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 Post subject: RCA am Solid State Radio Model RZG 120, 111Y, 111T, 9Volt
PostPosted: Nov Thu 30, 2017 1:19 am 
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Joined: Nov Wed 29, 2017 10:53 pm
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Location: Georgetown, Brown County, SW OH
Greetings ! :)

I just registered here as a new member and need help with adjusting/repairing the subject radio.

This is a radio I've kept in a drawer since childhood (now age 76) and it has some sentimental value to me. If possible, I would like to improve/stabilize channel selection.

There is a label on the inside of the back that has the subject identification, along with "Consumer Electronics Division, Indianapolis, Indiana 46201, Range AM 540 - 1600 Kilocycles and serial number 911702"

Attached is a picture of the circuit board and I added a tiny red arrow pointing to what appears to be the channel selection device in the upper-right corner of the picture. This device is embossed "JAPAN SANESU ELECTRONICS" and has two slotted screws; the upper screw in the picture has A6 embossed next to it and the lower screw has 15H embossed next to it. At the left edge of the device there are two tiny hex nuts; the upper nut has C2 embossed next to it and the lower nut has C1 next to it.

Does anyone know if the two slotted screws can be turned CW or CCW to improve/stabilize channel selection ? If so, do you know what the effects would be in each direction of these screws ?

Any other comments you can make to help will be appreciated.

Thanks :wink:

ToddB76


Attachments:
File comment: Circuit Board, RCA Radio Model RZG 120, 111Y, 111T
RCA am Radio Circuit Board Photo, 9V, mod. RZG 120,111Y,111T, 540 -1600 Kilocycles, Ser. 911702.jpg
RCA am Radio Circuit Board Photo, 9V, mod. RZG 120,111Y,111T, 540 -1600 Kilocycles, Ser. 911702.jpg [ 60.09 KiB | Viewed 408 times ]
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 Post subject: Re: RCA am Solid State Radio Model RZG 120, 111Y, 111T, 9Vol
PostPosted: Nov Thu 30, 2017 1:55 am 
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Those two screws are trimmers for adjusting the oscillator and antenna tuned circuits. Most likely they are neither your problem nor your solution.

Can you describe in a bit more detail what you mean by "unstable channel selection"? It almost sounds as if the tuning knob is loose from the shaft of the tuning capacitor assembly (that's what the whole unit inside the clear plastic case is).

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 Post subject: Re: RCA am Solid State Radio Model RZG 120, 111Y, 111T, 9Vol
PostPosted: Nov Thu 30, 2017 3:30 am 
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There are several methods to improve your radio's performance, but the first step would be to change the (normally 4) Electrolytic capacitors. Adjusting the antenna trimmer can be beneficial, but re-capping and aligning the IF's should come first.

Image

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 Post subject: Re: RCA am Solid State Radio Model RZG 120, 111Y, 111T, 9Vol
PostPosted: Nov Thu 30, 2017 5:40 am 
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Joined: Nov Wed 29, 2017 10:53 pm
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Location: Georgetown, Brown County, SW OH
Thanks for your reply Tom K6Vl ! :)

As I turn the selector dial starting at AM station 55 and slowly rotate CW toward station 16 at the far end, there are a lot of audio "scratchy" static and "crackling" sounds and stations do not come in (lock-on) at that end of the dial, but two or three channels do come in at the far end near channels 9, 12 and 16.

ToddB76


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 Post subject: Re: RCA am Solid State Radio Model RZG 120, 111Y, 111T, 9Vol
PostPosted: Nov Thu 30, 2017 6:26 am 
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Hi fifties.....Thanks for replying ! :wink:

I have the RCA Radio Service Data, File 1969, No. 14 shown in your post. In addition, when I became interested in electronics a few years ago, I bought a HAKKO FX-888D Soldering Station kit and a few soldering supplies.

However, I'm still a beginner and learning. Before making this reply I did a little research on the Internet and found the following link : https://antiqueradio.org/recap.htm, so I'll be studying the different subjects offered, in particular re-capping.

Do you know if Antique Radio website has a tutorial explaining how to align the intermediate frequencies (IF's) ? Otherwise, if you have time for "show & tell" that would be appreciated.

Your help is much appreciated.

ToddB76


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 Post subject: Re: RCA am Solid State Radio Model RZG 120, 111Y, 111T, 9Vol
PostPosted: Nov Thu 30, 2017 8:04 am 
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Hey Todd, we are always glad to help beginners, and I'll be happy to walk you through an IF and then RF alignment, after you have replaced the E-Caps.
For that you'll need good lighting and magnification, solder wick or a sucker, and a pencil iron, 25-40 watts. Make sure you ID each cap's polarity positions as you remove it.
Also, I would suggest testing the set after each cap replacement. That way, if you goof up, it's narrowed down to the last cap you did.

Richard

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 Post subject: Re: RCA am Solid State Radio Model RZG 120, 111Y, 111T, 9Vol
PostPosted: Dec Sun 03, 2017 7:03 am 
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Location: Georgetown, Brown County, SW OH
Hi fifties ! :)

I reviewed the Circuit Schematic and Replacement Parts list in my copy of the RCA Radio Service Data, File 1969 No.14 and discovered there are actually (7) Electrolytic Capacitors (EC's). I copied these below in the following order from left to right, Symbol NO., Stock NO. and Specifications.

C7, 116230, 30µf, 6V
C13, 116228, 5µf, 6V
C14, 116230, 30µf, 6V
C15, 116228, 5µf, 6V
C17, 116981, 100µf, 10V
C18, 116981, 100µf, 10V
C19, 117831, 30µf, 10V

Attached are scanned pictures of the subject radio circuit board, Top side showing components and Bottom side showing soldered connections.
With reference to the Top side and the (4) square-top metal cans, each with a colored/slotted adjustment screw, black, white, yellow or red, upon close observation I noticed that the coating of the square/flat brown component against the can with the red adjustment screw had melted in two spots and glued it's self to the side of the can ! I don't know the proper name of the cans or the brown component offhand, however, I assume the brown component is defective and may have also caused damage to the adjacent can.

Looking at the Bottom side of the circuit board and the soldered connections, at age 76 with Parkinson's disease, I'm definitely not steady-of-hand enough to do any desoldering/resoldering on this tiny crowded board ! :roll: So, guess I'll have to drop this project, sorry to say. :cry: I could adjust the slotted screws in the square clear-plastic component for the station dial and the (4) square-top metal cans if you think that might help the problems mentioned in my post #4.

Otherwise, if you think tinkering with the slotted screws would be a waste of time, then I do have a simpler electronics kit that I can do and that will satisfy me for the time being.

Thanks for your help so far and please let me know what you think about adjusting the slotted screws on the subject RCA radio.

ToddB76


Attachments:
RCA am Radio Mod. RZG 120, 9V, 540-1600 Kilocycles, Ser. no. 911702, Circuit Board Components Side_edited.jpg
RCA am Radio Mod. RZG 120, 9V, 540-1600 Kilocycles, Ser. no. 911702, Circuit Board Components Side_edited.jpg [ 66.44 KiB | Viewed 269 times ]
RCA am Radio model RZG 120, 9V, 540-1600 Kilocycles, serial no. 911702, Soldered Components Side.0002.jpg
RCA am Radio model RZG 120, 9V, 540-1600 Kilocycles, serial no. 911702, Soldered Components Side.0002.jpg [ 49.96 KiB | Viewed 269 times ]
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 Post subject: Re: RCA am Solid State Radio Model RZG 120, 111Y, 111T, 9Vol
PostPosted: Dec Sun 03, 2017 10:26 am 
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Hey Todd, I'm sorry to hear about your ailment, and it's preventing you from replacing the E-Caps. Doing that would be the most beneficial way to to improve the set's performance, but you can only do what you are capable of.

OK, first, I'm guessing that the brown stuff against the can with the red core is a glue, the purpose of which is to seal it from adjustment, and you DO want to leave that one alone, as it's the oscillator coil.

The cans with the black, white, and yellow cores are the IF's. Tune the radio, in the daytime, to a weak but non-fading station. Use a plastic or wood blade to adjust the cores. Sometimes you can get away with a metal screwdriver, but if you stick it into a core and the audio changes, you can't use it.

Adjust one core very slightly; we are talking about an eighth to a quarter of a turn or so, to see if the station increases in volume and clarity. Do that with the other two as well. Normally, adjusting one can will make a difference, and the other two won't, so you have to try all three.

As to an RF alignment; notice that there are two screws on the backside of the tuner. One is the oscillator trimmer, the other the antenna trimmer, but we don't know which is which. Tune the set to a station near 1400 kilocycles, and very slightly adjust one of the screws. If the station disappears, that's the oscillator trimmer. Adjust it back to get the station, then go to the other screw, which would be the antenna trimmer. Adjust it for loudest volume.

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 Post subject: Re: RCA am Solid State Radio Model RZG 120, 111Y, 111T, 9Vol
PostPosted: Dec Sun 03, 2017 4:43 pm 
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Posts: 12
Location: Georgetown, Brown County, SW OH
Hi fifties,

Hope springs eternal ! :wink:

I'll follow your advice, using a little plastic screw driver, and report the results.

Thank you so much for the help.

ToddB76


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 Post subject: Re: RCA am Solid State Radio Model RZG 120, 111Y, 111T, 9Vol
PostPosted: Dec Sat 09, 2017 2:26 am 
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Please note: My original Post #10 that appeared here has been deleted, due to an error in the label under the attached photo (The word "trimmer" was incorrect and has been removed in accordance with fifties post and critique).

See my "re-do" post below.

ToddB76


Last edited by ToddB76 on Dec Sun 10, 2017 8:16 pm, edited 2 times in total.

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 Post subject: Re: RCA am Solid State Radio Model RZG 120, 111Y, 111T, 9Vol
PostPosted: Dec Sat 09, 2017 6:42 am 
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Hey Todd, always glad to help out you youngsters, eh eh... :wink:

I haven't found the IF's to have a common designation from the makers, and noticed that they can be referred to as IF's, IF Transformers, IF coils, etc. Technically they are filters comprised of two coils, one or more caps, and a Ferrite core. Their purpose is to pass only the frequency they were designed to carry, and reject all others. Usually that frequency is 455 kilocycles.

One critique on the label of your scan;
RCA am Solid State Radio Circuit Board, 9V, mod. RZG 120, 540 -1600 Kilocycles, Ser. 911702 , 4 metal trimmer cans, 001.jpg

The cans are not trimmers. Three are IF filters, and one is the oscillator coil. The only trimmers are located on the back of the tuning capacitor (the two screws).

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 Post subject: Re: RCA am Solid State Radio Model RZG 120, 111Y, 111T, 9Vol
PostPosted: Dec Sat 09, 2017 10:38 pm 
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fifties......Thanks for your reply on Dec Sat 09, 2017 6:42 am.

I tried to removing the word "trimmer", but the website program
doesn't allow Editing the label window, only the message window. :(

Do you know of another method other than the Edit feature ?

ToddB76


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 Post subject: Re: RCA am Solid State Radio Model RZG 120, 111Y, 111T, 9Vol
PostPosted: Dec Sun 10, 2017 7:44 am 
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Sure. First edit the label in your PC by right clicking the scan and clicking on rename. Then click on edit for your post, delete the current scan, and add the new one, with the edited label.

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 Post subject: Re: RCA am Solid State Radio Model RZG 120, 111Y, 111T, 9Vol
PostPosted: Dec Sun 10, 2017 7:10 pm 
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Location: Georgetown, Brown County, SW OH
Please note: This is a re-do of my original Post #10, to remove the word "trimmer" from the label under the attached photo.

New Member: ToddB76 Post #10
Post subject: Re: RCA am Solid State Radio Model RZG 120, 111Y, 111T, 9Vol
Joined: Nov Wed 29, 2017 10:53 pm
Posts: 7
Location: Georgetown, Brown County, SW OH

Posted: Dec Sat 09, 2017 2:26 am

Hello ! :D

Back again with a question about components on the subject radio circuit board.

See Attached picture with red arrows pointing to 4 square-topped metal components, each with a different color adjustment screw.

In his above post, fifties called the one with the red screw an "oscillator coil" and the other three having either black, white, or yellow screws "IF's", which stands for Intermediate Frequency according
to what I found on the Internet.

Question: Are those above terms what the electronics industry calls these components, I mean their "official" names ?

In addition to your answer on the above specific question, any information or explanation you care to make
will be appreciated.

Thanks for your help ladies and gents. I'm still trying to educate myself on this fascinating subject of electronics !

ToddB76

Last edited by ToddB76 on Dec Sat 10, 2017 1:30 pm, edited 1 time in total.[code][/code]


Attachments:
RCA am Solid State Radio Circuit Board, 9V, mod. RZG 120, 540 -1600 Kilocycles, Ser. 911702 , 4  metal cans, 001.jpg
RCA am Solid State Radio Circuit Board, 9V, mod. RZG 120, 540 -1600 Kilocycles, Ser. 911702 , 4 metal cans, 001.jpg [ 69.08 KiB | Viewed 142 times ]
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 Post subject: Re: RCA am Solid State Radio Model RZG 120, 111Y, 111T, 9Vol
PostPosted: Dec Sun 10, 2017 9:07 pm 
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You are doing fine, Todd. How did it come out when you adjusted the IF cores and tuner trimmers? Any improvement?

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 Post subject: Re: RCA am Solid State Radio Model RZG 120, 111Y, 111T, 9Vol
PostPosted: Dec Mon 11, 2017 12:07 am 
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fifties,

I had just completed a reply to you and clicked the "Preview" button. Instead of seeing a preview
of my reply, I got a dialog box requiring me to Login again. So I obediently logged in again (again,
because I had already logged in at the outset.), and assumed I would be taken back to my reply
to Submit. Bottom line, my reply disappeared ! :shock: Guess I was "timed out" or something. :?

Is there a way to retrieve a post when this happens ? Or do I have to re-write the whole thing over again ?
Otherwise, all my thought, time and work are gone, gone, gone.

After years and years of posting on many website forums, you would think I could remember to periodically
do a SAVE when realizing it's taking a long time to finish.

ToddB76


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 Post subject: Re: RCA am Solid State Radio Model RZG 120, 111Y, 111T, 9Vol
PostPosted: Dec Mon 11, 2017 12:28 am 
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Hey Todd, that's happened to me here as well, on occasions when they've had server issues, and unfortunately, the attempted post is gone forever. Just re-post as soon as possible, while you remember what you could. Also, be sure and check the "remember" box on the log-in screen, and you then will always be automatically logged in.

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 Post subject: Re: RCA am Solid State Radio Model RZG 120, 111Y, 111T, 9Vol
PostPosted: Dec Mon 11, 2017 2:23 am 
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fifties wrote:
Hey Todd, that's happened to me here as well, on occasions when they've had server issues, and unfortunately, the attempted post is gone forever. Just re-post as soon as possible, while you remember what you could. Also, be sure and check the "remember" box on the log-in screen, and you then will always be automatically logged in.


Thanks fifties :wink:

I'm now re-writing the lost post in Word Pad and will then Copy & Past it in this thread.

ToddB76


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 Post subject: Re: RCA am Solid State Radio Model RZG 120, 111Y, 111T, 9Vol
PostPosted: Dec Mon 11, 2017 5:35 am 
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fifties,

I haven't adjusted the IF cores or tuner trimmers yet, as I'm waiting on delivery of two anti-static screwdrivers
ordered from e-Bay with ceramic flat bits of the correct size for adjusting the Black, White and Yellow IF cores and
the two trimmer screws for RF alignment on the back side of the tuner, one screw for the oscillator and the other
for the antenna. I'm in no hurry and would rather have the proper tools for making these adjustments. I'll be sure
to post the results when finished and it will probably be late December or January before I receive these screwdrivers.

With reference to the second paragraph in your post dated Dec Sun 03, 2017 10:26 am, in quotes below, I wonder if
that "glue" might be a dielectric material to electrically insulate the red core oscillator coil from the square, brown, flat
component close to it (See paragraph below titled "A polarized dielectric material" I copied from Wikipedia.).
BTW, In my copy of the "RCA Radio Service Data, File 1969 No. 14" the "Chassis Layout and Replacement Parts" sheet
identifies that square, brown, flat component as C 4, a 140 pf 5%, 50v., mica capacitor. Also, in reference to the red
core in the L 2 oscillator coil, I believe you are saying "Don't adjust the screw on that component.".....correct ?

"OK, first, I'm guessing that the brown stuff against the can with the red core is a glue, the purpose of which
is to seal it from adjustment, and you DO want to leave that one alone, as it's the oscillator coil."


A polarized dielectric material

A dielectric (or dielectric material) is an electrical insulator that can be polarized by an applied electric field. When a dielectric
is placed in an electric field, electric charges do not flow through the material as they do in an electrical conductor but only
slightly shift from their average equilibrium positions causing dielectric polarization. Because of dielectric polarization, positive
charges are displaced toward the field and negative charges shift in the opposite direction. This creates an internal electric field
that reduces the overall field within the dielectric itself. If a dielectric is composed of weakly bonded molecules, those molecules
not only become polarized, but also reorient so that their symmetry axes align to the field. The study of dielectric properties concerns
storage and dissipation of electric and magnetic energy in materials

ToddB76


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 Post subject: Re: RCA am Solid State Radio Model RZG 120, 111Y, 111T, 9Vol
PostPosted: Dec Mon 11, 2017 8:48 am 
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ToddB76 wrote:
Also, in reference to the red
core in the L 2 oscillator coil, I believe you are saying "Don't adjust the screw on that component.".....correct ?


Correct.
Will look forward to your upcoming post, once your tools arrive.

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