Tube radios and printed circuit boards

[Telecolor 3007]

Well, I got me an nice East-German (G.D.R.) made tube radio. The bad thing: printed curcuit boards. On A.F. no big problem, but on audio, where tubes (valves) are generating heat, the board startes to go nasty in time.
Did U.S.A. or West-German made radios hade this problem?
Anyway, in the future, I will not buy anything with tubes and printed circuits..

[Electronic M]

We had a LOT of tube radios with PCBs in the US. It was most common in AA5s but everything up to high-end stereo/TV combinations.

Most PCB US sets that I have seen are VERY reliable. The only annoyance with US PCBs of the tube era is it isn't hard to lift traces when soldering a replacement part in.

[Electronic M]

Oops double post...

[maxhifi]

I actually prefer printed circuits, they are very consistent and reliable. Point to point is a rat's nest by comparison. Lifting traces can happen, but if you use solder braid and proper temperatures it is much less common.

You shouldn't worry, tube equipment from table radios to powerful high end audio amplifiers has lasted many decades with printed circuits.

Of course there is always the poorly designed exception which overheats and bakes the board, I am speaking generally above.

[dieseljeep]

Originally Posted by maxhifi

I actually prefer printed circuits, they are very consistent and reliable. Point to point is a rat's nest by comparison. Lifting traces can happen, but if you use solder braid and proper temperatures it is much less common.

You shouldn't worry, tube equipment from table radios to powerful high end audio amplifiers has lasted many decades with printed circuits.

Of course there is always the poorly designed exception which overheats and bakes the board, I am speaking generally above.

Zenith tried PC boards in a few models of 5 tube table radios, CA 1956. They were very poor! The traces lifted when doing just minor repairs. They quit using the boards after about one model year.
Even the first model Royal 500 was hand wired!

[madlabs]

I hook and loop repair on early PCBs where I can. I generally dislike that type of repair as it looks sloppy to me. But better that than delaminating the traces.

[JohnCT]

Originally Posted by Telecolor 3007

Well, I got me an nice East-German (G.D.R.) made tube radio. The bad thing: printed curcuit boards. On A.F. no big problem, but on audio, where tubes (valves) are generating heat, the board startes to go nasty in time.
Did U.S.A. or West-German made radios hade this problem?
Anyway, in the future, I will not buy anything with tubes and printed circuits..

It depends on the actual printed circuit. My understanding is that some traces were added to the substrate while others used a bonded copper layer that was etched. The additive boards were crap.

RCA was big with printed circuits early on and they were always excellent. The biggest problem with RCA was that the solder crystalized on high heat components like resistors and tube sockets over the years. Trying to resolder them was problematic. Back in the late 70s when RCA tube TVs were still plenty I used to invert the chassis and scrape down the tube sockets with a jeweler's screwdriver, apply liquid flux and use a high wattage iron to get the solder to reflow. Once done, they were rock solid.

I remember working on a B&W console TV (thinking it was a mid 60s Philco) with printed circuits sometime in the mid 70s, and this board was so crappy that as soon as the soldering iron was applied, the foil would roll back to the next component. I ended up pretty much having to hand wire from point to point anywhere I needed to solder. Those were exceptions though. Thank God..

John

[MadMan]

There are many online services that will print circuit boards for you, if you design it.

[dieseljeep]

Originally Posted by madlabs

I hook and loop repair on early PCBs where I can. I generally dislike that type of repair as it looks sloppy to me. But better that than delaminating the traces.

Admiral recommended that procedure in the mid 50's. I never did! I seldom had trouble with trace lifting.
Hook and loop connections, I was always wary about loose solder joints where the original component was soldered to the trace.

[Telecolor 3007]

Originally Posted by MadMan

There are many online services that will print circuit boards for you, if you design it.

I don't any software that converts a scanned image into a ready to print one

[MadMan]

Originally Posted by Telecolor 3007

I don't any software that converts a scanned image into a ready to print one

Then do it the hard way lol

I mean, if you really were willing to go the whole nine yards and reprint a circuit board, you could remove all the components from the old one, and put it on a flatbed scanner. The scanned image would be fairly accurate in terms of dimensions, it could be used to design a new one.

[Electronic M]

If you watch Mr Carlson's lab on YouTube he designs his circuit boards on a cad program, prints them, uses a laminator to transfer the ink from the paper to the board and etches his own boards... If you were serious about remaking bad boards on you could probably reproduce one by scaning it, cleaning and repairing the image in a drawing program, then print it and follow Mr Carlson's method...