View Full Version : 1948 (TS-4H) Motorola VT71 restored!
bandersen 06-05-2009, 09:45 PM zenithfan1 inspired me to post a little photo diary of my VT71 restoration.
Enjoy.
Arrival. It's in good shape aside from all the knobs being wrong.
http://www.bobandersen.com/images/TS4H/s001.JPG
Pretty much all original.
http://www.bobandersen.com/images/TS4H/s002.JPG
Ugh. Need to re-solder a CRT pin.
http://www.bobandersen.com/images/TS4H/s004.JPG
Apparently, this is the melted CRT mask. It hit a few tubes and the speaker
http://www.bobandersen.com/images/TS4H/s007.JPG
I really hope I never need to do this again!
http://www.bobandersen.com/images/TS4H/s008.JPG
Refinishing the cabinet. Citristrip is my favorite stripper lately.
http://www.bobandersen.com/images/TS4H/s009.JPG
Applying new decals from radiodaze.
http://www.bobandersen.com/images/TS4H/s013.JPG
The usual. Replaced the selenium with silicon. Wax caps with poly. And HV caps from Allied.
http://www.bobandersen.com/images/TS4H/s018.JPG
Ready to fire up. Got those knobs from a blonde VT71.
http://www.bobandersen.com/images/TS4H/s019.JPG
First signs up life using a 7VP1 CRT from an RCA WO-56A scope.
http://www.bobandersen.com/images/TS4H/s020.jpg
Seems safe enough to hook up the 7JP4
http://www.bobandersen.com/images/TS4H/s021.JPG
Old components. Those two caps in front were the source of much hair pulling. They came from the vertical oscillation/sweep circuit.
I assumed that mica caps rarely go bad. Boy was I wrong.
http://www.bobandersen.com/images/TS4H/s022.JPG
Replaced the 12AT7 and got my 1st stable image
http://www.bobandersen.com/images/TS4H/s023.JPG
Here it all is back together. I still need to track down a fine-tuning knob and do something for a CRT mask.
http://www.bobandersen.com/images/TS4H/s031.JPG
Here's some of the gear I used.
http://www.bobandersen.com/images/TS4H/s040.JPG
Dan Starnes 06-05-2009, 10:48 PM Great post,, loved it!!!
Eric H 06-05-2009, 11:07 PM Very nice, that stuff isn't foam however, it's the infamous VT-71 mask that is always melted, it's water soluble, not that that's any help when it's on a speaker cone!
Renovated Radios makes a repro mask now for about $43.
bandersen 06-05-2009, 11:28 PM Very nice, that stuff isn't foam however, it's the infamous VT-71 mask that is always melted, it's water soluble, not that that's any help when it's on a speaker cone!
Renovated Radios makes a repro mask now for about $43.
Wow! They can really melt all over like that? I guess that makes more sense than a maniac with an insulating foam canister :o
Tube TV 06-06-2009, 05:43 AM Looks great ! , the VT-71 is next on my list to get .
They sure look like a fun set to restore .
So how long did it take from start to finish ?
Tony V 06-06-2009, 07:03 AM Nice job! It looks like the crt was in good shape also as you dont see many with a perfectly centered picture. I hope to do both of mine soon!
-Tony
Sandy G 06-06-2009, 08:18 AM The chassis is clean & purty enuff to be left out of the case...Great job !
jpdylon 06-06-2009, 09:58 AM Nice job. Especially like the way that cabinet turned out. I'll have to try that citrus stripper
zenithfan1 06-06-2009, 03:38 PM Beautiful job! It looks new! Thanks for sharing, I'll have to try that stripper too.
bandersen 06-06-2009, 05:55 PM ... So how long did it take from start to finish ?
About a month working ~ 2 hours a night. Would have been a week less if I had replaced those mica caps from the start!
bandersen 06-06-2009, 05:58 PM I'll have to try that stripper too. They changed the formulation recently and it's even nicer now. It leaves your place with a nice smell of oranges :)
bandersen 06-06-2009, 06:04 PM The chassis is clean & purty enuff to be left out of the case...Great job !
Thanks! I went a little nuts on cleaning up that copper :o
Sandy G 06-06-2009, 06:10 PM Which was the one of these little guys that the mfger had to be "cute" & used an 8" CRT ? I thought it was Motorola...
bandersen 06-06-2009, 06:17 PM Nice job. Especially like the way that cabinet turned out...
Thanks. Here's the stuff I used. I like Behr - it's all water soluble.
bandersen 06-06-2009, 06:19 PM Which was the one of these little guys that the mfger had to be "cute" & used an 8" CRT ? I thought it was Motorola...
Yep. They made a few models with an 8" CRT. I haven't found any yet.
http://www.tvhistory.tv/1949-Motorola-9T1-Bakelite-8in.JPG
bandersen 06-12-2009, 09:55 PM My Astro Dog antenna can still pull in WGN in chicago :D Last man standing.
Tinman 06-12-2009, 10:04 PM That's a cool set. I had one of those over 20 years ago. Got it free, found a NOS CRT for it for $38, and got it running. I was in High School at the time.
I ended up selling it to a teacher, of all people, for $600. Well, he did beg and plead for a year to buy it.
Memories...
To think I was 17 when I repaired that Motorola. And then there was the Muntz set...
bandersen 06-12-2009, 10:31 PM I had a blast in HS too. I was lucky enough to have the 'electronics' shop class all 4 years. 1st year was house wiring. 2nd year a little tubes then all transistors. 3rd & 4th years - work on whatever you wanted. This was the early 80s though so I ended up making a 'new wave' electronic drum kit :guitar:
Tinman 06-12-2009, 10:53 PM I had a blast in HS too. I was lucky enough to have the 'electronics' shop class all 4 years. 1st year was house wiring. 2nd year a little tubes then all transistors. 3rd & 4th years - work on whatever you wanted. This was the early 80s though so I ended up making a 'new wave' electronic drum kit :guitar:
I built my own Pay tv decoder in HS as an electric shop "project" :D
The thing worked GREAT!
Sometimes I miss those days. There was so much wonderment for electronics.
Fixing old TV's was a lot of fun, and I learned a lot.
Working on this digital crap with ROHS compliant boards you can't really solder on has really taken the charm out of the hobby.
There's NOTHING like a good tube set. :thmbsp:
bandersen 06-12-2009, 11:19 PM I built my own Pay tv decoder in HS as an electric shop "project" :D
The thing worked GREAT!...
Oh man, I'd forgotten about those :D I think RadioElectronics published instructions or maybe I got them mail-order? I thinkd they called it a sync-restorer. Mine only worked so-so, but loads of fun. I kinda miss looking cross-eyed at the squiggly video :tongue:
[QUOTE]Working on this digital crap with ROHS compliant boards.../QUOTE]
Is that the crap without lead? I've noticed my 20 year old solder works better than new stuff!
Tinman 06-12-2009, 11:29 PM Oh man, I'd forgotten about those :D I think RadioElectronics published instructions or maybe I got them mail-order? I thinkd they called it a sync-restorer. Mine only worked so-so, but loads of fun. I kinda miss looking cross-eyed at the squiggly video :tongue:
It was an ON-TV decoder. I used 1% tolerance parts. The thing was rock stable.
Well, didn't mean to hijack this thread, though. I'll miss analog. It has given me many good years in the hobby.
Restoring a vintage set will feel different now, without native content to watch on it.
bandersen 06-12-2009, 11:31 PM NP. There are a couple Motorola VT71s and a suitcase on eBay right now.
bandersen 06-18-2009, 12:46 AM I did a little test with my Blonder Tongue BAVM-z. I attached my DVD player to the input and a short wire to the RF output. I picked this up on the VT71 about 40 feet away.
There are a bunch of these on eBay going for about $10.
Dr Who anyone?
http://www.bobandersen.com/images/TS4H/drwhovt71.jpg
zenithfan1 06-18-2009, 06:58 AM Nice! I'll have to try that myself!
bandersen 06-18-2009, 03:15 PM Here's what they look like. The BAVM-z has a hardwired output channel. You can adjust the input audio and video levels and the RF output power.
The 'Agile Modulator' line lets you change the output channel on demand.
You might need some female RCA to co-axial adaptors to hook it up to your existing gear.
zenithfan1 06-18-2009, 03:47 PM I have got to get some of those, I haven't found any yet. Probably looking at the wrong times. I wanted to build a multi channel output using those and a combiner like a friend of mine did so the Space Command sets can work other than getting cable. This way I could use converter boxes on my favorite channels plus a channel for DVD or whatever.
spartanmanor 06-18-2009, 04:31 PM Great stuff!
I'm surprised the picture is that clear with just a short wire off the modulator. What antenna is the moto using, is it still hooked to that "astro dog," or are you using something larger. And the 2nd doctor is my favorite, it's too bad they lost so many of his stories. I've got 4 of these motorolas sitting in the attic awaiting restoration.
Gohan 06-18-2009, 04:54 PM Good job! Looks very nice!
Gohan
bandersen 06-18-2009, 05:57 PM I'm surprised the picture is that clear with just a short wire off the modulator. What antenna is the moto using, is it still hooked to that "astro dog," or are you using something larger. And the 2nd doctor is my favorite, it's too bad they lost so many of his stories. I've got 4 of these motorolas sitting in the attic awaiting restoration.
I switched to a proper set of rabbit ears. The astro dog is actually a pretty lousy antenna. I used a vertical wire about 12 inches long on the modulator.
Troughton is my fav too. I've been watching the whole series (recons included) from the very beginning. I'm up to Moonbase :)
M3-SRT8 06-18-2009, 06:01 PM That's good work, Banderson.
Your Troubleshooting Skills are better than mine...
LJB:smoke:
Sandy G 06-18-2009, 06:49 PM I wish I knew how to work on TVs like that, but I'm too damn stupid to figure it out...I'm serious. I NEVER COULD make head nor tail out of basic electronic theory, & I've studied it, had people try to "splain" it to me, watched instructional videos...The whole 9 yards...It's like there's a 10' high wall there that can't be breached...Its like its worse than Chinese Algebra or some damn thing...I am in utter AWE over you wahoos who CAN & DO work on 'em, & can make 'em "shine" like that..My hat's off to you..But I'm still not 100% convinced that electronic theory, watts, volts, amps, capacitance, resistance, diodes, triodes, etc, all that stuff is a bunch of made-up hooey to keep us peasants in utter thrall, that Electronics really IS actually magic, & all youse byrds are really wizards 'n' warlocks, practising your arcane & black arts...
Phil Nelson 06-18-2009, 08:30 PM Would have been a week less if I had replaced those mica caps from the start!
For a long time, I ignored micas in the belief that they were almost always good. I learned different on my 630TS when a pal tipped me about checking a couple in a known trouble area.
Like many other 60-year old things, micas are starting to show their age. I don't shotgun them without testing, as I do paper caps, but I'm alert that they don't all stay perfect forever.
Nice job. I'm a Citri-Strip fan, too. And I will even forgive you this time for using polyurethane <holds up garlic, makes sign of cross> :)
Phil Nelson
zenithfan1 06-18-2009, 09:19 PM I looked for modulators and found a few. Thanks, your post reminded me to keep looking for them. The last time I checked the bay a few months ago I found none and forgot about it.
bandersen 06-18-2009, 10:49 PM Nice job. I'm a Citri-Strip fan, too. And I will even forgive you this time for using polyurethane <holds up garlic, makes sign of cross> :)
Phil Nelson
This was actually the 1st time I ever used it. I decided to give the whole line of Behr water based products a try on the project. The results are OK and cleanup was a snap, but it's not as good as more traditional products.
I've used hand rubbed tung oil and spray lacquer in the past. What do you recommend?
bandersen 06-27-2009, 11:30 PM I wish I knew how to work on TVs like that, but I'm too damn stupid to figure it out...I'm serious. I NEVER COULD make head nor tail out of basic electronic theory, & I've studied it, had people try to "splain" it to me, watched instructional videos...The whole 9 yards...It's like there's a 10' high wall there that can't be breached...Its like its worse than Chinese Algebra or some damn thing...I am in utter AWE over you wahoos who CAN & DO work on 'em, & can make 'em "shine" like that..My hat's off to you..But I'm still not 100% convinced that electronic theory, watts, volts, amps, capacitance, resistance, diodes, triodes, etc, all that stuff is a bunch of made-up hooey to keep us peasants in utter thrall, that Electronics really IS actually magic, & all youse byrds are really wizards 'n' warlocks, practising your arcane & black arts...
I dunno about all that :scratch2: Although I do have a BSEE, I got all my practical knowledge from hanging around hamfests, forums like this and a whole lot of tinkering.
I think it just takes time to sink in. Hopefully, it will all make sense to you soon.
Phil Nelson 06-28-2009, 01:19 AM I've used hand rubbed tung oil and spray lacquer in the past. What do you recommend?
Normally lacquer -- the same thing originally used for the majority of old radio and TV cabinets. Easy to use, dries fast, and can be reversed if you don't like the outcome and want to start over. Poly can provide a very shiny finish, but if you've ever tried to strip it, you'll know why it's not my favorite.
Phil
Arkay 06-28-2009, 02:35 AM I wish I knew how to work on TVs like that, but I'm too damn stupid to figure it out...I'm serious. I NEVER COULD make head nor tail out of basic electronic theory, & I've studied it, had people try to "splain" it to me, watched instructional videos...The whole 9 yards...It's like there's a 10' high wall there that can't be breached...Its like its worse than Chinese Algebra or some damn thing...I am in utter AWE over you wahoos who CAN & DO work on 'em, & can make 'em "shine" like that..My hat's off to you..But I'm still not 100% convinced that electronic theory, watts, volts, amps, capacitance, resistance, diodes, triodes, etc, all that stuff is a bunch of made-up hooey to keep us peasants in utter thrall, that Electronics really IS actually magic, & all youse byrds are really wizards 'n' warlocks, practising your arcane & black arts...
Wizards 'n' warlocks, practicing arcane and black arts?
Just take a look at Phil Nelson's avatar (above in this thread). I think there is your answer! :D
Actually, it does take some time --and a GOOD teacher or book (some are impossibly obtuse)-- to catch on. Give it time and keep trying, if it matters to you. Eventually, you'll learn it.
As for the restoration that is the topic of this thread, man, that is beautiful! Very, very nice to see that people are continuing to restore these old sets even in the face of the death of analog, and a quality job like yours is an inspiration to all of us who restore anything. Thanks for sharing it! :thmbsp:
Incidentally, if anyone has sets like that one which they don't want anymore since there are no more analog broadcasts, there are people in other parts of the world like Hong Kong, who can still use them to receive analog TV broadcasts over the air. I don't mind taking charge of seeing that they find good homes, if you send a few those smaller sets to me! :D
Back on topic (:D), I use a citrus-oil based cleaner, which, while it can partially strip very old finishes if you work it hard enough, wasn't designed for stripping. Think I'll try the stripper version next. The citrus smell is sure a LOT nicer than that horrible, toxic smell that most commercial strippers have. I used some commercial stripper on some vintage (metal) fans recently, and despite pretty good ventilation, felt sick afterwards. (:puke:) :nono: :thumbsdn:
bandersen 06-28-2009, 01:47 PM Normally lacquer -- the same thing originally used for the majority of old radio and TV cabinets. Easy to use, dries fast, and can be reversed if you don't like the outcome and want to start over. Poly can provide a very shiny finish, but if you've ever tried to strip it, you'll know why it's not my favorite.
Phil
I've tried using Watco spray lacquer a few times, but had trouble with runs. That's why I tried wipe-on poly with this project. I just picked up a can of lacquer to try brushing it on with my next project.
I had concerns sbout stripping the poly too, but CitriStrip takes it right off - no problem.
bandersen 06-28-2009, 01:52 PM ...Back on topic (:D), I use a citrus-oil based cleaner, which, while it can partially strip very old finishes if you work it hard enough, wasn't designed for stripping. Think I'll try the stripper version next. The citrus smell is sure a LOT nicer than that horrible, toxic smell that most commercial strippers have. I used some commercial stripper on some vintage (metal) fans recently, and despite pretty good ventilation, felt sick afterwards. (:puke:) :nono: :thumbsdn:
Don't think I've seen the 'puke' emoticon used before :)
I believe Methyl Chloride is the nasty stuff in commercial stripper. I sometimes use it after the CitiriStrip to remove any last traces of goo.
Phil Nelson 06-28-2009, 07:49 PM If you have some spray lacquer left, try practicing on a junky piece of furniture. It's not a black art, or I wouldn't be able to do it respectably. To avoid runs, keep the spray moving and follow the directions about the correct distance to spray from. It's often better to apply two thin coats than one thick one.
I have never tried brushing lacquer, but my one experiment with brushing shellac left a lot of brush lines. Perhaps brush lacquer is mixed to dry a little slower than the spray stuff.
Phil
zenithfan1 06-28-2009, 08:00 PM Don't think I've seen the 'puke' emoticon used before :)
You must have not read all my posts, that's one of my favorite emoticons.LOL I also like puke 2, see: :puke2:
:D
Sorry to be OT. To make it better, your set is simply gorgeous, I have to find me one! You do some great work, or is it black magic.....Hmmmmm.
bandersen 06-28-2009, 11:14 PM If you have some spray lacquer left, try practicing on a junky piece of furniture. It's not a black art, or I wouldn't be able to do it respectably. To avoid runs, keep the spray moving and follow the directions about the correct distance to spray from. It's often better to apply two thin coats than one thick one.
I have never tried brushing lacquer, but my one experiment with brushing shellac left a lot of brush lines. Perhaps brush lacquer is mixed to dry a little slower than the spray stuff.
Phil
They claim it has a leveling agent and will leave no brush marks. I need to do some selective refinishing on upcoming projects and figured this was the way to go.
I've gone through a couple cans of spray lacquer while restoring two radios. The results were OK in the end, but I found it frustrating. I also had trouble if I put too light a coat on - the surface would be all rough. A couple times a few random large droplets spurted out of the spray can too.
I suppose I do need more practice.
What brand of spray do you use?
Here's one of the radios I used spray lacquer on. I just need to find time to put the new grille cloth in.
Phil Nelson 06-29-2009, 12:09 PM I have used a lot of Mohawk spray lacquer. Available as colored toner in addition to clear. Google for "mohawk lacquer" and you'll find suppliers. I have also used Deft, but that's available only in clear in my local stores.
Serious refinishers buy spray equipment and mix up their own juice, but I have been satisified with spray bomb results, so far.
Yes, putting on too light a coat (incl. moving the sprayer too fast or holding it too far away) will give you an uneven coat. You want to spray just enough so that it all blends into a uniform layer, but not so much that it runs. Practice helps.
Large droplets may come out if your sprayer is almost empty. It also might be a cheap brand with a cheap nozzle, or simply a dirty nozzle. Follow the directions and spray with the can upside down for a second when you are finished, to clear the nozzle.
That cabinet looks pretty sassy. Hard to tell from photos, but do I see pores on the top? If you have stripped down to bare wood, you often need to use grain filler to close those pores. Otherwise, they'll be visible in the finish no matter how many coats of lacquer you apply. I hate grain filling and I'm lousy at it, so I usually try to remove old finish in a way that doesn't require it.
Enough nitpicking. That cabinet looks good. A useful book is "The Weekend Refinisher" by Bruce Johnson. He gives practical advice about all sorts of finishes, including brushing lacquer. Your library may have a copy.
Phil Nelson
bandersen 06-29-2009, 01:26 PM ...do I see pores on the top? If you have stripped down to bare wood, you often need to use grain filler to close those pores. Otherwise, they'll be visible in the finish no matter how many coats of lacquer you apply. I hate grain filling and I'm lousy at it, so I usually try to remove old finish in a way that doesn't require it...
Yes, there are pores although it's nowhere as noticeable in person. I didn't have much choice with stripping this cabinet - the original finish had mostly flaked off. They used a thin filler and porous veneer to get that 'bullet' shape. Also, this has a faux 'photo finish' on the front.
I've had some success filling in grain by sanding between coats to filling the voids.
Thanks for the tip on Mohawk. I think I'll give it a try on an upcoming project.
Bob
bandersen 07-20-2009, 10:26 PM I had been using the crappy JFD metal ballast tube that came with this set, but no more!
I just scored some Amperite ballast tubes :banana:
http://www.bobandersen.com/images/TS4H/01-01.jpg http://www.bobandersen.com/images/TS4H/01-04.jpg
These are glass enclosed balllast/regulator tubes filled with an inert gas. They really soak up the juice when the sets turned on and protect all those series wired tubes.
Technically, this tube is designed for the TS-18 chassis which specifies a 111 and 132 ohm element while this TS-4H calls for 105 ohm elements.
However, I've done the math and here's what I come up with. Yes, the 7JP4 draws 600ma and is in both strings.
Series Filament #1 Series Filament #2
Tube Type V A Tube Type V A
V-13 25L6 25 0.3 V-12 25L6 25 0.3
V-8 6SL7 6.3 0.3 V-6 6AU6 6.3 0.3
V-10 12SN7 12.6 0.3 V-12 6AG5 6.3 0.3
V-11 12SN7 12.6 0.3 V-17 12AT7 6.3 0.3
V-18 12SN7 12.6 0.3 V-2 6AG5 6.3 0.3
V-15 7JP4 6.3 0.3 V-3 6AG5 6.3 0.3
75.4 V-4 6AG5 6.3 0.3
V-5 6AU6 6.3 0.3
V-16 6AL5 6.3 0.3
V-15 7JP4 6.3 0.3
81.7
Assuming 117 VAC at the outlet, here's what I get which is not far off the TS-18 values.
(117 - 75.4) / 0.3 ~ 140 ohm
(117 - 81.7) / 0.3 ~ 120 ohm
That just leaves one issue - the pinout differs by one pin. I just needed to move the AC line from pin 5 to 6. No biggie.
http://www.bobandersen.com/images/TS4H/01-02.jpg
Here it is in the set ready for testing.
http://www.bobandersen.com/images/TS4H/01-03.jpg
Here's a crappy little video show it in action. One of these days I'll hook up my good digital video camera.
http://www.youtube.com/watch?v=HC86eiGhw_o
So, if you can find one, you shouldn't have any trouble using them in a VT71 set.
zenithfan1 07-21-2009, 11:33 PM Looking good! I can't wait until mine come! I hate the crappy metal ones.
compucat 07-22-2009, 06:58 AM I just ordered two of the glass ballasts from Ebay. When looking for these, search for amperite ballast tube. I still may make a resistive replacement as these are hard to find.
bandersen 07-22-2009, 05:33 PM I just ordered two of the glass ballasts from Ebay. When looking for these, search for amperite ballast tube. I still may make a resistive replacement as these are hard to find.
They sure are hard to find and I have four sets that need one! I'd been researching technique to make resistive ones for weeks before coming across these and even ordered some resistors. So I make make up one or two as well.
jeyurkon 07-22-2009, 08:54 PM Weren't the original ones that you need the amperite 17A470303? Vacuumtubesinc has two of them.
John
zenithfan1 07-22-2009, 09:41 PM One of mine arrived with a broken element :tears: I hope I can get a replacement.
bandersen 07-22-2009, 09:47 PM Weren't the original ones that you need the amperite 17A470303? Vacuumtubesinc has two of them.
John
Ah yes, so they do and almost twice what I paid for these ;)
That's why I did the math to see if the '459 was a good substitute. According to my calculations (which have been confirmed by others), this tube is actually better. The two filament strings in the TS-4* chassis are not equal and 105 ohms is a bit too low when using modern line voltages anyway. I'd also noticed that my filaments were running a little hotter than they should.
Now, there a nice even glow with this ballast tube :)
That being said, I imagine the '303 Amperite glass tube is superior to the '303 JFD metal ballast tube. I'm curious if someone has used the '303 and has any thoughts on it?
bandersen 07-22-2009, 09:51 PM One of mine arrived with a broken element :tears: I hope I can get a replacement.
Damn, that blows :mad:
Looks like he has a few left. I hope you can exchange it for a good one.
Bob
jeyurkon 07-25-2009, 05:10 PM In searching for this particular ballast for the past couple of years all I had ever found were posts from others also looking for them, going back quite a few years.
I'm surprised that the guy still has 8 left. I bought two, one as a spare. It was difficult to resist buying more.
John
compucat 07-25-2009, 11:08 PM In searching for this particular ballast for the past couple of years all I had ever found were posts from others also looking for them, going back quite a few years.
I'm surprised that the guy still has 8 left. I bought two, one as a spare. It was difficult to resist buying more.
John
My two 17A485459 ballast tubes arrived today and now my 9VT1 lives again. These glass tubes are so much better. I bought two so I would have a spare. I was tempted to buy more as well but I thought of the many others who have been looking for these. I am thinking of making a resistor replacement, mounting it in the set with an octal plug and if ballast tubes ever go extinct I can just plug in my resistor network and keep the set going. I want to refinish the cabinet, replace the torn grill cloth and add retrace line suppression to my set. It works very well of an Insignia DTV converter.
jeyurkon 07-26-2009, 04:24 PM Another good reason for making a resistor replacement is that if you have a problem with the set or need to do work on it you can test it with the replacement without worrying about blowing the easily destroyed ballast.
John
Ok, you all convinced me to try these. I ordered 2. Now do I understand correctly that these gas filled glass ballasts regulate current as the set comes on, so there would be no need to add a filament transformer to protect the 7JP4? - as I had been planning to do.
I have 3 ts-4j chassis: one just missing the ballast, and one missing the ballast and flyback. I figured I would try these tubes with those chassis (if I can find a flyback for that one). The third chassis was modified already for filament transformers, but whoever did it made a real mess of it with 3 separate filament transformers and a variety of series-parallel circuits. I got that one to work using that scheme eventually after I sorted it out, but it didn't work that well, and all those transformers didn't really fit under the chassis. On that one, given it's already modified, I thought I might as well go with making a ballast from resistors, and adding a filament transformer for the crt. Or maybe even try to make it into a transformer set entirely with all 6v tubes.
jeyurkon 07-26-2009, 11:28 PM Ok, you all convinced me to try these. I ordered 2. Now do I understand correctly that these gas filled glass ballasts regulate current as the set comes on, so there would be no need to add a filament transformer to protect the 7JP4? - as I had been planning to do.
...
Based on tests that I did with a ballast that had only one bad filament I would have said no. That they behave just like a resistor. However, I was testing them under steady state conditions and as I raised the current the power dissipation got to a very high level before seeing any glow of the tube. I was afraid the Bakelite base was going to start burning.
Watching Bob's video of the tube as his set warm up changes my mind. The brief high current causes the filament to get hot enough to change resistance significantly and protect the 7JP4. The current when the tubes are cold must be much higher than what I tested the ballast to.
John
Tubejunke 07-26-2009, 11:59 PM [QUOTE=Adam;2907263]I have 3 ts-4j chassis: one just missing the ballast, and one missing the ballast and flyback. I figured I would try these tubes with those chassis (if I can find a flyback for that one). QUOTE]
I still have a small inventory of Thordarson and Merit NOS replacement flybacks and yokes. If you can get a part # cossreference for me I'll se if I have it.
Thanks, but the sams leaves all the cross-reference columns blank for the flyback. So I don't know if they even made a replacement for this one or not.
bandersen 02-24-2012, 11:31 PM I had originally refinished this cabinet with water based poly, but I've learned a lot since then. So I'm re-refinishing it using traditional materials.
The poly came off very easily with Citri-Strip.
http://farm8.staticflickr.com/7187/6927572777_72bd72ba92_z.jpg (http://www.flickr.com/photos/70039806@N00/6927572777/)
Next, a little brown mahogany stain.
http://farm8.staticflickr.com/7067/6927572909_4ffbaf1afa_z.jpg (http://www.flickr.com/photos/70039806@N00/6927572909/)
Then, grain filler.
http://farm8.staticflickr.com/7049/6781452736_618bf2f0b5_z.jpg (http://www.flickr.com/photos/70039806@N00/6781452736/)
I've used burlap in the past to remove the excess, but this time around I'm using a scraper. Really just an expired credit card. it worked out quite well.
http://farm8.staticflickr.com/7038/6781452942_c558b2119f_z.jpg (http://www.flickr.com/photos/70039806@N00/6781452942/) http://farm8.staticflickr.com/7185/6927573493_be3e940cf0_z.jpg (http://www.flickr.com/photos/70039806@N00/6927573493/)
I darkened in the pin-striping and edges with dark brown hobby paint then sprayed on some lacquer sanding sealer.
http://farm8.staticflickr.com/7204/6927573753_175906101e_z.jpg (http://www.flickr.com/photos/70039806@N00/6927573753/)
I applied a set of new gold decals to the control area.
http://farm8.staticflickr.com/7199/6781453680_0c5b23bd19_z.jpg (http://www.flickr.com/photos/70039806@N00/6781453680/)
Next up a little toner lacquer and the finish coats.
fox_rivers 02-25-2012, 12:26 AM I had originally refinished this cabinet with water based poly, but I've learned a lot since then. So I'm re-refinishing it using traditional materials.
The poly came off very easily with Citri-Strip.
http://farm8.staticflickr.com/7187/6927572777_72bd72ba92_z.jpg (http://www.flickr.com/photos/70039806@N00/6927572777/)
Next, a little brown mahogany stain.
http://farm8.staticflickr.com/7067/6927572909_4ffbaf1afa_z.jpg (http://www.flickr.com/photos/70039806@N00/6927572909/)
Then, grain filler.
http://farm8.staticflickr.com/7049/6781452736_618bf2f0b5_z.jpg (http://www.flickr.com/photos/70039806@N00/6781452736/)
I've used burlap in the past to remove the excess, but this time around I'm using a scraper. Really just an expired credit card. it worked out quite well.
http://farm8.staticflickr.com/7038/6781452942_c558b2119f_z.jpg (http://www.flickr.com/photos/70039806@N00/6781452942/) http://farm8.staticflickr.com/7185/6927573493_be3e940cf0_z.jpg (http://www.flickr.com/photos/70039806@N00/6927573493/)
I darkened in the pin-striping and edges with dark brown hobby paint then sprayed on some lacquer sanding sealer.
http://farm8.staticflickr.com/7204/6927573753_175906101e_z.jpg (http://www.flickr.com/photos/70039806@N00/6927573753/)
I applied a set of new gold decals to the control area.
http://farm8.staticflickr.com/7199/6781453680_0c5b23bd19_z.jpg (http://www.flickr.com/photos/70039806@N00/6781453680/)
Next up a little toner lacquer and the finish coats.
Looks good! What was wrong with the water based poly?
bandersen 02-25-2012, 01:00 AM Just like regular poly, it looks kinda "plasticy" compared to lacquer. Lacquer is also what they used originally. That being said, I have seen refinishing done with poly that looks pretty good and you'll find plenty of arguments pro/con poly vs. lacquer.
Personally, it took a while to get the hang of lacquer, but now I really like it.
Reece 02-25-2012, 10:50 AM I always use lacquer since it's what was used from the early thirties on (shellac before that.) I keep a few old credit cards too, just for scraping off filler. Filler makes a big difference in the look and makes finishing easier as the pores of the wood are closed and it doesn't take as many finishing coats. Good looking job!
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