EUROPHON PROFESSIONAL 2 - FIX ONE HF BAND NOT WORKING - SWITCH DEAD

Hello guys!

Haven't been here for a while on these forums!

I recently came across this Europhon Profesiional II, very good receiver, but it has a problem. The switch for a SW band (4-8 MHz) is dead, it has a bad contact. I tried spraying it with contact spray, but it didn't solve the problem. I cannot replace the switch, it is not an option.

Has anybody got a suggestion?

73s and happy DX,
Patrik 327CT002

Hi Patrik,

The type of switch gear used in these radios were fairly common in many pieces of electronics equipment of the era. (Push button latching switch arrays.) They did however suffer from standing around for a long time and garnering quite a bit of surface corrosion in them.

Whenever I've run across problems with them so long as they mechanically function is to do the same as you've tried with application of switch cleaner.  Deoxit D5 is awesome stuff but also comes with an awesome price! Nowadays I tend to use Servisol Super10 it being a much cheaper option.

Usually I apply some switch cleaner and then run through the switches pushing them as often as I can to make sure the cleaning compounds can work through and also to wear off any surface corrosion. Usually does the trick.

If not then worth looking for 'dry joints' on the solder connections to the PCB as even a mechanically solid joint can be an awful electrical contact especially after a few decades of lounging around. (I tend to check/resolder most joints around vintage switch gear and usually successfully fix such issues.)

If none of that is successful then it's always worth making sure jumper/connecting wires haven't broken off but you may need a schematic or very good eye for detail to reconnect it.

A schematic/circuit diagram is available at radiomuseum.org but you may have to join to gain access to it :-

https://www.radiomuseum.org/r/europhon_professional_ii.html


I have in the past disassembled such switch gear to repair them, it's a fiddly job but do-able.
(Usually a collection of similar switch gear can be a good source of spares/replacement.)

The only other thing I can think of is to check the trimmer capacitors surrounding them which are switched in along with inductors to change bands. If any show signs of bad corrosion they can also stop the functionality of the radio.

That's all about the best I can suggest and I hope you get it fixed.  


All the best,
Victor

Hi Victor!

Always first on my posts! 

I've tried to put switch cleaner A LOT (it became a lake :-) ), but it still didn't fix the issue. Capacitors aren't a problem 100% because the circuitry works very good (picked up radio Romania on 41m inside my house with a 50 cm telescopic whip)

I'll try resoldering the connections.
I doubt I can get the switches replaced, I can't find a matching system.

If none of this works, I'll try to connect a external switch in parallel with this contact, so that when you want to receive this band, you push the faulty switch in to select the non working band, and using the external switch to make it receive.

Thanks and 73s!

Patrik 327CT002

Ha! Ha!

You know me Patrik, love me vintage radio stuff!

The exact same switch gear can be hard to find but a lot of it was similar enough to be a suitable replacement for each other. (You might have to play with the latching springs etc.) Otherwise your idea of an external switch at least presses a nice vintage radio back into operation.

I'll have fingers crossed that it is as simple as dry solder joints but wish you the best of luck with it all otherwise.

(I absolutely love the smell of old radios especially with that vintage rosin/PCB when you touch a soldering iron to it!! )


73's to ya!

Victor

Yes!

Thanks again Victor, I'll see if I can do this. As you know I am young, so I don't have a lot of experience, but I try to do my best :-).

I'm going to solder that now, and I'll ask my father if he has a contact spray that is more aggressive to corrosion.

Otherwise I have to open it again, because I have to mount a new telescopic element, because the original one is broken.

73s thanks!

Patrik

All we can do is our very best Patrik and you do seem to do rather well.

I also remember you being quite young (are you 14 yet?) but I'd never treat you any differently than I would anyone else. Your experience with such tasks will grow and probably has already surpassed many people who are much older.

Again, the very best wishes to you and your pursuits and do send my best to your Father. (Who must be so proud of you. )


All the best,
Victor

Hi Victor!

Thanks for all the help (yes I am 14 now (I was 13 when I joined))!

I tried resoldering, but it didn't solve the problem. Unfortunately I'll have to do that 'switch' mod. I did receive amateurs on a band that is working (8 - 16 MHz) on 20 meters, and it also has a band that works from 1.8 - 3.8 MHz so in the evening I'll try that.

Especially today and tomorrow, there is the CQWW 160M SSB so, that will be a cool experience.

The AM antenna (ferrite) is also very good, the longest I've had 234 mm, I tried it yesterday, i could completely wipe out a 9+40 signal from a local hill by turning it the opposite direction!

I'll get you notified on the 'switch' mod.

73s thanks!

Patrik