Packard Bell 17VT1
 

Subject: CRT Testing

I would never have thought of acquiring this set, but a friend (I’ll call him Philo) rescued it from someone who was putting it out with the garbage. He plugged it in and the screen lit up, so he shipped it to me. For free, I’ll try to put the set in working order. Philo will get a kick out of that.

I’ve pulled the chassis, and all the parts are there. The only shipping damage is one broken tube and a broken escutcheon, both easily repaired or replaced. And the yoke is loose on the CRT neck.

My next step will be to check continuities to ensure other significant components aren’t dead. I’ve tested the tubes, including the CRT.

I’d like an experienced person to assess my test results on the 17AVP4. With a Beltron 8080A, 6.3 heater volts:

No shorts.
Ten seconds to reach 0.45mA.
After four minutes, it reaches 0.55mA or maybe 0.65mA.
Interrupt: Current immediately decreases, reaching almost zero in seven seconds.

https://c1.staticflickr.com/5/4213/3...48a1377d_z.jpg

So, before I spend any time on this set, what can I expect from the CRT?

Thanks all,
Henry

How long did you have thee CRT running on the tester ? I like to leave them run 30 minutes to a couple hours to "wake" them up. Often emissions, cutoff and life test will improve.

Thanks. I only ran it five or ten minutes. I'll run it for a couple of hours this afternoon and see what I get.

I checked the heater voltage from the 8080A. It was probably 6.7 volts for the previous test. I adjusted it to 6.3 volts and ran it for 90 minutes. This time it took about 2 minutes to peak at barely over 0.2 mA, then slowly decreased to 0.15 mA where it stayed for the entire test period--then dropped to less than 0.05 mA in a few seconds.

Entirely hopeless? Even if it's hopeless I'm going to play with the restorer just to see if the meter and indicator lights work.

After you let it "cook" for a while, if it's still really weak, you can also try running it at, say, 8V for 10 minutes, then put it back down to 6.3 and test it again. Has worked for me. Only time I tried "restore" was on a Trinitron, and it made it much worse, rather than better.

I left the instrument on for several hours and tried increasing the voltage for 10 minutes, but had little change in subsequent test results. Then I ran the restoration procedure one time. After that the test meter rose promptly to .85mA, the minimum "good" result. When the voltage is cut, it only held that current for two or three seconds. I repeated the test two days later with the same outcome. So, I'll proceed with the electronic restoration and hope for the best.

Since you've got the Beltron, run a clean cycle on the tube. Won't hurt a thing and it's very likely to bring that tube right back, even without running a full restore cycle on it. I just can't say enough about Beltrons. :banana:

After reviewing my personal notes and retrieving deleted email, I now recall that I ran a cleaning cycle first without even a flicker of the lights, then did one restore cycle. That's my story and I'm sticking to it!

That is normal. Do you have any idea how many tubes you'd need to clean at once to make all the lights in your house flicker? :D

If you knew me better, you’d realize that I might take down the entire power grid by changing the batteries in a flashlight. (Just ask my wife what happened the first time I tried to fix a toilet.)

Starting on the Packard Bell 1956, 17-inch, B/W.
 

Well, it only took me six months to get back to this. I did a quick repair on the escutcheon and reassembled it for photos.

https://farm5.staticflickr.com/4703/...5b342fb5_z.jpg

.
. It's a 1956 Packard Bell 17VT1--a cube with a rectangular CRT in front, knobs on one side, and a simulated wood finish. Chassis V8-1.

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Before I pull the chassis again, I have an opening question:

Should I pull the CRT first to start the chassis work?

Thanks,
Henry

Henry, it would certainly make life easier. But the question is are you up to reinstalling the CRT and all that goes with it?

Your call...

Thanks. Did that last night. Only had to cut six (clearly colored) leads from the yoke. Yoke, ion trap, etc. stays on the neck. The yoke is loose anyway.
- Henry (formerly of Indian Head, Silver Spring, Baltimore, Columbia, and Frederick)

Sometimes if the yoke does not slide off easily over the base cap, a little gentle heat from a hairdrier is helpful.

jr

kvflyer, AKA Don Cavey. Worked C&P Telephone, Columbia, Arbutus, Cockeysville, Manor, Essex, etc. Now retired in for 15 years ... Fernandina Beach, Florida! No snow to shovel.

Wrapping a thin card stock shim around the glass over the bakelite base can also help.

Done That Already
 

Removing the CRT with the accoutrements attached was simple. Aquadag coating (or whatever) looks intact.

https://farm5.staticflickr.com/4721/...241da678_z.jpg

Cleaned up the chassis a bit, and now I'm checking continuities through all coils. The yoke checks out OK.


https://farm5.staticflickr.com/4620/...b11e86a3_c.jpg

A Little More Help, Please
 

Below is a photo of the wiring of one of the 'lytics. It appears to be factory-wired, but I can't reconcile it with the Sams schematic, parts list, and the info stamped on the can.

https://farm5.staticflickr.com/4704/...efa7ca2c_c.jpg

So, please tell me that I'm reading it wrong or, if the schematic and the wiring disagree, which I should do--follow the schematic or duplicate what's already there.

Thanks,
Henry.

The schematic is wrong!
The 6AS5 audio output tube is used a voltage divider as well. The voltages shown are way off. The voltage on the cathode should be at least 100 volts or more.
Just wire it the way you find it! It worked before! :scratch2:

Thank you. I'll proceed as advised and I'll keep in mind the voltage discrepancies when I get there.

The plate and the screen should read the full B+ of the set, 250 to 280 volts or so. The cathode should read 110 volts or so, to supply the IF and a few other circuits.

The "half-circle" symbol next to the voltage readings indicate that these particular voltage readings are referenced to another point other than chassis ground.

I don't know where they referenced from, as all the components are going to chassis ground! :scratch2:

Moving Forward
 

Regarding the Sams 6AS5 schematic error, I got the Rider schematic, and it shows the correct wiring and voltages. The voltage shown on the Sams schematic are measured from a 110 volt line, so that explains why they're all about 110 volts too low.

https://farm5.staticflickr.com/4665/...af4171595b.jpg

I'll be ready to power up the set in a few days. My concern is how to set up the CRT off the chassis. I can't imagine trying to check voltages with the CRT mounted on the chassis. I made a connector for the yoke wiring from an octal base and socket. It has plenty of extra length, but it'll be easy to shorten it. The solder connections are insulated with 1/4-inch irrigation tubing which fits snugly but slides on and off easily.

https://farm5.staticflickr.com/4757/...7b242625_z.jpg

The limiting factor is the six-inch high voltage line. I have some cable rated 40 kilovolts. The CRT is 15 kilovolts. Is it feasible and safe to splice 14 inches of that to extend the original 6-inch cable?

Temporarily extending the EHT lead won't be a problem. Just insulate it well. In Aus we had a set with a similar layout (Thorn Atlas) and that's how I used to work on them. You will also need to arrange a connection from the aquadag to the chassis. By the way I noticed the exhaust tip on one of the tubes in the tuner has been knocked off and the getter is white.

Just a quick note to say your photography in this thread is outstanding, I wish I could take pictures like that!

It sure is. Care to share what camera you used?

I have a Nikon Coolpix P610. My photography secret is having no particular skill, but abundant time and patience. I may take 10 or 20 exposures for a single shot, varying the angle and lighting (flash; incandescent; LED; flash plus incandescent; etc.) Then I manipulate the jpegs (color saturation, intensity, gamma, brightness, etc.) and remove whatever I don't want in the picture--such as distracting background. Then if I don't have what I want, I start over.

Strange Little Capacitors
 

Thanks for the advice on managing the CRT, especially the reminder to chassis-ground the aquadag. I'll also have to make a simple wooden cradle for the CRT to hold it steady and keep it from rocking back onto the neck.


I disassembled the tuner--that is, I took out the drum to access the caps and resistors. I could have skipped this step because even though some resistors are slightly outside the specs, I'm not going to replace them.

What's new to me is the capacitors used for wires going through the metal chassis into the tuner. I have a vague notion that the current passing the metal wall creates mysterious electromagnetic radiation which is suppressed by the mysterious capacitors. I took one apart, and I still can't see how they're constructed.

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I'm asking about this because I need to know how to replace the one I destroyed--or it I need to replace it at all.

Also, while I'm here, I've been meaning to ask about this for years--what kind of capacitor is this little guy. It's 4.7pF (I wrote "27" because it's C27). My tester is only reliable down to about 10pF, so I never know what to do with them.

https://farm5.staticflickr.com/4711/...74cd10373e.jpg

Thanks for the help,
Henry.

TIP: Unless you are good at TV sweep alignment NEVER touch pf rated caps or the feedthrough caps on the tuner (unless you have a darn good reason to suspect they are bad)...Doing so can screw up the alignment.

When you say destroyed the feed through cap do you mean cracked the dialectric ? If so just leave it alone as long as it's not shorting to ground. I've never replaced one or seen one that needed replacing but I've seen a few that have been cracked but caused no noticeable issue. I think you would cause much more damage trying to replace it. Tread very carefully around the tuner and IF strip. Small value ceramic and styroseal caps are generally very reliable. A full IF alignment is not for the faint hearted.

No Sharp Points?
 

First, regarding the feed-though cap: When I say "destroyed," I mean it. Fortunately, I studied sweep alignment for two years at the Sorbonne. Unfortunately, this is not a French television set. But seriously, there's no need to despair. I want to get rid of this set as soon as I'm finished playing with it. The only way I can fail is by not doing anything at all. So, the project proceeds regardless of the outcome.

No Sharp Points?

I have a healthy degree of anxiety about high voltages. Somewhere in the Sams and Rider information there's a note to avoid sharp points in solder joints on high voltage lines. I'm not sure why, but I copied the original bulky, rounded connection to the base of the HV rectifier. What might happen if there was a sharp point? I also made the high voltage cable a foot longer (temporary) with plenty of insulation at the connection.

https://farm5.staticflickr.com/4676/...af5564f074.jpg

I envisioned a wooden cradle to keep the CRT securely positioned, but I found a more practical option.

https://farm5.staticflickr.com/4610/...3a87e563b7.jpg

I found one glitch in the tuner (besides the feed-through cap). There's no connection to the plate of the 6BC5. The circuit is open somewhere in the area shown below.

https://farm5.staticflickr.com/4663/...f26e1b32ee.jpg

I was getting inconsistent resistance readings in this circuit for days until I found one defective solder joint. After repairing it, there was still no connection to the coil or 110V line.

https://farm5.staticflickr.com/4653/...067b0ff717.jpg

https://farm5.staticflickr.com/4705/...ea263e50be.jpg

The open circuit must be between the two left contact strips in the picture, but the coil and connection are neither accessible nor visible.

https://farm5.staticflickr.com/4740/...ea8f30bf0f.jpg

It looks to me that if I can remove the single rivet, that the yellow plastic mount will slide off of the contact strips, and I'll have access to whatever is hiding behind it.

Before I attempt this, does anyone have a better suggestion?

Thanks,
Henry "The Destroyer of Caps."

I can't answer your tuner questions, but regarding rounded solder joints in high-voltage areas, spiky joints could encourage corona discharge (https://en.wikipedia.org/wiki/Corona_discharge), which may lead in turn to high-voltage arcing & sparks (never a good thing).

That CRT cradle is ingenious! More secure than my usual teetering pile of old bath towel or foam bits.

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

Thanks, Phil. I probably would have done the bath towels if I'd thought of it.
Do you have any thoughts on compensating or replacing a missing feed-though capacitor? It's in the 6.3V line into the tuner.

Non critical, just stuff the heater wire through the hole... perhaps bypass with a .001 (or so) cap to ground where the wire enters the hole.

jr

No Surprises Behind the Yellow Thing
 

Thanks for the suggestion on the missing capacitor.
I was wrong about sliding the yellow plastic thing off the contacts--the hidden ends of the contacts are anchored to the plastic.

https://farm5.staticflickr.com/4608/...b36fedf9c6.jpg

I don't know what I expected to find back there, but I didn't find it. There were no hidden surprises. So I stuck it back together. Next thing is to reassemble the parts and run some electricity through the set.

Well, Duh!
 

After reassembling the tuner, I finally found the missing connection and coil.

https://farm5.staticflickr.com/4752/...ea574ccff9.jpg

Will Wonders Never Cease?
 

Will wonders never cease? I got all the parts in the right places, and it works with a DVD player. I positioned the yoke retainer, yoke, and ion trap according to the dirty/clean lines on the neck, and the centering magnets according to my earliest photos. Beyond that I only had to adjust the outside controls and figure out that the DVD input plays on channel 13.

This is my setup: Isolation transformer, variac, chassis, CRT, mirror. A couple of questions on this photo.
1. This doesn't have a rubber cup guarding the anode connection. Is this unusual?
2. What is this chain for?

https://farm5.staticflickr.com/4723/...09ed9b62c5.jpg

I posted a short video on Flickr. It only works for me when I start my computer. Then, after one or two plays it won't work until I restart the computer. Maybe it'll work for you.

https://flic.kr/p/23KQVaY

I took a couple of screen shots this morning.

https://farm5.staticflickr.com/4669/...1d7d087ecf.jpg

https://farm5.staticflickr.com/4774/...d3295bd6f4.jpg

I'll try connecting an antenna, but as it stands this is a gratifying success for me. Thanks for all the help that made it work. If you can guess both films you get extra credit.

Congratulations! :thmbsp:

At that point in time, rubber cups were deemed an unnecessary expense in many monochrome sets.

Is there a place on the hv cage cover to attach the other end of the chain?

Video works fine on my iPad.

jr

I should've mentioned that it is attached to the HV cover.