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 Post subject: Show your utility monitor tv's?
PostPosted: Sep Sat 12, 2020 4:53 pm 
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Location: Detroit, Michigan
I found this 15" Q-TV Teleprompter monitor sitting curbside. Vintage 1993 monochrome, model VPS-15/SC, Dotronics 15VM936 display. Says "Made In USA" on the back of the cabinet, but "Made in Taiwan" on the power transformer. Other than a few scratches and scrapes in the cabinet paint, it's in excellent condition and complete. Since it was apparently used only sporadically for prompter duty, set had no dust inside at all. I plugged it in and it had a rastor, so I proceeded to set it up as a tv. I found it worked with the composite video input from my DTV converter, so I purchased a couple of RCA to BNC adapters from ABEL Electronics. The brightness was set up for teleprompter service and was extremely over bright, even at the lowest brightness setting. I replaced the 80K ohm brightness pot with a 1 meg ohm and knob(saved the original parts, just in case, ya never know, these could be thee hot retro gamer item someday). Since it was designed to mount by it's top with the display facing straight up, I had to install some stick-on felt feet on the bottom. Did a screen alignment with my B&K 1077B, and it has an outstanding picture, so I have placed it in my weekly rotation of working vintage sets. The pic has a very slightly yellow tint, unlike a regular tv. To improve visablilty, like those yellow tinted glasses? No audio or speaker, so I'm using my old Bose Waveradio as it's sound system. Inside, it's set up very nice, appears to be high quality, with plug in replaceable subsystem boards: A low voltage power supply, a video board, and HV deflection board. Nichicon electrolytics. The picture comes up very quickly, only about 3-4 seconds or so after switch on, I checked with my Kill-A-Watt, there's no instant-on. I've been able to find just about absolutely nothing online technically about this unit. The CRT has no nomenclature on it. The history of teleprompters is interesting. Is anyone else using a utility or industrial monitor for a tv?

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 Post subject: Re: Show your utility monitor tv's?
PostPosted: Sep Mon 14, 2020 4:19 am 
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I have modified open frame video monitors and built enclosures for them. The one in the article attached was a 525 line job, I modified it to auto-detect a 405 line signal (old UK system) and do a scan frequency conversion to a line rate of 10,125 Hz. The method I used (of my own creation, you won't see elsewhere) to do the scan frequency conversion, while still maintaining good H linearity is explained in the article. It is a very useful utility monitor to have on the bench being multi-standard. As noted there are other ways to do it re-configuring the H def yoke coils:

http://worldphaco.com/uploads/Autodetec ... nitor..pdf

Your monitor looks very nice.


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 Post subject: Re: Show your utility monitor tv's?
PostPosted: Sep Mon 14, 2020 4:44 am 
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I'm pretty sure that Dotronix would make a schematic available to you if you asked. I think they are still in business (at least their web site is still active). They made a ton of these basic monochrome monitors for re-packaging by other manufacturers. Q-TV used various models from Dotronix. The high brightness might have been a defect that caused it to be tossed to the curb. But is it possible that you do not have a 75 ohm terminator stuck on the loop-through BNC? I can't quite tell from the picture. And I really don't understand why the picture would have a yellow cast. I've worked around a few studios but have yet to work in one where they smoked so much that the teleprompters got yellow!


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 Post subject: Re: Show your utility monitor tv's?
PostPosted: Sep Mon 14, 2020 5:49 am 
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If you look closely with high magnification of the screen phosphor, when it is illuminated you will find is is comprised of a mixture of microscopic blue & yellow granules. It was not always like this prior to WW2.

In any case, some "P4" phosphor formulations could have a preponderance of either the blue or the yellow granules in the mix. When mixed about right the color has a somewhat silvery look to it (hence the silver screen) at other times not dissimilar to moonlight. P4 phosphors were made by more than one manufacturer, typically the one made by Dumont had a yellow cast to it. I have a number of P4 CRT's with a surprising wide array of "white". There is a yellow phosphor type, but generally that is long persistence. In addition, in the early 1980's Conrac manufactured a range of CRT's with a phosphor called "Paper White" which really did look like a white sheet of paper.


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 Post subject: Re: Show your utility monitor tv's?
PostPosted: Sep Mon 14, 2020 5:17 pm 
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Location: Detroit, Michigan
It has a switch controlled internal 75 ohm termination. Toggling this made no difference, other than degrading the basic picture quality in the off position. I cleaned the screen thoroughly like I usually do with Windex. I remember when I was a teen I had a mid 50's RCA 21" B&W console in the basement, the screen had a slightly red tint to it, compared to my Trav-ler 21" B&W on top of it.

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 Post subject: Re: Show your utility monitor tv's?
PostPosted: Sep Mon 14, 2020 6:50 pm 
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Vacuum tube/hybrid monitors are kind of a sub hobby of my TV collecting.

This is a 1954 Tel-instrument color monitor its design appears to be an RCA CT100 chassis stripped of it's RF,IF, and audio, with provisions added for underscan mode and RGB input. It is probably the only one left in existence.... supposedly they rebadged some as Dumont and one Dumont version exists.
Unfortunately it was used as a parts set in a previous life so it is missing the contents of it's HV cage, it's control door, all it's tubes, it's external power supply, and some of it's neck hardware. A year ago I found a dud 15GP22 for it and a yoke, but I still need the proper yoke bracket and purity coil. This monitor isn't going to run until I can source a CT100 parts chassis/set to fill in the missing parts.
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RCA TM-21 the first 21" color broadcast monitor. Using a whopping 62 tubes, and having things like regulated B+ power supply and video feedback that no consumer tube set would have; it is probably the most over engineered highest tube count tube color set ever.
It works but I need to fix a horizontal sync instability issue, and install the new color killer relays.
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Late 50s GE monochrome monitor: a fellow MSOE alumni fished it out of the trash a decade or two before I enrolled and I ended up buying it from him.
Conrac CYB21 the last round CRT color broadcast monitor. It's a hybrid tube/SS design and has line delay line edge enhancement system. It makes a picture atleast as good as a premium 90's consumer set.
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Sony badged Setchell Carlson 17" color industrial monitor. This was before the Trinitron and before Sony exported color TVs to the USA back then they were experimenting with the EIAJ RTR color VTR system and adding color to it so my guess is they ordered this monitor to demonstrate their VTRs for trade shows in the US. Setchell Carlson was a TV and monitor producer in minneapolis and was well known for their modular tube chassis. They made monitors under their name and under other names under contract. Some of these were used in early automated industrial manufacturing equipment. Convergence is wonky but it is working.
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Admiral 23" monochrome TV/monitor. It has a jack pack to interface with EIAJ VTRs and likely was a school/institutional monitor. It works as found.
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Setchell Carlson 23" monochrome modular tube school TV/Monitor/amplifier. Working as found it is a monophonic unit but has provisions for stereo audio amplification...if I had another audio module I could connect it to a stereo VCR/DVD player and watch monochrome stereo movies. Unlike many TVs it doesn't limit monochrome video response so video input gives spectacularly detailed monochrome picture.
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My RCA CT-100, 21CT55 and CTC4s all semi qualify as monitors too.... while not built with inputs, in 1954-55 at colors introduction TVs were selling poorly and purpose built broadcast monitors were both in short supply and expensive so IIRC RCA issued official bulletins on modifying these sets to act as video monitors. The mod involved making a small 2 tube video preamp and connecting it. The CTC4 had some circuits to change video response.
The circuit for the CT100/21CT55 I have built and tried with both sets and found it to be pretty good, though I prefer RF on those sets.


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 Post subject: Re: Show your utility monitor tv's?
PostPosted: Sep Mon 14, 2020 10:52 pm 
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I remember being amazed at the TM-21 when I started work at RCA Broadcast Systems in 1972, just out of college. There were still a few around in the camera and telecine labs, though by then of course we had mostly Conrac solid state monitors. I recall being impressed by the pair of 807 transmitting tubes in the TM-21's horizontal deflection. Also that it was so incredibly heavy -- I couldn't imagine how they were supported overhead in some studios.

Your TM-21 appears to be wonderfully clean, almost like new.

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 Post subject: Re: Show your utility monitor tv's?
PostPosted: Sep Tue 15, 2020 12:56 am 
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Very nice monitor collection! That Setchell-Carlson set is interesting; I have been trying to document their products for years. There isn't much information on the company out there.

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 Post subject: Re: Show your utility monitor tv's?
PostPosted: Sep Tue 15, 2020 4:02 am 
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Did Setchell - Carlson have anything to do with Stromberg - Carlson?

Back in the '60s I did a conversion on what looked like a late 50s Setchell - Carlson 14" metal case B&W portable to work on CCIR, i.e. 625 line 50Hz 5.5MHz sound. As I recall it worked quite well. Our Ch2 was received on Ch4 on the dial and channels 7, 9 and 10 were each one channel down. Incremental tuner, I didn't want to mess with it!

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 Post subject: Re: Show your utility monitor tv's?
PostPosted: Sep Tue 15, 2020 5:12 am 
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Thanks.

My TM-21 is missing the back and has a few knicks on the top and sides but pretty good overall. It's one of the later production runs that came with a 21FBP22 CRT (early ones used the metal 21AXP22) it uses a pair of some octal type (6CD6?) for the horizontal output and not the 807.

Setchell Carlson was not related to Stromberg Carlson as far as I know. Both companies were opperating separately in the 1950s and Stromberg Carlson made telephonic equipment as well. Setchell Carlson was absorbed by 3M Wollensak for a while and eventually got spinoff into IIRC audiotronics which was a big player in the arcade monitor biz and still survives today. Setchell Carlson always designed and built their own TV chassis (th :idea: ough their color did borrow circuit designs from RCA). Stromberg Carlson started out rebadging Dumont's....my Stromberg TV10 is literally a Dumont RA103 chassis in a restyled cabinet with SC part numbers painted over the Dumont transformer numbers.
I actually own 3 Setchell Carlson sets: the Sony badged monitor, the school monitor and a color console (I used to own a monochrome portable too). The color models have threads over on Videokarma if you dig.

A cool bit of trivia about Setchell Carlson modulator tube color sets is that they designed them so if the color circuit died the tech could pull the module and bring it back to the shop for service and the rest of the set would continue to work as a monochrome TV....this was an advertised feature!


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 Post subject: Re: Show your utility monitor tv's?
PostPosted: Sep Tue 15, 2020 6:44 am 
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Quote:
A cool bit of trivia about Setchell Carlson modulator tube color sets is that they designed them so if the color circuit died the tech could pull the module and bring it back to the shop for service and the rest of the set would continue to work as a monochrome TV....this was an advertised feature!


That's exactly what HMV did here with their 1st color sets, all SS by this stage though.

Stromberg Carlson and Admiral both had a strong presence in Australia for the start of TV here in 1956. Stromberg Carlson TVs were local designs based on Philips / Euro practice, unlike Admiral whose 1st sets were only slightly modified from US models.

Admiral used PCBs from the start.

Stromberg Carlson used a strange system of "peg strips" - most of the passive components were assembled onto modules constructed of these strips. Extra lead lengths were trimmed in a single operation and the module was then solder bathed.

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 Post subject: Re: Show your utility monitor tv's?
PostPosted: Sep Tue 15, 2020 7:20 pm 
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Setchell-Carlson evidently got their start with farm and home radios, and dabbled with public address equipment and intercoms. They had a relationship with a company called Dahlberg, and made the radio for their "pillow speaker" motel sets. Their frogeye table radios were quite popular; I have several, including the seldom-seen portable.

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 Post subject: Re: Show your utility monitor tv's?
PostPosted: Sep Wed 16, 2020 7:10 am 
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Quote:
and made the radio for their "pillow speaker" motel sets.

The Hot Pillow Trade, eh?
(Ask someone who's run a motel)

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 Post subject: Re: Show your utility monitor tv's?
PostPosted: Sep Wed 16, 2020 8:46 am 
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The best monochrome video monitor (in terms of Engineering quality) I have ever seen was made by Conrac. A 14" set.

Being a mil-spec monitor is was as though everything about it was uncompromising and not a dollar was spared making it. It also has a wonderfully austere look to it. The vertical scan osc is based on a UJT and it locks automatically to 50 or 60Hz scan rate and the AFC lock range is so good also 525 or 625 line rate.

Of course there is no manual for it. I traced out the entire circuit by hand and documented it.

The monitor has the most fantastic video black level clamp in it, which is a type of gated negative feedback loop, it exceeds the performance of any DC restorer or black level clamp in any video monitor I have seen. It turned out that the idea for this genius type of system was invented by Tektronix. (they have a habit of very clever discrete circuit designs as everyone who works on their scopes and test generators knows).

This monitor also has the distinction of not containing a single electrolytic capacitor, so I was won over by that in milliseconds, in conjunction with its other engineering features I decided to award it with the title of the best monochrome video monitor ever made. I even sent the Conrac factory a letter of congratulations.

If you want to learn more about this monitor and see how the Conrac company did it, here is the article, even the fixing devices used in it are inspiring:

http://worldphaco.com/uploads/The_1987_ ... nitor..pdf


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 Post subject: Re: Show your utility monitor tv's?
PostPosted: Sep Thu 17, 2020 12:56 am 
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I've been hanging on to this 27" Sony Pro Monitor for some reason.
It ancient by modern standards, it has multiple Composite inputs and a Scart connector, not even S-Video.

It works like new, and collects dust like no flat screen can ever hope to.
It's also a great door stop, if you can move it to the door that needs to be stopped.

I'd probably get rid of it, if I could still lift it.

Paid next to nothing for it some years ago, It's probably gone up since then what with retro gaming and all.

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 Post subject: Re: Show your utility monitor tv's?
PostPosted: Sep Thu 17, 2020 1:20 am 
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Those things are multi-standard too.

Reason for no Y/C input is there is no benefit - comb filter gives same performance from composite.

Did you ever try feeding that monitor with a PAL signal?

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 Post subject: Re: Show your utility monitor tv's?
PostPosted: Sep Thu 17, 2020 9:17 am 
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irob2345 wrote:
Those things are multi-standard too.

Reason for no Y/C input is there is no benefit - comb filter gives same performance from composite.

Did you ever try feeding that monitor with a PAL signal?


I don't have anything that outputs a PAL signal so no, also I don't think this one has a comb filter, I could be wrong of course.
I would actually say this monitor has lesser picture quality than my 1990 consumer grade XBR did (long gone), which did have a comb filter.

A couple corrections, it's a 25" screen (PVM-2530) and it does have S-video, the ones above serial # 200800 did and this one is 202,000 something.

Specs:
Inputs:
A/B NTSC composite video with 560 lines resolution.
S-VHS ( If the serial no is over 200800 or so, switch with the EIAJ-1 connector)
RGB
EIAJ-1 VCR connector ( 8 pins)
Computer Analog/TTL, D-sub 25 pin, at 640H and 200V pixels,
A/B Stereo Audio RCA inputs
Control S in and out.


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 Post subject: Re: Show your utility monitor tv's?
PostPosted: Sep Thu 17, 2020 9:57 am 
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Hmmm, looks like we saw a different model in Oz. I'd be surprised if yours isn't multi-standard though. All the ones we saw had the Philips digital multi-standard chipset.

Heavy, aren't they?

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 Post subject: Re: Show your utility monitor tv's?
PostPosted: Sep Thu 17, 2020 4:15 pm 
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Eric H wrote:
I've been hanging on to this 27" Sony Pro Monitor for some reason.
It ancient by modern standards, it has multiple Composite inputs and a Scart connector, not even S-Video.

It works like new, and collects dust like no flat screen can ever hope to.
It's also a great door stop, if you can move it to the door that needs to be stopped.

I'd probably get rid of it, if I could still lift it.

Paid next to nothing for it some years ago, It's probably gone up since then what with retro gaming and all.

Attachment:
sony-pro.jpg


When da corona beer virus is over or right now( if you don't believe in da rona) you could probably throw that picture on Craigslist with a price and watch some young spry gamer hand you money and carry it from it's current resting place.


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 Post subject: Re: Show your utility monitor tv's?
PostPosted: Sep Fri 18, 2020 12:12 am 
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Location: Belrose, NSW, Australia
Even better, put a gaming picture on it.

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