New proect! 1953 Hoffman Television Super Receiver Mark V Tv Phono Radio Console

[Yamamaya42]

turntable now working.

was in pieces when i got it.

https://i.imgur.com/oQpJZgJ.jpg
https://i.imgur.com/l6wpJFo.jpg

the Shure Crystal cartridge in there was quite deaf, and i was NOT about to pay $100+ for a replacement for something that would be rarely used, this is just for looks, eye candy, so I got a CHEAP ceramic one ($10) and glued it in place!
https://www.youtube.com/watch?v=XZ4fX4Akdxo

[Yamamaya42]

https://www.youtube.com/watch?v=L6A0UguQTV4

All done, for now, radio (FM) & Phonograph working, AM still a bit weird, but that will almost never be used.
Sensitivity and accuracy of the FM is impressive for something this old.
However, as mentioned the performance of the 6V6 outputs is rather sad, but not surprising, seeing that in this configuration it's rated at 14W max @ like 5-10% distortion? And that I'm sure would be with tubes in excellent condition, which I do NOT have.
May be able to get SOME improvement by a NOS phase inverter (6SN7GT) & MP6V6, but most likely not worth it at this point for something that will be used mostly for TV sound.

Speaking of which, the next phase of all this is trying to clear up the video on the TV by IF alignment, no easy task, with just a voltmeter and a digital RFfrequency generator.

[Yamamaya42]

https://youtu.be/DMDs4f7zv9M

all together now!

[Yamamaya42]

As you can see, the set is pretty close to done, just a few minor things to do to it left.

I decided NOT to attempt an IF alignment on it after seeing the video was cleaner on CH4 than 3, and may even be better on higher channels, and chances were 50/50 of making it worse/better w/o correct equipment, as sweep marker generators for 45.75mhz are sill around, but 25.5mhz is almost, but not quite unobtainium.
The picture it produces now is pretty good for it's age, just some slight ringing seen in it, not TOO bad, if I wanted it any better at this point, I'd have to make up a video amp and boost the composite input to 5v P2P, and right now, it's not really worth it.

All that remains to be done now is to replace the asbestos DEATH sheet heat shield that was above the AMP/Radio unit, that thing puts out a HECK of a lot of heat, perhaps add a fan to it, add a secondary grounding wire between all the chassis units, and add a master power strip, I don't like how it was all originally daisy chained.

[vortalexfan]

Originally Posted by Yamamaya42

As you can see, the set is pretty close to done, just a few minor things to do to it left.

I decided NOT to attempt an IF alignment on it after seeing the video was cleaner on CH4 than 3, and may even be better on higher channels, and chances were 50/50 of making it worse/better w/o correct equipment, as sweep marker generators for 45.75mhz are sill around, but 25.5mhz is almost, but not quite unobtainium.
The picture it produces now is pretty good for it's age, just some slight ringing seen in it, not TOO bad, if I wanted it any better at this point, I'd have to make up a video amp and boost the composite input to 5v P2P, and right now, it's not really worth it.

All that remains to be done now is to replace the asbestos DEATH sheet heat shield that was above the AMP/Radio unit, that thing puts out a HECK of a lot of heat, perhaps add a fan to it, add a secondary grounding wire between all the chassis units, and add a master power strip, I don't like how it was all originally daisy chained.

On most of the radios I've worked on that had a sheet of asbestos in the cabinet as a heat shield, I usually just leave it be if its still in good shape (which is usually the case 95% of the time on the radios I've worked on) because they say that as long as the asbestos isn't disturbed or flaking then you're ok to leave it in place, otherwise if its been disturbed, damaged or otherwise compromised then that's when you have to remove it.

As for disposal I don't know what the rules are for where you live, but where I live usually you just take the asbestos put it into a plastic bag and seal it up like you would any other garbage bag and then throw it in the trash dumpster, or take it to your local sanitary landfill to dispose of it.

Anyways I'm glad you got it up and running.

[Yamamaya42]

Originally Posted by vortalexfan

On most of the radios I've worked on that had a sheet of asbestos in the cabinet as a heat shield, I usually just leave it be if its still in good shape (which is usually the case 95% of the time on the radios I've worked on) because they say that as long as the asbestos isn't disturbed or flaking then you're ok to leave it in place, otherwise if its been disturbed, damaged or otherwise compromised then that's when you have to remove it.

As for disposal I don't know what the rules are for where you live, but where I live usually you just take the asbestos put it into a plastic bag and seal it up like you would any other garbage bag and then throw it in the trash dumpster, or take it to your local sanitary landfill to dispose of it.

Anyways I'm glad you got it up and running.

https://i.imgur.com/N4jmIbB.jpg

it clearly was NOT in good shape!

[Yamamaya42]

side by side!

https://www.youtube.com/watch?v=BLFuTNtgOm4

[Jeffhs]

Originally Posted by Yamamaya42

side by side!

https://www.youtube.com/watch?v=BLFuTNtgOm4

I just saw this post and am glad you are getting that 1953 Hoffman TV working. The only thing I would be concerned about is the fact that the picture does not fill the screen, due to the difference in aspect ratio. On a modern, flat screen TV this wouldn't be a problem, but with a TV which was made long before HDTV, any image having a 16:9 aspect ratio will produce a picture similar to a 4:3 TV with insufficient vertical sweep. This could and likely will cause screen burns at the top and bottom of the screen; of course, these screen burns will damage the tube in a short period of time. I would be very careful about this, as I don't know if replacements for the CRTs in either TV (or any CRT TV, for that matter) are even available any longer.

I don't know where you are getting the images you are displaying on your Hoffman combo and the other TV shown in your post but I would suggest, if you are using a DVD player, setting the device to "zoom" so the image will in fact fill the screen. This will prevent screen burns and, again, certain damage to a CRT which may or may not be available any longer, as I mentioned above.

[init4fun]

Originally Posted by Jeffhs

This could and likely will cause screen burns at the top and bottom of the screen; of course, these screen burns will damage the tube in a short period of time.

Um, , , , nope, ya got it backwards

Since the top and bottom of the screen are NOT being illuminated, how in the Hell could the phosphors there be burned? If anything, it would be the middle area of the screen which IS being illuminated that would see degradation of the phosphors that the top & bottom wouldn't, but not at the doom & gloom rate that your trying to convey here

[Yamamaya42]

Originally Posted by Jeffhs

I just saw this post and am glad you are getting that 1953 Hoffman TV working. The only thing I would be concerned about is the fact that the picture does not fill the screen, due to the difference in aspect ratio. On a modern, flat screen TV this wouldn't be a problem, but with a TV which was made long before HDTV, any image having a 16:9 aspect ratio will produce a picture similar to a 4:3 TV with insufficient vertical sweep. This could and likely will cause screen burns at the top and bottom of the screen; of course, these screen burns will damage the tube in a short period of time. I would be very careful about this, as I don't know if replacements for the CRTs in either TV (or any CRT TV, for that matter) are even available any longer.

I don't know where you are getting the images you are displaying on your Hoffman combo and the other TV shown in your post but I would suggest, if you are using a DVD player, setting the device to "zoom" so the image will in fact fill the screen. This will prevent screen burns and, again, certain damage to a CRT which may or may not be available any longer, as I mentioned above.

that is an automatic "feature" of the cable box that is being used to feed all the TVs i have, when it goes from a HDTV source, it does an automatic letterbox mode if the source was NOT hd, then it would fill the screen, the risk of any kind of burn in is very very small, as the full screen is still being scanned, and would have to be run in letterbox mode for many hours to have any bad effect.

[Yamamaya42]

Still not happy with the way the amp in the radio sounds, just distorts too easily.
YES, it's only about 10w max if even that, but dang, it sounds rough.
But before I go investing in a pair of $55+ audiophile 6V6GT outputs, or a new Hammond 1609a output transformer to replace the old one that may/may not be damaged, ($100+), gonna spend $20 to update what's already done.
https://i.imgur.com/hDSVECe.jpg

As said before, the 5U4 is out of the circuit and replaced with silicon diodes, the secondary is now tapped at 300vac , r 160 was replaced with a 600 ohm resistor.
The 20uf (450v) caps were replaced with 22uf @ 450v, although I saw no sign of ripple, I am upgrading caps at A & B to 39uf, the paper caps that were replaced, C148,149,150,151, all came from a kit, cheap, but I never had a problem with them so far.
They came in 2 volt ranges, 400v & 650v, the .001s were in the correct range, the .022 was not, so right now there are 2 400v .047s in series, (0.0235), not sure if this matters much at all, BUT, I'm gonna replace all 4 of them again with precision Panasonic caps 5%.
I only found 1 bad resistor, r157, aside from the burned up r158, both of which are new, but I'm also replacing all the 20% 470k 47k ones with 2%, even though they checked OK while I have it apart again.
I really have no idea if this will make any difference or not, It's a Mystery, Charlie Brown!

[nasadowsk]

If you have a two channel scope, try connecting to the grids of the output tubes, and invert the one input. That might reveal a bad phase inverter section (try at low, and distorting volume, with a freq generator.

Also, I once fed an output transformer from the speaker end and looked at the playes (obviously, power OFF).

Something to think about

[vortalexfan]

Originally Posted by Yamamaya42

Still not happy with the way the amp in the radio sounds, just distorts too easily.
YES, it's only about 10w max if even that, but dang, it sounds rough.
But before I go investing in a pair of $55+ audiophile 6V6GT outputs, or a new Hammond 1609a output transformer to replace the old one that may/may not be damaged, ($100+), gonna spend $20 to update what's already done.
https://i.imgur.com/hDSVECe.jpg

As said before, the 5U4 is out of the circuit and replaced with silicon diodes, the secondary is now tapped at 300vac , r 160 was replaced with a 600 ohm resistor.
The 20uf (450v) caps were replaced with 22uf @ 450v, although I saw no sign of ripple, I am upgrading caps at A & B to 39uf, the paper caps that were replaced, C148,149,150,151, all came from a kit, cheap, but I never had a problem with them so far.
They came in 2 volt ranges, 400v & 650v, the .001s were in the correct range, the .022 was not, so right now there are 2 400v .047s in series, (0.0235), not sure if this matters much at all, BUT, I'm gonna replace all 4 of them again with precision Panasonic caps 5%.
I only found 1 bad resistor, r157, aside from the burned up r158, both of which are new, but I'm also replacing all the 20% 470k 47k ones with 2%, even though they checked OK while I have it apart again.
I really have no idea if this will make any difference or not, It's a Mystery, Charlie Brown!

If you need some 6V6s I have about 20 of them all of them test like new yet and are all pulls from radios that I ended up junking out because they had bad power transformers or output transformers or other issues (also some of them came to me from people who just gave me old boxes of tubes that they found at estate sales beause they knew I fixed old tube radios and could use them.
I've actually got a couple of matched sets of Sylvania and RCA and GE badged 6V6 GT tubes and I also have a matched set of Zenith 6V6G tubes that were pulled from my old Zenith 10S690 radio that I gutted, I've also got a matched set of 6V6GTs that are badged Capehart that came out of an old Capehart all-in-one Console from the late 1940s or early 1950s, so lots of possiblities, just let me know and I can send you some for the cost of shipping.

[Yamamaya42]

Originally Posted by vortalexfan

If you need some 6V6s I have about 20 of them all of them test like new yet and are all pulls from radios that I ended up junking out because they had bad power transformers or output transformers or other issues (also some of them came to me from people who just gave me old boxes of tubes that they found at estate sales beause they knew I fixed old tube radios and could use them.
I've actually got a couple of matched sets of Sylvania and RCA and GE badged 6V6 GT tubes and I also have a matched set of Zenith 6V6G tubes that were pulled from my old Zenith 10S690 radio that I gutted, I've also got a matched set of 6V6GTs that are badged Capehart that came out of an old Capehart all-in-one Console from the late 1940s or early 1950s, so lots of possiblities, just let me know and I can send you some for the cost of shipping.

Thanks for the offer,

I wish I had seen it BEFORE i had ordered the set of new jj 6v6GT matched pair Friday, but Oh well.

I did put in the 2 bigger filter caps (39uF 500V) and the Panasonic film caps replacing the cheap generic ones, also put in the 1% grid resistors, BUT, i also found that I missed a bad resistor before, and that was the 47k resistor on the cathode of the phase inverter, (r154) which was up at 168k, all of this has made a noticeable improvement, but I can still push it in to clipping, and I can obviously push the 12 inch speaker too hard, I'm sure i reaching the limit of what this amp was meant to do, and it was not very much, as I noted before, the output transformer seems REALLY small.

[Progman64]

I just picked up a Hoffman Super Receiver Mark V . TV,radio,record payer. I plugged it in and the set turned on and crt lite up very bright and radio turned on. I tested the crt and came back very very good, Fly back and yoke look like they need to be replaced. Are these parts replaceable? I would like to get the chassis rebuilt. Any suggestions??