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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: Dec Mon 19, 2016 10:31 pm 
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There are several people here who have worked in a radio/TV shop. I worked in a TV shop for about 2 1/2 years around 1965. We worked on all brands. I have worked on my own sets since then.

The thing that is of interest about having slug tuned coils is that there are no variable capacitors to cause trouble. There can be mechanical problems with variable capacitors. Unfortunately there can also be problems with the fixed caps used with slug tuned coils, just less likely.

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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: Dec Tue 27, 2016 3:10 pm 
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Two issues today involving crackling contacts.

TOUCHY TUNER CONTACTS - the tuner contacts, after cleaning, multiple deoxit sessions, and even abrading with a mild sanding stick, are still very scratchy. A nudge on the tuner knob causes crackle. I'm not concerned about having to fiddle with a knob when I want the TV to run - that goes with the territory on these old sets. What I am concerned about is that, no matter the fiddling, the connections are not sound, leading to worse reception than I could get. Any suggestions on how to improve these old worn contact points?
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Touchy Tuner Contacts.jpg
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Z202 CAN CRACKLING - while searching for the thermal sound problem, I noticed that two wires into Z202 (which contains two variable chokes, two caps, one variable cap) were very touchy, making the sound crackle whenever they were touched. I opened up the Z202 can and traced it to the center screw - the variable cap C202C. The variable chokes were also a bit scratchy when touched. I sprayed deoxit into them and twirled the screws. The chokes improved, but not the variable cap. My plan is to use more deoxit, remove the component for better access if I have to and look for contamination or shorts. I might re-solder some connections. Questions:
- how would you go about this?
- if the variable cap needs to be replaced, do I order a whole new Z202? Or do we order the individual pieces inside it?
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CAN GROUNDING - I noticed that there is a wire going to the base of C202C, but nothing else. The schematic says it goes to ground. I noticed that with the set on and the can disassembled, the use of different sized metal screwdrivers affected the sound. It occurred to me that the grounding was achieved via the fastener to the top of the can - that connected the screw to the chassis/ground. I jumpered it and the sound was then consistent (but still not great due to the ongoing thermal problem).
Question - are lots of other screws grounded this way? Are they something that should be cleaned? There are very many adjustment screws, all of which risk throwing the set out of alignment, no?
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Z202 Jumpered.jpg
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Adjustment Screws.jpg
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ALIGNMENT - once Z202 is back in place, I plan to simply adjust the screws until the sound seems ok. But these are alignment/trim screws, right? I've been told not to mess with them, and I know aligninging/trimming involves a scope and such to get them set just so.
- how hard is it to learn to do alignment/trim?
- how much would it cost to have someone else do it?
- is there anyone left on earth who knows how to do it?


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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: Dec Wed 28, 2016 7:25 pm 
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UPDATE: I turned the set on today, sound was dim but audible. Tappng on Z202 didn't do much. Fiddling with the screws didn't cause any crackling really, even the variable cap. So maybe the deoxit had an effect.


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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: Dec Thu 29, 2016 4:54 am 
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The alignment for the video IF should not be touched without the correct equipment. That typically is a sweep generator and a scope. And even with the correct equipment the procedure is difficult. For the sound alignment you can sometimes do that with just a voltmeter. See if your service literature (Riders if I remember correctly) has the alignment instructions. If it does, see if there are instructions for the sound using only a fixed frequency signal generator and a voltmeter. If you find that, a tuned in signal can stand in for the signal generator. But make sure you identify what adjustments are what so that you do not change the wrong adjustment.

If you find out that the best sound and the best picture occur at different fine tuning settings, you can "walk" the sound alignment to better match the video alignment. Adjust the fine tuning closer to the best picture without the sound becoming too bad. Then do the sound alignment. Repeat until you have both a good picture and good sound.

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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: Dec Thu 29, 2016 6:45 am 
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re tuner contacts in the old days we would clean them with a pencil eraser. i wouldnt use sand paper on them unless you are very carefull and make sure all debris from the sandpaper is removed from the contact and tuner shaft. even then dont. any debris that comes off the sandpaper wont do the contacts or tuner shaft any favor wearing them out as the tuner is turned.

re twiddling knobs dont. if i understand correctly the part you are talking about you can mess up alignment twiddling those knobs. this would require special test equipment to correct. if you ever do turn one of the knobs that effects alignment mark the shaft and base with a straight line and count the number of turns you move it and make note of the direction you turn it so it can be returned to origional position.

re Z202 whether you replace individual components or change it as a unit you will probably need to do an alignment to the circuit after the replacement. i dont have the schematic so i cant see the circuit involved but it will require test equiptment to align any tuned circuit once components are changed. one good thing once you restore the ground wire on C202C to ground the problem may clear. also make sure the can is back in place correctly before condemning z202 as bad. that can is a shield and must be in place and properly grounded to do its job. the problem you mention could be caused by the ground on c202c not being grounded properly. be very carefull poking around a live chassis with a metal screwdriver. personally i wouldnt do it.

CAN GROUNDING - I noticed that there is a wire going to the base of C202C, but nothing else. The schematic says it goes to ground. I noticed that with the set on and the can disassembled, the use of different sized metal screwdrivers affected the sound. It occurred to me that the grounding was achieved via the fastener to the top of the can - that connected the screw to the chassis/ground. I jumpered it and the sound was then consistent (but still not great due to the ongoing thermal problem).
Question - are lots of other screws grounded this way? Are they something that should be cleaned? There are very many adjustment screws, all of which risk throwing the set out of alignment, no?

any ground that isnt connected can cause lots of problems. i would replace the ground wire as it was shown originally on the schematic. what may have happened is someone disconnected the ground while preforming service work and forgot to reconnect it. if their is a ground wire their that isnt connected to anything obviously it needs to be connected to ground. yes sometimes a ground is achieved by the can connection to the chassis. one thing that comes to mind is some filter condensers achieve their connection to ground by the metal can. some have a negative terminal on the can. some filter condensers are isolated from ground. those adjustment screws all affect proper operation of the set. check the schematic and if it shows a ground connection check that it is there. if your worried about the ground connection measure from the ground terminal to the chassis with an ohm meter with the power off. if you get around zero ohms on the lowest ohms range the ground is fine. if not find out why not.

ALIGNMENT - once Z202 is back in place, I plan to simply adjust the screws until the sound seems ok. But these are alignment/trim screws, right? I've been told not to mess with them, and I know aligninging/trimming involves a scope and such to get them set just so.
- how hard is it to learn to do alignment/trim?
- how much would it cost to have someone else do it?
- is there anyone left on earth who knows how to do it?

you have very little chance of getting the alignment correct doing it by ear or by sight if it is in the video circuit. not having the schematic i dont know what circuit z202 is in though.

alignment instructions are in the service notes for the tv. some circuits are fairly easy some require special proceedure. i remember one tv where the service notes required you to modify a tube to do the alignment by clipping a pin of the tube and connecting to the stub of the lead. it allways requires specialized equipment which can be expensive and requires knowledge to use.

no idea what it would cost now. the person who taught me would charge 25 dollars an hour plus parts. that was along time ago. i heard shops now charge around 80 dollars an hour.

i think it would be hard to find a shop that would know how to work on vacuum tube equipment. i can remember allready in the 90s going to a service shop and asking them to test tubes for me and being told they didnt know how to wait till the owner came in and maybe he would know since he was around during that time period. most shops have gotten rid of the older equipment along time ago by now. with the prominence of flat screen tvs now i doubt you will find a shop that knows anything about crt televisions once the older guys retire or die off.

what state are you in. if you are near worchester ma there is a guy on this forum named leigh who is there. maybe he would help you. other guys here live in different states. i wouldnt trust shipping the chassis though which is why i said someone near you.

i no longer have the equipment to do alignment work or i would help you if you were near me.


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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: Dec Sat 31, 2016 3:55 pm 
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Thomas - on the CAN GROUNDING - it's not that the ground wire was disconnected - the *is* no ground wire. There is only one wire attached to the variable cap at the bottom, no other wire. What I figured out is that what attaches it to ground is the screw stem, with the little fastener on it, which holds it to the can. That creates a connection to the chassis, which is ground.

What I'd like to know from everyone is does that sound correct? Is his how it was done?


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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: Jan Sun 01, 2017 2:23 am 
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Most manufactures did not use adjustable caps. They only used adjustable inductors using ferrite cores. Typically the cores had threads on the outside and had a hex shaped hole in them so they could be adjusted with a plastic hex shaped tool. I have an RCA set that did not bother with a can. For those that did have cans, they were only to provide shielding. But in the early days the manufactures were trying to figure out how to make TVs and came up with a variety of ways to do things. I don't think that your set has anything missing. What you have is just the way they made it.

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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: Jan Sun 01, 2017 8:36 am 
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Thomas - on the CAN GROUNDING - it's not that the ground wire was disconnected - the *is* no ground wire. There is only one wire attached to the variable cap at the bottom, no other wire. What I figured out is that what attaches it to ground is the screw stem, with the little fastener on it, which holds it to the can. That creates a connection to the chassis, which is ground.

your set is a bit older than i have experience with but my opinion is if the schematic shows a ground wire it should have one. check the terminal the schematic shows is the ground connection and see if there is any evidence of something ever being soldered to it. if there is that is your answer if there isnt then i guess im wrong. that cap should have a connection to ground and i dont think it is through the can. what u described about things being sensitive to being poked suggests a bad connection somewhere.

the screw sticking out of the top sounds like an adjustment for a variable inductor. it wouldnt have anything to do with the cap i dont think. not being able to see what you are talking about i could be wrong but i have never seen or heard of a variable cap with a screw shaft sticking out the top.

now you have me wondering what is going on. what place is z202 connected in the circuit. i only have riders manuals which i finally found the disk for. the part numbers will be different from sams so i need to know where z202 is located in the circuit to find it in the riders schematic.


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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: Jan Mon 02, 2017 7:36 pm 
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Bad news. R100 is overheating. When I turn the set on there is no sound, no picture - just a sizzling sound. I traced it to R100, which bubbles and has dripped wax. you can see a spot on R100, below the black capacitor, where it appears to have melted or arced or something - don't know if that means anything.
Leading up to this I'd done two things, before which the set worked:
- I sprayed deoxit into the various cans, from below the chassis. I did this thinking that it helped with Z202 which was crackling and now is not, so it might help with the other cans. I sprayed it into all of the holes under the chassis, including the one that goes into the black box component that the pen is pointing to in the second photo. What is that component? Deoxit is not conductive, is it? I've let it dry for a few days in case it was, but R100 still sizzles.
- I replaced R204 and R207. I did this as they measured high and I was trying to solve the sound problem.
I suspect a short is delivering too much current to R100. I'll be looking for that. In the mean time, any advice? How should R100 look and behave? How hard is it to replace?
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R100 overheating.jpg
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What is it.jpg
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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: Jan Tue 03, 2017 1:50 am 
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Resistors of that type often fail with a short to the metal case. It is possible that something is drawing too much current but more likely that the resistor just failed. You replace it with several separate power resistors and some terminal strips to mount them on. The schematic should show the resistance of the various segments.

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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: Jan Tue 03, 2017 2:44 am 
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i wonder if the resistor that is now boiling is what was causing your thermal problem. replace r100 with the same wattage and resistance value as the origional r100. then bring it up on a variac and monitor current flow. if something is drawing to much it will show up. if you notice any over heating of r100 or the tv is drawing to much current power down and find out why.

it is possible that the only problem with r100 is that it changed value from age. if r100 dropped in value enough it would cause more current flow. the lower it drops in value the more current would flow till it burns its self out. while not as likely as increasing in value resistors can drop in value from deterioration.

i found a philco manual for your tv online plus i checked the riders manual for it and z202 is wired different in the philco from the riders. all of them have one end of c202 grounded just in different ways. without seeing what you have in your tv i have no clue which is right. are you using the factory schematic riders or sams. you might want to check all three and see which is closest to the way your tv is wired. according to riders there were lots of production changes to your tv.

the antique television museum has the philco factory service notes.

the part with the pen pointing to it cant be seen clearly in the pic you posted but it looks like some kind of transformer or possibly a filter choke.

deoxit is not conductive if it was it couldnt be used as a contact cleaner. if it is a transformer or choke the only possible damage from spraying it with deoxit i can think of offhand would be if the deoxit dissolved some of the enamel insulation on the wire used to wind it causing a short between two or more turns of wire.


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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: Jan Tue 03, 2017 3:09 am 
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Would I need 5-watt or 10-watt power resistors? I found these at tube depot - would these be appropriate?
https://tubedepot.com/products/10-watt-power-resistor?gclid=CjwKEAiAkajDBRCRq8Czmdj-yFgSJADikZgg2_9k-dTXLGqqygJ3rFTmZmGouk-H8mfAZhHmbQiZNBoCwFPw_wcB


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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: Jan Tue 03, 2017 3:10 am 
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Thomas13202 - how does one "monitor current flow"? I have a multimeter, but where exactly do I connect the probes? What do I look for, exactly?


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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: Jan Tue 03, 2017 3:38 am 
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Well, the parts list does not show any power ratings. See if there are enough voltages shown on the schematic to find the voltage at each connection to that resistor, or at least a few places. Then subtract the readings to get the voltage across each section. The power will be the voltage squared divided by the resistance in ohms. For example, a 100 ohm resistor with 20 volts across it would dissipate 20 times 20 divided by 100 which is 4 watts. If you can figure the wattage in each section, buy a resistor rated at double that power.

To measure current, most meters have a current measurement setting. You have to disconnect a wire and connect the meter between the wire and where it was connected. But if R100 has an internal short to the chassis then the current could be very high and damage your meter.

Another way to find the current through a resistor is to measure the voltage across it. The current is the voltage divided by the resistance in ohms. For a 100 ohm resistor with 20 volts across it the current would be .2 amps or 200 milliamp.

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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: Jan Tue 03, 2017 4:12 am 
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Thanks Tom. I've already fried one multimeter. Could I just by 10-watt resistors? Or must I determine just the right wattage? They are not expensive, and I'd just as soon skip the current-checking, which I'm not an expert at, though I'd figure it out if I had to - look how far I've gotten already!
Edit: I do have a high-voltage probe, would that be useful here?


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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: Jan Tue 03, 2017 4:37 am 
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10 watt resistors would probably be OK. And if one ran too hot you could buy a higher wattage resistor and not have wasted much money.

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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: Jan Tue 03, 2017 5:12 am 
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Are power resistors like capacitors, where the wattage rating must meet a threshold, but going above it, even far above it, is ok? Suppose I just bought, say, 25-watt resistors. Would they be ok? Can the wattage be *too* high, electrically speaking?


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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: Jan Tue 03, 2017 6:04 am 
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sdyer wrote:
Are power resistors like capacitors, where the wattage rating must meet a threshold, but going above it, even far above it, is ok? Suppose I just bought, say, 25-watt resistors. Would they be ok? Can the wattage be *too* high, electrically speaking?
The wattage only needs to be high enough. The only problem with using resistors with a wattage higher than needed is that they are larger and you may have a problem making them fit.

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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: Jan Tue 03, 2017 11:53 am 
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ok what i was talking about monitoring the current is some variacs have an ameter built in. the built in ammeter measure current flow through the variac and since the set is plugged into the variac it measures the current the set is drawing. if there were a short somewhere in the tv it would draw excessive current and would tell you shut me off now. you can do the same thing with a kill a watt if you dont have a variac. you can alsoa use your kill a watt to measure how many watts your tv is drawing. your tv shouldnt draw more than 275 watts. there may be a brief power surge till the tubes warm up but that is normal. it may go up above 275 watts and drop very quickly.

according to riders r100 is a 3 section canned ohm resistor containing r100a r218 and r405. this is the rectangle can mounted on the chassis in your pic.
r100a voltage dropping resistor 820 ohms in power supply
r218 plate dropping resistor 1500 ohms in audio circuit
r405 plate filter resistor 6200 ohms in rf circuit
while you can check each section with an ohm meter and replace only the section that is bad since you already recapped the whole set it is no longer original so to avoid problems just disconnect the whole thing and replace all three resistors. in this case i would grind off the head of the rivets on the outside of the chassis and remove the whole thing. mount terminal strips where the original canned ohm resistor was and use the original wires to connect to the new resistors. make sure the correct wire is connected to the correct resistor. this will require tracing the wiring to find out what wire connects where.

if i remember correctly a canned ohm resistor is one huge wire wound resistor with taps at the various resistance points needed. from left to right in your pic the spacing of the terminals of the canned ohm resistor in your pic i would say the 820 ohm resistor is between terminal one and two. the 6200 ohm resistor is between terminal two and three and the 1500 ohm resistor is between pin three and four. check the wiring to make sure im right. you could also measure between terminal one and two two and three and three and four and check the resistance with the set powered off. if two of the sections read close to what they should be that means you know what resistor is where. do not under any circumstances connect the new resistors to the terminals on the canned ohm resistor.

i would say 10 watt resistors should be fine. like tom said if they run hot you can always increase the wattage. higher wattage than the original wont matter. never use lower wattage. the resistance value should be as close as possible to the original value. never under any circumstances should it be more than + - 20 percent of the original value. some circuits require a closer tolerance.

i used to have an ohms law calculator but no longer have it. math always confuses the heck out of me for sure.


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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: Jan Wed 04, 2017 5:15 am 
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I can find 820 ohm and 1500 ohm 10-watt resistors, but I can't find a 6200 ohm. Does anyone know where I could get one in that particular value? If I can't find it, I can put in series 5k, 1k, 200 ohms to make it, right?


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