View Full Version : A little Surprising, CT100 Fans
pugs5061 09-04-2011, 08:58 PM Anyone interested? No Affiliation, just kinda surprised by it.
http://www.ebay.com/itm/140602442172?ru=http%3A%2F%2Fwww.ebay.com%3A80%2Fs ch%2Fi.html%3F_from%3DR40%26_trksid%3Dp5197.m570.l 1313%26_nkw%3D140602442172%26_sacat%3DSee-All-Categories%26_fvi%3D1&_rdc=1
miniman82 09-04-2011, 09:10 PM Yours was first!
I sent a message as soon as I saw this, perhaps I can convince him to sell me the whole set instead of parting it out? Wouldn't that be a shame!
CoogarXR 09-04-2011, 09:22 PM I notice that he says it was sitting in a store window for 45 years and the cabinet is bare, from what I presume was the sun beating on it. Wouldn't this damage the phosphor coating on the CRT too?
I am still a novice in this area, but I just wonder...
miniman82 09-04-2011, 09:29 PM "Will ship insured UPS"
:yikes:
Please God, NO! Better insure it for $5,000, I promise he'll collect on that one. Those freaks destroyed a 21" tube Scotty sent me, you can see the results in my signature. :thumbsdn:
Kevin Kuehn 09-04-2011, 09:42 PM It's too bad he won't keep this whole set together.
Interesting double reflection in the picture of the CRT face.
miniman82 09-04-2011, 09:59 PM It's too bad he won't keep this whole set together.
Don't be too sure, he just replied to my message.
Looks like I might own a CT-100! :banana: :banana: :banana:
Electronic M 09-04-2011, 10:09 PM I hope you get the whole set Nick. I believe that there is someone who had repro vertical convergence transformers for the CT-100 made and is selling them on the ETF classifieds.
You NEED a CT-100 it is all that is keeping you from having every color RCA chassis from prototype to CTC 4.
Maybe after that you can get the ones between CTC 4 and 9 and start your own RCA color museum.:scratch2::naughty:
Tom C.
Kevin Kuehn 09-04-2011, 10:24 PM Don't be too sure, he just replied to my message.
Looks like I might own a CT-100! :banana: :banana: :banana:
That is great news, congratulations. :thmbsp:
miniman82 09-04-2011, 10:52 PM It's official, I am the new owner!
Bonus info:
He has already completely recapped the chassis and done an alignment on it, so my road ahead will be short.
http://videokarma.org/attachment.php?attachmentid=171509&d=1315194607
Even the original peaking coils are still good, it must not have played for very long at all. Work stopped when the vertical convergence transformer went out, so I will be calling John Folsom to see if he has any of his new ones still available. Cabinet is sun baked, but otherwise in good condition. Has all the knobs. Of course, CRT is good. :thmbsp:
Kevin Kuehn 09-04-2011, 11:08 PM Wowzers! And even a very neatly done recap. I think it was another of your lucky days. :yes:
miniman82 09-04-2011, 11:27 PM I seem to be having a lot of those, huh? Being in the right place at the right time has a lot to do with it, just yesterday I was camping in Springfield. Bad storm came, blew the tent down!
Kevin Kuehn 09-04-2011, 11:37 PM Camping can be a pretty dangerous activity. We had a similar experience this spring, only we saw this one coming. We literally threw 3 tents in the back of my van and took off running.
TerrySmith 09-04-2011, 11:48 PM You are the luckiest guy in the world! I'd be heading to the store and buying lottery tickets.
David Roper 09-05-2011, 12:25 AM You're one of us now. http://fc03.deviantart.net/fs31/f/2008/228/2/f/Zombie_Emoticon_by_Dystopia3000.gif Do you know if this one is already in the database?
John Folsom 09-05-2011, 09:23 AM Nick, way to go! Give me a shout if you need a newly made convergence transformer for the CT100 chassis.
Pete Deksnis 09-05-2011, 10:07 AM Do you know if this one is already in the database?
As I have mentioned in the past, eight years ago in early 2003 some 25 entries in the Living CT-100 List were lost in a computer HD crash. Since then a handfull have been recovered from various means, but although the Merrill-in-a-window description sounds familiar, I have not been able to match this set to an entry in the list.
So Nick, pls pass along the chassis serial number when it becomes available to you.
Thanks,
Pete
zenithfan1 09-05-2011, 11:55 AM :jawdrop:Wow! Congratulations Nick! You really are one lucky bastard! :D
I can't wait to see it in person.
miniman82 09-05-2011, 12:36 PM Nick, way to go! Give me a shout if you need a newly made convergence transformer for the CT100 chassis.
I will be needing one, according to Jeff. I will wait till I have the chassis in my possession to contact you though, that way I know this is not a dream. :D
Kevin Kuehn 09-05-2011, 12:39 PM You going to go pick this one up in person?
miniman82 09-05-2011, 12:40 PM Just received a few more pictures from Jeff, here they are.
http://videokarma.org/attachment.php?attachmentid=171516&d=1315244353
http://videokarma.org/attachment.php?attachmentid=171517&d=1315244353
miniman82 09-05-2011, 12:40 PM You going to go pick this one up in person?
Too far away, someone from U-Ship will get it for me.
Kevin Kuehn 09-05-2011, 12:45 PM Boy he sure has that chassis cleaned up nice. And the cabinet don't look too bad either. Least you won't need to buy gallons of stripper.
jr_tech 09-05-2011, 01:26 PM Wow! Not too shabby!!! :banana::thmbsp::banana::thmbsp:
Congratulations!
jr
holmesuser01 09-05-2011, 01:48 PM I'm so glad to see another CT-100 saved.
Bruce
sampson159 09-05-2011, 04:49 PM cant wait to see this one up and running.great score and good to know artifacts of our youth are being preserved for the future.please post as many pics as you can when putting it together
John Folsom 09-05-2011, 05:25 PM Nick, just curious... who was the seller? I think I can provide you with the missing tuner cover if you need it.
pugs5061 09-05-2011, 05:35 PM My post was first but I think you were the lucky one here! Congratulations! I knew I was in no position to have bought it but I'm glad its saved and in good hands.
miniman82 09-05-2011, 07:58 PM Nick, just curious... who was the seller? I think I can provide you with the missing tuner cover if you need it.
You have PM, not sure if he wants his full name public.
cbenham 09-05-2011, 08:04 PM Wow! Not too shabby!!! Congratulations! jr
You got a great looking set there. I hope it comes to life and makes great pictures.
Regards,
Cliff
reeferman 09-05-2011, 08:18 PM Congrats! It's hard to believe this was to be parted out. Thank goodness you saved it. And to think I was impressed when the Sear's tower opened.
miniman82 09-06-2011, 12:12 AM Maybe after that you can get the ones between CTC 4 and 9 and start your own RCA color museum.
At this point, the only one I haven't owned is a CTC-5. I had and sold a nice CTC-9, that was my first roundie. As you know I'm working on veneering the CTC-7, I have no desire to own anything after CTC-10. If I could one day own a Wingate, that would be about the only thing I'd consider collecting. The first 3 is enough for me, though if a Model 5 showed up...
Electronic M 09-06-2011, 01:06 AM Nick my friend, when it comes to RCA color sets you are a guy that wants the best and gets the best. I have no doubt that you will be celebrating the acquisition of Model 5andor a Winate soon. I can't help but envy your legendary RCA collection, ya lucky dawg.
ChrisW6ATV 09-06-2011, 01:23 AM Congratulations for your latest acquisition, Nick, and welcome to the CT-100 club. I see that this set's channel-selector knob appears to be light-colored, as is mine, though I have seen others that are darker.
Regarding the seller, he is apparently a ham-radio operator as am I; most hams I have ever met are good people do deal with.
jmdocs 09-06-2011, 12:58 PM Wow, congratulations. Quite a find. You really do have TV mojo, as the hippies used to say. So when are you opening your museum? ;)
(That CTC-9 is still doing great, by the way; the Kovacs color special DVD was especially sweet.)
Steve D. 09-08-2011, 01:33 AM As I have mentioned in the past, eight years ago in early 2003 some 25 entries in the Living CT-100 List were lost in a computer HD crash. Since then a handfull have been recovered from various means, but although the Merrill-in-a-window description sounds familiar, I have not been able to match this set to an entry in the list.
So Nick, pls pass along the chassis serial number when it becomes available to you.
Thanks,
Pete
Pete,
If memory serves, and that's saying a lot.
I recall an AK post many years ago about a sun baked CT-100 that stood in a store window in Kansas. Looked very much like Nick's faded cabinet.
-Steve D.
miniman82 09-10-2011, 06:51 PM Set is ready for pickup! I'm in the process of booking through U-Ship at the moment. :banana:
http://videokarma.org/attachment.php?attachmentid=171601&d=1315698610
Electronic M 09-10-2011, 08:40 PM Sweet! It will be cool to see that CT-100 running next to a working prototype, 21-CT-55 and CTC-4 someday....you are going to need to get a bigger treasure display wall, and maybe some extension cords to run all of them at once without tripping the breaker, and some more antenna matching transformers, coaxal cable, cable splitters, etc.... You know what, that collection is too much trouble, and as SandyG likes to joke you should box them up and send them to me. LOL.
Glad you saved it.
Tom C.
miniman82 09-13-2011, 03:01 PM Shipping is booked through U-Ship now, just waiting for confirmation of the arrival!
miniman82 09-23-2011, 07:32 PM Set will be here early tomorrow morning!
ggregg 09-23-2011, 09:29 PM Can't wait to see it. Congradulations, Nick!!
Electronic M 09-23-2011, 10:07 PM Awesome! :thmbsp:
miniman82 09-24-2011, 10:46 AM And here it is!
http://videokarma.org/attachment.php?attachmentid=171714&d=1316877917
http://videokarma.org/attachment.php?attachmentid=171713&d=1316877917
In a box were all the spare parts including another CRT mask, 2 panes of glass, the knobs, and random hardware. Looks to be all there and in great shape, except for the channel indicator which was all faded from being in the sun. I have another but it's not original, and I have no idea where it came from. It seems to have followed me home from the ETF meet, but I honestly don't remember picking it up. Someone must have slipped it into my poclet or something, because back then I had no use for a CT-100 knob.
miniman82 09-24-2011, 11:15 AM Just tested the 15GP22: great emission at only 4.5 volts on all 3 guns, needle doesn't dip into the bad zone until the heaters are completely dark. In other words, it's like brand new. Now off to start a resto thread, first thing that needs attention is the cabinet. It's not in very bad shape structurally, but the finish on 3 sides did get stripped off by the sun.
Phil Nelson 09-24-2011, 11:48 AM Man, you must have been livin' right, to get such a reward.
Looks like new, apart from the sun fading.
If you remove the bezel, or just lift up the lid, you'll see the original cabinet color areas that weren't exposed to the sun. That will guide you in refinishing. The original color may be redder than you're expecting.
If your decals can't be salvaged, I have a spare set that I'll donate to the cause.
Enjoy!
Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html
holmesuser01 09-24-2011, 11:53 AM I'm so glad to see another of these sets has been found!!
miniman82 09-24-2011, 12:14 PM Man, you must have been livin' right, to get such a reward.
Nope, just in the right place at the right time. Don't you have a pair of 15G's? :D
If you remove the bezel, or just lift up the lid, you'll see the original cabinet color areas that weren't exposed to the sun. That will guide you in refinishing. The original color may be redder than you're expecting.
Good idea, I'll pull it and see what the finish looks like. I've seen these in 3 different hues now: one that looked almost orange in tint, more than a few with the stock reddish look, then there's Bob and Steve's sets that have a very dark mahogany finish. I'm shooting for as close to stock as possible.
If your decals can't be salvaged, I have a spare set that I'll donate to the cause.
You have PM. :thmbsp:
Electronic M 09-24-2011, 02:13 PM Sweet now you've got two good 15" color tubes and a chassis to run them in that doesn't need to be reverse-engineered! :thmbsp:
miniman82 09-24-2011, 03:29 PM Yup, just waiting on the new convergence tranformer. I think I'll use the CTC-2 to see what kind of color pic I can coax out of the developmental tube, I just hope the 16" mask will mount inside the CT-100 cabinet without a whole lot of molestation.
stromberg6 09-24-2011, 05:00 PM SO happy to see the posts. Thanks Nick! :yes:
Phil Nelson 09-24-2011, 11:04 PM I'll pull it and see what the finish looks like. I've seen these in 3 different hues now: one that looked almost orange in tint, more than a few with the stock reddish look, then there's Bob and Steve's sets that have a very dark mahogany finish. I'm shooting for as close to stock as possible.
This photo of my refinished cabinet was taken in a room with lots of natural light. It gives a pretty fair idea of the color. The refinisher did a dead-on match to the unfaded parts that had been protected by the bezel forever. You can see how the cabinet is redder than the doors and radio cabinet in the background.
I use one of John Folsom's transformers and it works like a charm.
Mailed the decals today. Enjoy.
Phil Nelson
http://antiqueradio.org/art/RCACT-100CabinetRefinished.jpg
Electronic M 09-24-2011, 11:12 PM Been awhile since I read your merril restoration on your site, and was very suprised seeing that photo as I forgot how beautiful the cabinet on your set looks.
Phil Nelson 09-25-2011, 12:09 AM No credit to me. The guy who refinished it is a master. His day job is designing & building custom furniture for spoiled people. He appreciates older things, tho', and will do a little restoration job like this as relaxing change, if I'm willing to wait (and wait) until it fits his schedule.
Phil Nelson
Glenz75 09-25-2011, 06:09 PM It gives me a real buzz to see the lengths that are gone to here to save these sets :yes: Just great stuff and such awesome looking RCA's. Nice cabinet work too by the way :)
Cheers
Glen
miniman82 09-30-2011, 03:44 PM Got the replacement decals the other day, thanks Phil!
miniman82 10-03-2011, 10:39 PM Update: John Folsom mailed me the replacement convergence transformer, so I set about mounting it into the old shell. I chose to mount it with screws so it's easily removable, as opposed to the more laborious process of potting in silicone. When installed, then only thing you can see is the rear nut. Not too bad. Now to hook it up, let's see what this thing can do! :banana:
http://videokarma.org/attachment.php?attachmentid=171782&d=1317699493
http://videokarma.org/attachment.php?attachmentid=171783&d=1317699493
http://videokarma.org/attachment.php?attachmentid=171784&d=1317699493
John Folsom 10-04-2011, 01:00 AM Outstanding, Nick. Can 't wait to see if fired up!
miniman82 10-05-2011, 11:49 PM Got the rest of the set put back together, everything is soldered up and ready to go!
http://videokarma.org/attachment.php?attachmentid=171802&d=1317876526
http://videokarma.org/attachment.php?attachmentid=171803&d=1317876526
miniman82 10-05-2011, 11:59 PM Can't wait to see if fired up!
John, you don't know how prophetic those words were! :smoke:
Slowly applied power through the variac, but I didn't get to more than 50 volts before I heard a loud SNAP! Instantly, I shut it off to investigate. Turns out the foul smell was coming from the vert ht/lin pot in the front, must have tin whiskers or something. This also caught my eye: a 5.6k resistor with a huge crack in it! :nono:
http://videokarma.org/attachment.php?attachmentid=171804&d=1317876861
It now reads out at 12k, so obviously it will need to be replaced before I go any farther. Between that and the bad pot, I think my weekend is already full.
John Folsom 10-06-2011, 12:57 AM Don't worry Nick, whatever it is, you will overcome! Can't wait to see you get it going.
miniman82 10-06-2011, 01:33 AM You're right, as usual. lol
5.6k resistor was feeding the vertical output transformer, and the vert height pot was in fact guilty of carbon tracking. Looks to me like it had found a path from the carbon element to case ground, but I don't have a suitable replacement...
Any help?
Electronic M 10-06-2011, 12:22 PM First time I saw a carbon comp resistor crack length wise. Next power up you might want to pull some tubes and power up a few sections at a time so as to minimise the chance of frying something less replacable.
miniman82 10-06-2011, 11:25 PM Only other thing in that circuit is the vert transformer, which is not really in any danger. Found the bad section in the pot, it was arcing right to the case.
http://videokarma.org/attachment.php?attachmentid=171805&d=1317961370
Robbed a replacement element from a doner chassis, put it back together. Here goes round #2... :thmbsp:
miniman82 10-07-2011, 01:35 AM New issue...
Put the chassis back in, fired it up. HV is clearly working, I can see blue glow from the shunt regulator. But when the anode lead is connected to the tube, I get this sizzling sound like it's shorting to something. I'm reasonably sure I have the CRT installed correctly: anode clip, rubber boot, mumetal shield, retaining bracket, ect. Anything that could cause the anode to sizzle that I'm not aware of? Tried another HV boot just in case it had a hole or something, same result.
Pete Deksnis 10-07-2011, 07:48 AM I've had that, or something similar, happen to a Merrill that hadn't been under power for an extended period. I cleaned the boot, particularly inside, and the interface between the flange and glass. It finally stopped frying. Never found the exact cause though.
Pete
miniman82 10-07-2011, 11:19 PM The Merrill oracles have spoken, and they are right as usual!
Cleaned the heck out of the CRT and insulating boot, ladies and gentlemen we have....something! :banana:
http://videokarma.org/attachment.php?attachmentid=171810&d=1318047268
Obviously, the thing still has a lot of issues. Vertical is working, though it's not near as tall as it should be. HV and HO cathode current still need to be checked. But at least I have proved that this thing still works, which means the cabinet needs to go to the refinishing guy ASAP. Think I'll finally buy my own HV meter this weekend, unless Wayne or Mark would like to pay the Merrill in a window a visit. :scratch2:
John Folsom 10-07-2011, 11:53 PM Its Alive! For a HV probe, I recommend one that plugs into your DMM, not one with a meter built into the handle.
ChrisW6ATV 10-08-2011, 01:51 PM That is great to see. Once you have light on the CRT face, you are 90% there.
David Roper 10-08-2011, 02:53 PM Of course it's just the other 10% that's so damn aggravating....
miniman82 10-08-2011, 03:25 PM Of course it's just the other 10% that's so damn aggravating....
Speaking of which...
I was a dumbass and decided to twiddle around with the IF alignment, since I wasn't passing a video or audio signal at all. Should have done some voltage measurements first, damn tuner wasn't getting any B+! :rolleyes: The alignment wasn't far off thankfully, I only had to tweak a few transformers to get it looking respectable. But I followed the loss of power back to it's cause, which ended up being the field neutralization pot on the LV cage.
http://videokarma.org/attachment.php?attachmentid=171812&d=1318105469
This isn't a normal pot though, it's tapped in the center. Anyone have a spare they could donate to the cause, or know of one that's available on the open market? I suppose this would explain the excessive B+ voltages as well, since half the chassis wasn't being powered.
reeferman 10-09-2011, 08:45 PM Murphy's Law says it takes 95% of the time, money, and efforts to complete the first 90% of the project and 95% of the time, money and effort to complete the last 10%.
Phil
Steve D. 10-09-2011, 10:13 PM Murphy's Law says it takes 95% of the time, money, and efforts to complete the first 90% of the project and 95% of the time, money and effort to complete the last 10%.
HUH! I think Murphy needs to brush up on his math. Or am I missing something here?
-Steve D.
Phil Nelson 10-09-2011, 10:22 PM This isn't a normal pot though, it's tapped in the center. Anyone have a spare they could donate to the cause, or know of one that's available on the open market?
Mark Oppat has load of controls. He also rebuilds them.
http://oldradioparts.net/controls.html
Phil Nelson
miniman82 10-09-2011, 10:47 PM Thanks for the link, Phil. John Folsom says he has one to send me, but I might pick up a spare if Mark has one.
ChrisW6ATV 10-10-2011, 12:15 AM Murphy's Law says it takes 95% of the time, money, and efforts to complete the first 90% of the project and 95% of the time, money and effort to complete the last 10%.
That is how my hot tub project has seemed to go.
ChrisW6ATV 10-10-2011, 12:17 AM HUH! I think Murphy needs to brush up on his math. Or am I missing something here?
-Steve D.
Murphy has no problem with his math at all. The rest of us, yes, we have BIG problems with Murphy's math!
Steve D. 10-10-2011, 01:02 AM Murphy has no problem with his math at all. The rest of us, yes, we have BIG problems with Murphy's math!
I'm familiar with Murphy's law. I break it all the time. I guess I never heard it expressed in those terms.
-Steve D.
Eric H 10-10-2011, 12:47 PM Sounds a lot like Drag Racing law, it takes 90% of the money to get that last 10% of performance.
Dave S 10-10-2011, 08:12 PM Its Alive! For a HV probe, I recommend one that plugs into your DMM, not one with a meter built into the handle.
Hi John,
You've got me curious: why do you recommend one over the other? I've never heard that before.
--Dave Sica
John Folsom 10-10-2011, 10:46 PM The HV probes with the built in meter have a tiny scale which goes from 0 to 30 or 40KV; not much resolution. The ones which plug into a DMM have much better resolution.
miniman82 10-20-2011, 04:51 PM Took John's advice, ended up with a Coline 40Kv probe (model HV40B) from Ebay for around $70. Nice unit, even has spring loaded covers that slide over the terminals when it's unplugged. I was able to verify that I have a solid 19.5Kv coming out of the HV rectifier, and the regulator looks like it's doing it's job as well. But another problem surfaced: if I tried to get the picture into focus, all I got was some very pissed off sounding arcing and a bad smell...
http://videokarma.org/attachment.php?attachmentid=171929&d=1319146789
Focus pot appears to have bought the farm, probably as a result of years of wear or maybe the old convergence transformer taking a dump. As predicted by John, it only arced when near the high potential side of the pot. On visual inspection there is a good big of gouging in the carbon element, it only reads 3.2 meg now vice the 5 meg it should be according to the schematic. Once it's replaced I should be able to get a decent picture on the screen, so off to the interwebs I go in search of a new one. :thmbsp:
miniman82 10-26-2011, 01:10 AM I had a go at replacing the pot with a standard type, which actually still had the same part number called out in the Sams for this set but with a much smaller element (think volume control). I can now confirm that a modern Clarostat A47-5MEG-S will arc right accross all the terminals with focus voltage applied to it, so it's back to the drawing board. :D
Phil Nelson 10-26-2011, 02:21 AM Can you temporarily substitute a couple of fixed resistors for this pot? A workaround might let you make progress on other issues while you hunt for a replacement.
Just a thought.
Phil Nelson
Steve McVoy 10-26-2011, 07:18 AM I have used a smaller value pot with fixed resistors on each side (you have to experiment with them to find where you get the proper focus range). This way there is less voltage across the pot, therefore less chance of arcing.
Electronic M 10-26-2011, 01:05 PM Another possible temporary option would be to get one of those giant, old, high-watt, ceramic, wire wound resistors (I used to have a bunch, but have not seen them since the last move) some had a side of the wires exposed and a slidable center tap thus makeing them a (very annoying to adjust) slide potentiometer.
EDIT: There is a surplus store in Orlando called Sky Craft that has some of the type I mentioned above and may have the right value with an adjuster. These resistors have no insulation on the center adjuster so you would have to jury rig one or keep the set off when adjusting it.
miniman82 10-26-2011, 07:55 PM I have used a smaller value pot with fixed resistors on each side (you have to experiment with them to find where you get the proper focus range). This way there is less voltage across the pot, therefore less chance of arcing.
The thought had occurred to me, but I don't have any 2 watt megohm value resistors lying around to experiment with. If I can get my hands on some, I suppose it would be possible to use a 1 meg pot so it's dropping less voltage across it.
Steve McVoy 10-26-2011, 08:19 PM You don't need 2 watt ones. If you use several, the heat dissipation will be through all of them, and 1 or even 1/2 watt ones can be used.
miniman82 10-26-2011, 10:06 PM All I have is 1/4 watt, lol!
Time to experiment I guess.
miniman82 11-14-2011, 02:25 AM Thanks for the input Steve, you were right! I was sure I'd have the same arcing issues across a 1-meg pot as I did with the 5-meg, but that didn't happen at all. I ordered a 2w 1-meg pot and some 1-meg fixed resistors, to try and get the correct range for this CRT. I spent the last few days playing around with it and ended up with a trio of 1-meg resistors before the pot (on the high potential side), then the pot with the original 8.2-meg on the other end of it going to ground. That got me to the point where I can dial it in exactly, but there's very little range. Not that it matters, so long as it's sharp at some point. Didn't even have to take the metal back off the pot to make it work either, no zapping whatsoever. Result is below, though there's still some issue with the color circuits. I can't get any color on it no matter what I try, so I suspect the reference oscillator is not working or something. I'll dig into it next chance I get, hopefully the next pic I post is in glorious 1954 COLOR!
http://videokarma.org/attachment.php?attachmentid=172191&d=1321258876
miniman82 11-15-2011, 01:59 AM I was right, the local 3.58Mhz oscillator is not running. Actually it starts out running when power is applied and tube starts to warm up, but the output quickly shrinks to nothing. Curious...
Voltage readings on the osc tube (V29b in Sams) are all wrong:
Pin 1 (plate): 50 volts, should be 95
Pin 2 (grid): 0 volts, should be -9
Pin 3 (cathode): 0 volts, which is normal
In other words instead of oscillating, the waveform collapses for some reason and the tube is left biased on which drags down the plate voltage. I'm not versed in oscillators, so I tried the following:
Different 6AN8: no change
Different crystal: no change
Removed the quadrature amp tube, in case it was messing with the oscillator: no change
Removed both phase detector tubes: no change
So the question now becomes: what's causing the local oscillator to be unstable? I attached a video, so you can see exactly what I'm talking about. This is the scope attached to pin 8 of the quadrature amp, V28a in Sams.
View My Video (http://tinypic.com/r/24xhrvo/5)
John Folsom 11-15-2011, 08:24 AM Nick, 1. Try adjusting the coil in the cathode circuit of the oscillator tube (make not o the starting position so you can put it back if the adjustment does not help). 2. Try adjusting the transformer in the plate circuit of the reactance tube. If this helps, then go through the color AFC procedure.
miniman82 11-15-2011, 10:27 AM Tried the coil in the cathode of the osc tube, no joy. Haven't yet tried the one in the reactance tube plate circuit, because I'm not sure what it does. This circuit is a lot different than the ones I'm used to playing with in later sets, most have the triode for reactance and the pentode for osc duty. But I'll mess with the other coil tonight when I get off work. What do you make of the scope trace coming and going?
Phil Nelson 11-15-2011, 01:35 PM If you master the color AFC procedure, you can come and do my set. I'm waiting to try it again until I get some more grown-up test equipment and develop a bigger brain :)
Phil Nelson
miniman82 11-15-2011, 05:42 PM AFC alignment isn't too bad, you just need a pair of meters and a good head on your shoulders. I think the problem with your set is the local oscilator is drifting too far off frequency, so far that it's beyond the phase detector's ability to pull it back in. Not sure why that is, but my guess will be the capacitors in the tank circuit drifting. When that happens, you won't be able to use the coil to get it back in spec. Same thing happened to my CTC-7, the osc coil is at the end of it's travel but it locks in.
miniman82 11-15-2011, 11:25 PM Just remembered I have a CTC-2B chassis, so I'm going to borrow both the reactance and oscillator cathode transformers from it to try and diagnose this issue.
miniman82 11-17-2011, 03:54 AM Swapped in the pair of transformers from the CTC-2B.....
....................
Nothing! Same result as before, so now I'm scratching my head because there's only 1 other cap and 1 other resistor in the whole oscillator. So while I'm sitting there wondering what my next move is going to be, I got a sneaking suspicion that something was staring me right in the face. I proceeded to put my DMM across the little inductor feeding the reactance tube grid and... INFINITE! Unbelievable! I swear this is the last time I ever trust these stupid little piles of crap, no matter how good they look. From now on, they will be replaced on sight no questions asked. I will install the rest of them from the kit I assembled later, since all I wanted to do up to this point is prove the chassis and tube worked well. Cabinet can now go off to the refinishing guy in Milwaukee.
http://videokarma.org/attachment.php?attachmentid=172226&d=1321522716
After replacing the bastard little inductor, the scope showed that the oscillator now worked as it should. No more mysteriously shrinking waveform, and actually the open inductor explains why the proceedure for zero-beating the oscillator didn't work, since they have you ground the grid of the reactance tube through that same coil. Obviously, the result was dramatic: instant color lock!
http://videokarma.org/attachment.php?attachmentid=172225&d=1321522716
Has a pretty obvious drive line now, I hadn't seen that before. Just another thing to add to the mental list of things to remember for later on. Right now I have a good chassis with color, and a tube with great emission just waiting for a nice cabinet to live in. I can't wait to drop it off, I just know Dennis will make it look like a million bucks!
:banana:
sampson159 11-17-2011, 07:32 AM i have been following this thread intensely.so glad you have got it solved.post many pictures of the screen with images.you have worked hard and i am happy for your success.another ct 100 lives!
Phil Nelson 11-17-2011, 01:37 PM the little inductor feeding the reactance tube grid and... INFINITE!
The previous owner of my CT-100 had done some work on it, and he included a couple of parts bins in the deal. One of them had drawers full of little inductors. Seemed odd at the time, but I guess the inductors in that model are notoriously junky.
Those color bars look promising.
Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html
Pete Deksnis 11-17-2011, 02:12 PM the brown inductors in a CTC2 chassis are not the problem. It is always the chalk-white ones that rot open after 40-years in a garage or attic, and even after 50- to 55-years under better environmental conditions.
Pete
miniman82 11-17-2011, 08:12 PM Yep, the brown ones always seem to be good, I think the white ones had something in the material surrounding the coil which causes the thin copper wires to corrode and open up. If you look closely, you can most times make out some green stuff on either end of the coil where the wire leads go into the body of the coil. That's copper corrosion. I tried repairing one once, but it's impossible. Even if you could get the lead in wire repaired, the coil is just as bad on the inside. I cracked one open with pliers, it's not a pretty sight. Anything the white stuff touches gets destroyed.
ChrisW6ATV 11-18-2011, 02:12 AM On the other TV forum, I asked if that was one of the infamous peaking coils... I can see from your picture (and description of green corrosion), the answer is "yes".
I am glad you have a raster on that set-nice progress.
miniman82 11-18-2011, 04:06 PM Here's the list of inductors which can be bought at Digikey for the CTC-2, a few have asked for it.
From phase detector to reactance tube grid: M10101-ND (1 piece)
Matrix output to CRT: M10093-ND (3 pieces)
Y-line, near delay line: M10082-ND (1 piece)
R-Y demod/amp: M10083-ND (2 pieces)
Q demod: M10098-ND (1 piece) and M10127-ND (1 piece)
Y-line near 2nd video tube, and matrix power input: M10106-ND (5 pieces)
ChrisW6ATV 11-18-2011, 04:57 PM Thank you for posting that list; I know some of my coils need to be replaced, and my CT-100 should be my next project before too long, I hope.
miniman82 11-20-2011, 10:17 PM Cabinet is off at the refinishers! Dennis asked me when I wanted it back: "this month or right before Christmas OK with you?" Man, this would be a sweet Christmas present to myself, huh? :banana:
Electronic M 11-21-2011, 12:34 AM A CT-100 for christmas......Can we trade places?
Just kidding.
Does sound like a nice Christmas present though.....
miniman82 11-21-2011, 12:52 AM I'd give anything to know what I know now and be in your shoes...
miniman82 12-31-2011, 07:41 PM Good news, I found the water slide decals floating around the living room today!
http://videokarma.org/attachment.php?attachmentid=172719&d=1325382050
Hope I can get it to Dennis before he's too far into the cabinet resto, I've never tried to do these before so I hope it doesn't give us too much trouble.
miniman82 02-20-2012, 02:19 PM Dropped off the decals to Dennis this past weekend, had a look at the cabinet- it's coming along nicely. Stain is on, the cracks from baking in the sun have been repaired, and Dennis told me it will be finished next weekend! All that remains is a trip to the spray booth, and it's done. He was able to get the stain very close to original, it's not too dark or light. My hope is to have the set assembled and running no later than 2 weeks from now, should have pictures of it then.
miniman82 02-21-2012, 08:11 PM LoL, if only....
http://videokarma.org/attachment.php?attachmentid=173448&d=1329876589
I found this trolling the internet for 15GP22's today, I think it's leftover web garbage from the Ebay listing. 10 bucks would be a hell of a deal, would it not? :yes:
miniman82 03-04-2012, 04:38 PM Just got back from Milwaukee a little bit ago, picked up the cabinet from Dennis. Looks pretty good, considering what it looked like to start off with. :yes:
http://videokarma.org/attachment.php?attachmentid=173586&d=1330900675
holmesuser01 03-04-2012, 04:55 PM OMG! Lovely new cabinet for a grand lady!
kvflyer 03-04-2012, 07:13 PM I would certainly say that it looks good. Glad that you have it back.
Pete Deksnis 03-04-2012, 07:25 PM Looks like new, Nick...
ChrisW6ATV 03-04-2012, 11:11 PM That looks nice indeed.
Electronic M 03-06-2012, 12:21 AM That cabinet looks awesome!
I'll have to stop by some time to see it once you get it back together.
miniman82 03-08-2012, 09:37 PM I'll have to stop by some time to see it once you get it back together.
Time is nigh, Tom. :thmbsp:
http://videokarma.org/attachment.php?attachmentid=173612&d=1331263843
I think I'll fire it up tomorrow, to see if I can get some correct color bars on it. I jacked the alignment up when I last messed with it, so I'll be stuck using composite input only for the moment. Actually I've been tossing around the idea of converting all my sets in the same fashion, but my increasing skill at using the B&K 415 is making me rethink the idea. I'll give another alignment a go before I make my decision.
mpatoray 03-08-2012, 10:49 PM Nick,
The set looks amazing, can't wait to see it fully operational with those lovely "Technicolor colors" on the 15GP22!
ChrisW6ATV 03-09-2012, 12:07 AM That set looks great.
bandersen 03-09-2012, 12:25 AM Veeerrrry nice :tresbon:
Phil Nelson 03-09-2012, 01:49 AM Cabinet looks nice, indeed.
Color bars! Color bars! Color bars!
Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html
miniman82 03-12-2012, 10:55 PM Color bars! Color bars! Color bars!
OK, ok, ok already! :D
http://videokarma.org/attachment.php?attachmentid=173648&d=1331610228
I had to replace more parts to get to this point though, turns out the 'I' section of the chroma channel was completely dead. That ended up being, surprise surprise, another bad peaking coil. This time it was the one feeding the 'I' phase splitter, which led to complete lack of 'I' information to the matrix. The clue was the 'I Gain' pot having no effect on the picture, and the colors being generally messed up. Replaced it with one of the ferrite spares I had floating around, and it perked right up.
Still remaining is the IF alignment, which I totally screwed up earlier. I think I'm going to have to use the mod marker function of the 415 to tune all the coils independently first, then move on to a regular alignment to finalize the response. That will allow me to finally get some DVR stuff on the screen, to see how well it really performs. I'm also noticing a slight drive line in the picture, even though the pot is at minimum. I'll probably have to change some values under the hood to get it a tic lower, so the line will go away. Other than that, it's looking pretty good if I do say so myself. :yes:
Sandy G 03-12-2012, 11:00 PM Looks purty close to Glorious Lokkipop Color t'me...
ChrisW6ATV 03-12-2012, 11:22 PM Nice to see another CT-100 brought back to life.
DavGoodlin 03-13-2012, 07:24 AM That deserves to be on a magazine cover. So bright and sharp. SWEET!!!
Phil Nelson 03-13-2012, 11:15 AM Looks very promising.
You are showing incredible restraint in not hooking up a DVD player yet. I doubt I could have waited this long to see some motion on the screen, hear some sound, etc.
Phil Nelson
Pete Deksnis 03-13-2012, 01:22 PM I'm also noticing a slight drive line in the picture, even though the pot is at minimum. I'll probably have to change some values under the hood to get it a tic lower, so the line will go away. Nick,
Something simple to check: Some CTC2 schematics incorrectly show the HO coupling cap [mounted above chassis next to the drive pot] as 0.01 uF, where the final design value is 0.0015 uF. That alone can cause an overdrive line if there's a 0.01 instead of the correct 0.0015 (or. of course, a 0.001 uF is good too).
Pete
Electronic M 03-13-2012, 01:26 PM Niiice! :thmbsp:
jr_tech 03-13-2012, 04:00 PM VERY NICE, indeed ! :thmbsp: :banana::banana::thmbsp:
WOW!
jr
holmesuser01 03-13-2012, 04:03 PM Beautiful CT-100. I'm just thrilled to see these sets alive again!
miniman82 03-13-2012, 04:32 PM Something simple to check: Some CTC2 schematics incorrectly show the HO coupling cap [mounted above chassis next to the drive pot] as 0.01 uF, where the final design value is 0.0015 uF. That alone can cause an overdrive line if there's a 0.01 instead of the correct 0.0015 (or. of course, a 0.001 uF is good too).
You are the oracle, Pete! I was unaware of this, but I checked the chassis and it has the correct .0015uf in it. I could try a slightly weaker horizontal osc tube before making circuit changes, less output=less drive. If that doesn't work, I'll have to fool around with the parts.
columbia 03-14-2012, 11:57 AM What a beautiful set!
miniman82 03-14-2012, 08:04 PM I finally got around to adding a CT-100 page to my site, it can be viewed at the following link:
http://miniman82.4t.com/custom4.html
electronjohn 03-17-2012, 11:10 AM Beautiful! A video time machine for sure.
KentTeffeteller 03-17-2012, 05:26 PM A nice time machine. Love that Lollipop color. Beautiful CT-100. Top of the Merrill crop. Thanks for sharing your journey.
old_tv_nut 03-17-2012, 07:49 PM I finally got around to adding a CT-100 page to my site, it can be viewed at the following link:
http://miniman82.4t.com/custom4.html
Gorgeous, gorgeous, simply Gorgeous!
Those are the best looking bars I have seen. Most CT-100s start out too blue, which is easy to do because of the wide difference in drive/beam current needed in the red gun to make illuminant C (daylight white). The green usually requires a bit more current than the blue also, I believe. There also can be weak tubes in the matrix that mess up the color.
As was heard in the Zenith lab when RCA introduced the early chassis, "27 controls, each one making it worse!"
jeyurkon 03-17-2012, 08:20 PM Really nice! :yes:
miniman82 03-17-2012, 08:22 PM Wait till I actually set the thing up- the CRT needs to be degaussed, and I haven't converged it yet either. Oddly I seem to have stumbled across a set of screen pot settings that were correct when the I channel was still dead, guess it was just dumb luck. Anyhow, this set will have to get put on the back burner again temporarily. I have a power point presentation to get ready for the ETF meet, and the proto chassis is being shipped to Hilliard this week.
Sandy G 03-17-2012, 08:25 PM Dah-Yum, Me Olde Sonne, I dunno if I'd wanna let that prototype outta me Sight, much less trust it to the Tender Mercies of the Shipping Company goons...Just sayin'...
miniman82 03-18-2012, 01:07 PM It will be properly insured, believe me.
miniman82 03-25-2012, 12:12 AM Mmkay, back to the CT-100.
Today marks the third round of alignment attempts with this set, but my tenacity has finally paid off. This chassis has the most complicated IF section of any I've ever come across, having 7 total amplifier stages versus the typical 3 or 4 of a more 'evolved' set. Most people say it only has 6, but they are missing the true 1st stage which is built into the tuner. If we're only talking chassis IF stages, then 6 is technically correct.
Anyhow, you'll recall that I messed up the alignment when I first got it. Before I got the 415 my thought was to just run it as a monitor by installing a composite preamplifier, since I didn't think I'd ever be skilled enough to align a set this complex, but that darn 415 is a TV service persons wonder tool. First thing I tried to do was just see if I could look at the response curve, and make adjustments to all the slugs to make it right. Big mistake. I ended up farther off than when I started. After all normal attempts failed, including following the instructions in Sams, I resorted to the B&K manual.
In the B&K manual, it makes reference to a function called 'modulated markers'. This is used when one would like to tune a single coil or trap, such as the sound trap and so forth. What I found was that I could tune every coil in the strip one by one by using the individual markers, peaking and trapping as needed. Here's how it works: you inject the signal from the 415 at the osc injection point on the tuner, to bypass fine tuning and go directly into the strip. Then you activate one marker at a time, and basically target coils till they peak or detune as required. Example- the sound trap needs to have minimum passage at 41.25, so you turn on that marker and adjust till it nulls the signal as much as possible (the signal is a 400hz modulation that shows on the scope as a sine wave). On others you want to see maximum response, such as 42.67 and so forth. Once I had gone through all the coils twice and was satisfied I had done it correctly, I went back and looked at the overall curve and it was much improved! It was good enough that I could get back to tweaking the overall response in the normal fashion, and eventually ended up at a point where I thought it might work pretty well. The curve now closely matched what I saw in other sets, so I stuck the chassis back into the cabinet. I was again disappointed.
Now I'm beginning to think that the composite input option is looking pretty good, but I noticed that the AGC pot had almost no effect on signal strength. I had on screen what looked like classic signs of AGC trouble, such as washed out picture and terrible sync horizontally. I had initially written this off as being related to the bad IF alignment, but since I was now convinced I had the curve correct, I had to start thinking of other faults. First thought is a bad AGC pot, but dismissed that since it actually did something (not much though). Then it dawns on me- I have a tube tester, let's check the tube!
Sure as sh!t, the triode section of the 6AN8 which does duty as the AGC amp was completely dead! Wouldn't even budge the needle off the bad stop, I double checked against a new one. So in the new tube went, and viola the set sprang to life! I was now able to get respectable color bars through the antenna terminals, so I decided to hook up cable and here's what I saw:
http://videokarma.org/attachment.php?attachmentid=173753&d=1332651939
Now I'm getting stoked! It's actually receiving signals and displaying color pretty well at this point, so the next steps are lowering horizontal drive just a tad, fixing the focus range so it's sharp, and a complete convergence setup. Right now blue is a little high in the top of the screen, but the rest seems more or less in line. I think I'll follow the procedure for convergence in Sams first, hopefully it will work and I'll be able to show some really nice pics at next update!
:banana:
ChrisW6ATV 03-25-2012, 12:31 AM It looks good!
kvflyer 03-25-2012, 09:12 AM All I can say is, "Amazing!"
old_tv_nut 03-25-2012, 10:19 AM Great progress - keep at it!
stromberg6 03-25-2012, 10:34 AM Nick, reading your last post, and seeing the pic made me smile. Super progress! Thanks for the update!! :yes:
Kevin
Electronic M 03-25-2012, 04:13 PM Shoot, if you keep getting better at alignment I may have to bring my CTC4 chassis back down to you and let you have at it. :D
Nice job on that alignment BTW!:thmbsp:
miniman82 03-25-2012, 05:30 PM No problem, the CTC-4 is a lot easier than this thing. Just stop by, I'll give it a once-over while you wait.
Electronic M 03-25-2012, 07:29 PM No problem, the CTC-4 is a lot easier than this thing. Just stop by, I'll give it a once-over while you wait.
Sounds Great! I'll bring the old 4 down next time I'm out by you then.
miniman82 04-15-2012, 03:13 PM Finally had a few hours to play with the CT-100 this weekend, so I converged it. By far, the easiest set ever! In less than 15 minutes I was watching baseball, so I'm putting it on the 'done' list.
http://videokarma.org/attachment.php?attachmentid=173975&d=1334520536
http://videokarma.org/attachment.php?attachmentid=173976&d=1334520695
Sandy G 04-15-2012, 03:50 PM Dah-Yum...That looks GREAT !
ChrisW6ATV 04-15-2012, 09:46 PM Excellent work, I am jealous.
Electronic M 04-16-2012, 01:37 PM Very nice!:thmbsp:
Eric H 04-16-2012, 01:59 PM This is awesome, it's been a while but remember this thread started out as a 15GP22 for sale from a set that was being parted out, what a shame that would have been!
It looks incredible!
Pete Deksnis 04-16-2012, 05:43 PM Nick,
Crosshatch looks nice; horizontal linearity at the left side of the screen can be a pain sometimes.
No horizontal overdrive visible; did you have to make some alterations or did it go away?
Pete
Tom S 04-16-2012, 07:19 PM Don't be too sure, he just replied to my message.
Looks like I might own a CT-100! :banana: :banana: :banana:
Wow a hell of a find. Good luck. Want to see it when it's all done.
miniman82 04-16-2012, 07:43 PM Wow a hell of a find. Good luck. Want to see it when it's all done.
:scratch2:
Umm, it is done...
I'm putting it on the 'done' list.
Incidentally, if anyone in the area would like to stop by and see my small collection, I'm game. Just shoot me a PM, and we'll set something up.
pete deksnis]horizontal linearity at the left side of the screen can be a pain sometimes. No horizontal overdrive visible; did you have to make some alterations or did it go away?
Does it look a little off to you? I admit, I haven't revisited the horizontal oscillator setup procedure since I got it running right, probably time to make sure I still have equal peaks and check that lock in is right on target.
I had to change the value of R176 (Sams), it was 47k now it's 22k. Making that change got me to where the drive control actually has some range instead of being at it's extreme CCW position. The real cause of the issue is the negative voltage coming from the power supply is a bit off for some reason; it reads -24 or so when in Sams it calls for a full -30. Still don't know why it's low, the only thing that could cause it is a iffy choke or 2R191 being low in value. They both check out within tolerances, so I made the drive mod. Also, horizontal cathode current is reading nice and low post-mod. I think when I first read it, I got 168ma or something? It's lower now, checking in at a solid and steady 140ma. So I trust the mod isn't having any negative impact on the performance of the horizontal output stage. <shrugs>
Phil Nelson 04-16-2012, 11:18 PM I'm putting it on the 'done' list.Excellent work. It's fun to see a CT-100 looking so good.
Phil Nelson
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