same issue, except, this one had louder than normal hum when power switch was in off position. was working great minus the hum when turned off, then the hum went away and no modulation, no modulation light flickering on voice audio. great rx and everthing else works great. I have replaceda couple caps but plan to replace them all and look at modulation transformer as well.
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ROBYN T-123B help needed
- Thread starter Crambone
- Start date
Did any of you guys get your Robyns working. I am just starting on radio repair and could sure use your expertise. I cant find a Sams Photofacts for it, so I am flying a little blind without the pictures and identification arrows. Can anyone help me? Can anyone share with me a PDF copy?
There is a thread at the top of the CB section
www.worldwidedx.com
Go there and ask if Dan or another member has a photo fax for your radio.
73
Jeff
Sams PhotoFacts Collection
I have almost a complete set of Sams PhotoFacts for CB. If anyone needs info on a specific cb radio just like me know and I will see if I have that Volume. KEEP CB ALIVE!
73
Jeff
Shadetree Mechanic
Delaware Base Station 808
My experience with this class of radio goes back to the 23-channel models before the 40-channel expansion. Makes me a bit jaded, but there are weaknesses in every design, including this one.
I do not recommend a tube-type Robyn as a first project. Aside from the issues of age, and capacitors that get replaced because of age alone, mileage is an issue with these. They pack a lot of radio in a small package. The heat they generate causes it to age rapidly. Low mileage works in your favor. High mileage will lead to aggravations more often than not.
Biggest reason to leave this radio alone, and the other related Panasonic-made CBs is the way they locked the ferrite tuning slugs in the IF and RF transformers. When a slug was peaked at the factory, white enamel paint was dribbled down the inside of the coil's core. This stabilized the tuning slugs for the trip across the Pacific from Japan to the USA.
More often than not, we see cracked slugs in these IF/RF transformers. Someone thought that just twisting the alignment tool harder would break the adjustment free. Nope. Just cracks the slug. Now when you turn the tool inside the tuning slug's hex hole it forces the broken parts outwards, like the centrifugal clutch on a go-kart. No way it will ever turn inside that coil again with a crack in it. Has to be removed in tiny pieces.
You may imagine this leaves an opportunity to damage the coil getting the broken slug fragments removed.
We found that toluene was the only solvent that loosened the white enamel paint and could free up the adjusting slugs. But you have to go easy on that stuff. It will also loosen the glue that holds the coil's core fastened to the base plate.
Panasonic made this radio in Japan for other brands. Gemtronix, Teaberry and Lafayette come top mind.
Years ago I would compare these radios to a small mammal. High metabolic rate in a small package, prone to a short life span.
Bringing one of these back to life and proper performance will be a multi-faceted project if you're up to the challenge. The challenge level tends to increase with the age of the radio. And with the mileage that has been put on it. A new-old-stock radio, or one that went into grandpa's closet before he used it a month is usually the best kind of starting point, especially if it was kept in a closed carton.
73
