Revisiting the Sony BVM 20F1: BKM-21D no colour fix, operation hours, & transcoding composite to RGB

The Sony BVM 20F1 is a top contender to be the king of all 4:3 standard def CRT’s. I had recapped and calibrated the monitor before tucking it away into storage, and have since enjoyed gaming on a widescreen CRT. But a high end consumer CRT doesn’t match the sharpness and accuracy of this 900TVL Broadcast Video Monitor.

I pulled the monitor out to find it inconsistently displays PAL 60Hz in full colour via the BKM-21D addon card. While capacitors were on order, I also went on a composite to RGB transcoding venture to bypass the BVM’s malfunctioning composite video board.

After going down the transcoding rabbit hole, and with advice from Savon Pat, I recapped the BKM-21D to have clean composite video in PAL 60Hz. Attached below is the link to the cap list.

Most topics covered should also be applicable to the BVM 14F1 and other monitors that also accept the BKM 21-D option card such as the BVM D20F1. The 20F1 suffix differs depending on region eg. 20F1U (US,) 20F1E (Europe), 20F1A (Australia), 20F1J (Japan). Other topics include degaussing, operation hours in standby, auto calibrating to SMPTE colour bars without the BKM 14L probe, 75ohm termination and firmware revisions.

Transcoders tested:
- Sony YR-421 S-video to RGB through JP21 (converted to Euro-Scart)
- Extron CD 900 composite and S-Video to component and RGB (RBGs, RGsB, RGBHV, YPbPr via BNC)
- OSSC Add-on board composite and S-Video to component and RGB (YPbPr through RCA and RGB through Scart)
The transcoding segment is a prime example of what happens when a company clones a product and calls it their own. Buy from the original creators:
Retrotink 2x Pro

A warning that working on a CRT can be dangerous and if not lethal. You should not attempt to open up or fix anything IT without having good understanding of safety precautions. I am not responsible for any harm or damage done to anyone or anything. After all, this video is just a video diary of my progress. And if you have epilepsy or photo sensitivity, I do not recommend you watch this video. 
#crt #retrogaming #pvm #crtgaming #trinitron #transcoding #tvrepair #soldering #sony

Links
Original BVM 20F1 recap and upgrade video

BKM 21-D capacitor list

Sony BVM 20F1 operation and service manual

F series BVM firmware

Credits

RetroRGB
Sony YR-421 analysis
Interview with ​⁠Phonedork, brief discussion of the BKM 14L probe

​⁠​⁠​​⁠​⁠Zez Retro
Sony YR-421 review

​⁠​⁠​⁠​⁠​⁠Wren Tubes
Degaussing using a drill

Andrew One Man Band
Bob Ross Joy of painting cover

00:00 Intro
03:30 Testing operation hours
05:50 Auto calibrating
07:52 BKM-21D composite video
10:52 Transcoding composite to RGB
19:34 Recapping the BKM 21-D
21:54 Summary

[squiddude]

A little more info about the auto preset calibration, as far as I know it only affects the colour voltage levels, not the colour temperature controls, and as such it should be ran before calibrating white balance with a colorimeter. You can see what it affects in Maintenance → Setup (but be warned, going into the setup menu will set the phase, chroma, brightness and contrast values in the user preset menu back to 1000). For the autocalibration process itself, the monitor expects full field colour bars from a reference pattern generator. I've had good luck on all of my BVMs with my LT-448 pattern generator, Wii YPbPr is probably the closest you can get to that with consumer equipment. Also, as you can see in the setup menu, there's independent controls for RGB, YPbPr, composite and a few others, so I always make sure to run the auto calibration on RGB and YPbPr separately to make sure they're all set up correctly. btw, I think there's a couple of reasons the MiSTer doesn't work very well for this : the 240p test suite itself doesn't output reference quality colour bars on original hardware on any console as far as I know, but the MiSTer accentuates this by having large issues with its analog output. Depending on the I/O board you use, the voltage levels can be way off (the official one is the worst, it can vary by ~±100mv, which is a lot considering the standard for analog video is 700mv on a full white screen). The retrocastle I/O board is actually almost perfectly on spec, and it's great for RGBs output, but it still suffers from inherent issues with RGsB (sync on green) and YPbPr output. RGsB has a large green deficiency (it was reading 750mv on red, 870mv on green, and 750mv on blue, it should be 700mv, 1000mv and 700mv respectively), and while YPbPr has the correct colour voltages relative to each other, it's 60% lower than it should be (on my calibrated 20F1, reference reads 100 nits at 100 IRE, but the MiSTer was reading 60 nits). Hopefully this information helps somebody out :)

[Misterfabuleux]

Very interesting video, many thanks 😉

[twotone]

I've also had the same difficulty trying to run the auto calibration on my D20F1U. It's comforting to see someone else having the same issues on a similar set. I was worried something was wrong with my set.

[LghtOn]

Always wanted to understand TV better, especially Analogue TVs, just never got round to it. ✌🏽

[sasheendowlath]

While I haven't attempted this yet, I did pick up a used colourmunki photo a few years back for CRT calibration. Its a spectrophotometer as opposed to a colorimeter, so hopefully wont be subject to the shortcomings of ageing colorimeter filters.

[crt_rex]

Loved the chill intro. I had a lot to say about PAL that would probably make many people angry and prompt the superior colors, RGB SCART availability and America=Satan responses, but as far as gaming, and for a lot of things I personally want to do, such as playing my intros and breaks on VHS while on stream, it has been the bane of my freaking existence, and I have grown an almost irrational disdain and hatred for it over the years. In addition to consoles and even CRTs, I now need to import VHS players from back home as well, to do the stuff I need. Granted, I chose to move here, so it is what it is.

But onto more positive things, have you ever seen or heard of the BVM-1911 (BVM-2011P in Europe)? It's also 900TVL and reminds me a bit of your pride and joy there, just older. I managed to get one, and out of my 30 plus CRTs at this point, it is my damn favorite. The only reason I haven't made a playthrough video on it yet is because I will have to carry it to the shed, where I record my videos and do my streams, and man, that's a good deterrent. Loved the video as usual, great job. PS edit: beautiful dog at the end.

[unchiga]

Loving your videos, very well made and informative. I just ordered a BVM-20F1U and its currently in freight delivery. I'll be looking to your channel for some guidance, its also recently been recapped and calibrated by SavonPat

[crtautist]

Wow quality footage of them scanlines. wats ur secret?

[ChrisPaterson_]

I've got a BVM-14H5A and PVM-14L5A, PVM-20L5J. I find the BVM to be much more fussy about inputs than my PVMs. It is just weird behaviour, where as I can just connect anything and everything to my PVMs and they display fine. One of the reaons I never use my BVM, really should move that guy on.

My setup is full component for convience, no switching inputs or changing settings it is sweet.

[LetsPlayKeldeo]

Hey sorry to ask here like that but I have an Sony BVM but the picture collapsed and I dont know where to start faultfinding on the unit

[AnotherFreakingDude]

Video editing on PowerPoint? Pfffft, real men edit straight up with FFmpeg writing every parameter on the command line.