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 Post subject: philco predicta holiday not making high voltage
PostPosted: Jun Mon 20, 2022 6:41 pm 
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I have a philco predicta holiday. That looks like it has been for the most part recaped and restored when I got it, But it did not seem to be generating high voltage (no highvoltage sound and no picture.) But the light lit and the added fan turned on.The fused resistor is blown. Does that mean there is a short somewhere? What would have caused this and could it have destroyed other parts too? This tv has a crt brightener. I don't have a tester for crts but it's probably weak.

I would love to have this tv going.

Thanks, Dylan


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 Post subject: Re: philco predicta holiday not making high voltage
PostPosted: Jun Mon 20, 2022 7:34 pm 
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Joined: Nov Thu 11, 2010 5:03 pm
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Location: Pewaukee, WI
Location: Pewaukee, WI
If it is an original fusistor it could have blown from a fault or could have rotted open...Many of the fusistors used in those were the sandohm style that corrode open from age. The service manual is on earlytelevision.org under Post War -> Technical Information -> Philco (then look up chassis number from your set).
In the service literature there's a current rating for the fusistor. You can connect a fuse of the same current rating in place of the fusistor and check the set.
You won't get high voltage if the fusistor is open and hasn't been replaced with something (like a fuse).
If the fuse doesn't blow and you don't get HV measure the grid voltage on the horizontal output tube with respect to chassis. It should be a negative voltage somewhere in the -50 to -75V ballpark. If the voltage is closer to zero or positive diagnose the horizontal oscillator.


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 Post subject: Re: philco predicta holiday not making high voltage
PostPosted: Jun Mon 20, 2022 8:25 pm 
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Joined: Apr Sat 06, 2013 1:18 pm
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Location: New Hampshire
If the fuse doesn't blow and you don't get HV measure the grid voltage on the horizontal output tube with respect to chassis. It should be a negative voltage somewhere in the -50 to -75V ballpark. If the voltage is closer to zero or positive diagnose the horizontal oscillator.[/quote]
Ditto
If you have B+ measure the G-1 of the hoz out tube. Must be very negative , see
manual. If it is the hoz osc is OK. If not hoz osc is not working. Its called "divide & conquer".
The fusable blows for no reason, age, or a shorted rectifier as a rule. It also slows the charge to the 'lytic caps. Replacement should keep its "fusable" specs.

73 Zeno 8)
LFOD !


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 Post subject: Re: philco predicta holiday not making high voltage
PostPosted: Jun Mon 20, 2022 9:57 pm 
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I found a new old stock fused resistor that matched the schematic. The TV did start squeeling from the high voltage, the CRT did start up. At first the CRT hat a line on the screen. As the tubes warmed up the line got bigger and started rolling. I did not see static or hear anything but a slight hum from the speaker. Do I need an antenna to see static? If I could find the pots to adjust the picture do you think I could expand the line to fit the whole screen and adjust the vertical hold to stop it fromrolling?


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 Post subject: Re: philco predicta holiday not making high voltage
PostPosted: Jun Mon 20, 2022 11:04 pm 
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Joined: Jan Thu 01, 1970 12:00 am
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Location: Woodinville WA 98072
The Sams Photofact for this set (I believe the Holiday is chassis 9L37) identifies the picture adjustment pots. Read the section "Hidden Adjustments" on the first page:

http://www.earlytelevision.org/pdf/phil ... _439-1.pdf

Regards,

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


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 Post subject: Re: philco predicta holiday not making high voltage
PostPosted: Jun Mon 20, 2022 11:27 pm 
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Joined: May Thu 14, 2015 3:15 pm
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Location: Dallas, TX
If you ever see only a bright horizontal line, turn down the brightness immediately or it could burn a line into the screen phosphor.
You may have a problem with the vertical output tube or the vertical could be working poorly because a supply voltage developed in the horizontal section is not proper.
These problems actually may be caused by a tube developing a short or something similar.
Adjustments don't suddenly go wrong.
No you do not need an antenna to see snow.

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Tim
It's not the Destination, It's the Journey.


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 Post subject: Re: philco predicta holiday not making high voltage
PostPosted: Jun Tue 21, 2022 1:28 am 
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I attached my Atari to the Predicta and after fiddling with the horizontal hold an vertical hold I got a some what steady but blurry and still shrunk picture. It seemed like the pots were dusty or bad, becouse it sometimes fliker into almost the whole screen. I am going to try to find some electronic or brake cleaner. Still no sound though. I also took off the CRT brightener and it looks bright enough.


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 Post subject: Re: philco predicta holiday not making high voltage
PostPosted: Jun Tue 21, 2022 3:08 am 
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Don't use brake cleaner - you'll destroy the pots. Get some DeOxit F5. Have you tried adjusting the height control? Each of the 3 controls on the side have a second control you get at by sliding a small flat bladed screwdriver down the hollow control shafts. Height is the inner control of the middle control (vertical hold).


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 Post subject: Re: philco predicta holiday not making high voltage
PostPosted: Jun Tue 21, 2022 10:41 am 
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I have not tried to clean them yet and but I did get the screen to a bigger size with the hidden pots. I also got the sound working by wiggling a tube. I don't think the socket was broken I just think it was dirty so I cleaned it. Now there is some waving in the picture, could that be from the couplates that were not changed? The V hold still won't stop moving perfectly, could be that I have not cleaned it.


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 Post subject: Re: philco predicta holiday not making high voltage
PostPosted: Jun Tue 21, 2022 1:58 pm 
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Joined: May Thu 14, 2015 3:15 pm
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Location: Dallas, TX
Since the horizontal and the HV seem to be OK, we can probably say the lack of HV (your original problem) was due to the fusible resistor being bad or blowing.
Your primary problem is in the vertical deflection. After adjusting the height somewhat, the linearity is way off. Something in the vertical has failed. Since the set has most of the likely capacitors replaced the problem could be a tube (vert. oscillator, vert. output), corroded tube socket/pins, a couplate or a resistor.
There is a small chance that it is something else.
Rather than buying a tube tester (assuming you don't have one) it would be cheaper to buy some NOS vertical tubes.
You could measure some voltages in the vertical section to narrow it down some.

Where are you located?

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Tim
It's not the Destination, It's the Journey.


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 Post subject: Re: philco predicta holiday not making high voltage
PostPosted: Jun Tue 21, 2022 2:39 pm 
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I think it is blurry and the audio is a little distorted because it is not fine tuned correctly. When the the fine tuning is fully turned one way it is the clearest but it still seems like I need to turn it to make it eaven more clear. Shouldn't the best reception come in when the fine tuning is close to the middle? Is there an adjustment for this somewhere?


I do have a tube tester but it recently stopped working. I will do some testing of other parts though. I am in Iowa so it does get humid but I don't think it was stored it a very humid place. It looks like this TV was taken care of.


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 Post subject: Re: philco predicta holiday not making high voltage
PostPosted: Jun Tue 21, 2022 6:10 pm 
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Location: Dallas, TX
When I said corrosion I didn't just mean just iron rust but oxidation of other metals or accumulation of dirt from the air.

Did you adjust something other than the fine tuning?
The vertical looks full height now. However the image was sharper in the picture before.
Most probably doing an adjustment to give the fine tuning control further effect would involve doing an alignment, which is rather involved and requires much more equipment. The alignment would not have suddenly changed either. I think you are attempting to fix a failed part by changing adjustments which probably will not get you where you want to go. The adjustments are there to compensate for component variations and also aging. Changing the fine tuning could effect the synchronization pulses that time the beginning of the vertical and horizontal scans.

What tube tester do you have?
Fixing the tube tester may be something you should do now. They generally are simpler than the TV.

I ask about your location because you didn't include it in your registration info and it may effect where you could find parts and help.

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It's not the Destination, It's the Journey.


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 Post subject: Re: philco predicta holiday not making high voltage
PostPosted: Jun Wed 22, 2022 3:34 pm 
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I have just been adjusting the knobs and the pots hidden on the back of the knobs.

I have a SICO model TW-11 tube tester.

Now there is a humming coming from the circuit board with the output tubes or from near it. I don't know if the noise was there before or if it is supposed to sound like that. Could be coming from the horizontal out tube. I have heard those go bad often.

I think the distortion of the audio is probrobly because the speaker might be blown. I will repair it if it's blown.

It looks like the waviness of the picture has gone down alot so I wonder if a capacitor (couplate?) Has started to reform.

Without me adjusting anything it seems like the fine tuning is a little better but still not as good as I thought it would be.

Doe anyone know if there anyplace that might have replacement predica holiday antennas? On mine the antenna is missing but the circuit board it would have attached to is still there.


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 Post subject: Re: philco predicta holiday not making high voltage
PostPosted: Jun Wed 22, 2022 3:49 pm 
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Is there a sharpness control?


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 Post subject: Re: philco predicta holiday not making high voltage
PostPosted: Jun Wed 22, 2022 4:41 pm 
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Joined: May Thu 14, 2015 3:15 pm
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Location: Dallas, TX
I think I had gotten your set mixed up with another Predicta that there is another thread about.
In your case, if I understand correctly, you have not see it work properly recently. That mean that the problems could have happened more gradually or perhaps the last person to work on it never got it working right. You might have to treat this set as one that was not worked on correctly. The replacement capacitors might not be the right values, I would double check them. The fact that the CRT had a brightener on it when it probably did not need it indicates someone tried to fix another problem with it instead of fixing the real problem.
You need to work on correcting one thing at a time. Try not to jump to conclusions like the speaker being blown.

I think there is a local/distant switch on this model, if it is set to distant and your signal is too strong it could overload the input and cause problems.

Only electrolytic capacitors can reform and that is very iffy. It is possible that there is a problem in one or more couplates.

This link was posted in another thread. It gives a good overview on restoring Predictas.
http://www.earlytelevision.org/pdf/pred ... _final.pdf
Antennas are not sold, however there are some old rabbit ear antennas that can be scavenged for replacement parts.

That tube tester is a rather simple emission tester (as opposed to a transductance tester). A problem would be that it was made around 1954 and Predictas came out in about 1959, so the set uses some tubes that did not exist when the tester was made. Accurately setting the tester for those tube would be unlikely.

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It's not the Destination, It's the Journey.


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 Post subject: Re: philco predicta holiday not making high voltage
PostPosted: Jun Wed 22, 2022 4:56 pm 
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Location: Austin, TX
I would spot check some resistors since they often drift high in value. It seems to depend on how it was stored, and how good the batch of resistors was. Some sets are fine, while others have dozens of badly out of tolerance resistors. The couplates can also cause trouble (usually drifted resistors).

I would try running it without the brightener to see if it produces an acceptable picture. Sometimes they were added unnecessarily when something else went wrong.

You might try a different video source since video games often took some liberties with the video signals. It might not strictly meet NTSC specs. A DTV converter box should provide a more accurate video signal.


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 Post subject: Re: philco predicta holiday not making high voltage
PostPosted: Jun Wed 22, 2022 9:09 pm 
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I actually took the speaker out and hooked up one of the same value and it fixed the audio.

It is on local.

I did take the brightener off and it seems bright enough.

I have already tested the TV with my NES, Atari and a digital converter box. The converter box came in with probrobly the best picture but it still has some problems. The waviness only sometimes happened with the converter box.


The picture looks worse in-person, I think the camera trys to do something to make the picture look more focused.


I will check all of the parts tomorrow, I won't be around tonight.


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 Post subject: Re: philco predicta holiday not making high voltage
PostPosted: Jun Thu 23, 2022 12:15 am 
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Joined: Jan Thu 01, 1970 12:00 am
Posts: 461
Location: Middletown NJ
Good move pulling the brightener unless absolutely necessary, it finishes off a decent tube sometimes. If you find you need couplates there is a company making reproductions and they work.


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 Post subject: Re: philco predicta holiday not making high voltage
PostPosted: Jun Thu 23, 2022 12:41 am 
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Joined: May Thu 14, 2015 3:15 pm
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Location: Dallas, TX
Do you have a copy of the SAMS service manual 439-1 ?
It can be downloaded here.
https://www.earlytelevision.org/tv_sche ... hilco.html

As far as sharpness is concerned there is no adjustment for it. Components that may effect sharpness are around the video output tube, V4 6AW8A. That tube as well as V3 5AM8 are possible problems, also these
capacitors C20,21,22 and C24, resistors R30,31,32,33,34 and R35.
Check the voltages on the CRT (V14) pins.
pin 2 and/or pin 6 420V,
pin 3 0V,
pin 4 0V or 280V or 420V
pin 7 varies with brightness control, could be around 35V.

There is a approximate focus adjustment, it involves moving a connection to one of 2 or 3 places on a terminal strip. Not vary exact.
You should be able to get better vertical linearity by adjusting the various vertical adjustments, linearity, height and hold. If not then there could be another problem in the vertical area, tube, cap, resistor or couplate.

I don't know what you mean by waviness.

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Tim
It's not the Destination, It's the Journey.


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 Post subject: Re: philco predicta holiday not making high voltage
PostPosted: Jun Thu 23, 2022 4:35 am 
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Joined: Jan Thu 01, 1970 12:00 am
Posts: 461
Location: Middletown NJ
A word on the focus circuit, on pins 2/6 That is the focus circuit, if you see the 420v is derived through r37 which is dropping the 425v boost from the flyback. What are your power supply voltages with the set running? If the boost is low the focus will suffer. How does +280v, +425v look? Low power supply voltages will give the insufficient vertical sweep too. I always thought the "focus tap" system was stupid, highly imprecise your options are +420v, +280v, GND. they were too cheap to use a pot.


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