So here's a picture I finally managed to capture. For anyone not familiar with the Tram D201 CB base radio, most of them were built with large printed circuit boards with four tube sockets on one and nine on the other. Each of these circuit boards has another, smaller circuit board plugged in at a right angle, standing up. Tram called them "auxiliary" boards.
Huh?
The original radio was built in the traditional way with each tube socket in a hole punched into a steel chassis deck. all the resistor/capacitor/choke jelly-bean parts were strung point-to-point between tube sockets and tie-strip lugs. The change to printed circuits had taken over nearly all other electronics products, mainly because it reduces assembly labor in a big way. The soldering on these circuit boards is not done by hand with a soldering iron, but on a waterfall of molten solder they call "wave soldering".
I think the standup plug-in "auxiliary" boards were caused by insufficient real estate available on the large boards. Somebody chose the size of the main circuit boards before finding room for all the parts. Maybe. I'll probably never know for sure what they were thinking.
Automation. 1970 style. The labor cost of stringing all those parts and soldering them all by hand was just too much. All this boring trivia leads up to a fault this radio is famous for. Crackle and crunch noises that come from any vibration of these "auxiliary" standup circuit boards. The reason for all this racket is the metal pins these boards plug in to. Tram used round pins. Trouble is, the spring contact in the plug sliding over it wears out the shiny plated surface that maintains good, quiet metal-to-metal contact.
The pressure concentrated in that tiny area wears away that coating.
A closer view makes it a little clearer.
The noise this causes may make earthquake sounds when the audio plug-in board gets this way. Or it may just cause the receiver signal to cut out if the board behind the VFO knob gets noisy.
We just replace the round pins with square ones. Yeah, they just barely fit in the circuit-board holes. But they won't acquire the same bad habit as soon. The contact surface of the spring inside the socket will now be spread across the flat face of the new pin, not the tangent point of the round pin.
I've been singing this same blues tune for decades, but I finally got a couple of clear pics showing the wear pattern on worn-out round pins. Couldn't resist sharing.
73
Huh?
The original radio was built in the traditional way with each tube socket in a hole punched into a steel chassis deck. all the resistor/capacitor/choke jelly-bean parts were strung point-to-point between tube sockets and tie-strip lugs. The change to printed circuits had taken over nearly all other electronics products, mainly because it reduces assembly labor in a big way. The soldering on these circuit boards is not done by hand with a soldering iron, but on a waterfall of molten solder they call "wave soldering".
I think the standup plug-in "auxiliary" boards were caused by insufficient real estate available on the large boards. Somebody chose the size of the main circuit boards before finding room for all the parts. Maybe. I'll probably never know for sure what they were thinking.
Automation. 1970 style. The labor cost of stringing all those parts and soldering them all by hand was just too much. All this boring trivia leads up to a fault this radio is famous for. Crackle and crunch noises that come from any vibration of these "auxiliary" standup circuit boards. The reason for all this racket is the metal pins these boards plug in to. Tram used round pins. Trouble is, the spring contact in the plug sliding over it wears out the shiny plated surface that maintains good, quiet metal-to-metal contact.
The pressure concentrated in that tiny area wears away that coating.
A closer view makes it a little clearer.
The noise this causes may make earthquake sounds when the audio plug-in board gets this way. Or it may just cause the receiver signal to cut out if the board behind the VFO knob gets noisy.
We just replace the round pins with square ones. Yeah, they just barely fit in the circuit-board holes. But they won't acquire the same bad habit as soon. The contact surface of the spring inside the socket will now be spread across the flat face of the new pin, not the tangent point of the round pin.
I've been singing this same blues tune for decades, but I finally got a couple of clear pics showing the wear pattern on worn-out round pins. Couldn't resist sharing.
73
