[standardtwin]

Hi folks,

Am working on a 42-380. What electrolytic do I buy for the 8-8 #20 in the diagram?. I'm new and don't understand the nomenclature for this particular rating. The others are straightforward.

Has anyone tried the solid state plug in for the 6X5GT tube, that's out on the web and Ebay?. From what I read, it sounds like a reliable fix.

THanks!!

[Arran]

Leave the 6X5 alone, if they were as bad as the chattering classes think on the barking dog forum all of these sets would not have survived until now. Not only have they survived but there are hundreds of sets, manufactured by Philco, Packard Bell, and other makes that employed them and the vast majority still have their original power transformer. In fact I am working on two right now, they are Canadian built Electrohome sets, one has an issue with an inductor but it is not the power transformer, nor is it the filter choke, it's the antenna coil, probably due to a lightning strike. If a set is designed to use a tube rectifier I would stick with the tube rectifier, ready made SS subs can cause all kinds of problems from the B+ being too high to the fact that they are instant on. You can use a SS rectifier but you usually need to make your own using a current limiter and a dropping resistor, many of the ready made ones are often just straight diodes epoxied in a tube base.
With regard to the dual section filter capacitor, I think that you will have to make your own using individual electrolytics. There are some multi section caps still available but they are expensive and the selection is limited. You can have a go at restuffing the original can, or just install the new ones under the chassis someplace, such as on a terminal strip.
Regards
Arran

[GarySP]

If you install electrolytics underneath in the chassis, don't forget to remove the original cap from the circuitry. All kinds of problems will present themselves if you don't. Leave the old cap in, just disconnect it from the radio. Take care, Gary

[Eric T]

I am also currently working on a 42-380. I am replacing the 8-8mfd dual electrolytic with two 10mfd 500V electrolytics. I am replacing the 18mfd electrolytic with a 20mfd 500v electrolytic.

When exact values for capacitors are not economically available, my general rule of thumb is to use the next higher mf value available and match or exceed the voltage rating. These older electronics have pretty high tolerances.

Since the original part is a cardboard tube under the chassis instead of a top mounted metal can, I wouldn't worry about stuffing caps. That is, unless you think someone is going to disassemble the radio to see if you did a good job of restuffing the cardboard tubes.

My radio came with a 6X5GT in it, and the power transformer windings have good resistance readings all around. I think the hullabaloo is more focused on the 6X5G rectifiers. I've not heard anything bad about the 6X5GTs.

[klondike98]

You can find some helpful information for begilnners on recapping at Phil's Old Radios as well as searching the threads on this phorum.

[Arran]

Sometimes I will restuff a cardboard tube electrolytic, even if it is under the chassis, just for neatness of installation. It's very easy to group two or more radial lead electrolytics together, then to add some wire leads for the negative and two positives, a little heat shrink tubing where necessary, and then to wedge it all into an old cardboard capacitor tube followed by hot melt glue.
These days it's harder to find a good selection of good quality electrolytics with axial leads then it does to find radial lead ones, so you can either stuff the radial lead one into an old capacitor can or tube with wire leads, or install a terminal strip to mount them on, again with wire leads. Or if you are lucky find a place under a tube socket, or an existing terminal strip, to install them.
Getting back to the 6X5s, I'm not sure that there really was a problem with the 6X5Gs, the only sets that I have heard of having problems with 6X5Gs or 6X5s of any sort were some of the 1940 brand Z models, particularly the 10 and 12 models that used 6X5s in pairs, and with marginal power transformers, to power things like push pull 6V6s and 6F6s. So was it the 6X5s that were the problem or is it that the Order of the Big Black Dial fanboys don't want to admit the Commander "Used Car Dealer" Macdonald and company came up with a poorly thought out power supply design in the name of tube stuffing a chassis? I've never heard of any problems associated with 6X5GTs at all, though some claim they are equally suspect. In the case of Philco 42-380s I think they used either 41s or 6K6s in the power output stage, which are lower current tubes originally designed for car radio use, and the plate voltages are well bellow the maximums for a 6X5.
Regards
Arran

[Eric T]

Arran, you are right about the 42-380 using push-pull 41s in the audio output stage. The schematic shows their plate voltages at 190V -as you said- well below maximum voltage for the 6X5.

[codefox1]

For a quarter you can get a pair of diodes to perform as rectifiers, and if really needed spend another dollar to tame the B+, and leave the old 6X5 disconnected except for heater burning forever, or remove connections entirely to spare the unneccessary load to the power transformer. The radio won't care, and provided you have replaced properly the capacitors and anything else in the voltage tree, you are just about there! I'd add an appropriate fuse as well if it were to be in my home.

[Arran]

For a quarter you can use a pair of diodes to replace a type 80 as well, but why bother modifying a set that uses such a common rectifier tube?
Regards
Arran