Admiral 24A12 restoration

[bandersen]

What a surprise - I scored another Admiral set
They must have been very popular in Chicago back in the late 40s. I find more of this brand than any other.

This is the sister set to the very similar looking 20X122 which has a gold bezel and single chassis while this set has a white bezel and a split chassis.

This is the first set I've picked up from an active smoker.
I didn't think much of it when I picked it up, but after I got it home I really noticed that both it and I stunk

He had it running when I came to pick it up - ugh. I switch it over to channel 6 (low power analog station) and heard some nice audio - even without an antenna, but no picture.
The price was right though so I brought it home.



First, I cleaned the knobs. One, it's easy. Two, I just picked up some Simichrome and was curious to try it. Man, this stuff is incredible!


Only one scratch in the cabinet that I've noticed.


I've only done a little cleaning, but the bakelite 'grain' looks really nice.


It appears that someone worked on this set in the mid-80s based on the date codes on the caps.


The lower chassis is a bit rusty.


Made in good old Chicago


I put some felt pads on the bottom so it's easier to slide around and protect my floors.


The 10BP4 tested nearly dead at first. I let it cook for a few hours at 7 volts and it improved until it was just touching the green. I may try rejuvinating once I get the set running.


Here are a couple videos of me checking it out and trying to get it running.
The 1B3 appears to be bad and the 1/4 amp fuse was blown. I replaced the 6BG6, 1B3 and fuse and tried to power it up.
The fuse blew again. I need to do some more checking now. I sure hope the flyback is OK!

Any ideas?


Admiral 24A12 part 1
Admiral 24A12 part 2

[electronjohn]

Nice set, sir! I'm sure you'll have it playing fine in no time.

[DaveWM]

I would check the grid of the HOT for bias, maybe a leaky coupling cap.

[bandersen]

Originally Posted by DaveWM

I would check the grid of the HOT for bias, maybe a leaky coupling cap.

Yep, the culprit was some bad caps around the HOT. Specifically, the multi-section electrolytic C422. I haven't replaced any of the other electrolytics yet or even touched the lower chassis, but I will. It's running pretty darn well right now and I can't wait to see how much better it might get with a full recap.

I also discovered several dubious repairs like these two 0.001 MFD caps in the sync inv. / disc. circuit. I have no idea what type of cap is correct or what the voltage rating should be.
I just went with what I had on hand - 630 V poly caps. Does anyone have a parts list for a 20A1 chassis that does specify these caps?



Also the original 8.2K power resistor in the HV cage is open and was bypassed at some point with the smaller green one. That's a shame because I really like that old style ceramic resistor.
I'll try to dig up one that looks better and mount it properly.


There's an interesting metal hoop under the HV rectifier tube. I wonder what that's for?


Here's the first picture I got using rabbit ears and local lower power channel 6 using a 5AXP4 test CRT.


And here it is using the 10BP4 The CRT is brighter than I was expected based on the weak test reading. I guess time will tell.






It's nice to have an easy restoration for a change

[Sandy G]

I'm in love...An' in awe ! (grin) Those Bakelite Admirals are just SOOOOOO purdy...

[Phil Nelson]

Gorgeous. I should look for an Admiral like that. Plenty of elbow room under the chassis, and a nice turret tuner.

Hard to believe you have such a nice picture with practically no work. I seem to end up with dogs of the other kind; weeks of slaving and scratching my head, and I finally get a picture looking that good . . . almost!

Phil

[jr_tech]

Great find! it is nice to get an easy one once in a while!

"There's an interesting metal hoop under the HV rectifier tube. I wonder what that's for?"

If it is connected to the high voltage, I suspect that it serves as a (anti) Corona Ring, to reduce the possibility of corona and arcs between the sharp points under the tube socket (such as cut off wires and socket pins) and the chassis.

jr

[bandersen]

Originally Posted by jr_tech

Great find! it is nice to get an easy one once in a while!

"There's an interesting metal hoop under the HV rectifier tube. I wonder what that's for?"

If it is connected to the high voltage, I suspect that it serves as a (anti) Corona Ring, to reduce the possibility of corona and arcs between the sharp points under the tube socket (such as cut off wires and socket pins) and the chassis.

jr

That makers sense. Yes, it's connected to the HV - also the metal ring around the tube socket.

[bandersen]

Originally Posted by Phil Nelson

Gorgeous. I should look for an Admiral like that. Plenty of elbow room under the chassis, and a nice turret tuner.

Hard to believe you have such a nice picture with practically no work. I seem to end up with dogs of the other kind; weeks of slaving and scratching my head, and I finally get a picture looking that good . . . almost!

Phil

Thanks. I've found about 20 caps in this set that have 80s date codes. So I'm not the first to restore it. I'll probably end up replacing all of those though. Hard to believe the mid 80s was 25 years ago now!

Speaking of dogs, the previous owner had two dogs. So in addition to being stinky from cigarette smoke it's full of dog hair!

I bet I'll spend more time cleaning it than soldering

[Reece]

Very nice pictures! Amazingly sharp. I noticed that set used a 6X5 in the power supply section. Those have been known to short and take out a power transformer. Here is a whole discussion about the early vs. the later version of the tube, the later "X" plate design usually deemed more rugged. One good idea is noted: provide a separate 6.3 volt transformer for the 6X5 heater, so that if it does short, it won't take out the power transformer. Some just replace the tube with a couple of diodes.

http://antiqueradios.com/forums/view...&highlight=6x5

[bandersen]

I put up a couple more videos showing the first video images using the 5AXP4 and 10BP4.

Part 3: Recapping and using a 5AXP4

Part 4: Using the 10BP4

I've heard that the single 20X1 chassis from 1948 performs better, and am curious to put that to the test. Here's a portion of the schematic for one.

It doesn't use a sync. discriminator like this set from 1949 does. I would think using a discriminator is a superior design

[DaveWM]

wow that looks nice! great finding one that required so little to get going

[wa2ise]

Mine (Model 24R12) actually worked before the recap. This back in 2000. Here it is above, after a recap anyway, with the game on. These sets seemed to have been well engineered and tough to kill. The weakest spot seemed to be the door that hides the controls between the channel and volume knobs.

[bandersen]

Originally Posted by wa2ise

Mine (Model 24R12) actually worked before the recap. This back in 2000. Here it is above, after a recap anyway, with the game on. These sets seemed to have been well engineered and tough to kill. The weakest spot seemed to be the door that hides the controls between teh channel and volume knobs.

Nice set
A guy in Nebraska tried to talk me into buying that same model set and trust that it would survive shipping. I learned my lesson after destroying a similar bakelite set and turned him down.

I've heard that Admirals are hard to kill as well. Almost temps me to try powering up a couple I've haven't gotten around to yet

Yes, they almost always are missing that door. I only have one set that has it's original door and even that one is cracked

[Dan Starnes]

That plays impressive for a CRT that was reading basically dead. Never thought about letting one cook like that,, Will try that in the future. Nice score!!