Sony HB-75p and Akai LED tv connected via scart cable gives a few problems.

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By WillemH

Rookie (21)

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03-02-2021, 16:55

As the title says it, I have some problems with this combination.
The scart cable is completely wired.

During starting of the HB-75 everything looks good on the TV, starting up Basic is also not a problem.
From time to time however the screen turns blue for a moment (as the TV should do without any input) and then the Basic screen comes back.
Also sometimes the basic screen shifts to the left a little so the first 2 digits of the line numbering are not visible then.
The screen comes back to normal after a couple of seconds.

It is not a big deal but is just frustrating that I cannot figure out what is wrong.

If somebody has an idea, please let me know.

Regards, Willem.

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By WillemH

Rookie (21)

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04-02-2021, 11:16

Nobody?

By Bastiaan

Champion (333)

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04-02-2021, 12:01

maybe your LCD does not support all the old resolutions used by the MSX?

Try some screen commands in Basic.

By Meits

Scribe (6373)

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04-02-2021, 12:45

Have you tried different screens?

By WillemH

Rookie (21)

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04-02-2021, 17:08

The LED TV supports all the resolutions.
I do not have another (small enough) TV to check.

By Grauw

Ascended (9824)

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04-02-2021, 17:48

It sounds like a sync signal issue on either the computer’s or TV’s side…

You could try to use a SCART to HDMI adapter to convert the signal, it may have better signal tolerances.

Also as a test, try the COLOR 15,1,1 : CLS and COLOR 1,15,15 : CLS BASIC commands, they turn the screen black and white respectively, I’ve seen before that this can trigger issues with sync.

By WillemH

Rookie (21)

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04-02-2021, 18:48

I will try tomorrow.
Thanks for the message.

By SkalTura

Champion (323)

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05-02-2021, 07:53

I used a SCART Scaler to connect my MSX to an LCD monitor, and had this same problem.

The solution for me:
In screen 5, load a black image with a white border around the entire image. Then auto-centered the monitor.
After this, everything was visible in all screens from screen 0 to screen 12...

Maybe this will work for your TV as well...?

By WillemH

Rookie (21)

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05-02-2021, 08:45

All,

I have tried everything without result.
The switching back to the blue screen and returning to normal (basic) screen happens from time to time, no regular intervals.
The same for the shifting to the left of the screen.

Yesterday evening I opened up the case of the computer, mainly to discover why the cursor buttons sometimes fail to react (I think I will replace them if I can find the correct types here in The Netherlands) and noticed 2 leaking capacitors (47uF, 16V) on both voltage regulator prints (5V and 12V). I will replace them also.

By sdsnatcher73

Paragon (1859)

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05-02-2021, 09:21

Your issue is most likely caused by the sync on the SCART outlet. If the sync is lost your screen will loose the signal, also the shifting in the horizontal plane as you describe is a sync issue.

The screen blanking is probably vertical sync and the screen shifting horizontal sync. Now this could be caused by the computer but also by the tv not detecting the sync properly. Most likely it is just the combination that has issues an the most likely reason is the HB-75P not sending a clean sync but composite video instead. Some monitors/TVs don’t like that.

In this thread it is suggested to use a so called sync stripper. This takes the composite video as input and delivers a clean sync signal as output. That would be worth trying imho.

By WillemH

Rookie (21)

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05-02-2021, 13:21

I think that may solve he problem.
I have already ordered the correct switches below the cursor buttons and the capacitors.
I will order the sync stripper also.
Once everything is delivered I will install everything and give feedback here.

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