'53 Packard Bell TV - need advice

[whitekingd]

This beast gets brighter and brighter for the first half hour or so after it is turned on. Do you suppose it's the electrolytic caps? They are the originals. The picture tube was rebuilt about six years ago, but it did the same thing before and after the rebuild.

If I replace the electrolytic caps, will it throw the set out of alignment? Thanks for any advice you can offer!

 

[cadman]

When you first turn it on, does the picture look almost like a photo negative with lights and darks reversed? If you crank the brightness to full does this occur?

 

[whitekingd]

I would have to say no to both questions.
The picture looks fine always, except for the brightness creeping up. I just keep turning it down. However, the other night, it brightened to the point that the brightness control was all the way down, but the picture was still fine.

 

[rp2813]

I'm confident the set needs a re-cap.  What you describe sounds like one or more capacitors are changing in value as the set operates for a while.

 

It's a matter of course with any vintage TV to give it a re-cap.  Once that's done it's often the case that nothing else is needed.  Tubes are rarely the problem.

 

[cfz2882]

bad capacitors

i have had a few bad capacitors with some of my electronics-and some very old
caps still going strong;
what did need to perform capacitor repairs on:
-1937 zenith radio-original filter cap still good so kept it in use for
originality and coolness,but some of the paper caps were"leaky"causing
weak distorted sound.
-1939 western radio-had bad filter cap,bad hum
-1962 stromberg carlson AM/FM tuner-bad filter cap,hum and strange tuning eye
display
-1981 RCA tv-bad filter cap,strange picture!
-2002 desktop computer,bad filter caps(!),would jam every time HD shifted
heads
one on the recap project list-'57 hotpoint portable TV-got it going years
ago with a bad solder joints and bad tube repair,performance is about 60%
but repair of any bad caps along with a weak tube i didn't have at the time
as well as a check and repair of any carbon resistors that have "drifted"
should have it going nicely.
When i do a recap i don't just throw a bag of cheapie junk in the project
device;i always use u.s made sprauge electrolytic caps whenever possible
for u.s.equipment,philips for european stuff.
I always try to use my vintage tube stuff every few months to keep the caps
"filmed"

 

[tolivac]

some things I have seen on electrolytic caps over the years-they last much longer if the equipment they are in is left on.the on-off cycles stress them and the rectifiers.The studio equipment in the places where I work the electrolytics in the console power supplies often last for years or even decades.Consumer equipment is hardest on them since it is usually never left on-allways cycled on and off.If you do have tubed gear or other vintage electronic gear-use it now and then to keep caps "formed".for a lot of tubed gear-replacements are getting harder to find-and beware caps that have been sitting on the parts shelf for years and years-they go bad.If you have a capacitor tester such as an older Sprague"Tele-Ohmike" cap tester you try to form them with that.I have salvaged some that way from caps sitting on shelves here at work.Now the transmitters that used those have been surplused-but some of their spare caps are still here-the caps used in some of the low voltage power supplies that provided plate and screen voltage to the low power stage tubes that were in those older SW sideband transmitters.In some peices of equipment where ease of service is important the caps had octal plug bases like octal tubes.Replacing them was as easy as replacing a tube.Have worked with transmitters and some jukeboxes that had these.

 

[whitekingd]

The Leslie organ speaker also used the "plug - in" electrolytic capacitors. Great design!

Since I'm on a budget, should I start with the electrolytics and see what happens? Or is it more likely the paper/wax caps? Thank you all for responding! I really appreciate the help.

 

[tolivac]

The "Plug in" electrolytics may be hard to find.And as I say before beware of older ones that have been sitting unused for years.In a way electrolytic caps are like batteries-they get their capacitance from electrochemical reactions sort of like a battery.Using them keeps these chemicals and the dielectric layers "formed" thru non use these layers deteriate.

 

[tolivac]

The electrolytic cap is the most likely culprits.However if your equipment is working OK-and well-like no blowing of fuses upon starting,hum or other noises-then maybe its best to leave it alone.No sense in replacing parts that are working.

 

[cfz2882]

gassy rectifier tube

when i was fixing the 1939 "western"radio,its rectifier tube was very gassy
and had a pretty blue nitrogen haze around the plates while in operation-
rectifier was a '61 date code GE tube,later GE tubes seem more prone to this
condition than mid-50s and earlier GE tubes...
The '57 hotpoint portable TV has two selenium rectifiers in a voltage
doubler arrangement and series string tube heaters.
A 1960 portable TV i have has two white ceramic silicon diodes that plug
in like fuses-brand of those diodes was something like"sarkes tarzanion"
A 1942 elecronics book i have has selenium rectifiers in it so those must
been in use at least that early.

 

[cadman]

Anyone running selenium rectifiers in their vintage equipment is best served to switch to a 1n400x diode arrangement. Those rectifiers have a nasty habit of shorting with age and when they do they release gaseous selenium which is poisonous. The new diodes will have less of a voltage drop so consider a series resistor to bring B+ back into check if necessary. -Cory

 

[tolivac]

"gassy rectifier tube"

In some older radios the tube may very well be a mercury vapor rectifier tube-does it have a type#83?the "83" was a full wave mercury vapor rectifier tube.Its normal for them to glow a dull blue color when the equipment is turned on.Bigger cousins of this tube were used in the radio and TV transmitters I worked on.Another thing on mercury tubes-if they are glowing a blue-white color-then too much current is being drawn thru the tube.and you can tell mercury tubes by the splotches of liquid mercury on the sides and bottom of the tube.and of course don't open them.For selenium rectifiers-often called the "smelly sock" diodes-the odor they put out when failed-and yes the vapor is toxic.Sarkes Tarzian made all types of semiconductor devices at one time-and even a 250W TV transmitter driver unit.Worked on one of these-came from Ch#2 Vermillion,SD.Was loaded with the SK diodes in its 600V-1200V main power supply.Had to replace all of them-something like 12 diodes per rectifier leg-a bridge rectifier.48 diodes in all.the old plug in ones.for the selenium diode replacement-1N4004-4006 diodes are good replacement-should give plenty of voltage leeway when run from the 120V powerline.and of course the selenium rects will blow "stinky" when the filter caps go shorted.(electrolytics)and very large selenium rectifiers may be found in battery chargers-the resistence charactoristics of them made the selenium diodes ideal for battery chargers.Then there were the very old chargers that had mercury vapor rectifiers in them-often called "tungar" tubes or bulbs.Tungar was the company that made them.

 

[paulg]

Paper /wax

The chances of this being an electrolytic capacitor issue are slim in my opinion. Usually they fail and stay failed - or drift over years but not normally hours.
The bias voltages at the CRT are key here. Probably there is DC level drift over time.
If you're not into that - check for wax capacitors in the video output circuitry. One is probably leaky which changes the bias to the CRT. Bring out the freeze-spray and hair-dryer! Remember those days?
Actually I had a similar but opposite problem on my 1949 GE. The picture would start bright then go dim, very gradually, over time. The vertical retrace cap (wax) to the CRT cathode was leaky causing a bias change with its DC level of the cathode going up (dark) versus down (bright).
Personally, I think these types of TV problems are fun to fix. I wish I was in your neck of the woods. I'd come over with my VTVM, a bag a caps and we'd be off !

 

[whitekingd]

paulg

Damn! I wish you were closer too. Oh well. I will start looking at those caps and replace what I can afford. I thank you and everyone for the great advice!!

 

[rp2813]

Capacitors don't cost much.  Your biggest investment will be in the time it takes to identify them, determine their values, and replace them.  Doing them all makes the most sense, or you'll be going back into the chassis on a regular basis.  If you can find the SAMS Photofacts for your set and you know how to read it, that should be your first order of business.

 

[tolivac]

Sometimes HV electrolytics may be harder to find-those that have a working voltage of over 450VDC.that is the problem I am facing with recapping my McIntosh MC60 "mono"block amps.They need caps for 550VDC working voltage.So far no luck.I may have to look into using oil-film caps.sort of like electrolytics-but use plastic film in a mineral oil dielectric fluid-transmitters use these.they are bulkier and more expensive than electrolytics-but can last much longer.Oil film caps can be used in power supplies up to and including 30KVDC.and these caps can be dangerous-electrolytics can lose their charges due to deielectric leakage-oil ones do not.You have to keep the terminals of oil caps shorted to prevent a charge from building up on them.On high voltage-high value ones the charge can kill you!for these guys-in the transmitters I operate and repair-your grounding hook is your BEST freind!!

 

[cfz2882]

capacitors

true,even the best quality capacitors are not that expensive-maybe $10-12
for big filter caps-AFAIK,the chassis mount"can"capacitors are not avalible
recently manufactured but modern caps are much smaller so you can leave the
chassis mount multi-section filter caps in place disconnected with seperate
axial lead caps secured nearby and wired in.
Tolivac-the rectifier tube with the blue haze was a 5y3,but i will keep my
eyeout for a #83 on my oldies-sounds like a neat tube.In a 1910 book on
electric cars,one of the chargers had a big mercury vapor rectifier tube
that had a central"chimmney"through it so a cooling updraft would develop
when the tube got hot-really cool looking tube!For early metallic rectifiers
i have some early,pre ww2,equipment with copper oxide rectifiers-look like
selenium,but much lower voltage handling per plate-about 3volts instead of
about 25v per plate with selenium.

 

[tolivac]

If the tube was a 5Y3-that is a HiVacuum rectifier-if the tube was glowing--yes,its bad.Replace it before it takes out the equipments power transformer.-or at least blows the equipments primary fuse.Beleive it or not for some "Hi End"-Hi Fi equipment is going back to using mercury vapor rectifier tubes-these are expensive and hard to find-I know-trying to get replacements for transmitters-the solid state replacement "tubes" are easier and less expensive to find.but they don't have that neat glow!Oh yes Copper Oxide rectifiers were used like selenium and look like them.another popular battery charger diode.Copper oxide devices can also be found to be used as early surge protector devices.They would blow when a surge was encountered and then blow the equipments primary power fuse to prevent further damage.However back to the TV mentioned before-I do beleive its the small value coupler or RF bypass caps that may be causing its problems.as other posters suggest--get the values the circuit calls for-warm up the soldering iron--and replace them!Have to do this with old amps-but be careful with the TV IF strips-these are probably still working.Its the caps in the audio,video,and sweep circuits that would be of concern.If you do replace caps or any other parts in the video,audio IF strips realaignment of them would be required.If the set is getting signals-the IF stages are probably fine-leave those alone.Remember if you are going to use the set with present broadcast sources(digital) you will need a convertor.and for use with a DVD player-a modulator-older sets didn't have dedicated video inputs.

 

[paulg]

McIntosh Monoblock

I too have a McIntosh on the bench. Didn't get too far with the repairs as I am so busy. MC75.
And NO. I will never sell it.. ever. Sentimental value.
But I will buy another if someone comes up with one.

Oh, my advice was a bit off before.
To fix the set I would need my VTVM, a bag of caps and a POT OF COFFEE. Then we would be good to go.
No coffee, no fixee.