LukeSimon
11-11-2021, 02:09 PM
This thread is to discuss the Portacolor's reliability and robustness. The TV is as simple as a color TV can get, and that gives it an advantage when it comes to reliability: the small number of parts in the simple chassis design means there are few opportunities for failure. However, there are two parts that tend to fail because GE used cheap capacitors and placed one of them in the worst location possible, right next to the hot HOT (Horizontal Output Tube)!
I am talking about the 2 white axial capacitors . Some mistakenly refer to these as ceramic capacitors, and they most definitely are NOT ceramic capacitors because ceramic capacitors are highly reliable and expensive. GE cut costs where ever they could with the Portacolor.
These capacitors are paper capacitors (also known as metal foil), which are inexpensive, but do not age well because they lack the self healing property that is common for many other types of capacitors. When a capacitor dielectric breaks down, leakage current increases, and if a capacitor has self healing, it means the dielectric can automatically repair itself. Without self healing, a capacitor eventually becomes a dead short! See this post (http://www.videokarma.org/showpost.php?p=3235889&postcount=18) for a simple upgrade of the chassis to replace the white axial paper capacitors with white axial metallized polypropylene capacitors, which have the self healing property. The other nice thing is the new capacitors are the same size, shape, and color as the original capacitors, so the chassis looks the same after the upgrade. The new caps look cleaner and newer, but otherwise are "true to original form". I've seen people use radial gumdrop caps to replace these paper caps, and it looks much less true to original form... but I am sure is functional.
http://www.videokarma.org/attachment.php?attachmentid=203625&stc=1&d=1636659060
GE also made a very bad design flaw in their choice of the physical location of the placement of the boosted B+ capacitor. It is right next to and almost touching the highest wattage vacuum tube in the TV! The horizontal output tube is hot, as it is the highest wattage tube in any TV. Tubes run hot to begin with, and the horizontal output tube is the hottest of the bunch. Why put the capacitor next to that?!?!
The boosted B+ capacitor is a paper in oil capacitor, rated at 85 celsius. Around that temperature, the oil starts to boil! This is why in many Portacolors, a waxy goop is all over the place inside the TV (see my picture above). Yes, Portacolors boil their boosted B+ capacitors. Surprisingly, the capacitor will work for some time after its oil starts to leak out, but eventually the loss of oil will accelerate the breakdown of the paper dielectric, resulting in a dead short from boosted B+ to B+.
One way to workaround this terrible placement for the boosted B+ capacitor is shown in the picture above: replace the capacitor with a higher temperature rated capacitor and double the voltage rating. This is the brute force way of solving the design flaw, but there is another way, and GE apparently used it.
GE knew about this design flaw, but even with the release of the final Portacolor chassis, the "HE" chassis, GE was still placing the boosted B+ capacitor right next to the horizontal output tube! Check the Photofacts for the HE chassis and you can see C268 in the lower left corner of the chassis is still right next to that very hot HOT!
http://www.videokarma.org/attachment.php?attachmentid=203627&stc=1&d=1636660644
I was surprised when I got my hands on an HE chassis from 1977 because the boosted B+ capacitor looked like it was missing! See the red circled area in the photo below. After poking the test leads for my capacitance meter into the empty solder holes for the boosted B+ capacitor, it tested as though the capacitor was there! After poking around more, I realized that the boosted B+ capacitor is soldered to a terminal lug that is mounted under the transformer that the blue arrow is pointing at in the photo below. Has anyone else seen this variation in the HE chassis? The additional cost of a terminal lug strip, a screw, and two short wires doesn't seem like much, but GE was stingy! Regardless, it looks like GE finally decided in the last few years of the Portacolor's production, to correct the biggest reliability design flaw in the Portacolor.
http://www.videokarma.org/attachment.php?attachmentid=203624&stc=1&d=1636657951
If you look closely at the picture above, next to the red circle, you can also see that the B+ white axial capacitor, C409, is also missing! That capacitor is in parallel with the high capacitance, electrolytic smoothing capacitors for the B+ power supply. Removing that capacitor increases the high frequency voltage ripple on the B+ supply because electrolytic capacitors are very high ESR compared to other capacitor types, but the TV runs fine without it. I bet for the first several years of the Portacolor, these capacitors did not fail, but after about 10 years, GE started to get lots of people complaining about their TV exploding and so they made two small adjustments to the failure prone capacitors.
I am talking about the 2 white axial capacitors . Some mistakenly refer to these as ceramic capacitors, and they most definitely are NOT ceramic capacitors because ceramic capacitors are highly reliable and expensive. GE cut costs where ever they could with the Portacolor.
These capacitors are paper capacitors (also known as metal foil), which are inexpensive, but do not age well because they lack the self healing property that is common for many other types of capacitors. When a capacitor dielectric breaks down, leakage current increases, and if a capacitor has self healing, it means the dielectric can automatically repair itself. Without self healing, a capacitor eventually becomes a dead short! See this post (http://www.videokarma.org/showpost.php?p=3235889&postcount=18) for a simple upgrade of the chassis to replace the white axial paper capacitors with white axial metallized polypropylene capacitors, which have the self healing property. The other nice thing is the new capacitors are the same size, shape, and color as the original capacitors, so the chassis looks the same after the upgrade. The new caps look cleaner and newer, but otherwise are "true to original form". I've seen people use radial gumdrop caps to replace these paper caps, and it looks much less true to original form... but I am sure is functional.
http://www.videokarma.org/attachment.php?attachmentid=203625&stc=1&d=1636659060
GE also made a very bad design flaw in their choice of the physical location of the placement of the boosted B+ capacitor. It is right next to and almost touching the highest wattage vacuum tube in the TV! The horizontal output tube is hot, as it is the highest wattage tube in any TV. Tubes run hot to begin with, and the horizontal output tube is the hottest of the bunch. Why put the capacitor next to that?!?!
The boosted B+ capacitor is a paper in oil capacitor, rated at 85 celsius. Around that temperature, the oil starts to boil! This is why in many Portacolors, a waxy goop is all over the place inside the TV (see my picture above). Yes, Portacolors boil their boosted B+ capacitors. Surprisingly, the capacitor will work for some time after its oil starts to leak out, but eventually the loss of oil will accelerate the breakdown of the paper dielectric, resulting in a dead short from boosted B+ to B+.
One way to workaround this terrible placement for the boosted B+ capacitor is shown in the picture above: replace the capacitor with a higher temperature rated capacitor and double the voltage rating. This is the brute force way of solving the design flaw, but there is another way, and GE apparently used it.
GE knew about this design flaw, but even with the release of the final Portacolor chassis, the "HE" chassis, GE was still placing the boosted B+ capacitor right next to the horizontal output tube! Check the Photofacts for the HE chassis and you can see C268 in the lower left corner of the chassis is still right next to that very hot HOT!
http://www.videokarma.org/attachment.php?attachmentid=203627&stc=1&d=1636660644
I was surprised when I got my hands on an HE chassis from 1977 because the boosted B+ capacitor looked like it was missing! See the red circled area in the photo below. After poking the test leads for my capacitance meter into the empty solder holes for the boosted B+ capacitor, it tested as though the capacitor was there! After poking around more, I realized that the boosted B+ capacitor is soldered to a terminal lug that is mounted under the transformer that the blue arrow is pointing at in the photo below. Has anyone else seen this variation in the HE chassis? The additional cost of a terminal lug strip, a screw, and two short wires doesn't seem like much, but GE was stingy! Regardless, it looks like GE finally decided in the last few years of the Portacolor's production, to correct the biggest reliability design flaw in the Portacolor.
http://www.videokarma.org/attachment.php?attachmentid=203624&stc=1&d=1636657951
If you look closely at the picture above, next to the red circle, you can also see that the B+ white axial capacitor, C409, is also missing! That capacitor is in parallel with the high capacitance, electrolytic smoothing capacitors for the B+ power supply. Removing that capacitor increases the high frequency voltage ripple on the B+ supply because electrolytic capacitors are very high ESR compared to other capacitor types, but the TV runs fine without it. I bet for the first several years of the Portacolor, these capacitors did not fail, but after about 10 years, GE started to get lots of people complaining about their TV exploding and so they made two small adjustments to the failure prone capacitors.