Soviet East German Radio

[Mark Hennessy]

Don't take too much notice of people who express strong opinions about tiny (often imagined) subjective differences in sound quality. Remember; we don't just hear with our ears

[Nowhere-Man]

Funny you should say but I do have a musician angle on this. I've written songs from Rock to Jazz, funk and soul.I dig the old Hammond Rock organs and Moog synths. The down side is musicians are buying up a lot of valves that come from gutted radios. I am not sure why the valve sound is so good but maybe the higher voltage and free electrons bear some influence. Anyway today I bought a spare iron as my old one seems to be not getting as hot as I'd like. I sort of got very lazy over Xmas and feel guilty over being so slow to get these radios sorted. Does anyone else struggle to be motivated in winter?

[Mark Hennessy]

It's pretty simple really - we like distortion. It's an essential part of the artistic process during the making of a recording. What matters is the exact nature of the distortion. Valves (and tape machines) generally make a sort of distortion that is "nice", and it is easy to measure and express the effect scientifically. It's is also quite easy to demonstrate that (a) there is stuff that you can measure, and reliably identify in a blind ABX comparison, and (b) there is stuff you can't. The latter is what I was referring to. Like it or not, we don't just hear with our ears. Beware of going down that road while you are trying to learn electronics - it will seriously hold you back.

[Crackle]

Hi NWM
One thing I would warn about when unsoldering, or soldering on printed circuit boards, (particularly the older ones from the late 50's early 60's) is the copper tracks can come unstuck and lift off the board. Dont worry too much, just be as gentle and as quick as you can when using the iron on the board. If a track breaks it can be repaired with a thin strand of copper wire bent to the shape of the track and soldered to what is left of it.

Mike

[Nowhere-Man]

Hi, That already happened months ago. Once bitten twice shy. There is debate about the valve radios that use boards. First you have Philips - feared by many due to the dia chord mechanisms. Also in the USSR and China, modern sets were being built into the Seventies. A lot of valve enthusiasts ignore some of these more modern sets and stick to point soldering on the older models. Actually I was going to postpone this project for a while longer and maybe tackle a Fifties Pye but I finally figured it's been on the shelf long enough. I must admit some of these PCB sets represent the peak of the valve radio era before the convenience of the transistor took over the consumer market. My guess is there were so many valves lying about in stock,countries like the GDR stayed with the transitional designs well into the Seventies. Funny really how valves phased out. These sets were high-tech and not even overly large. I can only speculate how mine ended up here from East Germany.

[Nowhere-Man]

Today hopefully the board comes off but only eased off to grant access to the knobs. These will be cleaned and the contacts checked. Then the board can be cleaned up and maybe renew some wax caps. It will probably be very dirty around the mechanism. There's wires I can see going into the knob assembly and a break wouldn't surprise me.

[Murphyv310]

Hi.
The only real issue with PCB valve radio's and TV's for that matter is heat......
Lots of manufacturers don't use stand off valve bases and ceramic beads on the wires from wirewound resistors. These two things would greatly improve the reliability of valve equipment using printed boards. This is one reason so many Radios survive with good old fashioned hand wired chassis construction.

[Nowhere-Man]

I have been struggling. No disaster yet or broken track but I am on unttrodden ground. The piano key mechanism is soldered to the board via tabs. All but one is at chassis potential. I only have access to the printed circuit side so I'm removing solder and then filing off any surplus. Even after that the tabs are a tight fit. I didn't want to repeat the mistake Crackle referred to of getting too much heat and damaging the board. Anyway I got one tab off with no track damage but it took some time.
Logic dictates if I can free the button tabs, I can ease the board free. The lower half of the board is freed up but the upper has been well and truly soldered to the chassis via the switch mech tabs.
I could use mega heat and just push the tab but it's so easy to damage the board.
Like I said I'm a bit out of my depth with this one but if you don't try you don't learn.

[Refugee]

What would happen if you remove the screws that hold the switches into the cabinet?
It aught to come out all in one surely.

[Terry]

I'm puzzled as to why you are trying to remove the switch from the PCB. What progress have you made tracing the feed to R12 from the switch bank?

Don't forget that you can get cracks in PCB tracks which are not easy to see. If the HT magically appears back along the track, it may be a case of locating the precise point at which the break has occurred, then repairing it by bridging it with a short length of tinned copper wire soldered across it.