[Marsupial]

if anyone following my (slow) restoration, here's the current state.

I am done with the section 2 paper caps, they are all changed for orange drops.

[Image: http://i146.photobucket.com/albums/r253/...0_9494.jpg]

Sections 1 and 2 are now working fine following Riders volume 19.

There's just one filter cap to change in section 1, and I need to find (and install) safety caps to replace the line filters.
Otherwise, I am now looking at section 3 - getting closer to trying to get FM back.

[Marsupial]

Today I let the radio play most of the day. Its the first time I really make it play since I started to fix it up, was nice. After 5 or so hours, the power transformer gets warm to the touch, nothing more.

However, the accumulation of heat from the tubes and transformers makes that the top of the radio gets a bit warm.

Is that usual? I didn't think it would happen, the radio doesn't put out that much heat. Maybe I should add a cooling fan or something?

Seriously, should I be worried about that fact, or is that usual for console radios?

[codefox1]

If it is playing well for 5 hours, I think you are in good shape. It is always OK to make sure there is adequate airflow, and sure, you could fit a little fan from an old computer power supply and use a wall wart to power it if you want.

[Arran]

I would replace the remainder of the capacitors and check the resistors for drifted values, a drifted bias resistors can cause the audio output tube/s to draw too much current making the transformer run warm. After five hours of use it isn't unusual for the top of the cabinet to get a bit warm or for the transformer to be warm as well, but not hot. If the line voltage is a bit high that can also cause the transformer to get a little warm if it's a 60 cycle unit, the 25 cycle ones don't seem to be bothered as much since the core is larger and takes longer to saturate.
Regards
Arran

[Marsupial]

How do we check resistor for values, do we need to cut them out of the circuit?

I guess I'll add a fan as a latter upgrade. After five hours, it is warm, not hot. I could keep my hand on the transformer without problems. Although my mains are at 125~126V, and 1940s electricity was bellow 120 (117V in 47 if I am right) so this might cause a bit more power.

I have read of others who reduce the incoming voltage in order to reduce power stress on the chassis; is that needed here? I wouldn't want to damage the power transformer if I can prevent it.

[codefox1]

I noticed you marked the caps with the schematic numbers which is great, never thought about doing that before. What kind of a pen did you use? Most of us mount the new parts with the value showing, but this is a great idea too. I'd try to include a hard copy of the schematic you used to reference the parts somehow within the set for future anthropologists to follow.

And an excellent restoration. Learn something every day from this forum.

[Marsupial]

Thanks!
you're the first to comment on this idea; I am happy someone else than me thinks it might become useful!
I got an original service manual just for the reason you mentionned. I plan on making a "revised" schematics later with the alterations (and my values for the non-exact replacements), and document with some pictures including before/after; put all that in an envelope and staple it in the interior of the radio for whoever ends up with it later. Who knows who's going to maintain this radio next... and when.


I tried a few types of markers, ended up with a plain black sharpie and it works good.



Thanks for the kind words on my ongoing restoration, I had tons of help from the community; when I acquired the radio, I never tought I'd change most capacitors in there to revive it. I too learn a lot every day!

[Marsupial]

Haven't worked on my console radio in a while, but just got the last of my spare tubes (to eliminate possible bad tubes from the diagnostics) - I was purchasing tubes for another radio and decided to get the last missing spares.
I somewhat tought one of the FM tubes wasn't good. So I tried with new tubes on the FM circuit. (2 tubes)

IT WORKS!!!

changed back to confirm which is the bad tube... it works as well with the old ones!!! ???!!?!
I haven't changed anything in the circuitery.

I guess one of the tube was badly socketed.

Well, besides from having lost 1 year of FM listening, I can't declare this as anything else than good news!

the FM circuit sounds AWESOME!
I didn't even get to recap that section yet, but the sound is amazing. I seem to be able to pick up more stations than with any other radios I have in here, even if it is an early "new-FM" set. Ok, it'll need alignment, but it does sound crystal clear. Better than the radio's AM.

Guess I'll start to listend to hockey on it again! (the AM station that used to play sports was merged with its FM counterpart, and AM is now mainly traffic report)

Can't wait for next year's hockey season!!


on another note, with summer in, I am looking about refinishing the cabinet.

[Marsupial]

How do I know if the SW section works? I seems to get only static on the SW band, and have no other SW radios to compare to. What should I be expecting?

I think this radio uses the same circuits for SW and AM. (let me know if I am wrong, won't be the first time)

[codefox1]

You need to follow the voltage divider chain first. I assume swithes have been cleaned as prescribed above. Probe gently with chopstick to prove contacts are being made. if you have a signal generator, try an alignment. That way you can see if IF stages are good. Somewhere between the loudspeaker and antenna will be the point of failure.

[Arran]

How do we check resistor for values, do we need to cut them out of the circuit?

No you don't normally need to cut resistors out of the circuit to test them, unless the resistor is paralled with another part and is reading lower then it should.
Regards
Arran

[codefox1]

All the old carbon resistors have drifted up as a rule, or have become porous, some way out of tolerence. Best just replace them. Cheap enough. I normally do at same time as caps.

[Marsupial]

codefox, I appreciate the concept of changing all and every resistors.
On a smaller radio, I would without any hesitation. I have a 5 tube radio that has less than 15 caps and about 20 or 25 resistors, all is going to be changed.

but that 47-1230 is a monster. There is more than 100 resistors, not all easy to reach due to the construction of the chassis. I've already spent quite some time on this radio, and it is far from being done. If I have to remove and replace every single components from the radio one by one to ensure there's no mess-ups, it could take years!

Right now the power and amp sections are redone. AM and FM works. the phono connection works (not the phono itself)
I am uncertain about SW being that I don't even know what to try to listend to (and there's still some bad caps in the AM/SW section so I hear a lot of noise)

I want to mention that the FM section is awesome. Better reception than modern equipment. And completely quiet between stations. Surprisingly awesome.

[Marsupial]

Should I be worried that FM plays less loud than AM?