Hi all, I haven't worked on many solid state radios. All my voltages on transistors check out good. I am getting 12v out of my electros...but the radio is dead, no static at all. Can anyone guide me through this...Thanks AL

Check that the connectors in the earphone jack are touching. If so, then do the second radio test, to validate the converter and power circuits.

The ear phone jack connections are good. Should I surmise the transistors and electro caps are good if they are reading correct voltages? How do I go about testing the output transformer? Thanks AL

It would be rare for a Transistor radio audio output transformer to fail, but you can validate continuity of both windings by using your meter.
Again, do the second radio test to make sure the converter stage is operating.

To verify that your speaker is working.
Remove the batteries from your set, or make sure that it is turned off.

Connect two flying leads to a 1+1/2 Volt battery.
Touch the ends of the wires from the AA on to the two terminals of the speaker.
You should hear a click each time a contact is made or broken.

A click will confirm that the speaker is not to blame for the silence.

Greg.

If you would like the 1958 photofact for your radio, let me know and I will scan it in high-resolution.



Greg.

Thanks Greg...I have the sam's schematic...anything else on the servicing would be helpful. What did you have in mind telling me to do second test...please walk me through it...Thanks AL

This is what Richard is referring to as The Second Radio Test.

Use a second radio switched on at moderate volume and tuned to somewhere around 1200kHz to 1400kHz (top end of the AM broadcast band). You don't have to be tuned to a station.

▲ This is your listening device.

Switch on your silent radio and hold it next (very close) to the second (working radio).
Tune up and down the band on your silent radio, and you should hear a squeal/whistle at some point on the working radio. This will confirm that the oscillator in your silent radio is running (working).

Greg.

No response doing the second radio test

I would then suggest changing the Electrolytic's. Regardless of your readings, they are most likely dried out after 62 years (the model was introduced in November, 1955), and that would be a real good reason why the set is dead.

Are you getting the 12V beyond the power switch ?

Have had a few radios of that vintage where the contacts wouldn't engage properly due to hardened grease or oxidation internally... Sometimes rapidly cycling switch will correct.

Very neat radio---could you post a few pics ???

John

Yes, I would definitely begin by replacing all of the electrolytic capacitors regardless. If the transistors on that radio have sockets, be sure that the transistors are properly seated. Also, check for cold and/or broken soldered connections. An oscilloscope would be invaluable here. By the way, was this radio an ebay purchase?

I have 2 Zenith 800 transistor radios that I bought on ebay as not operating, but found they both worked after I re-seated the transistors. Both radios have seen a lot of use, but still are good performers with all of their original components. - Mark

The switch checks out good. I got this radio from a co-worker who found it in fathers basement, and knew I was into old radio's. It is covered in dust, but no chips or cracks...I have not cleaned it at all. The back is with it but does not fit correctly. I will re check the seating of the transistors...since they are the plug in type. I will change the electro's and see if she comes to life...Thanks AL

Did you tell your co-worker the value of the radio?
I've seen some examples sell for upwards of $600.00

Greg.

Wow! I got radio about 10 years ago. I recently retired and have time to putter about. I had no idea that radio had any value.....Looks like I should get it going........Thanks AL

Al,
Matt did a youtube video on the Zenith Royal 800 transistor radio that I think you will enjoy:

https://www.youtube.com/watch?v=B7Qq_wR5oXo

Mark

Very Cool video....and radio sounds great! I have my work cut out for me.. Thanks AL

If you have a curve tracer handy that's reliable, you could simply pop each one of the transistors out (beginning with the audio output), and check them out the way. That would quickly eliminate a defective transistor as the source of the problem.

I don't have a curve chaser....But if the voltage is as schematic reads, would that be enough to verify transistors are good? Thanks AL