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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: Dec Wed 14, 2016 7:29 pm 
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Joined: Jan Sat 31, 2015 10:06 pm
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Thanks Thomas. I will check some of that out.


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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: Dec Wed 14, 2016 7:32 pm 
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Joined: Jan Sat 31, 2015 10:06 pm
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On the cabinet - I took it to Falvey Reinishing in Dorchester, MA (part of Boston). They confirmed that the veneer and all wood on the outside is mahogany, stained reddish, with clear lacquer. So - not walnut or another type of wood, not toned lacquer, not an amber lacquer finish. They were even able to sell me a roll of mahogany veneer!
Attachment:
Mahogany Veneer Roll.jpg
Mahogany Veneer Roll.jpg [ 80.19 KiB | Viewed 463 times ]


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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: Dec Wed 14, 2016 9:04 pm 
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Location: Rockford, IL
Good luck!! Veneering is,..,. A blast.. :lol:


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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: Dec Wed 14, 2016 11:00 pm 
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Joined: Jan Sat 31, 2015 10:06 pm
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Thanks Sam! I have never veneered before. I've asked for advice on the cabinet-specific thread at http://antiqueradios.com/forums/viewtopic.php?f=7&t=307372. Please go there and let me know what I need to know!


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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: Dec Wed 14, 2016 11:36 pm 
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Location: WI 54812
thomas13202 wrote:

the nos tube that caused buzz could have grid emissions. that can cause problems for sure. also the tube could be microphonic. did you check the pin out on the 6j6a and is it identical to the 6j6. if the 6j6 is a metal tube pin one will be grounded to the metal tube envelope. on a glass tube this is not the case. in some cases replacing a metal tube with a glass tube can cause a problem due to no shielding on a glass tube. to see if that is the case shield the tube by wrapping aluminum foil around the tube. ground the aluminum foil to the chassis. if the buzz goes away you know that you need to find the metal tube. usually the tube number with nothing after it is a metal tube with a g after it would be an early style glass tube envelope and gt after it would be the later style glass envelope.


Thomas, I don't think I've ever seen a metal 6J6? I thought they were always a miniature 7 pin glass type. They often have a metal shield installed which makes contact with a grounded metal socket base.


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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: Dec Wed 14, 2016 11:50 pm 
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Joined: Jun Thu 25, 2015 3:21 am
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i am not sure if it is a metal tube or not. that is why i said if it is a metal tube. if it is a 7 pin miniature tube it is definitely not metal. from the age of the set i was thinking octal tubes. while i have worked on televisions from the late 50s to early 70s i have never seen a tv as old as this one accept in pictures. i do not have the service notes in front of me.


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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: Dec Thu 15, 2016 1:28 am 
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Joined: Jan Sat 31, 2015 10:06 pm
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Thomas, the RF tubes are all glass like the 6AG5 below. All are in shield housings - see below. Also below is the schematic showing the three tubes - bottom up on the schematic corresponds to the tubes in the chassis picture left to right - 6J6, then the 6AG5 Mixer, then the 6AG5 RF amp.

Tonight I tried replacing both of the 6AG5 tubes. Neither fixed the problem. The set would warm up, sound would fail, then even if I turned the set off for a minute or two, when turned back on the sound was still out. Only when i let it cool fully would the sound come back. Since the tubes were not the problem, I replaced the original tubes. Taping the mixer tube caused some effect in the buzz, but it didn't fix it. So I suspect the mixer socket or some of the components connected to it. Could the mica caps and resistors in that circuit be affected thermally?
Attachment:
Rogers 6AG5 Tube.jpg
Rogers 6AG5 Tube.jpg [ 34.77 KiB | Viewed 447 times ]

Attachment:
6J6, 6AG5 Mix, 6AG5 Amp.jpg
6J6, 6AG5 Mix, 6AG5 Amp.jpg [ 44.03 KiB | Viewed 447 times ]

Attachment:
RF Tubes.jpg
RF Tubes.jpg [ 43.82 KiB | Viewed 447 times ]


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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: Dec Thu 15, 2016 3:39 am 
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sdyer wrote:
Thomas, the RF tubes are all glass like the 6AG5 below. All are in shield housings - see below. Also below is the schematic showing the three tubes - bottom up on the schematic corresponds to the tubes in the chassis picture left to right - 6J6, then the 6AG5 Mixer, then the 6AG5 RF amp.

Tonight I tried replacing both of the 6AG5 tubes. Neither fixed the problem. The set would warm up, sound would fail, then even if I turned the set off for a minute or two, when turned back on the sound was still out. Only when i let it cool fully would the sound come back. Since the tubes were not the problem, I replaced the original tubes. Taping the mixer tube caused some effect in the buzz, but it didn't fix it. So I suspect the mixer socket or some of the components connected to it. Could the mica caps and resistors in that circuit be affected thermally?
Attachment:
Rogers 6AG5 Tube.jpg

Attachment:
6J6, 6AG5 Mix, 6AG5 Amp.jpg

Attachment:
RF Tubes.jpg

ok yes a condenser or resistor can be affected thermally. try cleaning the tube socket and tube pins also.

is this a split carrier sound set? if so the problem can be anywhere in the audio path. if not the problem has to be past the point where video is split off from audio. i really need to find the disks with my riders manuals so i can check the schematic. in either case i dont think the complete problem is in the tuner as that would also affect the video i would think.

one other thought make sure the pin out and electrical specs is the same for the 6j6 and the 6j6a. i no longer have any of my tube manuals.

are you familiar with the procedure to use freeze spray to troubleshoot a thermal intermittent?

the fact that you had to wait for the set to completely cool does sound like a thermal problem.

the tubes you showed are either 7 or 9 pin minature tubes so no chance of the tube being a metal tube. if memory serves the only metal tubes had an octal base.


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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: Dec Thu 15, 2016 5:54 am 
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Joined: Jan Sat 31, 2015 10:06 pm
Posts: 299
From what I've read the 6J6A is functionally identical to the 6J6. The difference is that the 6J6A has a forced 11 second warm up time. I got a new 6J6A today, and the sound works now, as good as it did with the 6J6.


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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: Dec Thu 15, 2016 6:02 am 
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Joined: Jan Sat 31, 2015 10:06 pm
Posts: 299
I just ordered a can of this stuff to check out the thermal issue.
https://www.amazon.com/MG-Chemicals-Super-Spray-Aerosol/dp/B0047Y9DKS/ref=pd_sim_229_1?_encoding=UTF8&psc=1&refRID=S08E8FAEMSVN3WZEH59H


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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: Dec Thu 15, 2016 8:56 pm 
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Joined: Jun Thu 25, 2015 3:21 am
Posts: 1166
the spray u bought s. hould work fine.

just a thought but do you have a signal tracer. if you do wait till the sound goes out and using the correct probe starting at the first if tube work your way through the tubes in the audio circuit tilll you get to the tube where the sound is lost. the tube where the sound is lost is the defective stage. then spray the components in that stage with freeze spray one at a time. when you spray the component with a thermal intermittent the sound will come back. change that component. do not spray tubes with freeze spray. normally in a radio you would start with the rf tube but this is not practical in a tv.

if you had a vtvm stage gain mesurements would also narrow down the defective stage. the the freeze spray would locate any part with a thermal problem.

if the problem is in the tuner do not service it yourself. this can cause interesting problems if original lead dress is not followed or nearby parts are disturbed.

if parts are changed in the rf or if circuit then an alignment is needed. do not try to do an alignment without proper equipment as you can make things allot worse.

are the if coils in your tv slug tuned or do they use trimmers?


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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: Dec Thu 15, 2016 11:28 pm 
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Thanks Thomas. I think you're talking beyond my skill level. I don't have a signal tracer or a vtvm.


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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: Dec Fri 16, 2016 1:13 am 
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Joined: Jun Thu 25, 2015 3:21 am
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a vtvm is used the same way your multimeter is. if you can measure ac dc voltage resistance with a multimeter you can do the same thing with a vtvm.

re signal tracing. any good book on electronics repair written during the time period tube electronics was being used will explain how to do it. in audio circuits this can be done with a signal tracer or vtvm.

a signal tracer is basically an audio amplifier in a box used to trace an audio signal through a receiver. you connect the negative probe lead to ground then connect the positive lead of the correct probe to the grid of the tube and if you hear the sound at normal volume level and distortion free everything up to that point is working. then move to the plate of the tube and repeat the test. my signal tracer can handle the dc voltage present at the plate. if you want you can use a blocking condenser in series with the positive lead. in the case of your tv the stage where the signal gets weak is the stage the problem is located in. it is not hard to do with correct equiptment.

probes for a signal tracer is an rf probe sometimes called a detector probe or the audio probe. the rf probe is used to trace the signal from the rf tube to the detector tube inclusive. the audio probe is used in audio circuits. the same for a vtvm. a vtvm also has a high voltate probe to test the voltage at the crt etc.

i know you can learn signal tracing and stage gain measurements very easily after all you have been through with this tv. i would say this tv was what used to be called a tough dog. you got it much better than it was and are very close to victory.

stage gain mesurements. the signal voltage at the grid and plate is ac. you basically measure the signal strength at the grid of the tube then at the plate. if the voltage is higher at the plate than at the grid move on to the next stage. again a blocking condenser in series with the positive lead. the signal at the control grid of the next stage should be the same as the signal on the plate of the proceeding tube. if it isnt the problem lies between the plate of the proceeding tube and the control grid of the tube under test. if it is the same proceed to the plate of the tube under test and if it is higher move on till you find the place where the signal strength drops. that will isolate which stage is bad.

slug tunned if coils will have a shaft sticking up from the if can used to move a ferite core inside the coil. trimmer tunned if coils will have a round hole with a screw adjustment for the trimmer condenser. which does your set have?


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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: Dec Fri 16, 2016 2:51 am 
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Location: Gresham OR
Greetings from FixitLand!

Thomas stated: "slug tunned if coils will have a shaft sticking up from the if can used to move a ferite core inside the coil." That's not necessarily true! There are many slug-tuned coils (not just IF) which have NO shaft; the ferrite core has a hex-shaped hole into which you insert a plastic tool to adjust the core. (NEVER use a metal tool such as an Allen wrench!)

Take care,

J. E. Knox "The Victor Freak"


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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: Dec Fri 16, 2016 3:53 am 
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i stand corrected mr knox.


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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: Dec Sun 18, 2016 1:45 am 
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Thomas/Rojo - there are core-like adjustments in the set, where turning a knob or screw moves a shaft in/out along a sleeve. There are two in the tuner critic, and three adjustments on the back of the set for height and width. There are also a number of canisters on the chassis with one, two, or three screws sticking out. I assume those are used for trimming and aligning. I've no touched them.


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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: Dec Sun 18, 2016 9:00 pm 
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sdyer wrote:
Thomas/Rojo - there are core-like adjustments in the set, where turning a knob or screw moves a shaft in/out along a sleeve. There are two in the tuner critic, and three adjustments on the back of the set for height and width. There are also a number of canisters on the chassis with one, two, or three screws sticking out. I assume those are used for trimming and aligning. I've no touched them.


yes dont touch them unless you are sure what they do and have the proper test equiptment to adjust them. while it is possible to attempt to adjust height liniarity with it is best ho have a circular test pattern on the screen when doing so. all other adjustments except user controls should not be touched without proper test equiptment and knowledge of how to adjust it. if you are interested the service notes should have info on what you need where to hook it up and what to turn.


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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: Dec Sun 18, 2016 9:44 pm 
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Location: pensacola fl
That buzz could be several things. In inter carrier sets the whole rf/if can be responsible all the way to and including audio detector. The tube that caused the buzz if it was a video if or tuner tube could be because the tube's internal capacitance is different from the tube that the set was aligned with. A big cause of buzz in a properly modulated tv station signal is the tuner/if stages are a bit low on agc voltage for the signal being put through them. This causes the stage(s) to clip the signal enough to where the audio signal which is lower in level than the video signal has holes punched in it at peak white. This is evident if you use a scope with low cap probe and look at the audio i.f. signal through the audio i.f. stage. Use a field sweep rate for the scope and use external sync on scope and hook the external sync input to either the vertical oscillator or sync separator circuit preferably at the vertical sync integrator output. then you can see when the buzz appears if the video is riding the audio and causing holes in it. If the audio i.f. is clean then the audio detector is probably the cause. If your set has a discriminator with a limiter in front of it then both could be at fault and the secondary of the detector transformer may need a setting touch up. Grid components in the limiter grid as well as other components in the limiter need careful checking. If the set has a ratio detector with or without the limiter that electrolytic capacitor in the detector is a frequent offender. Not just value or leakage but also if the cap has high esr it will cause problems. When replacing it use a low esr type the value can be higher if need be with in reason say 100% increase max. I say all this assuming that the tuner is properly tuned in and the signal source is not over modulated and many vcr and dvd player can be as well as cable and satellite receiver can have this condition. The best way is to check on a known good set with the same r.f. cable moved from set to set with the same material on it.


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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: Dec Mon 19, 2016 4:55 am 
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Thomas and audioman - you must have been TV repairmen back in the day, no?


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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: Dec Mon 19, 2016 12:56 pm 
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to answer your question i was trained by and worked for a semi retired radio and tv repair man who got his training in the 1940s and i also had the benefit of a friendship with a person who was the engineer for the radio station in springfield ma from just before ww2 till it converted to solid state. i worked mostly on zenith rca as this is what was prevalent in my area that were made from the late 50s to the 70s. we never did solid state however. i also have worked on radios made from the 20s to the end of the vacuum tube era.


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