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  #31  
Old 01-21-2017, 12:56 PM
Tony F Tony F is offline
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Mrjukebox160, you are correct. It is indeed a 1000 pf cap. Although the one listed is not the one shown in the picture ! Obviously an error on Sams part. The schematic does not match the photo part number. Sorry, I was scratching my head.
I had another question regarding the networks. I've watched a lot of Bob's videos on the Predicta's. Is K2, the only network (vertical section) you have to use 1000 volt caps on ? I know the one cap on the chassis board C14 .0015 mfd is the only one rated at 1000 volts, and the cap on the network (1500 pf) is directly connected to this cap. Will a 2200 pf @630 Volt poly on K2 go "poof !" ? Can you get away with 630 volt caps for the other networks ? I ordered 1000 volt mica caps from JustRadios, but his micas stop at 1000 pf. You then half to use the poly series. I ordered 3 -1300 pf @ 630 Volt 1% for using with the 2 - 47K resistors on the K3 network (also vertical section). I know his "regular" micas are only rated for 500 volts.
Tony
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  #32  
Old 01-21-2017, 06:45 PM
mrjukebox160 mrjukebox160 is offline
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Oddly, on the Sams that network is shown as K5. I don't know how much A/C is getting through C14. The spikes might be too high for a 630 volt cap.
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  #33  
Old 01-21-2017, 06:49 PM
mrjukebox160 mrjukebox160 is offline
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I now see there is a "second" K5 listed. Must be another misprint. It looks like 630 volt caps would work for the other caps. in the networks.
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  #34  
Old 01-23-2017, 12:03 PM
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bandersen bandersen is offline
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Quote:
Originally Posted by Tony F View Post
Hi, On the link to the Sams you posted, the capacitor I'm referring to is C204 (it is shown in the photo of the top of the tuner). It has the 2 wires running through it. In my case there was only one wire. I was trying to add the 2nd wire for the lamp when it cracked. It is a 10L43 chassis. It comes up on page 5 of the pdf document. Also, the Philco service data seems to show it better on the schematic in regards to the 6.3 volt line than the Sams does.
Thanks !
Tony
There seems to be some confusion regarding the Sams. The cap in question is C222 in the Sams, not C204. They mislabeled it on page 5.

It's a 1,000 pF ceramic feed-through cap. That's a type of cap commonly used to feed signals and power into a shielded box like a tuner.

Something like this may work if you need to replace it.
http://www.digikey.com/product-detai...043-ND/2079617
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  #35  
Old 01-23-2017, 12:09 PM
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bandersen bandersen is offline
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Quote:
Originally Posted by mrjukebox160 View Post
Oddly, on the Sams that network is shown as K5. I don't know how much A/C is getting through C14. The spikes might be too high for a 630 volt cap.
Some confusion between the Philco service info and Sams.

The networks are labeled N1-N7 by Philco and K1-K7 by Sams and the numbers do not refer to the same parts.

N2 is the same as K5 and is the vertical feedback. Yes, it is the only network that sees a voltage spike needing a higher voltage cap. 630 is more than enough for all the others.
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  #36  
Old 01-24-2017, 07:11 AM
Tony F Tony F is offline
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Hello Bob, Thank-you for clearing that up ! I have a .0015 @ 1600 for that network. What about the 2200mfd that is used in the same network ? I have a 630 volt, but don't have anything at 1000V ? I will have to special order one if it is required. Also, I have replaced all resistors 1/2 watt with 1 watt, 1 watt with 2 watt. The only ones I'm questioning are the 3, 2 watt resistors R19, R40 and R45. These , I replaced with 2 watt ECG metal film, even though they are half the size of the original carbon comp ones. Nobody has any 3 watt metal film resistors in this area. I have left the WR4 (4100 ohm) and the R15A (5.6k 3 watt) one alone. I've pulled all 3 of the Can electrolyics and they all test good. Most are 20 to 30 mfd higher than the rating on the cans. I've pulled the solder from the traces on the board that cover up the holes where you added the 3 radial electrolyics to the board. Looks like I have to drill 1 or 2 holes (and run a small wire, like you did) to mount them. Also, did you mention that you used 1N5408 diodes to replace the original (34-8048-2) diodes ? It seems to be slowly coming together. I just wish the last person in this set didn't hack it up so much.
Thanks again for your valuable input.
Tony
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  #37  
Old 01-24-2017, 09:04 AM
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Take a look at the Philco service info. You can see there is 3.2 VDC and a 60 Vp-p signal on that 2200 pF cap. 630 volt is more than enough. 150 would even be fine. I did the same analysis on all the couplate caps and determined that 250 was fine for almost all. 500 covered the rest. Use 630 if you really want to play it safe.

I also use C0G ceramic caps. That's the type thats the most stable type of ceramic. Mica is fine too, but rather pricey for the larger sizes. I've dissected some couplates and they appear to be tubular ceramic caps except for the vertical integrator. That's some type of thick film hybrid module bult on a ceramic substrate.

I use the Vishay VR01, VR02 and VR03 series of 1, 2,and 3 watt resistors. I get them mail order from any of the major vendors. Dirt cheap, great quality and look sort of like the old carbon comps.

Yes, I use 1N5408 diodes exclusively for all my projects now. Rated for 3A and 1,000 PIV.
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  #38  
Old 01-24-2017, 09:57 AM
Tony F Tony F is offline
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All good info, I know you touch on these various things in your videos. I'll guess I'll have to re-watch anything having to do with the Predicta line and pause to take note. I have a cosmetic question. Has anyone had to replace the grill cloth in any of the Predicta line that uses cloth on the front ? If so have you found a close (suitable) match and where did you find it. This one is totally destroyed. I've been searching E-bay and locally and haven't found anything close.
Thanks !
Tony
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  #39  
Old 01-30-2017, 01:39 PM
Tony F Tony F is offline
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Has anyone run into this problem and is there an easy fix ? The 4 plastic "lugs" that are molded into the back of the picture tube cover are stripped. They must have had quite a workout in their lifetime. 3 are completely stripped, one is almost. I've thought of drilling them out slightly and epoxying some 8/32" nuts on the backside and using a couple of longer machine screws instead of the metal plastic thread screws, or are plastic "heli coils" available ? or maybe a plastic insert ?
Tony
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  #40  
Old 01-30-2017, 06:22 PM
madlabs madlabs is offline
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How about those plastic thingies they sell for putting screws in sheet rock and what not? I think they used to be called "mollies"? Just cut the flange end off. I was lucky, only one of mine was completely stripped so I just left it. I'ts not like they are likely to come flying off anyway, except maybe when moving the set.
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  #41  
Old 02-14-2017, 01:45 PM
Tony F Tony F is offline
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I thought I'd post a photo of the networks that I just finished. The only one I had to put a 600 pf mica on the backside was N3 because of lack of room on the front. I would have loved to have used smaller components like the ones Bob uses in his. Just had to work with what I could get up here. The local electronics store closed a few months ago and hopefully will be back at a new location soon. I also picked up a Blonde Holiday with a 21" screen over the weekend. It is in pretty good shape, missing the horizontal knob and the tuning knob is broken where it goes on the shaft. Looks like someone had the main board out a long time ago but didn't change too much. A few black beauties are split open. They did a sloppy job, also there is a booster on the picture tube, so I'm not sure what that means as far as the shape of the picture tube goes. I don't have a picture tube tester. I mounted some of the electrolyics on the main board but still need a 100mfd to complete it. I installed 2 new octal sockets. The others, I just tightened the pins on them. I ended up using 3- 1300 pf polys for N3 rather than 2- 1200's and a 1600 pf in the middle. The total capacitance was about 50 pf under 4000. Using the 2-1200's and the 1600 would have put it about 50 pf over 4000. Hopefully it will be close enough. I just have to coat them with epoxy and make them look rusty like the originals.
Tony
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  #42  
Old 02-14-2017, 02:06 PM
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Your N3 caps should be fine. I used three 1500s in the last few I made. Looks like those are polystyrene caps ? I understand those don't like the heat when soldering but are very stable.
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  #43  
Old 02-14-2017, 02:37 PM
Tony F Tony F is offline
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That's nice to know Bob. Yes overkill,.. I know now. Maybe on the next one I'll end up using 1/2 watt resistors and 500 volt micas instead of 1 watt resistors and 1000 volt micas. Being my first, i wasn't sure. After watching tons of your videos looks like the only critical cap was the 1000 volt job on N2. It is kind of confusing as the test point on the vertical tube looks like only 260 volts. I know you talk about the spikes though. The polystyrene is new to me too. They were the only size the JustRadios had that was close to the needed values. He had 1300's at 1%. I kept the leads as short as possible on the backside and some of the solder joints were quite close to them with no hint of melting. I can see that if you were to get your iron close to them they would melt. So far so good.
Tony
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  #44  
Old 02-14-2017, 02:55 PM
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Nothing wrong with overkill. Better than using underrated parts and having to pull the board again! Interesting that JustRadios has a wide variety of styrene caps at 630 volts. I was under the impression they weren't made anymore or hard to find. They are a bit pricey but not quite as much as mica.
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  #45  
Old 02-24-2017, 03:02 PM
Tony F Tony F is offline
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I finally got around to applying the epoxy coating and some Red Oxide Primer spray paint to the networks. They are about twice as large (taller) than the originals, but fit the board with no problems. Next is to install them and reinstall the main board. Thanks for all the tips Bob. Hope you are enjoying your new "digs".
Tony
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