Need TM-21 monitor manual
 

Howdy all,

Does anybody happen to have a service manual with schematic for the RCA TM-21 monitor?

I've struck a deal to purchase one, and would like to get a head start on the capacitor order.

I've always wanted a 21-CT-55, in order to get the larger, easier to watch 21 inch screen with wideband I/Q color (the 21-CT-55 is R-Y/Q, but I think it's a simple mod to switch it over to I/Q). Anyway, they keep eluding me, and the opportunity to buy the monitor came up; it has a 21 inch jug with wideband I/Q chroma demod. I figure it's the closest I'll ever get to a CTC-2B...

Your memory sucks, you know that?

I’m scanning mine this weekend, hold your horses. Lol

Hey Nick, mind posting that publicly (maybe through the ETF)?

Based on tube compliment and things I've read of the TM-21 I'd really like to see the schematic of one too.

Nick, I second Tom Cs' request. All the best, Tom.J

Sorry Nick. I completely forgot that you mentioned the manual on the phone last night.

Overworked and overtired. I was in a meeting most of the day yesterday. I was just leaving when I called you around 9 or 9:30? I think. Idk lol

I'm sleeping in Friday, Saturday, and Sunday.

No worries, I’m just ribbing you.

Yes, I would be interested in seeing the TM-21 manual, too, to compare to my TM-10 schematic. Just curious about how they differ.

Regards,

Phil Nelson
Phil's Old Radios
https://antiqueradio.org/index.html

Check out the article introducing the monitor in RCA's Broadcast News.

Definitely not a run of the mill consumer roundie in a metal cabinet...

The TM 21 was a wonderful monitor. At WHTN TV, we used one for many years, in a High band TRT 1B RCA video tape recorder. Yes, I said High Band, thanks to a high band conversion kit made by Allen Electronics. The hetrodyne high band color was nearly as good as our RCA TR 70 machines. Steven Allen was a mad genius!

Broadcast News:
"..the upper section of the front panel is hinged at the bottom, so that it can be dropped forward to permit convenient replacement of the kinescope"

Good to keep a stock of spare glass-metal-glass CRTs back then;)

Two versions of the TM21 were made.
 

The early one had a metal CRT. The later ones had a glass CRT. The attached picture is the metal one but I saw in the '66 terminal equipment catalog that they had switched over to the glass tube.
They're pretty reliable. The only thing I ever did was replace the horizontal output tubes once in the 2 years I was there.
That's the aural side of the TT25BL transmitter next to it.

I knew a guy who had a TM-21, but he parted it out for the transformers and other parts for his tube audio hobby. :thumbsdn:

The unit he had used a glass CRT. I assume it was a 21CYP22, because it had 2 anode connection buttons on it.

All the documentation I can find shows that the TM-21 was first built with 21AXP22As, then the second run was built with the 21CYP22A, the third run built with 21FBP22s, and finally the fourth run was built with 21FJP22s.

In theory, you should be able to take a fourth run monitor (like the one I'm buying), swap out the anode lead, add a piece of external safety glass, and pop in a 21CYP22A or 21FBP22. I intend to do so.

Did anybody say TRT-1b?
 

I know its not part of the thread but I thought I'd show a picture of one for you guys who have no idea of what he's talking about. This one is Allenized also. But it was heterodyne color unlike the direct color from the TR-70 machines next to it. There are two more racks for the servo that are not visible in this picture.
We used a Conrac CYA monitor in the tape room. This picture is from early 76. In May of '76 we installed our first TCR-100.

Ben, Here's an RCA ad for the TM-21. Get some help when moving that beast.

-Steve D.

A few years ago, just after digital happened in TV, I was allowed to roam through the storage rooms of a large TV station. There were tons of old monitors, VTR's, rack mounted tube equipment, etc. there.

There were 3 TM-21's there. I was arranging to get one of them, and the chief engineer of the station told me he had promised them to someone else. So, I didn't get one.

The next time I was there, the entire room was empty. All I got was a beautiful old RCA oscilliscope.

Did the service info ever get scanned?

Apologies, between defending the country 14 hours a day and raising a family the time to sit and scan it escaped me. Not gonna happen this weekend either, due to sponsoring the kids Christmas party at the hangar. I’ll get to it eventually, prob just shoot it out to Steve so the museum can host it.

I can tell you what happened to all that obsolete equipment. It went to the dump.
What happens is that somebody higher than the CE decides they need the space (for a new sales office) and they pitch it.
What I've noticed is that TV stations hang on to that equipment because its on the inventory. When I was in TV, I told the management that they should sell it while there is still a market for the equipment. Otherwise it will become so obsolete that NOBODY wants it.
It was well known that the station was cash strapped and I was able to sell some of the equipment to employees (production types) at a fair market price for the station.
I remember the smile on the girl in accounts receivable's face when I brought up a purchaser with a check in his hand and a bill of sale for her to sign.

I had a beautiful TM21 that was on the floor palleted and covered that was in my fire almost 3 years ago. The last time I saw it was only smoked up a little. The fire department went in with a bobcat with claw (without my knowledge) and absolutely destroyed it like a gov't demil with half of the building contents. I only found 2 small pieces of it in the pile they put out in the parking lot. I did find the front door with small damage on it that can be fixed back. I'm still sick over it.

I have since found another replacement with a roll around cart that needs shopping out. The damper tube gets very hot. It will be a nice sidekick along side of my TK41.

Hello All,
Our museum VRCMCT has generously been given two TM-21 monitors. They were used in Hartford CT at channel 3 for many years, and need total restoration (which may or may not happen to both; one, for sure). I took a look inside the top, and saw that all tubes except for the CRT are missing, so a tube hunt in our tube room is needed. Then, there all the electrolytics! Gonna have some fun :yes:! Going to return to check the CRTs later this week, and will proceed from there. Any encouragement will be VERY welcome!
Please see attached pics
Kevin G.

Awesome donations those are.

They definitely deserve a resto. If your museum ever decides that it only needs one I'd be glad to trade a good chunk of change to have the spare in my collection.

Makes me smile when I see some significant items from the past being saved. I love the graphics on the cabinets. Maybe it could be some kind of team effort and restore them both.

2/3/18:
Checked emission of the two CRTs today. The 21FB has very good emission from all three guns. It had been replaced, but couldn't see any date code yet. The 21FJ checked "dead" :tears:, but I'll return next week with a different CRT tester that has a more "gentle" restoration procedure. Didn't use the "brute force" method of my older B&K. I'll also start pulling tubes from storage to use on the FB monitor. More to come! :yes:

2/6/18
Began re-populating the four chassis with tubes today. Still need a few more, but most are in place. Found a 20 amp variac in the back room, so will use that to slowly power up for the "smoke test". That probably won't happen for about two more weeks. Next task is cleaning and checking wiring for no cracks or insulation trouble. It looks clean, except for the time-accumulated dirt and dust.
More pics attached.

Rack mounted TM-21's in our KTLA-TV remote bus mid 60's. The Crown Coaches were purchased in 1964 from the defunct Red Skelton Red-EO-Vision Videotape production co.

-Steve D,

Did the TM21 manual get scanned? I didn't see one at the ETF.

IF anyone wants to sell a TM21 ... I'm looking for one, top priority,
even higher than a 21CT55.

I scanned one that Dave Abramson lent me... which reminds me, it's sitting on my desk at work. I'll get her uploaded here soon and pass a copy along to Steve. I need to mail that back to him ASAP. I purchased Nick William's TM-21. Maybe someone else will come forward with one to sell...

There was one at the ETF the year that Ed Reitan passed on. 2016 maybe? It sold for only $500 IIRC. Do you care if it has a 21AXP22, 21CYP22, or 21FJP22? Obviously the 21AXP22 would be preferable, but you just aren't going to find one. If a 21FBP22 would be acceptable I'm sure you could find one rather quickly.

I would actually prefer one of the all-glass CRTs.

As promised, the manual. Since I couldn't slice the binding off of it to run it through the scanner, I was forced to try and scan it manually on a flat bed scanner. This didn't work as it cut off the information near the binding. I then took it to a friend with an book archivist's scanner and he did what he could with it. A lot of the pages are distorted as the book refused to lay flat properly. Still in all, it is readable, and that's what matters. The PDF is in grey-scale to save on ink if printing out a segment.

http://www.earlytelevision.org/tv_sc...broadcast.html

The schematic diagrams at the end are pretty difficult to read in the PDF, so I have uploaded Hi-Res copies here.

https://thumb.ibb.co/ch1iWc/20180404_104622.jpg https://thumb.ibb.co/crGHrc/20180404_104642.jpg https://thumb.ibb.co/dyhOWc/20180404_104654.jpg https://thumb.ibb.co/en5MHH/20180404_104723.jpg https://thumb.ibb.co/n9PFcH/20180404_104743.jpg https://thumb.ibb.co/fWQcrc/20180404_104826.jpg https://thumb.ibb.co/jHdVBc/20180404_104835.jpg https://thumb.ibb.co/ndvMHH/20180404_104852.jpg https://thumb.ibb.co/fnj3Wc/20180404_104905.jpg https://thumb.ibb.co/hLH1HH/20180404_104915.jpg

That link simply does not work! At all. A message says the URL is malformed. Perhaps you could upload it to the ETF?

The schematics simply don't work either. Blank page.

When I tried that link, all the anti-virus software on my machine blew up, claiming it's an unsafe URL (which may or may not be true, but . . . ).

Phil Nelson

I don't believe the site has any viruses, but I run a Linux machine so my antivirus responds differently to what are very different threats. To err on the side of caution, don't use that link. Just grab it from the ETF here:

http://www.earlytelevision.org/tv_sc...broadcast.html

All of the thumbnails of the schematic show up on my MacBook pro computer.

-Steve D.

The thumbnails show up on my computer, but when I click on them, I get a page
that gives the EXIF data if you click a button, but a blurry full screen image appears
for about 1/4 second and then that area of the screen turns blank.

Strange how computers or servers vary. I can blow up each thumbnail and get very clear images of any section of that thumbnail. This is a screen shot. Even clearer looking directly at screen.

-Steve D.

This is the "normal" behavior of images posted to imgbb. My Windows machine, my main Linux machine, my phone, my tablet, and my significant other's Mac all act like Steve's Mac. I'm at a loss to explain the issue.

In any case, I've sent you an email with the full-size images linked to above Doug. Check your email.

I got the ones sent by email. They are quite a bit sharper but more artifact ridden and
grayer than the screen shot. I cleaned them up and sent them to the ETF.

Its clear that people's mileage will vary.

Oh yes: do people have screen shots of these things? The monitors I mean,
showing color pictures.

My counting on fingers is probably inaccurate but it says 61 tubes.

Did you account for dual section tubes like the 12AX7 and 6080? I would not be surprised if there were 61 tube sections, but there are probably substantially fewer actual tubes.