Problematic Spidola 231

[WilliamTK1974]

Hello,

I received a Spidola 231 in the mail yesterday, and I'm pretty sure I bought it for the Young Octobrist pins the seller put in the box.

This one seems different than my other Soviet radios. The turret tuner is present, but a different design than one would find in a VEF 206 or Selena 2XX series. The contacts on the small boards in the turret are flat, and they're swept through two metal contacts that meet in a V in the center. The bands are LW, MW, 52M, 49M, 41M, 31M, and 25M. There is space on the turret for two additional boards. Seems some of these came with VHF, but not this one.

Cosmetically, it's decent. Sadly, I had to break the factory seal on the back to get into it. Someone left batteries in it to leak at some point, and the sponge was deteriorated and left dust everywhere.

I'm going to take the battery terminals out and let them soak in rust remover. I tried to sand the rust off, and while that helped, it wasn't a cure.

Of course, I've had to see if I could make it work, so I put six good D cells in and switched it on. The speaker popped, but that was it. No reception. I've since taken each one of the boards off the turret and carefully used Tarnite metal polish on the terminals. They may not be perfectly clean, but they're a whole lot better than they were. Some of them were completely black before I used the polish.

After doing that, I had another go, but got the same response. There's a transformer down near the battery box that gets hot to the touch, and I wonder if it's having a problem. I really expected the terminal cleaning to make a change. Also, nothing happens when I turn what I think is the volume control. No crackles, static, more hissing...

Sadly, it seems there's precious little information about these out there. I would like to get it going if at all possible. Any assistance would be appreciated.

Thank you,
-William

[Records]

I'm no expert on these but it is possible one of the problems maybe the transistors, a lot of transistors of this age can suffer from tin whiskers, basically you get a growth inside the transistor and it shorts it out. There are ways of getting rid of the whiskers but it doesn't always work, I will leave that explanation to more experienced people on here.

[paulsherwin]

The Russian germanium transistors used in Soviet radios aren't known to have tin whisker problems. I think the 231 uses silicon transistors anyway, being a 70s design.

Things getting hot normally suggests a failed output transistor. You should start by measuring the current being drawn - I would expect this to be very high (10-20mA would be normal).

Unfortunately I have no personal experience of the Spidola models, so can't give specific advice.

[ms660]

Any use?:

http://www.radiohistoria.sk/Oldradio...DOLA%20231.pdf

Lawrence.

[orbanp1]

Hi William,

RM has a page on the radio, it also has the schematics that you can download:
http://www.radiomuseum.org/r/vef_spidola_231.html
Here is a link to the full manual in Russian:
http://www.radiohistoria.sk/Oldradio...DOLA%20231.pdf
Those should be enough to get the radio going.

From the schematics it looks like it is a slightly updated version of the VEF-206 series radios.
It does not look like it ever had a VHF band, probably just other SW bands.

Good luck, Peter

[paulsherwin]

That circuit does suggest PNP Ge transistors throughout. The USSR stuck with Ge for longer than the rest of the world, particularly in consumer electronics. Presumably the military and industry had first pick of Si devices as they became available.

[WilliamTK1974]

Many thanks to those who shared a schematic. My searches last night came up with what I thought was a schematic, but having it presented here confirms it. Now, if only the manual were written in English... Google translate isn't much help, and I'm curious about a couple of the switches.

As far as output transistors go and possible failures, it appears from the schematics and the circuit board diagram that the transformer labeled TP2 is the one that's getting hot to the touch. So, maybe transistors T11 and T12 could be suspect? Looks like they might can be removed from their sockets... And there's a solder joint on a resistor in the nearby vicinity that could be suspect... Hmmm... The plot thickens and the game's afoot!

[paulsherwin]

If one or both of those transistors has failed short circuit then a lot of current will flow through the OP transformer primary which might cause it to get warm. The first thing to do is to remove the transistors and test them.

If they test bad you could probably confirm they are responsible by replacing them with a pair of jellybean PNP silicon transistors like the 2N2907 or BC327, though the bias arrangements would need to be modified to use these permanently.

[WilliamTK1974]

Is there any trick to getting them out? Just pull, or what?

I'm afraid if I pull any harder that I'll break the circuit board. They're in there quite tight.

[paulsherwin]

Sorry, I don't know the arrangement used here. Are you saying that the transistors are in sockets? If so, they should just pull out. If they're soldered in then unsolder them, taking care not to overheat them.

As I said earlier, I have no personal experience with this model.

[WilliamTK1974]

T11 and T12 weren't in a socket. They were in a plastic mold that bent the collector back from the emitter and base. It just looked like a socket.

I desoldered them carefully one at a time and tested them with my inexpensive analogue multimeter. According to the test procedure I used, they both test as good transistors. So, I used my 30W soldering iron to put them back.

Problem is, nothing has changed. I thought it was possible the solder joints could have been bad and that re-soldering them would fix that. But there's still no sound and the Tp2 transformer is still getting hot. What next?

[AC/HL]

If you lift R52 the output transistors shouldn't have any bias, so should be turned off.
Does the transformer still heat up?

[paulsherwin]

C57/C58 would cause overheating if they failed short circuit, though that isn't very likely.

[Steve_P]

Disconnect the speaker socket and see if it springs to life....

Cheers,

Steve P.

[WilliamTK1974]

If you lift R52 the output transistors shouldn't have any bias, so should be turned off. Does the transformer still heat up?

I removed the resistor. There was a bit more crackling from the speaker, but the transformer still gets hot.

C57/C58 would cause overheating if they failed short circuit, though that isn't very likely.

How can I test for this?

Disconnect the speaker socket and see if it springs to life....

I tried bridging the terminals on the earphone socket. Very slight crackling from the speaker, but nothing else.

['LIVEWIRE?']

Disconnect one end of both C57 and C58 to check if they are leaky or short circuit, though, as Paul Sherwin says, this is most unlikely. Not sure if the o/p transistors are germanium, or if this has already been mentioned, but Ge Transistors can suffer from internal faults. Check the DC readings on both, and, if they are housed in a common heatsink/cooling clip, try removing that in case internal faults in the transistors are causing the problem. (I assume the o/p transistors are metal can types)

[WilliamTK1974]

Originally Posted by 'LIVEWIRE?'

Disconnect one end of both C57 and C58 to check if they are leaky or short circuit, though, as Paul Sherwin says, this is most unlikely. Not sure if the o/p transistors are germanium, or if this has already been mentioned, but Ge Transistors can suffer from internal faults. Check the DC readings on both, and, if they are housed in a common heatsink/cooling clip, try removing that in case internal faults in the transistors are causing the problem. (I assume the o/p transistors are metal can types)

If the caps are the issue, what will happen? Humming, buzzing, or nothing?

The transistors are soldered directly to the board near each other. They're labeled as G402E, that would appear to be germanium. But since they've tested good, what else could be wrong with them? They're in a tall, gray metal can.

['LIVEWIRE?']

If the G402E transistors are similar in costruction to the AC12x types used in the UK and Western Europe in the 60s & 70s they may suffer from the 'tin whisker' problem often referred to in this forum, in which whiskers growing inside the can short circuit, sometimes intermittently, to one or more parts of the transistor. I know that this should show up on a resistance test, but it may be worth checking for any resistance between the metal can and the lead-outs, particularly if, as I mentioned, the two o/p transistors are fitted into a heatsink or cooling clip.

[paulsherwin]

This radio uses Ge transistors throughout despite the late date - the USSR only sorted out the mass production of silicon transistors in the early 70s, a decade after the Europeans, Americans and Japanese. USSR Ge types aren't known for tin whisker problems though.

There is guidance on testing Ge transistors here.

[WilliamTK1974]

I disconnected C57 and C58. No change. TP2 still gets hot. I also noticed a bad solder joint on the collector for T8 and resoldered it, but that didn't make a difference either.