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 Post subject: 1968 Packard Bell CQ-956 Color TV
PostPosted: Aug Thu 13, 2020 5:52 pm 
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Location: Sioux Falls, SD
I have from time to time kept an eye out for a nice color tube tv and I believe I got lucky this week. After the first guy couldn't arrange a time to pick it up I was next and grabbed it. The TV was purchased locally and been in town ever since, it currently belonged to the grandson of the original owner. Visually it is in very good condition; knobs are present, grill cloth clean, no chips, dents, scratches, or worn finish. I cringed a bit at pickup as it was plugged in and running, that said there was raster. Also it was a heavy beast to load.

Once home a quick inspection showed a few screws missing on the back panel so someone has been inside before, no immediate red flags or visible hacked parts, the picture tube and chassis have matching serial numbers, note the picture tube is a 25XP22 while SAMS lists a 25GP22A, the chassis number is 98C19.

This is my first color TV with my only other experience being small 7jp4 TVs, I have lots of learning ahead. I ordered the SAMS folder and first up will be to replace the electrolytic caps and then the real troubleshooting starts. I plan to scan this site for additional troubleshooting advice but will welcome it here too. I did find a case study on this TV in the 1981 Electronic Servicing Magazine: https://worldradiohistory.com/Archive-PF-Reporter/80s/EST-1981-02a.pdf

From some searching it looks like this TV had a list price of $599, that’s about $4,500 in today’s dollar. If out there I sure would appreciate sharing any old advertisements or literature.

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 Post subject: Re: 1968 Packard Bell CQ-956 Color TV
PostPosted: Aug Thu 13, 2020 9:45 pm 
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Location: Pewaukee, WI
Nice Danish modern cabinet.

What to do depends on how cautious you are. Given that is mid to late 60s I'd probably power it up with a metered variac or dim bulb tester and see what it does.

The cabinet style makes it worth a new CRT if the old one is shot, but typically it's a good idea to check the CRT emission and balance before you buy.

It's a good idea to change the Electrolytic caps if you plan to use it heavily and want better reliability. There may be paper dielectric caps in there if PB was still using those blue plastic tubular caps when they made that.


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 Post subject: Re: 1968 Packard Bell CQ-956 Color TV
PostPosted: Aug Fri 14, 2020 2:20 am 
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If you are thinking of the ones with 516 as a code number, every one that I encountered was leaky.

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 Post subject: Re: 1968 Packard Bell CQ-956 Color TV
PostPosted: Aug Fri 14, 2020 9:40 am 
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It looks like P-B went down the road of brand Z, and Motorola with those solder junction pins, the chassis layout seems to be all their own. Those pins should make parts replacement easy. You just heat up the pin with a solder gun, or iron, and the component lead slide right out. I'm surprised that anyone in North America was still using paper caps by then, paper-mylar maybe, but not paper. Packard Bell was likely one of the first to use imported parts in their TVs, later importing chassis or rebadged sets from Japan, so they may have been using paper caps from there.
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Arran


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 Post subject: Re: 1968 Packard Bell CQ-956 Color TV
PostPosted: Aug Sat 15, 2020 3:35 am 
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The story that I heard was that one of the Zenith engineers defected to Motorola, and brought the idea with him. As for Japanese parts, the first ones that I ever saw were electrolytic capacitors in a 1958 Sonic transistor radio.

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 Post subject: Re: 1968 Packard Bell CQ-956 Color TV
PostPosted: Aug Sun 16, 2020 1:49 pm 
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Interesting about the Japan components discussion, I am beginning to go through the TV and noticed the front controls face plate has a made in Japan stamp on the back side. The face plate is some kind of heavy cast metal. Note the attached UHF/VHF tuner each had made in the USA stamps.

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 Post subject: Re: 1968 Packard Bell CQ-956 Color TV
PostPosted: Aug Sun 16, 2020 2:19 pm 
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Also I have removed the chassis, dusted it off and and looked for any obvious components that need to be replaced. Interesting I could not see any repairs made to the chassis, if repaired they used period correct parts and were very clean about the installation, no tacked on parts or cut leads. Now I would guess there were several tubes replaced, half were branded Packard Bell while the rest where other brands, mostly GE, and all of the tubes were equally dusty, no recent work here as best I can tell.

Question, what kind of service work would a TV from the late 60s require, was it common to just need tubes replaced? See below for what I found. Also the 2nd Chroma Bandpass Amp-z Demodulator (V11 in SAMS) calls for a 6au6a but a 6gy6 was being used, the diagram on the back of the chassis also lists a 6au6a as the correct tube. Was using this 6gy6 a mistake or a close enough tube to get by or would there be a reason for the substitution?

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 Post subject: Re: 1968 Packard Bell CQ-956 Color TV
PostPosted: Aug Mon 17, 2020 3:33 am 
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Look at the beautiful machine tool work on that diecasting. No wonder stuff like this was sourced from Japan. They really took pride in the workmanship.

Pye in Australia in the 1970s used to import TV front panel inserts and badges for their TVs from Japan. It was known internally at Pye as the "jewelry" and it certainly had a jewel-like quality. Here is an example from 1977, the color wave symbol and surrounding panel:
Attachment:
Pye_22A6C_Panel.jpg
Pye_22A6C_Panel.jpg [ 285.56 KiB | Viewed 1609 times ]

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Wax, paper, bitumen, cotton, high voltages - what could possibly go wrong?


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 Post subject: Re: 1968 Packard Bell CQ-956 Color TV
PostPosted: Aug Mon 17, 2020 8:35 am 
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Location: British Columbia
Tim Tress wrote:
The story that I heard was that one of the Zenith engineers defected to Motorola, and brought the idea with him. As for Japanese parts, the first ones that I ever saw were electrolytic capacitors in a 1958 Sonic transistor radio.


That sort of fits since many of the American made low voltage caps from that era were junk, like the Nashville ones, and Sonic was probably an off brand who was looking at pinching pennies. Either that or it was a rebranded Japanese set, or at least used the chassis from one. Of course I am also assuming that it was all original, and that someone didn't replace the Nashville caps with Japanese ones later.
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Arran


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 Post subject: Re: 1968 Packard Bell CQ-956 Color TV
PostPosted: Aug Mon 17, 2020 3:39 pm 
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It was a TR-88; American made, with GE transistors and those infamous Automatic IF transformers. I still have the chassis, but the pressed board cabinet fell apart many years ago. I have been looking for another one for a long time, but it's evidently an uncommon set. I have owned it since 1962, and the Japanese "Cosmic" capacitors were in there when I got it .

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 Post subject: Re: 1968 Packard Bell CQ-956 Color TV
PostPosted: Aug Sun 23, 2020 2:17 am 
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Location: Sioux Falls, SD
Today I got all of the electrolytic capacitors replaced, replaced the line filter caps with safety Y2 caps and replaced the bridge rectifier diodes. Also swapped out all of the tubes with NOS or tested good tubes. I used an old NES that feeds RF in on channel 3. I am able to get sound and I can get a visible black and white image, but no color. I have to turn up the brightness way up to get a good image but then the screen is blurry/fuzzy, I suspect the CRT us nearing the end.

Now the big issue is that after about 5 minutes of running I get a hissing noise from the high voltage cage, the screens then goes dark and it pops the built in circuit breaker. I let it cool down and I got the same sequence a 2nd time. I tried a 3rd time swaping back to the original HV tube and got the same issue after a few minutes. Any thoughts?

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 Post subject: Re: 1968 Packard Bell CQ-956 Color TV
PostPosted: Aug Sun 23, 2020 11:09 pm 
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It sounds like you have high voltage leakage somewhere. Turn the set on in a darkened room, and CAREFULLY look for a bluish discharge. It could be the HV rectifier socket, the filament winding on the flyback, or the flyback transformer itself.

Since the circuit breaker is tripping, you have an overload. Look at the horizontal output and damper tubes, and see if either one is turning red, before the breaker trips. Since you have a focus problem, check for anything burnt in the focus rectifier and coil area.

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 Post subject: Re: 1968 Packard Bell CQ-956 Color TV
PostPosted: Aug Mon 24, 2020 8:16 pm 
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The blurry picture may be a result of low HV incorrect focus voltage, misadjusted G2/screens, or if scanlines are sharp and video is blurry it could be a tuner or IF issue.

You want to start by fixing the HV system issues including the arcing and shut down issues.


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 Post subject: Re: 1968 Packard Bell CQ-956 Color TV
PostPosted: Oct Tue 13, 2020 2:16 am 
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Location: Sioux Falls, SD
I picked up a HV probe and was able to do a bit more testing. The high voltage measured approx 26K volts as best I can read the meter dial gauge. The schematic specs 23k to 25k volts, do I need to try to turn this down or am I close enough? As before after about 5 min the TV starts to make noise and then trips the breaker. I was watching the back as this happened and I could see the horizontal output tube start to glow red hot and then it trips out. Note all of the tubes have been replaced with NOS tubes so I would like to think its not the tube...


Here is the HV schematic.
Image


As for checking components I don't see any visually bad parts, I few notes
1) the wire going into the horizontal output tube grid cap had lost some insulation right near the cap, probably from running hot over time, I cut it back a bit and re soldered it so there is no exposed wire
2) the wingdings in the fly back transformer measured ok
3) the focus coil and resistor measure ok


I did notice during operation the shunt regulator had a nice green glow, I assume this is normal, sorry the pic didn't turn out very good
Image


I am reading up on my next steps but welcome any thoughts or advice. I feel like there is a component that is heating up over time and then causing an issue with the horizontal output tube. Could it be as simple as needed to adjust the horizontal output? Would there be enough adjustment to cause the issue I am seeing?
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 Post subject: Re: 1968 Packard Bell CQ-956 Color TV
PostPosted: Oct Tue 13, 2020 2:50 pm 
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You have a heavy load on the horizontal output tube. Are the CRT voltages OK?

One likely suspect is C114; if it is going leaky, the 6BK4 will draw excessive current, and load down the whole HV circuit. The test for regulator current will show if the problem is there.

Monitor the grid voltage of the 6LQ6 as the set warms up. If the negative voltage starts to drop, that indicates a loss of drive from the horizontal oscillator, or leakage in the coupling capacitors C166 and C167.

Another good possibility is a short in the focus transformer L42. Check the windings of that coil, and the flyback, for any signs of overheating. Also, check the HV rectifier socket assembly for any signs of burning or arcing to ground.

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Last edited by Tim Tress on Oct Tue 13, 2020 3:22 pm, edited 1 time in total.

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 Post subject: Re: 1968 Packard Bell CQ-956 Color TV
PostPosted: Oct Tue 13, 2020 3:18 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 385
Since the horizontal output is red plating, you should start be checking the grid voltage on that tube. It looks like it should be -56v. If it's not negative enough, check all of the caps and resistors in the grid circuit. The efficiency coil will also affect the HOT current, but it's unlikely to be far enough off to cause red plating.

It's not a good idea to blindly replace all of the tubes, even with NOS. Most of them were probably fine, and certain ones (mainly tuner and IF) can affect alignment. There's also no guarantee that your NOS tubes were all good, or even really new.

A green glow in the shunt regulator isn't normal, and might mean it's gassey. You may see an orange glow deep inside the tube shaped plate with a dark picture (it's the only tube that should ever red plate).


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 Post subject: Re: 1968 Packard Bell CQ-956 Color TV
PostPosted: Oct Thu 29, 2020 3:51 am 
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Joined: May Sun 18, 2008 3:18 pm
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Location: Sioux Falls, SD
In addition to the above suggested capacitors to replace I checked all of the resistors around the horizontal output/high voltage circuit and found a few to replace. I ordered parts and make the following changes.

  • Replaced the horizontal output tube as I am not sure of it's state now
  • Replaced the HV rectifier as it was gassy
  • Replaced C166, C167, C114
  • Replaced R204
  • Replaced R212, R214, R213 with HV resistors and centered the HV adjust pot, these had measured high which may be why the HV was running high at 26K volts
  • Hooked up meters for testing

I installed the chassis and tried again but unfortunately tripped out the breaker. here are my notes:

  • At no time did the horizontal output tube glow red
  • I had the lights off several times while running and as the HV cage area started to hiss but I could not see any arcing
  • The horizontal output tube current first measured at 235ma so I turned down the horizontal efficiency to bring it just under 225ma
  • On the second try the horizontal output tube current measured at about 125ma, I didn't make any adjustments this time so I am not sure why it was lower
  • On the second try I remembered to hook up my DMM to measure the horizontal output grid voltage on pin 2 & 6, it measured at -56v while the schematic specs only -46v
  • HV measured at 24k volts on the first try and 23K volts on the second try
  • I let the set cool for 30 min and tried a third test, this time the horizontal output tube current measured approx 50ma but had -68v on the grid, adjusting the horizontal efficiency didn't affect anything so I turned the set off and am at a stopping point

As before when testing I could get a steady readable picture, it is still only B/W and blurry. Any thoughts on why the horizontal output grid voltage is running 10+ volts too negative and then got worse. Would this ultimately lead to something overheating and trip the breaker or would the symptoms point to a second issue to fix, I am open to your thoughts.

Further schematics for the above referenced circuits
Image

Image

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 Post subject: Re: 1968 Packard Bell CQ-956 Color TV
PostPosted: Oct Fri 30, 2020 12:30 am 
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Location: Dallas, TX
A couple of thoughts.
Maybe the hissing and the breaker opening are separate issues. Where in the circuits of the TV is the breaker located?
What else could be drawing excessive current?
You might be able to localize the source of the hissing by using a large plastic tubing like a stethoscope. Something like
half an inch diameter, holding one end up to your ear.

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


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 Post subject: Re: 1968 Packard Bell CQ-956 Color TV
PostPosted: Oct Fri 30, 2020 3:47 pm 
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Pull the horizontal output tube and see if the circuit breaker still trips. You could have a B+ short somewhere.

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 Post subject: Re: 1968 Packard Bell CQ-956 Color TV
PostPosted: Nov Tue 03, 2020 1:02 am 
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OP wrote: "I have to turn up the brightness way up to get a good image but then the screen is blurry/fuzzy, I suspect the CRT us nearing the end."



If it were me, and before I would do anything else, I would definitely give the CRT an emission test at the very least. Next, I would certainly check the capacitors in the HV section, and perhaps starting at the horizontal output. In addition, I would look for cold/loose solder joints in the HV section as well, but don't rely entirely on sight alone. Wiggle each component with your finger to verify that it's securely in place.

By the way, that's a sharp looking color tv.


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