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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: Apr Tue 28, 2015 4:08 pm 
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300 VA should be fine for your TV, so feel free to work with the variac you got. Good job on fixing the tube socket. That happens from time to time, and repairing them is tricky. Transplanting a good unused socket pin to the offending location takes some work, but is a good way to fix that kind of problem. Some kinds of sockets are easier than others for that kind of repair.

After you get things running, you may find that some of the mica caps also need to be replaced. Until recently, we could all treat mica caps as fairly reliable items that usually did not need to be replaced, but these days, mica cap failures are occurring fairly often. If you end up seeing problems in circuits that have micas, replacing them may make sense (but I probably wouldn't recommend replacing them just yet). Also, in the tuner and IF stages, it's best not to replace micas unless you really have to, since replacing them can upset the alignment.

Your cabinet restoration is going to be an interesting project!

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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: Apr Tue 28, 2015 8:06 pm 
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Thanks Tom. I'm getting close to being able to apply power. All but one of the paper caps and about half of the electrolytics are done. Found some differences from the schematic. Also, I'm having problems with the final 3 cans - see below.
Attachment:
File comment: This was not on the schematic, but I replaced it as I found it.
Not on schematic.jpg
Not on schematic.jpg [ 58.47 KiB | Viewed 3053 times ]

Attachment:
File comment: All the paper caps are done, except for one .5 I need to order (notice the one on the middle left with blue tape on it).
Recap day 4.jpg
Recap day 4.jpg [ 86.81 KiB | Viewed 3053 times ]

Attachment:
File comment: Hard to read the cans, schematic doesn't say Voltage.
Stupid cans.jpg
Stupid cans.jpg [ 59.17 KiB | Viewed 3053 times ]

For the electrolytic cans: it is impossible to read some of the info, as the engraved sides of the sliver ones are turned toward the giant power thing. From the schematic I can get the MF value, but not the voltage. Also, for some cans, like the black one, it has two 30's inside but with different voltages.

Questions:
How can I get the voltages that go with these electrolytics?
How do I know which pin underneath is which voltage, when the can indicates two of the same MF but different voltages?


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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: Apr Tue 28, 2015 9:35 pm 
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Reading the cans of electrolytic caps that are turned in unfortunate directions is a common problem. I have a small mirror and flashlight I use to try to have the best possible chance of reading these, but sometimes you just can't.

I looked at the circuit, and I would suggest the following voltage ratings for the three electrolytics you pointed out:

C101A - 20 uF 450 V
C101B - 40 uF 450 V

C514A - 10 uF 450 V (this is in the same can as C101)
C514B - 10 uF 50 V (also in the same can as C101)

C102 - 30 uF 450 V

C422A, B, C, D - all 10 uF 450 V

The reason I know that C514B can be low voltage is because it is the cathode bypass capacitor for the horizontal output tube, which should not go above 30 volts or so.

It's possible that some of the ones I've marked as 450 V are a little lower, such as 350 V, but most of us don't stock caps in so many different voltages, so you may simply want to use 450 V caps for all of those. I can't easily discern from the schematic if a cap could be a little lower than 450 V. In a few cases, the cap might need to be even a little higher, such ass 475 V, but I'm not aware that any in this set fall into that category.

For cases where you can read the side of the capacitor, I presume you are familiar with the fact that there are different "shapes" used to distinguish the sections (half-round, square, and triangle). These are shown in the markings on the side of the can, and are cutouts in the bakelite wafer from which the terminals protrude on the bottom of the can. That way you can tell which terminal is what.

If you're uncertain as to whether you've got caps in there with the right voltage rating, when you power up the set, raise the voltage slowly on a variac while checking the voltage across the caps in question. Raise it a step, and then check them. If the voltage exceeds the rating on your cap, stop and replace with a higher voltage one. If you are able to get all the way to full applied power, and the caps don't exceed their rating, you're all set.

If you don't want to wait for your 0.5 uF to arrive, you can temporarily sub in two 0.22 uF caps in parallel and that will probably be close enough for now. When your 0.5 uF cap comes, you can permanently install that one.

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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: Apr Wed 29, 2015 1:52 am 
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If you are going to restuff the cans then you can read them when you take them off, otherwise you migh slide a mirror between the cap and transformer.
Alternately you could unbolt the transformer and move it aside just a little, that would also make it eaier to clean the rust of the end cap.


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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: Apr Wed 29, 2015 2:26 am 
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I ended up taking some foil, wrapping it around the can and using a stubby pencil to do a rubbing on the can. So now I know what it says on the outside - see below. Tom - I did not know what those symbols on the cans meant. Good to know! But, under the chassis I can find no trace of them anywhere, so they're no help to me. BTW the schematic I'm using is for chassis 122 - http://www.earlytelevision.org/pdf/philco-48-1000-122-rider-tv2.pdf. The cap numbers and values look a bit different than what you listed, Tom.

Below I've listed the three cans, from the outside of the chassis toward the center. For each I list what the outside of the can says, what Cap number it is (if I can tell), the cap I intend to use (if I can tell), or a question (if I cannot tell). If anyone can help me fill in the blanks, that'd be awesome.

Silver can (closest to the edge of the chassis in the photo above):
40/475 - C105A - I'll use 40/500
10/475 - ?? One of the 10s is C513A, the other C513B. Which gets the 475V and which the 25V?
20/475 - C105B - I'll order a 20/500
10/25 - ??

Black can (middle):
30/475 - ?? One of these is C103, the other unused, but there's no way to tell which is hooked up under the chassis. I have a 30/500 that I'll use and that ought to do, no?
30/400 - ??

Short silver can (furthest from the edge in photo above):
10/475 - C328A - I'll use 10/500
10/475 - C328B - I'll use 10/500
10/475 - C328C - I'll use 10/500
10/475 - C328D - I'll use 10/500


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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: Apr Wed 29, 2015 2:39 am 
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The symbols are on the bottom of the capacitor on the Phenolic wafer, either stamped into it on the outside of the lug or cut out of the wafer right next to the lug, the latter can be hard to see sometimes because the rubber seal inside expands and pushes it's way through the small openings.

They are all in the same order though I think, i.e. the half round is always the largest cap, triangle next, then square then blank. I may have the order mixed up but you get the idea.


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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: Apr Wed 29, 2015 5:42 am 
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Yes - look a little closer and you'll discover those shapes in the brown wafer on the bottom of the can right next to the terminals. That should clarify everything. Recognizing those markings is essential for restoring antique electronics in general, so you'll want to get that figured out now.

I like your idea of making a foil impression of the stamped numbers where you can't see them directly. Very nice idea that I haven't seen anyone mention yet!

Sorry I used the schematic from the service manual for the list I made for you. In any case, you're likely to have all the values and voltages now given all the things mentioned above. Using 500 V caps in place of the 475s is a good choice.

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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: Apr Wed 29, 2015 4:35 pm 
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Here's the rubbing, so you can see how it turned out. Also below is the underside of the outermost silver can. I can find no symbols. Where am I not looking?
Attachment:
File comment: This is how I found 20/475 and 10/25.
Electrolytic Rubbing.jpg
Electrolytic Rubbing.jpg [ 44.3 KiB | Viewed 2990 times ]

Attachment:
File comment: Can has symbols, underneath I can't find them.
No symbols.jpg
No symbols.jpg [ 64.35 KiB | Viewed 2990 times ]


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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: Apr Wed 29, 2015 4:56 pm 
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That particular one is a bit of an unusual construction, but in any case, the symbols are usually on the outside of the terminals (covered by wires in your picture, so difficult to see).

Here's a picture from a chassis which has just arrived for restoration. On the left is the more common situation, with little cutouts in the shape of a box and triangle in the wafer right were the terminal comes out. On the right is a less common version with the shapes molded in (in this case, there aren't actually any terminals next to the ones I'm pointing to, but there could be if the cap had more sections).

Attachment:
Cap shapes 2.jpg
Cap shapes 2.jpg [ 74.16 KiB | Viewed 2984 times ]

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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: Apr Wed 29, 2015 5:16 pm 
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Looks like Tom beat me to it, but for additional clarification:

Image
Image


If there is any doubt, or if your particular wafer simply has no markings, use the schematic, trace each section to its nearest connected component, and label the wire that connects them with a bit of masking tape folded over the wire and then write the symbol on the masking tape with a permanent marker. Remove can, re-stuff, label the bottom of the can appropriately, reconnect the labeled wire, remove tape.


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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: Apr Wed 29, 2015 5:27 pm 
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Thanks Tom! (And thanks WeekendHacker!) Now knowing what to look for I can see that the cutouts are indeed there. Mystery solved.


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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: Apr Wed 29, 2015 5:33 pm 
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And just for fun:

Image


Image

Photoshop, or more accurately its early analog counterpart, apparently inserted your 48-1000 into an existing photo from 1946.


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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: Apr Wed 29, 2015 5:42 pm 
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LOL! Yeah, the picture was definitely composed - none of the angles or proportions are correct. The women aren't even facing the TV. Fun to see the parts re-used. Back when "cut and paste" involved actual scissors and glue.


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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: May Wed 06, 2015 3:01 am 
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The recap is complete. The last three electrolytic cans all went to chassis ground, so I found various unused chassis lugs to attach the new caps to. Is there any problem in that? Is this TV sensitive to lead length and positioning like some early FM radios are? How does it look to you all?
Attachment:
File comment: Got the last set of caps in the mail today and soldered them in.
Recap completed.jpg
Recap completed.jpg [ 81.46 KiB | Viewed 2892 times ]


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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: May Wed 06, 2015 3:04 am 
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With electrolytic caps, you do not need to worry about lead placement at all. In fact, you can wire them into completely different locations if that provides a better fit. Electrolytics are never used to handle high frequency signals, which is the only case where you really need to worry about lead placement.

You'll often see that the manufacturer wired clear across the chassis just to save some money by combining several electrolytics into a single can.

I often follow the wires to see if there is a more convenient location to put the replacement than right under the original can, which may or may not have enough room available.

Your cap replacement job looks very nice!

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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: May Wed 06, 2015 4:34 am 
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Getting ready to power it up sometime in the next few days. Just a few things left to do.
Attachment:
File comment: Picture tube cleaned, tubes back in the chassis. Just about ready to go.
Ready for Power.jpg
Ready for Power.jpg [ 68.61 KiB | Viewed 2883 times ]

One question: much of the black shielding on the picture tube has flaked off. Is it dangerous to use it with out that in place? I hear about x-rays. Can it be replaced? Or is it nothing to worry about?


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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: May Wed 06, 2015 4:44 am 
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No worries about the black coating for now. Later on you will want to restore that as well. Consensus here is to use a product called"Slip Plate", available at most auto parts stores. Search the forum for this product and study how it's used.

Don't be surprised if you plug it in for the first time and nothing happens. Don't be disappointed either. There will be a troubleshooting phase too. Looks good so far and you're getting close. Our fingers are crossed for you at this point. Fun stuff.


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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: May Wed 06, 2015 4:51 am 
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X-Rays from the picture tube are not an issue for 1940's sets like yours. It may be questionable to run the set with the HV cage open, but most of us believe even that is harmless. You need 25,000 Volts or more to produce X-rays of any consequence. Way more than a 10-inch B&W CRT will ever be exposed to in a 40's TV.


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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: May Wed 06, 2015 4:57 am 
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What is left of that coating needs to be grounded. There is probably some sort of spring or metal fingers attached to that frame around the CRT that does that. But then you have to verify that the metal frame is grounded. Most likely one of the wires in one of the cables coming from the chassis does that. But you should verify that the metal frame is grounded somehow. If not, you can connect a wire between the chassis and the metal around the CRT.

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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: May Wed 06, 2015 5:09 am 
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To be clear, the black coating is a conductive layer of graphite paint that forms one plate of a capacitor. Inside the CRT is an identical coating which forms the opposite plate of the capacitor. The CRT doubles as a high-voltage capacitor as well as a viewing device. The purpose of this capacitor is to filter noise from the HV. In practice there seems to be little or no benefit from such filtering, and it can usually be ignored. Most of us restore the coating with Slip Plate for aesthetic reasons first, and operational function of HV filtering second. If you want to be accurate, restore it. If you want to see it work first, you may do so with no great worry, and definitely no X-ray concerns. The coating is not "shielding" in any way.


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