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 Post subject: Magnavox Model MV21F
PostPosted: Mar Sat 17, 2012 1:50 am 
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Joined: Mar Wed 30, 2011 5:37 am
Posts: 832
Location: GA
I just won 2 sets on Ebay today. One is another metal cabinet Admiral to go along with the two 10" sets I have. I believe this one is a 14" set though, but the cabinet has been repainted according to the seller. I have an orphan 14" cabinet in my shop that I may put the chasis into after I get it going.

The other set is what intrigues me. It's a devistated Magnavox. Thisn seller had about 6 sets, and all had opening bids of $9.99. Most of the bakelite sets he had were mssing hard to find cosmetic parts which led me to bid on this wooden Magnavox. The cabinet is in horrbile shape from what I can tell in the pics, but I'm going to take it to a refinnishing shop anyway. My question is about the model #. The seller took 2 pics of the data plate on the back of the set which shows it as a Model MV21F. Style T146-223. I can't find anything like this in my Sams index, and I want to get a Sams while I'm waiting on the set to arrive. The closest I can find is in Set 153-8 for a model 21F86/87/88/89.

I may have bit off mor than I can chew on this one. It's got a brightner on the CRT, but I figured I couldn't go wrong for $10 even though the shipping is about $65. However the seller stated he had plugged each of the set in that he was selling and posted the same results on most of them: "couldn't leave set plugged in to do testing as transformer was smoking." I hope it was actually the HV caps smoking. Anyway, does anyone recognize this model so I can try to get a Sams for it?
Thanks
Doug


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 Post subject: Re: Magnavox Model MV21F
PostPosted: Mar Sat 17, 2012 2:36 am 
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Joined: Mar Thu 22, 2007 4:22 am
Posts: 46
Location: Milwaukee
I had the same problem with the Magie MV23A-1 that I have. I believe you have to locate the sams by using the number stamped on the chassis, not the model number on the plate you show in your photo.


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 Post subject: Re: Magnavox Model MV21F
PostPosted: Mar Sat 17, 2012 2:51 am 
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Joined: Mar Wed 30, 2011 5:37 am
Posts: 832
Location: GA
EXCELLENT: I just went back and look at the seller's pics. There is a label on the chasis that says CT277. That is in my Sams index as 148-8.
Thanks a bunch.


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 Post subject: Re: Magnavox Model MV21F
PostPosted: Mar Sat 17, 2012 2:52 am 
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Joined: Mar Sun 01, 2009 10:27 pm
Posts: 3246
Location: Ann Arbor, MI
By the way, tell the seller to stop plugging them in and testing them.

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Tom


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 Post subject: Re: Magnavox Model MV21F
PostPosted: Mar Sat 17, 2012 2:56 am 
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Joined: Mar Wed 30, 2011 5:37 am
Posts: 832
Location: GA
I just located a Sams on Ebay for it. Good point Tom. If he did too much damage, I may just be getting a basket of parts.

Doug


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 Post subject: Re: Magnavox Model MV21F
PostPosted: Mar Sat 17, 2012 8:56 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 12242
Location: Albuquerque, NM 87123
If the seller is in the habit of plugging sets in and watching the smoke come out you are not going to convince him to stop; he has made up his mind that he is right and nothing will change that.

I hope I am wrong, but I believe you have wasted a lot of money on shipping for junker sets.


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 Post subject: Re: Magnavox Model MV21F
PostPosted: Mar Sat 17, 2012 5:49 pm 
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Joined: Aug Thu 07, 2008 1:36 pm
Posts: 2257
Location: Orlando
I saw those and noted the "smoking transformer" multiple times, gaak...

I hope your sets were not too badly damaged by the smoke.


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 Post subject: Re: Magnavox Model MV21F
PostPosted: Mar Sat 17, 2012 10:20 pm 
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Joined: Mar Wed 30, 2011 5:37 am
Posts: 832
Location: GA
Luckily, the metal Admiral I bought was not in the "smoking" bunch. When the seller tried it, he posted pics of a partial raster. I bought one of these 14" Admirals 2 yrs ago, but some idiot had cannablized the tuner. Therefore I ended up parting it out and eventually using parts to repair the two 10" admirals I later bought. I did save the CRT, cabinet, escutcheon and knobs, and this set is missing the escutcheon & knobs. He posted the cabinet has been repainted, so I may just put the chasis in the orphan cabinet after I restore it.

Now, as far as the Magnavox, that does concern me somewhat. As I said in an earlier post, I hope it was the HV caps that were smoking and not the power transformer. He posted a pic of the chasis, and it's one of those transformers with the 5U4 mounted on the top of the transformer. I guess replacement, if needed, would be extremely difficult.

Like Tom said, I may have just bought a piece of high shipping junk. I guess I was just itching to get into another project. We'll see when it arrived.

Doug


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 Post subject: Re: Magnavox Model MV21F
PostPosted: Mar Wed 28, 2012 11:23 pm 
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Joined: Mar Wed 30, 2011 5:37 am
Posts: 832
Location: GA
Well they arrived today. I was a little disappointed in the metal cabinet Admiral. I was hoping it was a 14" set as I already have 2 of the 10" versions and a 14" parts set. However it was only a 10" version . I'll probably tackle that one 1st as my GE 805 is on hiatus waiting on a speaker reconing. The seller posted pics of it shopwing a partial raster. I did take it out of the cabinet today and noticed the CRT cap is VERY loose. I couldn't get anything to light at all. I hope the crt is not damaged. I'll check it out tonigjht.

On the wooden Maganavox, I am cautiously optomistic at most. It was in much worse shape than I feared cabinet wise. There was NO venere left on the top or sides, and a piece of moulding is missing on the front under the controls. The back was split in two, anmd when I attempted to take the chasis out, the bottom of the cabinet came apart from the rest of it.
These is moisture damage inside the cabinet also. Luckily, this set doesn't have any markings on the front as they are on the knobs and the nameplate on the back. Therefore a good furniture shop should be able to save it. It will all depend on the condition of the electronics.

I knew from the pics of the seller that there was a CRT brightener on the back, so I'm sure the CRT is bad. I am going to put my B&K rejuvenator on it tonight and see how bad it is. Alsom, recall that the seller had plugged it in and said "transformer smoked." I hope it's just HV caps.

With two sets needing restoration, I feel like a kid in a candy store tonight!
Doug


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 Post subject: Re: Magnavox Chasis CT 277
PostPosted: Mar Fri 30, 2012 3:45 am 
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Joined: Mar Wed 30, 2011 5:37 am
Posts: 832
Location: GA
As stated yesterday, I wanted to knock out that metal cabinet Admiral 1st. After replacing the recitifiers and recapping, it's playing pretty well. Some previous owner stole the speaker, so I need to order one and make a decision on repainting the matal cabinet. It's been repainted once and looks a mess. Since it's playing ok, it will go to the side so I can turn my attention to the Magnavox.

Last night, I hooked up my B&K CRT rejevenator. It showed no shorts, bu no emission or life. After 3 tries on the Dynmaic Intensifer (1st on Low, then Med, then Hi), I finally got the meter to read at 300. The CRT is a Sylvania. I've got new filters ordered. When they come in , and I get them replaced, I'll try a slow power up with my Variac. Here are 2 pics of the chasis on my table. I like the way this set is laid out. Everything is spaced out, and it should be easy to work on. Just hope the transformers are good.

Doug


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Mag chasis.jpg
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Mag side (2).jpg
Mag side (2).jpg [ 36.15 KiB | Viewed 2847 times ]
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 Post subject: Re: Magnavox Model MV21F
PostPosted: Mar Sat 31, 2012 12:14 am 
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Joined: Mar Wed 30, 2011 5:37 am
Posts: 832
Location: GA
I spent last night and today getting acquainted with the chasis. I've carefully replaced most of the paper caps already. I've got new filters on order, but I did have 3 of them on hand and replaced those 3. This set uses some odd values. For instance C5 is a 65 mfd @ 50V. The Sams lists it as a Vertical Output Cathode. It comes off Pin 8 of the Vert Output 6V6 and is in parallel with an 820 ohm resistor going to ground.

Question: Can I get by with using a 60 mfd in its place? I could parallel two 33mfds, but I hate to do that.

Another odd value is C4B. It is a 350mfd at 15V used for a horizontal output cathode. I'll have to see what I can come up with for that.

I took the HV cage off today and cleaned the cage with Spray Nine. The black cage had some rust so I ended up repainting it black then giving it 2 shots of clear. Upon inspecting the Hv area, I something odd. Here is a pic of it. Is that white chipped thing an old HV cap that failed at one time. I see one under the 1B3 tube.

The bottom of my power transformer looks almost new. The top, however is rusty. That is a good method of restoring these transformer cases?

Thanks
Doug


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Hv cage (2).jpg
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Transformer.jpg
Transformer.jpg [ 25.87 KiB | Viewed 2819 times ]
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 Post subject: Re: Magnavox Model MV21F
PostPosted: Mar Sat 31, 2012 12:36 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 4199
Location: Woodinville, WA USA
Doug66 wrote:
C5 is a 65 mfd @ 50V.
Question: Can I get by with using a 60 mfd in its place?
5 mfd is about 8% of 65 mfd. That's probably well within the original manufacturing tolerance for an electrolytic. The Sams may give the tolerance for that particular electrolytic. It's often higher for electrolytics than for other parts, as high as +-50%.

Phil Nelson


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 Post subject: Re: Magnavox Model MV21F
PostPosted: Mar Sat 31, 2012 12:48 am 
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Joined: Mar Sun 01, 2009 10:27 pm
Posts: 3246
Location: Ann Arbor, MI
Doug66 wrote:
Upon inspecting the Hv area, I something odd. Here is a pic of it. Is that white chipped thing an old HV cap that failed at one time. I see one under the 1B3 tube.

I think that what is under the 1B3 is the top half of that chipped thing, which most likely was a door knob cap used as the HV filter cap.

The capacitance provided by the outside conductive coating on the CRT should provide enough filtering, but you need to do something to properly mount the 1B3 socket.

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Tom


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 Post subject: Re: Magnavox Model MV21F
PostPosted: Mar Sat 31, 2012 1:00 am 
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Joined: Mar Wed 30, 2011 5:37 am
Posts: 832
Location: GA
Tom, I just went back and looked. You're right. That HV cap has come in half. The Sams says it's a 500mfd at 20KV. When I got the Sams, before the set arrived, I had an idea that the HV cap may need replacing. I order some 470mfd @ 20KV, but they are discs. Will they work. According to the tracking chart from where I ordered them, they should be here tomorrow.


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 Post subject: Re: Magnavox Model MV21F
PostPosted: Mar Sat 31, 2012 1:12 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 12242
Location: Albuquerque, NM 87123
I think you mean 500pf.

I would not use disc caps to replace doorknob caps.


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 Post subject: Re: Magnavox Model MV21F
PostPosted: Mar Sat 31, 2012 1:42 am 
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Joined: Mar Wed 30, 2011 5:37 am
Posts: 832
Location: GA
Just located the right doorknob style and ordered it. Thanks for the advice.

Doug


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 Post subject: Re: Magnavox Model MV21F
PostPosted: Mar Sat 31, 2012 3:53 am 
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Joined: Mar Sun 01, 2009 10:27 pm
Posts: 3246
Location: Ann Arbor, MI
The disc caps would work electrically but there would remain the problem of how to mount the 1B3 tube socket.

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Tom


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 Post subject: Re: Magnavox Model MV21F
PostPosted: Apr Sun 01, 2012 12:09 am 
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Joined: Mar Wed 30, 2011 5:37 am
Posts: 832
Location: GA
Some success today, then a failure:

Today I cleaned up the power tansformer with Spray Nine, maked the brackets off then sprayed the top with a shot of black. It came out good. I'll continue tomorrow with a shot of clear.
Now for the failure. the set is sitting on my dinning room table, and the cap is very lose from that questionable CRT. Part of the cap is missing anyway. Tonight, I walked passed it and my left arm bumped the cap. Actually, my watch struck the cap, and I heard a hissing like air leaking from a pool raft. I knew what that ment. That CRT was on it's last leg anyway, and I'm not even sure about how successful the rejuvenation I did the other night was.

The Sams lists 3 different sizes for this set; a 14", 16', and 17". Mine measures 14" across. There is no paper on the old tube listing what it is, and the tube layout in the cabinet doesn't not list the pic tube. For a 14", the Sams lists a 14BP4 and a 14CP4. The only notes are for a 14BP4 use a single magnet ion trap. Any ideas on which tube I should start hunting for?
Thanks
Doug


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 Post subject: Re: Magnavox Model MV21F
PostPosted: Apr Sun 01, 2012 12:38 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 12242
Location: Albuquerque, NM 87123
Is it 14" across or diagonally?


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 Post subject: Re: Magnavox Model MV21F
PostPosted: Apr Sun 01, 2012 1:00 am 
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Joined: Mar Wed 30, 2011 5:37 am
Posts: 832
Location: GA
It is 14" across and 16" diagionally. In that case, for a 16" tube the Sams list 16KP4, 16RP4, 16XP4, 16GP4, 16TP4

Doug


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