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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: Mar Sat 05, 2016 3:29 am 
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I can't get that video to play. I get a message saying that my browser can not play the video.
As mentioned it could be the horiz sweep gen running at the wrong frequency or corona. Try varying the horizontal hold control. If running at the wrong frequency then varying the hold control is likely to change the sound. If it is corona then you should be able to see if in a darkened room and the sound would not change much with the horizontal hold

Corona is generally caused by any connection running at high voltage that has a sharp edge or sharp point. You have to make sure that no strands of stranded wire are sticking out of a joint. And you have to have enough solder on the joint to make a rounded joint. Also make sure that there are no wires or any metal coming too close to the high voltage winding on the flyback.

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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: Mar Sat 05, 2016 3:39 am 
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It sounds like the Horizontal it way off frequency, as mentioned try turning the horizontal hold control while it's doing it and see if the pitch changes. It would also be worthwhile to do the arc test to the top of the 1B3 and see if you now have some high voltage.


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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: Mar Sat 05, 2016 5:26 am 
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Progress! I turned the variac up to the full 115 AC volts and got:
- arc at the top of the 1B3, with the screwdriver (this is good news - never had HV or this arc before today!)
- fluorescent light bulb lights up when placed near the flyback (another first)
- no corona - turned the lights out in the basement, very dark, saw nothing but the glow of the tubes
- Horizontal Hold makes the squeal change pitch
- 10 volts AC on 6BG6G pin 5, which is what the schematic says it should be, at exactly the Horizontal Hold position that makes the least noise. Was very slightly higher or lower if I adjusted HH either way.
I have a video of the arc at https://www.icloud.com/sharedalbum/#B0f5n8hH4m5dr7. The video also shows the change in pitch with the HH adjustment, and also that the sound is still playing, which I got many months ago.

Now some not good news:
- no arc at the top of 6BG6G. I tried both tubes I have, no arc on either one. The sound did crackle, though, when I touched the screwdriver to it.
- I swapped the vertical and horizontal 6SL7 tubes - now I got no arc on 1B3.
- I swapped the 6SL7 tubes back, and now get the arc again on 1B3.
- Still no arc at the top of 6BG6G with either 6SL7 tube arrangement.
- Still no raster or anything on the picture tube, though the filaments at the back continue to light up like they always have.

I've not tested the resistors out of circuit yet. I may test all combinations of 6BG6G and the two 6SL7 to see if any give an arc at the top of the 6BG6G. Btw adjusting the two horizontal control knobs at the back had no effect on the squeal.

Do I have a bad 6SL7, if one gives no arc on 1B3? Are they truly the same tube - I assume that because they have the same name/number, they are identical tubes? I've not tried my new 1B3 yet - should I - might it have an effect? Let me know what you all think. You've been very very helpful so far. I couldn't be making this progress without you.


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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: Mar Sat 05, 2016 7:23 am 
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If you have a good arc on the 1B3 then don't worry about the 6BG6, it's working and you're getting high voltage, at least to the top of the 1B3, it's possible you don;t have any at the bottom, or at the anode but lets assume for the moment that you do.

At this point you need to try adjusting the Ion trap on the neck of CRT, turn the brightness up about 2/3rds and twist the trap side to side, and slide it up and down the neck and see if you get any light on the screen, the correct adjustment is where it give maximum brightness.

I believe the CRT mount is grounded to the chassis through the wiring harness but you may want to connect a jumper just to be sure.


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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: Mar Sat 05, 2016 6:21 pm 
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sdyer wrote:
Progress! I turned the variac up to the full 115 AC volts and got:
- arc at the top of the 1B3, with the screwdriver (this is good news - never had HV or this arc before today!)
- fluorescent light bulb lights up when placed near the flyback (another first)
- no corona - turned the lights out in the basement, very dark, saw nothing but the glow of the tubes
- Horizontal Hold makes the squeal change pitch
- 10 volts AC on 6BG6G pin 5, which is what the schematic says it should be, at exactly the Horizontal Hold position that makes the least noise. Was very slightly higher or lower if I adjusted HH either way.
I have a video of the arc at https://www.icloud.com/sharedalbum/#B0f5n8hH4m5dr7. The video also shows the change in pitch with the HH adjustment, and also that the sound is still playing, which I got many months ago.

Now some not good news:
- no arc at the top of 6BG6G. I tried both tubes I have, no arc on either one. The sound did crackle, though, when I touched the screwdriver to it.
- I swapped the vertical and horizontal 6SL7 tubes - now I got no arc on 1B3.
- I swapped the 6SL7 tubes back, and now get the arc again on 1B3.
- Still no arc at the top of 6BG6G with either 6SL7 tube arrangement.
- Still no raster or anything on the picture tube, though the filaments at the back continue to light up like they always have.

I've not tested the resistors out of circuit yet. I may test all combinations of 6BG6G and the two 6SL7 to see if any give an arc at the top of the 6BG6G. Btw adjusting the two horizontal control knobs at the back had no effect on the squeal.

Do I have a bad 6SL7, if one gives no arc on 1B3? Are they truly the same tube - I assume that because they have the same name/number, they are identical tubes? I've not tried my new 1B3 yet - should I - might it have an effect? Let me know what you all think. You've been very very helpful so far. I couldn't be making this progress without you.


you can try swapping the 6sl7 that gave you no arc with a good one. it wont hurt anything. you may indeed have a bad 6sl7 but also the characteristics of a tube allow them to work fine in one circuit but not in another so while it may be bad it may also be good in another circuit. this is something a tube tester probably wont pick up. best test is substitution. yes if a tube has the same tube number it is the same tube. there can be some difference in mutual conductance or grid emition in one tube that isnt present in another tube of the same type.

your squeel is definately caused by the horizontal running off frequency. the coil you jumpered because it was open will eventually have to be replaced with one of the correct value to get the horizontal running 100 percent i am sure.

while you can test the resistors out of circuit with the readings you are getting im sure they are bad. by all means test them out of circuit. a general rule of thumb replace any resistor that is more than 20 percent + - out of tolerance.

if you have a high voltage probe for your meter try measuring the high voltage and the 2nd anode of the crt. do not attempt this unless you have a high voltage probe for your meter or the meter will be ruined and you will probably be shocked. once you know the high voltage is correct value then it is a matter of adjusting the ion trap with the brightness up about 2/3 of the way till you get the proper brightness picture on the crt.


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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: Mar Sat 05, 2016 6:54 pm 
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If the horizontal is running at the wrong frequency, that could reduce the high voltage (and the strength of the arc). One part that has a great influence on the frequency is that 560 mmf (pf) cap between pins 6 and 2 of the 6SL7. That is probably a mica cap. We used to think that mica caps never failed. But now we are finding that they do sometimes fail.
That coil is listed as a 60 mh coil. You may have to replace that before everything starts working correctly. Places to look for a coil include DigiKey and Mouser.

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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: Mar Sat 05, 2016 7:31 pm 
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Thanks guys. A few questions:
- Tom - my schematic shows L503 as a 6 ohm coil, not 60. Where are you getting your number?
- replacing the coil - do I search for a "choke"? "coil"? Also if you could share a picture of what a modern one looks like I'd appreciate it - will help ensure that I get the right component.
- replacing the resistors - do I need 1/2 watt? 1/4 watt?
- ion trap - that is the assembly with the two white cylinders on the neck of the CRT, right? If so, it is VERY tightly attached. What I mean is that it seems unlikely that it's moved, is now causing problems, and needs to be moved back to its proper position. It seems to me that it's just never moved. If that's so, why would it need to be moved now?
- high voltage probe - what exactly do I need? i.e. what do I search Amazon for? I've got a new analog multimeter, and have blown its fuse a few times (ordered a box of 100 - that ought to do), and it's not suitable for high voltage i'm pretty sure.


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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: Mar Sat 05, 2016 8:30 pm 
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For the coil, the closest standard values are 56 uh and 68 uh. So 56 uh would be the closest value. DigiKey part number M8190-ND looks to be the best fit with part number 495-6807-1-ND being another one that would work.

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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: Mar Sat 05, 2016 8:44 pm 
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sdyer wrote:
Thanks guys. A few questions:
- Tom - my schematic shows L503 as a 6 ohm coil, not 60. Where are you getting your number?
- replacing the coil - do I search for a "choke"? "coil"? Also if you could share a picture of what a modern one looks like I'd appreciate it - will help ensure that I get the right component.
- replacing the resistors - do I need 1/2 watt? 1/4 watt?
- ion trap - that is the assembly with the two white cylinders on the neck of the CRT, right? If so, it is VERY tightly attached. What I mean is that it seems unlikely that it's moved, is now causing problems, and needs to be moved back to its proper position. It seems to me that it's just never moved. If that's so, why would it need to be moved now?
- high voltage probe - what exactly do I need? i.e. what do I search Amazon for? I've got a new analog multimeter, and have blown its fuse a few times (ordered a box of 100 - that ought to do), and it's not suitable for high voltage i'm pretty sure.

The parts list section of the Riders manual shows the inductance. The DC resistance is not very important. The schematic lists it so that you can see if it is open or shorted. The heading for DigiKey is inductors coils and chokes.
I think that the original resistors are most likely 1/2 watt.
If it looks like the ion trap never moved then leave it alone until you have done other troubleshooting. Yours does look like it would not easily move around. On many sets it is held in place with a spring and can move if bumped.
Edit: Looking further I see that yours is an electromagnet and that there is an adjustment called beam bender. Draw a line on the shaft and the chassis to mark the current setting and then try adjusting it. Also, use the ohmmeter to see if it is open.

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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: Mar Sat 05, 2016 11:12 pm 
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For high voltage probes you may have better luck on Ebay. There are two main types. One is a self contained unit with a built in meter. The other type is an add on to a meter and is used in place of the normal positive test lead. This kind can only be used with a meter with a constant 10 Meg Ohm input resistance. Most digital multi-meters have a 10 Meg Ohm input resistance. Most analog meters have an input resistance that varies with the range selected. If the meter is rated something 20.000 ohms per volt then the input resistance does vary with the range selected.

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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: Mar Sat 05, 2016 11:18 pm 
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Beam bender - I turned the TV on, turned the beam bender control back and forth, to its limits. No change in squeal or TV behavior. Picture tube remained unlit.


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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: Mar Sat 05, 2016 11:19 pm 
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high voltage probe - what exactly do I need? i.e. what do I search Amazon for? I've got a new analog multimeter, and have blown its fuse a few times (ordered a box of 100 - that ought to do), and it's not suitable for high voltage i'm pretty sure.

im not sure if a high voltage probe were ever made for a multimeter. i was thinking you have a vtvm which you can definitely buy a high voltage probe for. they also sell some high voltage probes with a meter built into the probe handle. what you would search for is high voltage probe. this has a high value resistor built into the handle of the probe which allows you to read high voltage safely that is above the highest range your meter is capable of. not sure if there are any for sale now but i have seen them on ebay.

the impedance of a coil is measured in henrys and in your case is 60 henrys the dc voltage is something different which in your case is 6 ohms. unfortunately if memory serves the symbol they use for ohms is also used for henrys which is confusing.

i concur that you need to replace that open coil to get the horizontal working correctly. i would go with the part that was recommended by the above post.

i wish you all the best with getting this fixed. i am sure you are learning allot in the process.


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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: Mar Sat 05, 2016 11:54 pm 
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sdyer wrote:
Beam bender - I turned the TV on, turned the beam bender control back and forth, to its limits. No change in squeal or TV behavior. Picture tube remained unlit.


There would be no change in the squeal expected. I should mention that most beam benders use permanent magnets and are adjusted by moving them around on the neck of the CRT. Also they are most often called ion traps, although beam bender is a better description of what they do.

In order to prevent ions from hitting the phosphor and damaging it, the electron gun is tilted such that the ions will hit the neck of the CRT. The beam bender then bends the electron beam back towards the screen. The ions are also redirected, but much less than the electrons and so they still hit the neck of the CRT.

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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: Mar Sun 06, 2016 4:23 am 
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sdyer wrote:
Beam bender - I turned the TV on, turned the beam bender control back and forth, to its limits. No change in squeal or TV behavior. Picture tube remained unlit.


When you say beam bender control, are you talking about the double coil assembly on the neck of the CRT?
It's not really a control as such, it's just an electromagnet. If the circuit supporting it is not working then you won't get anything on the screen.

This is one of those situations where a 5AXP4 Test CRT would be very handy to have, it doesn't require the Ion Trap so it'll work even if the trap is non op.

It really sounds like you are getting some high voltage but perhaps not enough to light the heater in the 1B3 and let it reach the 2nd Anode.


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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: Mar Sun 06, 2016 9:33 am 
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I looked at the Riders manual for Philco 48-1000 ( http://earlytelevision.org/pdf/philco-4 ... er-tv2.pdf ) and it says there is a beam bender control in addition to the beam bender coil assembly. (Don't recall seeing that kind of control before, but there are lots of things I don't know.)

There are pictures and instructions for adjusting the beam bender magnets and control on pages 2-43 through 2-45 of the manual. The manual tells you the approximate starting position for the coil assembly and it says that the larger coil should be closer to the tube base. Note that you can slide the beam bender coil assembly forward and back along the neck, as well as rotate it around the neck.

Since the beam bender uses electromagnets, it might be interesting to measure the voltage at its coil connections.

Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html


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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: Mar Sun 06, 2016 8:38 pm 
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From the pictures posted and noting the way the beam bender is fastened, I think that is unlikely that the beam bender has been moved around.
The likely causes of no light on the screen are:
The high voltage is too low, possibly because the generator is running at the wrong frequency.
There is an electrical problem in the beam bender circuit. No voltage getting to the bream bender can be checked with a voltmeter and an open coil can be checked with an ohmmeter.
Wrong voltages at the grids and cathode of the CRT. Voltage readings would show this.

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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: Mar Sun 06, 2016 9:52 pm 
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Eric H - b "Beam Bender control" - I meant the control knob on the back of the chassis labelled "beam bender".


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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: Mar Mon 07, 2016 12:03 am 
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Is this a 100 ohm resistor, like I think it is? It is the same resistor in both photos, only the knob position on the MM is changed. Why these readings on the MM?
Attachment:
File comment: Doesn't the MM indicate 1000 ohms, not 100?
100 ohms 1.jpg
100 ohms 1.jpg [ 76.82 KiB | Viewed 2102 times ]

Attachment:
File comment: This looks like 125 ohms?
100 ohms 2.jpg
100 ohms 2.jpg [ 74.75 KiB | Viewed 2102 times ]


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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: Mar Mon 07, 2016 3:02 am 
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sdyer wrote:
Eric H - b "Beam Bender control" - I meant the control knob on the back of the chassis labelled "beam bender".


I saw that when I looked at the schematic, never saw that on any other set with an EM trap.


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 Post subject: Re: Philco 48-1000 Complete - how to restore?
PostPosted: Mar Mon 07, 2016 6:30 am 
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On measuring that 100 ohm resistor. If the meter works like mine, before you take a measurement you have to short the test leads together and then adjust the knob for a zero reading. You generally have to redo that every time you change scales.

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