Help with a Admiral Portable TV ,1950's
 

Hi, I am new member of this excellent forum, and this is my second post.
I just picked this nice Admiral up for $20.00.
Are these any good? I thought it was a great design, and in pretty good shape too. Only missing the antenna. Can't wait to clean it up, and recap it.
Since I am new to this hobby, (started my first TV just a few weeks ago),
I was wondering if there was any thing in particular I should be careful of, or watch out for when removing the chassis.
I just got it home today, and hooked up a RF modulator, there was clear sound, but there was also a constant loud buzz or humming. I couldn't get the picture still, and it seemed like the humming sound was possibly interfering with the picture.
Any help from the pro's would be welcomed!

Magnavox300

Prepare to do a full replacement of the capacitors, this could be the source of the hum and other troubles. C.R.T has a brightner and may need cleaning or rejuvenating.. I dont see a transformer on this tv and it will need an isolation transformer because the chassis is connected to one side of the AC line, Other than that,it looks promising.. :)

Steve..

Welcome to VK and to the wonderful world of vintage TV.

The humming sound you hear is likely 60-cycle AC hum. Your TV's picture is bending and will not stand still because the same 60-cycle hum is getting into the sweep circuits. These problems are almost always caused by defective filter capacitors in the set's main power supply. In a set as old as this one, it seems almost certain that the filters (and probably every other capacitor in the set) are weak or defective and must be replaced, as boobtubeman just mentioned. Once you do this, the picture should straighten up and the hum should disappear from the sound. There could be other reasons why your TV's picture is bending (incorrect setting of the AGC threshold control, defects in the AGC circuit itself, et al.), but I'd replace the filters and other caps first, just on general principles.

Your set is over 50 years old, so the filters must be replaced if the TV is to perform as the manufacturer intended. In fact, recapping, that is, replacement of defective capacitors, should always be the first step in restoring a vintage or antique television to past glory. Failure to do this, e. g. just plugging in the TV to the power line and turning it on without first recapping at least the power supply, may and probably will damage expensive and often NLA (no longer available) parts in the set.

Good luck. I've seen Admiral portable TVs like yours (I saw one in high school in the mid-'70s, in our basement electronics lab, when I was taking a basic electronics course), and they were good sets in their day. They can be as good as new or even better if the proper restoration procedures are followed. You will need an NTSC->ATSC converter box on your set to receive anything, as all full-power U. S. TV stations have transitioned to digital as of June 12, 2009; however, there may be some LPTV (low-power TV) or translator stations still operating in NTSC analog in your area, so you may get at least one channel with rabbit ears and without the box.

BTW, your set's picture bending could also be caused by incompatibility between your TV and your DVD player; I'd check into that if the picture still bends after replacing the filters. Modern DVDs and VCRs often do not work well with older televisions because of the set's sync circuits being unable to lock on to the RF modulator's own sync signals -- solidly or, in many cases, not at all. Older TVs were made with sync circuits designed to deal only with over-the-air TV signals, since today's advanced video technology (VCR, DVD, video on demand, et al.) did not exist when these sets were new. These sets may not operate properly with the non-standard (as the TV's sync circuits see it) sync signal from the modern RF modulator.

Thank you gentleman!
I plan on recapping everything, and can't wait to start!
Steve, any easy explanation of where the isolation transformer should go?

Jeff, I didn't know that some of these great old sets will not handle a dvd or video player very well.
I wish I could know for sure that this Admiral would before I start taking it apart!
Thanks!

Magnavox300

VCR's are the only things that can have major synch issues that I know of.

DVDs(and some other devices) can have macrovision which shows up as horizontal lines in an otherwise perfect(and synched) picture. Closed Captioning may or may not bother a set(I can't recall it being an issue with any of my sets), but is basically universal in all NTSC signals these days.

If macrovision closed captioning, etc. prove to be an issue there are boxes available to remove such from a video signal.

The isolation transformer is for the power connection for the set. Most sets without an internal power transformer have one side of the cord connected directly to the chassis which presents a shock hazard.

Welcome to VK, and enjoy your stay!

Thanks Tom,
I guess it is safe to assume that this Admiral should play movies just fine,
so I will go ahead with the project with all confidence.
After recapping and cleaning, I will take it from there.
I know some of my questions are obvious to most veterans,
thanks for everyones patience and responses.

Magnavox300

That model is a lot better than Admiral's earlier portables. Three stages of IF, keyed AGC and slightly easier to work on. Same basic circuitry as the larger screen sets, only in a smaller package.

Nice find and welcome to the forum. I believe I have the same set, but in silver. It's a P17E31 from around 1958.
I haven't had the time to restore mine yet. Here's the thread I created: http://www.videokarma.org/showthread.php?t=249661

Good luck. Bob

What kind of "box" gets rid of macrovision? I need one myself!

There are many different makes and models out there because people have wanted to get rid of the macrovision signal since it was introduced. I have an 80's vintage device called the Play-it-Right (can't remember the brand off hand) that I got for 5$ at a garage sale. It is about the size of a DTV converter box.

If you search Ebay (it will likely come up under copy protection remover or some such) you should find a plethora of them to choose from.

I just restored two of these, one the same colors as yours. (I have a third, but its CRT is completely dead). Both do work ok on the DTV converter boxes I have, but one has a little intercarrier buzz. The one that has buzz has a frozen 4.5MHZ if coil, so I cannot adjust it properly. I figured sound with buzz is better than no sound. (I may take this coil out of my third Admiral if I cannot get a CRT at some point). I would also recommend replacing the selenium rectifiers with solid state diodes(and a dropping resistor), although they may still work.

I replaced all of the paper and electrolytic capacitors. I also replaced the resistor in the series filiment circuit as they were both open. The trick is to get the electrolytics between the CRT and the chassis. Be carefull in placing them as there is not much room. If you place the electrolytics inside the cans of the old ones that would give you more room. Another issue is taking the set apart-be very careful as it is very easy to tear the speaker when removing the metal case. However, you can buy a speaker that works fine from RadioDaze for around $3.00, I did it. A final issue that I had is that the yoke cover had fell apart on one of them. I made another using polystyrene plastic, a compass, a hole cutter, a dremmel tool, a knife, and glue. It does not look nice, but works.

One final note is to check to make sure there are no shorts between the metal case and the chassis when you are finished. This is a hot chassis set with insulators to prevent the line voltage from reaching the case(like the Philco 17er). I also added fuses to both of my sets.

These have the switch going to the power supply instead of chassis. All you need to do is polarize the plugs (and hope your wall plugs are wired correctly).

AC/DC radios (and transformerless televisions) were made with hot chassis, one side of the line connected directly to the chassis (with some radios, such as Arvin's model 540T, in metal cabinets), for decades. The problem with a hot-chassis TV or radio is that the chassis will be "hot" with the full line voltage if the line plug is inserted into the wall socket one way, but will be "cold" (at ground potential) with the plug reversed. This assumes that the outlet you are using is wired correctly; some are not. It is always best to be absolutely sure of the polarity of the AC socket before simply assuming it was wired properly when the house was constructed. This is especially important if you decide to replace the original cord and line plug with a polarized one; if the AC wall socket is wired backwards, with the "hot" slot now ground and vice-versa, there can be real problems (such as a shock hazard or damage to the device plugged into the outlet) if the house fuse doesn't blow first -- as it should.

Radios and TVs with hot chassis in metal cabinets can be death traps if the house fuse does not blow in case of a short to ground. I once read of someone who was using an AC/DC radio in his bathroom, and accidentally contacted the hot metal cabinet while adjusting the volume or changing radio stations. The house fuse blew immediately, saving the person's life. Another, less fortunate case was that of a mother who was bathing her baby in the kitchen sink, with a plugged-in electric toaster nearby. The baby's arms got caught up in the toaster's AC cord, and the appliance promptly fell into the water. The house fuse, for whatever reason, did not blow when the toaster hit the water; however, the child was instantly killed.

i just got the same one off craigslist the same colors and everything for 20.00 mine will stay on back burnner for awile i have bigger fish to fry first

This set does have insulators built in to isolate the metal case from the chassis so that the metal case is not dangerous. However, during repairs and restoration shorts can occur, defeating this. This is the reason to check the resistance between the metal case and the hot chassis after re-assembly. Just in case, I would not recommend operating any hot chassis set(radio or TV) in a bathroom or other location where a lot of moisture is present.