Son HB-75P RGB output: blueish tint and washed out colors

By Wild_Penguin

Hero (538)

Wild_Penguin's picture

25-03-2019, 19:43

Hi all!

Recently did an RGB cable to connect to my projector. My NMS-2855 and AX-350II have an excellent picture with it!

However, the Sony HB-75P seems to be having some kind of problem. I'd like to know if this is by design (i.e. a "feature" of MSX1 VDPs and/or RGB implementation) or perhaps something is broken or adjustable.

The picture is somewhat too blue - it's quite usable but the difference is clear compared to the other two MSXes I mentioned. All blacks are slightly blue, nothing is really black. Reds are red and greens are green and yellow is yellow ... but the darker the color, the more blue. I believe whites are quite white, though.

I tried to adjust the R-G-B Vr's (mentioned in the SM on page 52 / 5-21). I couldn't get the picture any better it was when I started; I can get black to be black but then colors are quite washed out, or colors to near-perfect level, but then everything supposed to be black has a bluish tint to it.

There's the procedure to adjust picture in the SM from 6-1 onwards. Didn't touch the Video Level, do own an oscilloscope. Is this something I should attempt on adjusting (in case I want to perfect the picture) - go trough these and adjust the levels with the help of the oscilloscope?

A little bit of background: when I got this computer, it had the capacitors in the 12V and 5V power rails blown; these are in the SM on page 55 (5-24) and in the picture linked at the bottom of this post (after replacement). Miraculously I did try to power up the unit before I got it and didn't notice any problems, so the regulators do good enough of a job even without the capacitors Wink Recommendation: check your unit. Props for Sony for putting these, prone-to-explosion components on separate small PCBs, away from other components.

This is just a bit of information - in case other users don't have this problem, maybe some components didn't like the voltage fluctuations caused by missing capacitors?


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