Admiral 26R12 restoration - Page 4 - Videokarma.org TV - Video

bandersen · #46 01-06-2012, 03:20 AM

All the caps tested OK, but I think I found the problem. It turns out it works better if you actually solder all the connections

Now on to the cabinet.

holmesuser01 · #47 01-06-2012, 08:19 AM

Naah. Just makes for interesting problems later.

Please dont ask how I know this... Vivid memories of an RCA roundie flyback and one missed solder connection and a jumpy width that didnt happen until the entire set was put back together completely... set back and all.

bandersen · #48 01-06-2012, 03:11 PM

I let the set play for a couple hours and the audio issue has resurfaced. My next thought is that it could be the cap across the audio output transformer breaking down. The original was 600 v and I replaced it with a 630 v. I recall seeing a service note about replacing this cap with a higher voltage one.

Kevin Kuehn · #49 01-06-2012, 03:15 PM

That's weird if it's breaking down in that location. How many volts across it?

miniman82 · #50 01-06-2012, 03:28 PM

I always wondered why that particular cap was rated 1000vdc in sets, seems to me it shouldn't have more than about 400v across it at any point in time.

Kevin Kuehn · #51 01-06-2012, 04:49 PM

I suppose the audio signal can add to the DC volts, but I'd of never thought the audio signal would be very much for a couple watts TV speaker.

old_coot88 · #52 01-06-2012, 04:58 PM

Quote:

Originally Posted by miniman82

I always wondered why that particular cap was rated 1000vdc in sets, seems to me it shouldn't have more than about 400v across it at any point in time.

Positive-going back-EMF spikes can get stacked 'on top' of the supply voltage, 'specially if the voice coil were open.

kvflyer · #53 01-06-2012, 05:12 PM

Quote:

Originally Posted by old_coot88

Positive-going back-EMF spikes can get stacked 'on top' of the supply voltage, 'specially if the voice coil were open.

This question often comes up. Yes, there are spikes on that capacitor and it should be at least 1000VDC. I know that there are Orange Drops rated at 1600VDC out there. Might be a good thing to have. Also, not having a speaker connected can cause a high reflection of the signal back to the tube. I know this is just a 6V6GT single ended amplifier. But I have seen a few audio amplifiers that had the tube sockets burned. All because of the reflected signal. I don't think that you have to not use it now, but I would get some 1.6KV caps the next time you order some.

Kevin Kuehn · #54 01-06-2012, 05:44 PM

How bout a couple double value caps in series?

bandersen · #55 01-06-2012, 05:56 PM

I imagine that would work too. I do have a few of those orange drop 1600v on hand though. I'll install one later tonight and clean out the tube socket pins too.

I started on the cabinet this afternoon. 55 F and sunny

Never expected to be working on an unheated porch in January!

No chips or deep scratches. I'm going to clean it with some mild detergent then buff with Novus #2

The CRT gasket foam is rock hard and crumbling. I'll replace it with some closed cell foam insulation.

bandersen · #56 01-06-2012, 11:09 PM

I removed the faceplate and cleaned the cabinet with some warm soapy water.

The speaker cloth has faded quite a bit.

I recall someone had asked about the clarity of the faceplate. Here it is before any cleaning. I hope it clears up.

There's some flashing left from the bakelite molding process.

Time to finally lose the caster wheels. Now I can bring it inside.

kvflyer · #57 01-07-2012, 09:48 AM

Quote:

Originally Posted by bandersen

I removed the faceplate and cleaned the cabinet with some warm soapy water....

The speaker cloth has faded quite a bit.

Bob,

I see that you were able to remove the nuts that hold the speaker board to the cabinet. What method did you use? I started to take my speaker board out and the nuts didn't want to budge without breaking. Did you pry up on the two "capture" parts in the center of the nut? Did any of yours break?

Quote:

Originally Posted by bandersen

I recall someone had asked about the clarity of the faceplate. Here it is before any cleaning. I hope it clears up.

...

Bob,

I think it was me that asked about the clarity. I was able to polish the clear faceplate with no problem. But when I look at either one that I have (I have two) in bright light, the clear plastic has sort of a very faint swirl pattern in both of them. I suspect the plastic was about as clear as they could get it but there was still some kind of white swirl in it. Mind you, very faint and it doesn't affect the picture. But I was just interested to see if anyone else noticed it.

And for what it's worth, that foam gasket on mine was as crisp as a 50-year old wedding cake! I didn't replace it yet.

kvflyer · #58 01-07-2012, 09:49 AM

BTW, nice to see this restoration. My chassis is copper plated and the reason I have spare parts is because I bought a 16R12 for parts. Mine was missing the HV cage. I was lucky that both were copper plated.

Nice job as usual!

wa2ise · #59 01-07-2012, 04:14 PM

Looks like some idiot production manager was screaming at the workers to get productivity up. Which usually means the workers have to skip steps to keep the quality decent... So they didn't take the time to remove the flash.

bandersen · #60 01-07-2012, 04:46 PM

Quote:

Originally Posted by kvflyer

Bob,

I see that you were able to remove the nuts that hold the speaker board to the cabinet. What method did you use? I started to take my speaker board out and the nuts didn't want to budge without breaking. Did you pry up on the two "capture" parts in the center of the nut? Did any of yours break?
Bob,

I think it was me that asked about the clarity. I was able to polish the clear faceplate with no problem. But when I look at either one that I have (I have two) in bright light, the clear plastic has sort of a very faint swirl pattern in both of them. I suspect the plastic was about as clear as they could get it but there was still some kind of white swirl in it. Mind you, very faint and it doesn't affect the picture. But I was just interested to see if anyone else noticed it.

And for what it's worth, that foam gasket on mine was as crisp as a 50-year old wedding cake! I didn't replace it yet.

I used pliers on the four in the corners. I got a good grip on them and sort of unscrewed them while pulled back.
I tried to pry up the capture teeth with a small screwdriver on the rest, but couldn't manage it. I had to mangle them by bending them with needle nose pliers.
None broke though and I might be able to unbend and reuse them.

I propped it up in front of a window and, yes, it sure does have those swirls.

Here it is after cleaning with warm soapy water and Novus #2. Not much of an improvement. Those swirls are definitely in the plastic and not surface dirt.

Quote:

Originally Posted by wa2ise

Looks like some idiot production manager was screaming at the workers to get productivity up. Which usually means the workers have to skip steps to keep the quality decent... So they didn't take the time to remove the flash.

LOL - I bet you're right.