

It is filthy although relatively complete. The selenium rectifier shield is missing along with the back cover and four knobs. The cabinet is in surprisingly good shape apart from the speaker rust. (I plan to dismantle the original speaker and derust via electrolysis).

But the main concern is first to clean up the chassis and remove a fair bit of corrosion from the mouse home. It is pretty extensive in the corner next to the first Video IF but not irreparible.

I noticed that the front part of the chassis contains almost all the corrosion. I see that the corroded front section is attached to the rest of the chassis with self tapping screws. So I plan to begin carefully documenting and photographing the wiring crossing the chassis bridge and separate the chassis away to attend to the localized rust.

I have photographed the front chassis attached to the main chassis below.

[ARC Tech-109]

If you need the large roundie socket I have an extra one for the B&K 467.

[Penthode]

Thanks for the tip. I have a box of BK467 sockets I will look thru.

[Penthode]

I found an old label attached to the CRT leads.

The label reads Judd Electronic and the address is 16931 Schoolcraft.

I Googled Judd Electronic and nothing. I did find on Google Maps a Schoolcraft Road from just across the Canada US border where the set was found. Looks as if it was an early Detroit color tv.

You will see the label below, a Google map shwing a red dot to the right where I picked up the set and the Google Maps flag where 16931 Schoolcraft Road is. And finally the empty building where once stood Judd Electronic.

[vortalexfan]

Originally Posted by Penthode

I found an old label attached to the CRT leads.

The label reads Judd Electronic and the address is 16931 Schoolcraft.

I Googled Judd Electronic and nothing. I did find on Google Maps a Schoolcraft Road from just across the Canada US border where the set was found. Looks as if it was an early Detroit color tv.

You will see the label below, a Google map shwing a red dot to the right where I picked up the set and the Google Maps flag where 16931 Schoolcraft Road is. And finally the empty building where once stood Judd Electronic.

I believe (and don't quote me on this as roads in Michigan and Indiana use very different naming conventions) that the name "Schoolcraft Road" refers to the fact that if you follow the road long enough it will eventually take you to a Village called Schoolcraft, Michigan (which is between Three Rivers and Kalamazoo, Michigan on US 131 N.)

But like I said I don't know if that's why that road was named that or not, because like I said, in Indiana a road that was named after a nearby town was named that because that road would eventually take you to that town if you followed it long enough, which like I said I don't know if Michigan followed that rule or not when naming their roads.

Just my two wheat pennies worth.

[Penthode]

Interesting story about Schoolcraft Road. I will study the map!

Yesterday dismantled the rusty loudspeaker and put the frame into an electrolysis bath. Painted the frame silver this morning and will wait a couple of weeks before reassembling. Spent last night and this evening documenting and photographing the front chassis section which suffered from the mice next. I have removed the front chassis and have begun dismantling it. Fortunateltly pretty weel all the rust is around the first video IF stage and the audio amplifier. I shall concentrate cleaning this section up before proceeding to the rest of the chassis.

[vortalexfan]

Originally Posted by Penthode

Yes I am an inveterate 78 collector. The Rachmaninoff is the 1929 recording with Stokowski and the Philadelphia Orchestra and Sergei Rachmaninoff at the piano.

"Rachmaninoff Plays Piano Concerto No 2 (1929)" on YouTube
https://youtu.be/X_7O09ucelM

I have a small 78 RPM Collection myself, and one of the 78 RPM recordings I have is Rachmaninoff Playing his Piano Concerto No. 3 in D Minor with the Philadelphia Orchestra w/ Eugene Ormandy Directing (I'm assuming the recording was from the same time period as your Rachmaninoff recording which would fo been between 1929 and 1931 and it is a recording meant to be used on a record player with an electrical pickup as opposed to an old mechanical pickup device like the old crank-up victrolas had.)

The records and the case/jacket are in mint condition.

[Penthode]

The Rachmaninoff 3rd Concerto was recorded by the composer in 1939-40. By that time apart from portable record players, the living room record player was electronic. However in 1929, phonographs were still predominantly acoustic hence the recording equalization characteristics were governed by them. The characteristic in 1929 was "constant velocity" whereby the velocity of the stylus across the audio bandwidth governed loudness.

To improve disc signal to noise and also to increase playing time, a constant amplitude charactistic was introduced in the 1930's. Hence 1940 recordings played on an acoustic phonograph would have diminished bass frequencies and boosted highs, making the records sound shrill.

Unfortunately record equalization remains a little understood technological evolution which leads us to having to endure an obnoxious cacophony of Elvis Pressley and Eddie Fisher 78's on vintage 1910's era Victrolas at antique markets.

[Penthode]

Been studying, photographing, drawing and documenting the construction of the mouse affected chassis. I have decided to dismantle the affected areas, clean the chassis bright and apply a coat of zinc silver paint over the cleaned portion. I shall only begin dismantling after the total documentation leaves no ambiguity how to accurately reconstruct.

Meanwhile, the speaker de-rusting was complete and a coat of silver paint applied. The speaker has been reassembled and tested.

[ChrisW6ATV]

Originally Posted by ARC Tech-109

If you need the large roundie socket I have an extra one for the B&K 467.

Your B&K socket is likely the 14-pin one, that is what my 467 included and what fit all of the 21-inch round color CRTs. The 15GP22 needs a similar size but 20-pin socket. I would very much like to have one of those if I could find one; I either made an adapter with a bunch of alligator clip leads, or I just used loose clip leads, when I tested my 15GP22.

Penthode, this will be a great project!

[miniman82]

You’re in luck, this guy says he has like 17 of them...
I’d buy one, but I already have an adapter of my own.

https://www.ebay.com/itm/174268516102

[Penthode]

Originally Posted by miniman82

You’re in luck, this guy says he has like 17 of them...
I’d buy one, but I already have an adapter of my own.

https://www.ebay.com/itm/174268516102

Thanks! Although the universal leads work well on the Sencore tester. But it would be nice to use the B&K.

I would have liked to find a replacement 20 pin base for the 15GP22 as the one I have has been epoxied to fill a chunk that was missing. Chance of finding a base will be much less than the socket!

[Penthode]

Have been documenting and photographing extensively the IF stages and audio demodulator/ amplifier prior to dismanting the heavily rusted area.

Carefully drilled out the tag strips and tube socket and unsoldered and snipped away around the stages to lift portions complete away from the chassis. I will endeavor to keep as much as possible. But plan to replace at least 3 sockets heavily corroded and the last VIF located in the shielded box. The last IF socket appears very brittle from I suspect the enclosed heat. (I cannot get over there is six IF stages in all. It will be fun to re-align!)

You will see the chassis below cleared of components. I plan to go over the rusted area with Phosphoric Acid this prior to painting with zinc paint. I would like to reconstruct the chassis as close as possible to its original state apart from changing the paper capacitors to sprague orange drops.

Fortunately the rest of the chassis looks really good. Haven't ventured into the HV Box yet however...