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 Post subject: Hitachi 27" 27MM20B Dual-Scan CRT TV??
PostPosted: Sun Aug 15, 2021 9:33 pm 


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Guys, anyone here ever hear of an actual dual scan 15/31KHz television? I have an opportunity to get a literal PILE of these sets, which have been palletized, wrapped and are awaiting pickup. I was told they were 36" sets and I was hoping some of them might be of the same HD type that I used to have, but I had the lady in charge of them take a picture of the model # label and send to me and below is what it is. Supposedly its got a VGA input and can accept 31KHz as well as composite and S-Video? These sets were used at a school system, its possible they were bought to hook PCs to.

At first I was disappointed that they were not indeed the 36" model I was looking for, but this might be even more intriguing. Ive never seen anything like this in the US. Anyone ever see anything like it? If I choose to get them Im probably going to be out $1000 USD (just a guess) for LTL freight trucking, but theres supposed to be 46 (!) of these sets along with some VCRs and stuff. I would obviously be looking to sell most of them so I could at least recoup the costs. Its pretty crazy, but Im considering it.

jortego128@centurylink.net

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Info from a 1998 Hitachi press release:

Quote:
"To complete its UltraVision Digital lineup, Hitachi offers a Digital TV Ready model, the 27MMV30B. This unit blends the functionality of a TV and PC monitor into one unit, perfect for both the home theater and PC enthusiast. Connect a digital set-top box to the VGA input, and you get true 480p resolution. Connect a PC, and you get true VGA (640x480) resolution. "MMV is actually three TV's in one," said Ramirez. "It's a high quality analog TV, a digital ready TV, and a true VGA computer monitor." Available now for a suggested retail price of $999, this 27" Digital TV Ready model includes an UltraBlack picture tube, comb filter, VSM, and self-dynamic focus. It also offers complete MTS stereo/SAP with dbxÖ, a 181-channel TV tuner, 6 watt front firing speaker system, and VGA input for true VGA (480p) resolution."

https://www.hitachi.us/press/archive/09211998


Last edited by Josh128 on Tue Sep 14, 2021 12:46 pm, edited 5 times in total.

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 Post subject: Re: Hitachi 27" 27MM20B Dual-Scan CRT TV??
PostPosted: Sun Aug 15, 2021 10:58 pm 



Joined: 14 Aug 2017
Posts: 1669
Does the manual say it's dual scan? Without any other info, I would probably bet that the composite and s-video inputs go through an internal scan doubler. Some "PC TVs" in other regions did that and of course they were really just 31khz.


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 Post subject: Re: Hitachi 27" 27MM20B Dual-Scan CRT TV??
PostPosted: Mon Aug 16, 2021 12:46 am 


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Below is the link to the manual I posted the pic of. It doesnt say dual scan, but it only refers to 31KHz in regards to the VGA port, so I really dont know. Dual scan would be cool, but with the scalers available now, 31KHz if thats all it is, is fine. This set is also a shadow/slot mask CRT, not an aperture grill, so its going to be pretty unique if its just a 31KHz TV, Ive never seen such a thing, especially back in Feb of 1998. I believe that pre-dates all other HD-Ready tvs. It also includes an NTSC tuner, so it would have to have upscaling tech if its not a dual scan. I think dual scan would be more likely. Im not sure.

I'll probably have to rent a freaking storage unit if I buy these things, but Im a nerd who loves old display tech and I dont care. :lol: All I know is if these things are 27" slot mask 31kHz single scan or 15/31kHz dual scan, both are extremely unique as far as I know of. I'm going to contact the person in charge tomorrow to make sure they indeed do have a VGA port on them. If I get a surprise tractor-trailer load of 40+ regular old 15kHz sets Im going to feel a lot more stupid than I do now for considering them if they are indeed 31KHz units. :mrgreen:

https://www.epanorama.net/sff/Video/Pro ... MMV30B.pdf


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 Post subject: Re: Hitachi 27" 27MM20B Dual-Scan CRT TV??
PostPosted: Mon Aug 16, 2021 12:55 am 


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http://mikejmoffitt.com/articles/0051-nettv-rgb.html

I have this (it doesn't have a tuner but whateverrr), but you need to mod the SD daughterboard / add a new connector (I personally opted for 4 BNC instead of VGA) for RGB. The VGA port can sync to 720p as well / 1024x768 / 1080i etc.

As far as *on the same VGA connector*/same RGB input, there is the Toshiba TIMM and then a bunch of other presentation monitors, but obviously none of the latter qualify as a TV. The TIMM has a TV tuner, though... if you wanna get down to brass tacks. But unless a CRT TV has an ATSC tuner in it then it doesn't really matter anymore RE: internal tuners, heh (er, at least in NTSC-U land)
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 Post subject: Re: Hitachi 27" 27MM20B Dual-Scan CRT TV??
PostPosted: Mon Aug 16, 2021 2:57 am 


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Interesting. What year were those things made? I should find out more about these tomorrow. Hopefully I can get them shipped for under $1500, cause if not, I dont know Im going to do it. However, if those things are anything close to what you just posted, it would be WELL worth $1500 IMO. I'd just hate to get a truckload full of shit that somehow just down converts to 15kHz or something, you know?


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 Post subject: Re: Hitachi 27" 27MM20B Dual-Scan CRT TV??
PostPosted: Mon Aug 16, 2021 10:06 am 


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Service manual can be found on Elektrotanya:

https://elektrotanya.com/hitachi_27mm20 ... nload.html

Didn't really comb through it (although it does indeed look like it's dual sync), but I did notice that the tube model is a A68KSA30X which is also used in a bunch of arcade cabs. So you could possibly sell a few of them regardless if the actual electronics are any decent or not.


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 Post subject: Re: Hitachi 27" 27MM20B Dual-Scan CRT TV??
PostPosted: Mon Aug 16, 2021 10:57 am 


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Fantastic, thanks for that. I was thinking of the arcade monitor possibility as well. If the freight is not too insane, Im going to take the chance on it. My birthday is in two weeks. Last year I convinced my wife to let me get an arcade machine, I guess I need to outdo myself and go for this. I'll have to rent a storage unit to put this shit in lol. :shock:


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 Post subject: Re: Hitachi 27" 27MM20B Dual-Scan CRT TV??
PostPosted: Mon Aug 16, 2021 1:41 pm 


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where are you located? if it was a true dual scan chassis I'd probably buy one or two off you if within driving distance

if it's just a 31kHz set with a scan doubler inside, meh


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 Post subject: Re: Hitachi 27" 27MM20B Dual-Scan CRT TV??
PostPosted: Mon Aug 16, 2021 1:44 pm 


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The "MM" in the model number makes me think of these...

https://lowendmac.com/2019/rca-mm36100- ... t-display/

...which have 15kHz component! There is also a variant of the 'NetTV' (Sampo, w/ a monitor-grade Toshiba Microfilter tube) called the SME-32DL5 with 15kHz component
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 Post subject: Re: Hitachi 27" 27MM20B Dual-Scan CRT TV??
PostPosted: Mon Aug 16, 2021 2:06 pm 


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Kitty: Remember how we spoke about how the sets above could have possibly shared the same tube or components as the 36" Hitachi set I used to have? These could be similar to that, except 27" models. These dont have component inputs, just VGA, composite, S-video, and RF (analog). Looking at the pics they sent, Im almost positive theres at least 1 Ultravision Digital in there as well. This looks to be some really cool shit.

Max: Its very likely they are dual scan. In early 1998 Im not sure that upscaling tech was really a thing, these look to be monitors. Im guessing its going to be like that set Kitty posted above-- to get 15KHz RGB its probably going to need a mod, but the documentation posted above is kick-ass, that should be doable. Im down south in south central Louisiana. I'll definitely be looking to sell a lot of these sets-- if I can RGB mod them for 15KHz reliably I'll probably do that to some I sell as well. Im sure some will have to be shipped as well.

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 Post subject: Re: Hitachi 27" 27MM20B Dual-Scan CRT TV??
PostPosted: Mon Aug 16, 2021 2:08 pm 


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well shit I was just in Liberty, MS last week could have swung by on the way back

what makes you think it wouldn't accept 15kHz RGB on the existing RGB input?


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 Post subject: Re: Hitachi 27" 27MM20B Dual-Scan CRT TV??
PostPosted: Mon Aug 16, 2021 2:23 pm 


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maxtherabbit wrote:
well shit I was just in Liberty, MS last week could have swung by on the way back

what makes you think it wouldn't accept 15kHz RGB on the existing RGB input?


The OP spec sheet makes it sound unlikely / I also find it unlikely as I have seen zero 'prosumer' TV/monitors like this which accept 15+31 on the same VGA connector... only full-on pro/presentation monitors like certain NECs/Mitsubishis/et al :[

Except for the Toshiba TIMM, but that's 20" and from the earlier half of the 90s. Pretty much a separate category from these types of things

Josh128 wrote:
Kitty: Remember how we spoke about how the sets above could have possibly shared the same tube or components as the 36" Hitachi set I used to have? These could be similar to that, except 27" models. These dont have component inputs, just VGA, composite, S-video, and RF (analog). Looking at the pics they sent, Im almost positive theres at least 1 Ultravision Digital in there as well. This looks to be some really cool shit.


Yeah, I remember that! The 'MM' makes it even more likely to me... guess this may just be a slightly earlier variant (or if not earlier, simplified)
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 Post subject: Re: Hitachi 27" 27MM20B Dual-Scan CRT TV??
PostPosted: Mon Aug 16, 2021 2:57 pm 


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well I've skimmed the service manual and I'm inclined to agree that 15kHz RGB probably won't work out of the box

there are several ways to approach a mod though:
1) the neckboard has a RGB switch IC on it to switch between TV and PC RGB, which could be overridden while keeping the set in "TV" mode for HV drive purposes
2) the deflection circuit switch could be similarly overridden to TV drive mode while the set in in PC mode for RGB
3) do an old fashioned OSD mux on the TV side's jungle chip and just solder onto the existing VGA connector to grab the signals

all of these are subject to further review but I'm fairly certain that at least #3 would be pretty doable


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 Post subject: Re: Hitachi 27" 27MM20B Dual-Scan CRT TV??
PostPosted: Mon Aug 16, 2021 3:15 pm 


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kitty666cats wrote:
Except for the Toshiba TIMM, but that's 20" and from the earlier half of the 90s. Pretty much a separate category from these types of things



Fun fact about the Toshiba TIMM, btw - my friend discovered you can (if you wanted to for some reason) use the composite RCA input for sync while in RGB mode! Pretty cool; I really hope I come across a TIMM someday... but they are ridiculously hard to find.
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 Post subject: Re: Hitachi 27" 27MM20B Dual-Scan CRT TV??
PostPosted: Mon Aug 16, 2021 10:19 pm 


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Well, I pulled the trigger. 15 pallets of TV/Monitors and 1 pallet of remotes and/or VCR's and other assorted equipment. Tentatively scheduled to arrive Thursday or Friday. The shipping was VERY expensive, had to do FTL instead of LTL but I think I got a decent rate. Still, it was more than I was really comfortable spending for sight unseen gear, but I took a chance. Hopefully they are not 100% shit. :|

If it turns out they are indeed cool dual scan CRTs with a nice picture that can easily be modded for 15KHz RGB (though they do support S-Video if its not worth the trouble), I plan to thoroughly test and sell them for an affordable price. I would just like to be able to at least recoup my money for shipping eventually. Expect plenty of pictures and tests soon. Anyone interested in one just hit me up and we can work something out, I dont exactly expect they will sell like hotcakes, lol, but if they do what I hope they can do I'm pretty sure I'll be able to move some locally on FB marketplace. I can also ship, but of course thats going to be costly.


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 Post subject: Re: Hitachi 27" 27MM20B Dual-Scan CRT TV??
PostPosted: Mon Aug 16, 2021 11:45 pm 


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I like that they also have a port for a wired mouse, lol - I wonder if there's some interesting weirdness you could achieve with that port (via some clever modding or whatever)...
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 Post subject: Re: Hitachi 27" 27MM20B Dual-Scan CRT TV??
PostPosted: Mon Aug 16, 2021 11:55 pm 


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kitty666cats wrote:
I like that they also have a port for a wired mouse, lol - I wonder if there's some interesting weirdness you could achieve with that port (via some clever modding or whatever)...



Yeah, isnt that weird? I really have no idea what that could be useful for? What does it actually control? Were there some VGA cards that used pins on the D-Sub 15 port for mouse comms or something?


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 Post subject: Re: Hitachi 27" 27MM20B Dual-Scan CRT TV??
PostPosted: Tue Aug 17, 2021 1:28 am 


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I believe the mouse port allows you to use the television's remote as a mouse for the attached pc


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 Post subject: Re: Hitachi 27" 27MM20B Dual-Scan CRT TV??
PostPosted: Tue Aug 17, 2021 8:37 am 



Joined: 17 Mar 2018
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Josh128 wrote:
Well, I pulled the trigger. 15 pallets of TV/Monitors and 1 pallet of remotes and/or VCR's and other assorted equipment.


Exciting :!: I'll be keeping an eye on this thread :D


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 Post subject: Re: Hitachi 27" 27MM20B Dual-Scan CRT TV??
PostPosted: Tue Aug 17, 2021 3:10 pm 


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Nice find! Would be interested in picking up at least one of these from you when the time comes, if you have a list going put me down as interested. been wanting a larger size vga crt for some time. Not sure of what it would cost to ship to Maine though.

Looking forward to seeing how these look in your testing!


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 Post subject: Re: Hitachi 27" 27MM20B Dual-Scan CRT TV??
PostPosted: Wed Aug 18, 2021 6:21 am 



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Josh, are you aware of the CRTGaming subreddit? If you have any trouble moving a number of sets, you'll probably find interested people over there.


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 Post subject: Re: Hitachi 27" 27MM20B Dual-Scan CRT TV??
PostPosted: Wed Aug 18, 2021 11:01 am 


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Thanks! I browse there from time to time but I actually hadnt thought of that for these sets. Thats a great idea. I procured a storage unit yesterday, but that will probably house less than half the units, lol. Im going to need to move these as quick as possible.

Im stressing about the delivery, my workplace gave permission for me to use one of our forklifts to unload the truck, but they were iffy about liability and such. Im going to have to make 3 to 4 trips with my pickup and 16' tandem axle trailer to get that stuff out of the yard. A lot of stress, sweat, and body aches incoming, lol. :shock:


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 Post subject: Re: Hitachi 27" 27MM20B Dual-Scan CRT TV??
PostPosted: Wed Aug 18, 2021 11:10 am 


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Save some strenght for the pictures. We are all waiting for those :mrgreen:


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 Post subject: Re: Hitachi 27" 27MM20B Dual-Scan CRT TV??
PostPosted: Wed Aug 18, 2021 1:04 pm 



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I love ridiculous operations like this :D A couple of years ago, I helped a friend unload and test 30 PVM 2950 cubes in flight cases. What anawesome afternoon that was.


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 Post subject: Re: Hitachi 27" 27MM20B Dual-Scan CRT TV??
PostPosted: Wed Aug 18, 2021 2:29 pm 


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Josh128 wrote:
Thanks! I browse there from time to time but I actually hadnt thought of that for these sets. Thats a great idea. I procured a storage unit yesterday, but that will probably house less than half the units, lol. Im going to need to move these as quick as possible.

Im stressing about the delivery, my workplace gave permission for me to use one of our forklifts to unload the truck, but they were iffy about liability and such. Im going to have to make 3 to 4 trips with my pickup and 16' tandem axle trailer to get that stuff out of the yard. A lot of stress, sweat, and body aches incoming, lol. :shock:

guess you will just have to not drive the lift into anything, I have faith in you bro


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 Post subject: Re: Hitachi 27" 27MM20B Dual-Scan CRT TV??
PostPosted: Wed Aug 18, 2021 6:45 pm 


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Update: Equipment was picked up without incident from the origin facility 880 miles from me and is en route to my location, ETA tomorrow afternoon.

Fingers crossed it arrives on schedule and in good shape and the unloading goes smoothly. :)


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 Post subject: Re: Hitachi 27" 27MM20B Dual-Scan CRT TV??
PostPosted: Thu Aug 19, 2021 8:14 am 


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I'm curious what the tube model is, and the inductance of the deflection yoke. I may be interested in one or a few (acknowledging that shipping cross-country is unpleasant).
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 Post subject: Re: Hitachi 27" 27MM20B Dual-Scan CRT TV??
PostPosted: Thu Aug 19, 2021 10:45 am 


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I have an el cheapo Chinese L/C meter thats pretty accurate in what Ive tested so far, so thats something I can check and post here for you. I assume thats to cross reference to some type of arcade monitor? Also Mike, do you mind taking a quick look at the circuit layouts shown in the service manual posted above and let me know what would be your chosen approach to a 15kHz RGB mod? Assuming that 15kHz RGB/VGA doesnt work out of the box, which I intend to try as well.

Im nervous about unloading all this today. Not about my ability to do so, but about nosy co-workers, potential for some T-storms today, and me trailering the pallets out of there and to a safe location without anything toppling or getting wet.


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 Post subject: Re: Hitachi 27" 27MM20B Dual-Scan CRT TV??
PostPosted: Thu Aug 19, 2021 12:39 pm 


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Oh man this is super exciting!

Looking forward how this all ends, thanks for taking the time to share your adventure!


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 Post subject: Re: Hitachi 27" 27MM20B Dual-Scan CRT TV??
PostPosted: Thu Aug 19, 2021 3:17 pm 


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The TV has a TA1268N,from looking at the service manual it should be very easy to get rgb going,don't think it will work with the vga by default as the rgb is for the osd.

But really awesome score you got,if you were closer I definitely buy one but I know shipping would be killer.


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