6x5 rectifier tube
 

the 6x5 rectifier is a full wave rectifier so im wondering if this tube goes bad can it be replaced with a resistor for the heater if its in a series string set and placing 2 diodes in place. this tube is from a teletone tv 208 and it also has a 25z6 positive i think half wave and i know 1 diode can be used in that place with IIRC a 50 ohm resistor for the heater. please correct me if im wrong.

I would leave the tube in place, and disconnect the plates, and bypass it with a pair of diodes, maybe with some series resistance added to each one. This way--the tube is still there--and LOOKS like it is working--but is bypassed.

I drew a diagram of that very thing for a Zenith radio.

6X5 in a Teletone 208? where? I don't see it on the schematic:

http://www.earlytelevision.org/pdf/T...Sams-90-11.pdf

:scratch2:
jr

Yes teletone 208 but the schematic shows a ballast tube in place of the 6x5 is that I have on this set. Maybe the schematic is an early one with the ballast and mine a later.

Possibly the other way around! The later production set probably uses the ballast tube. :scratch2:

Timmy most have a very early production set, 1st run tv-208's were a tv-149 in the suitcase housing. The tv-149 does have the 6X5 in the circuit. All the best, Tom

Interesting! Does the set work with a 6X5 in that position? :scratch2:

jr

If you want to replace the 6X5 (the easy way) with a solid state replacement here is a link to one that you just plug in.

http://www.tedweber.com/wx5

Trouble with those tube's is that they are known for heater to cathode shorts, and when they short it takes out the power transformer. Also Using diodes and resistors should work as well, but you might want to leave the filament in circuit for appearance. Not sure what value resistors are needed as I would assume it depends on the current draw of the radio.

Wow! How did they make that fit? Never have seen one... could you post a few pictures of this rare beast?

jr

Ok jr tech I was not very clear on my comment. 1st run 208 used the 149 circuits, 2ed run and later use the circuits you see in Riders and Sams. Hope I made myself more clear on this. I worked on 1 or 2 of run 1 tv-208 but don't own 1 do own a run 2 set. All the best,Tom

The 6x5 is in the exact spot where the other run chassis has the ballast. So I'll have to keep in mind that these tubes are known for heater cathode shorts and there is no power transformer to worry about cooking in the event the tube goes bad. What ohms would be ideal to replace the heater loads on the 25z6 and 6x5 tubes, would 15 ohms 10 watt for the 6x5 and 50 ohms 10 watt for the 25z6 be close ?

Not real close... R=E/I

for the 6X5, I get R= 6.3 volt / 0.6 amp. so R = 10.5 ohms. 15 ohms is a little high, but with todays higher power line voltages will likely work ok.

for the 25Z6 I get R= 25 volt / O.3 amp , so R = 83 ohms. I would not use a 50 ohm resistor there.

10 watt resistors should be adequate.

jr

Well ok but again with the higher line voltages I may try a 100 ohm resistor should I need to for the 25z6 . So I guess it's safe to say that any 25 volt tube that resistance should apply to all. What's odd about this teletone is the schematic for the tv208 is identical to the set I have but there is a lot that's different between the SAMs and what I have . Early television only has the SAMs I have but clearly it is very different , the ballast I don't have and the amount of power supply caps, I only have half the caps that the SAMs shows so there must be an early and late and the tv 149 is totally different then what I have which is what the SAMs shows from early television.

Could somebody post a schematic of the circuit area where the 6X5 is used?

Looks like you could use an adapter to go from an octal socket to a 7 pin and use a 6X4.

Not sure anyone has one but the picture of the set in the SAMs under teletone tv208 in early television is what I have but like I said it's clearly different. I would like to see the right schematic for this set too.

Well if they did use the circuit of the TV-149 in the 208, it should be something like this:

http://www.earlytelevision.org/pdf/T...Sams-56-22.pdf

Perhaps Timmy could trace out the circuit around the 6X5 and 25Z6 and draw a schematic showing how the power supply is wired. Again I ask, does the set actually work or at least do the filaments light up with the 6X5 installed?

jr

No it's not working yet I'm in the process of recapping so if there are any problems later I'm sure I won't be able to rely on the schematic that's out there now. I was just looking into these tubes because they are the source of b+ along with one selenium which will be replaced with a 1n4007 diode later. And now he reign that the 6x5 is known for cathode shorts so there is nothing like a reliable silicon diode and maybe leave the tube in for show, long as it still lights. This is just in case later on I will have this info to do if I could not obtain these tubes. Kind of a backup plan, alternate.

I was puzzled over the references to the 6X5 being "used as a ballast". Does that mean the diodes are paralleled and used in lieu of a nichrome wire dropper tube? :saywhat:

I don't think that anybody indicated that the tube was actually used as a ballast, only that it occupied the same socket location as was occupied by the ballast in later sets. :scratch2:
I would love to see a schematic for the set that Timmy has, but very likely the schematic is close/same as that of the TV-149, which has an 80 ohm dropping resistor in the heater circuit and also a selenium rectifer as well as the 25Z6 and 6X5.

jr

Well I looked at the tv149 schematic and it's different as it has 2 - 25z6 tubes and mine only one so I can't go by that schematic should I need to.

:scratch2: I hope this means your intentions are to get this set working perfectly in it's original configuration , and then when it's working perfectly as designed you will consider any modifications ? Restored correctly , the circuit will function as it's manufacturer intended , and that should be the baseline from where any modifications to the power supply are considered .

Myself , I'd restore it to what I'd call 99.5% original , I'd leave all the tube circuits alone modification wise and use a modern diode (with resistor) in place of the Selenium (which would remain on the chassis but with both of it's wires run to a terminal strip)

As you've already noted , this set has no power transformer to roast , so there really is no need to play "hot potato" with the 6X5 here .

Yes I always restore what was there originally including tubes however if a specific tube was not available I would like another option in place to replace a tube if possible which in this case I can do so if needed. And it's possible to just use a modern diode without a resistor because what I sometimes do is the resistor in series with ac I will up the ohms for both the diode, increased voltage which is only a few volts and also the increase in line voltage which seems to vary from area to area. The aim here for me is to always get a set working the way it was intended and what annoys me because it always has to be perfect while I don't consider myself a perfectionist , I want it right, even down to the flow of solder, it don't look right I do it again. :yes:

The TV-149 schematic that I linked to shows only one 25Z6 but each section of it is drawn as a separate 1/2 tube. Is that what you are counting as two tubes?

jr

Yes you are right it is shown in 2 sections but one tube but this is definitely not the same schematic for the set I have since the 149 is one a piece chassis and mine is a 2 piece chassis. Even the power supply caps are different.

Just for S&G's, look up the schematic for the early model, Hallicrafters T54. The power supply circuit looks very similar, including the resistor values.
The Sams for one of those models, shows the electrolytics drawn with the wrong polarity. :thumbsdn:
BTW, what's so bad with the newer issue 6X5's. I'd leave it as-is. :scratch2:

I really need the right schematic because there are resistors that don't have colors and I need to know the right value, they are bad.

Could you draw out a schematic of how the components in the circuit are connected and post it here? Perhaps we can back-enginner the circuit and figure out what the resistor values should be. :scratch2:

jr

SAMs photofact
 

I'm still looking desperately for what I believe is the right SAMs for a teletone 208 r because the 208 and the 208 tr have a ballast but mine don't. There are 2 SAMs that I know of, 90-11 and 95-6 both are not mine but I don't know the SAMs number for the 208r . Mine has the round plug that connects both chassis together like the tr and the tr also has the round plug. The 208 has the square plug and a ballast, the 208 tr has the round plug and a ballast, the 208 has the round plug and NO ballast. Does anyone have this print ?

There is no separate listing for the 208R, only the TV208 and the TV208TR. Have you looked at both Sams? If not, I should have both.

I've got a pristine folder 95-6 if you still need it.

Cheers,

I didn't actually look at the 208 tr but the 208 I did . I read a post on antique radio I think it was and someone there had the same problem with or without the ballast. Well maybe it is the 208 tr until I could see some of it I will know. If someone could show me a part of it I will know if it's the one, thanks

Your set is probably wired for the ballast. I've seen it a bunch of times some tubes and or ballasts fail, the owner pulls the tubes to test looses them and years later some dope randomly sticks any old tubes in the sockets hoping to make it look better or work. Pull the chassis and carefully compare to both versions.

This has a 6x5 in the place where the ballast would be and it has 2 resistors wired in and they are old original and they are the ones that are in the ballast in the other set that has one. Besides mine has 2 12sn7 for vert amp and multi the other 208 has a 6sl7 . But overall I recapped it and has great sound and picture from the little I can see the vert height or size there is only one pot is maxed and it's only about 2 inches it won't fill the screen. So I need the SAMs to check voltages to see what's going on in the verticle, it would help as now Im done aside from checking resistors which I did changed a few in the verticle and it improved very little.

It's vertical!

Well all the crazy things about these teletone tvs I had pulled a 6sl7 out of the vert amp but the tube lineup on the cabinet showed a 12sn7 belongs there so again there are so many differences with these because I put the 6sl7 back in and the verticle is fixed. So maybe it is infact a 208tr but without the ballast.

Does anyone know if there is a retrace mod out there for the teletone 208 tr. most pin 3 of the 7jp4 go to ground but the teletone goes to DC restoration.

I need to find the values for the Micas in the verticle and the 208 don't show what I have and the 149 shows Micas but Alittle different wiring and shows 5000 pf but I can't be sure if this is the correct value or not. Maybe the 208tr is the one I'm looking for, would anyone post the 208tr or sell me a print but I would like to know if this is what I need for sure.

The value of the micas are most likely right. If you don't know how to read them here are 2 sites you can get info on how to read them. http://radioremembered.org/capcode.htm and http:www.tpub.com/neets/book2/3g.htm there were 2 other sites but they are now porno! All the best, Tom