Motorola 52L1

[danrulz98]

(Note: My camera takes BIG pictures, so I have linked to them instead of embedding them)

Little something I picked up for $5 at a yard sale.

It probably works, I haven't plugged it in yet, I don't really want to.
It seems to be in really good shape except for being very dirty on the outside.
http://i46.tinypic.com/118lkyc.jpg
http://i48.tinypic.com/29zeedk.jpg
http://i45.tinypic.com/jgiha8.jpg

Internally, it's in even better shape. There was a case screw missing, but I found it floating around in there, one of the plastic standoffs inside the case that held the chassis was broken.
http://i47.tinypic.com/2dac21t.jpg
http://i45.tinypic.com/30at8c7.jpg

All tubes are present, and only one looks like it's been replaced (its a Raytheon instead of a Motorola)
http://i48.tinypic.com/1z9gl3.jpg

Its all original inside the chassis. There's also an interesting component for switching between battery and AC power.
http://i45.tinypic.com/24zhmrp.jpg
http://i46.tinypic.com/20krq69.jpg

It looks like some of the wires might be a little burnt. Should I replace these?
http://i46.tinypic.com/3094s2h.jpg

A different view of the AC-DC switch, and some lovely paper caps in this baby
http://i46.tinypic.com/rqxjlz.jpg

I am curious as to what this even is, it looks like a multi-section ceramic cap.
http://i45.tinypic.com/23wse9f.jpg

So, hoping to get this baby all fixed up Might be a nice little radio.

My camera died shortly after taking these pictures, so video will have to wait.

I also wanted to ask, whats the best place to get a schematic?
I found one, but I can't seem to download it...

[electroking]

Interesting pictures, but you will have to teach your camera to focus on the
right target... Or use more light to get better depth of field.

The multiterminal ceramic thing is an early integrated circuit (all passive devices),
sometimes known as a Couplate (TM). Be sure not to break it, some are
very hard to find (especially a type used in a battery tube radio, I would assume).
Good luck!

[bandersen]

That's a nice radio. Here's a schematic you can download for free: http://www.nostalgiaair.org/resources/057/M0012057.htm

I'd replace the wires if they look like they might short out. Otherwise, I'd leave them alone.

[danrulz98]

The only light I took this with was the florescent lights in my shed.
I had my camera set to "full auto" mode too, could try a manual focus (its actually a camcorder).

So, I'm guessing I should not try to replace this couplate thing?

And, thanks an ton Bob! I'll be sure to look there next time.

[bandersen]

Yeah, I'd leave it alone. I've yet to run into a bad one.
If you had to though, you could build one from discrete components like guys have done for Predicta TVs.

[leadlike]

in small radios, the couplate is usually in the audio amp. If you have audio, it is working, and there is no need to mess with it.

[danrulz98]

So it would use a solid-state like device instead of a tube?

[bandersen]

It's all tubes except for the selenium rectifier on the AC line. The couplate is the dashed box in the upper-right of the schematic with four capacitors inside. If it was bad, no audio signal would get to the 3S4 output tube.

[danrulz98]

Ah, alright. That makes a lot more sense.

[Reece]

BTW, just to nitpick (!) that replaced tube is probably a Raytheon, not a Rayovac? Don't think the latter got into tubes?

[Phil Nelson]

I used to have one exactly like that. Motorola made loads of portables in the early 1950s, often with more interesting cabinets than other manufacturers.

I bought mine at a swap meet because I needed change! I wanted to buy a certain radio, but that seller wouldn't take a check and couldn't make change. I stepped next door, bought this for $5 (getting change), and went back to the first booth with the right amount of cash in hand.

Many of these portables are amazingly clean inside. I think the owners got tired of buying batteries and put them away before long.

The electronics are very conventional. It's a good idea to replace the electrolytic capacitors in the power supply. After that, it may just spring into life.

Phil Nelson

[danrulz98]

Originally Posted by Reece

BTW, just to nitpick (!) that replaced tube is probably a Raytheon, not a Rayovac? Don't think the latter got into tubes?

That's what I actually meant to say.. I have no idea why I put "Rayovac".
I discovered that there was an RCA tube behind it, so maybe its not all original like I thought.

Originally Posted by Phil Nelson

I used to have one exactly like that. Motorola made loads of portables in the early 1950s, often with more interesting cabinets than other manufacturers.

I bought mine at a swap meet because I needed change! I wanted to buy a certain radio, but that seller wouldn't take a check and couldn't make change. I stepped next door, bought this for $5 (getting change), and went back to the first booth with the right amount of cash in hand.

Many of these portables are amazingly clean inside. I think the owners got tired of buying batteries and put them away before long.

The electronics are very conventional. It's a good idea to replace the electrolytic capacitors in the power supply. After that, it may just spring into life.

Phil Nelson

I think I read your article on it...

Well, a bit of an update. I wrote down the values of all the caps so I could go into town today and pick some up (as well as a new soldering iron tip).
I discovered three caps that are .05 mF @ 400 vdc. But, one is maybe 3/4 the size of the other two. How is that possible? Maybe a later replacement part?

I also looked into the electrolytic. It's a three part one.. I don't think I'll be trying to restuff the can. It didn't seem like a very well made one.
I cut off the paper casing and it looked like a lot of tar melted off the inside of the metal can and was all in the paper casing Nasty...

I'm not sure what the numbers mean on here, maybe you guys can give me a hint.
http://i48.tinypic.com/34hf3n6.jpg

I'm guessing this means that two sections are 40 uF at 150 volts and one is 250 uF at 10 volts.

I also looked at the output tube on it and noticed that there was very little letting in it and what there was was white around the edges. I thought maybe it was a manufacturing error until I looked at the tube more closely. It's got a crack right across the bottom

EDIT: Duh, forgot I had a schematic and parts list. Found the values of that cap.

Edit2: It also appears that the selenium rectifier was replaced with a big diode... Hmm.

[danrulz98]

Its re-capped completely (along with my tube tester) and all the tubes test good.
Still though, not sure if I should fire it up just yet. I know you guys power up your TVs and stuff with a variac, but I don't have one...

Also managed to burn myself for the first time on the soldering iron..

[bandersen]

Welcome to the "burnt finger" club I'm sure we've all got a few battle scars.

A 'dim bulb tester' is fine for radio work. You can slap one together for a couple bucks. I made mine with an extension cord, light bulb socket, duplex outlet and a scrap of wood.
Check this out http://www.ppinyot.com/dimbulb/dim_bulb_tester.htm