Need any T7937 information

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Door dhau

Paragon (1558)

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05-03-2005, 05:34

I'm looking for any information on MSX1 "Engine" chip from Toshiba - T7937 (V9918 + AY8210 + Z80 all in one).

Ideally I need pinouts. Or a scan of service manual for Toshiba HX-51 or 52. I have a computer with this chip inside, and it only has composite output. I'd like to try and get RGB out working. I need to know what pins of T7937 are providing R, G, B and sync signals.

Please take a look, may be you have the service manual somewhere around... Thanks!

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Van dhau

Paragon (1558)

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10-03-2005, 19:42

Still need the info... Anyone? Please?

Van Alexandre_Taito

Champion (325)

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10-03-2005, 19:52

Van Alexandre_Taito

Champion (325)

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10-03-2005, 19:55

Hum...everything in portuguese...Here is some help:

R - pin 37
G - pin 39
B - pin 41
Sync - There is NO separate sync output, but you can use pin 17 (composite video signal) or pin 35 (Y - Luminance signal) as a sync source. Since the Sync is a NEGATIVE pulse the sync detector will look only for the negative component of the signal. Anything else???

Van dhau

Paragon (1558)

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10-03-2005, 22:02

Thanks, that's great for start! My girlfriend speaks Portugese, so I'm fine, more or less. Great help, brother!

Van HansO

Paladin (672)

afbeelding van HansO

11-03-2005, 08:43

Hum...everything in portuguese...Here is some help:

R - pin 37
G - pin 39
B - pin 41
Sync - There is NO separate sync output, but you can use pin 17 (composite video signal) or pin 35 (Y - Luminance signal) as a sync source. Since the Sync is a NEGATIVE pulse the sync detector will look only for the negative component of the signal. Anything else???

Yes, using the composite signal or (better) luminance as sync will work.
Add buffers to these outputs, do not connect directly to a RGB monitor.
A simple example is the RGB output I have in my SVI.738, http://www.funet.fi/pub/msx/mirrors/hanso/hwdoityourself/rgbmsx1.pdf
Any video buffer circuit will do.

Van Algorythms

Champion (285)

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11-03-2005, 11:43

You don`t REALLY need all that if it`s to difficult for you to make. I just used 4 condensators on my 738.
-Dan

Van dhau

Paragon (1558)

afbeelding van dhau

11-03-2005, 15:15

Algo, What is the value of capacitors (condensators) you used? Thanks!

Van HansO

Paladin (672)

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11-03-2005, 15:47

Algo, What is the value of capacitors (condensators) you used? Thanks!
Video inputs are 75 ohm loads. That is quite a heavy load and that is why I suggest buffers. While it works with capacitor coupling to a 9938 (1 uF would be large enough) it might be too much load for the T7937, resulting in a washed out picture or loss of sync or even blow up the IC. And the only supply of these chips is another MSX!

Van dhau

Paragon (1558)

afbeelding van dhau

11-03-2005, 19:01

HansO, is there some integrated IC, wich have similar functions to the discrete schematics from http://www.funet.fi/pub/msx/mirrors/hanso/hwdoityourself/rgbmsx1.pdf ?

I'm sure modern electronic devices have some analog for output bufferization.

Van HansO

Paladin (672)

afbeelding van HansO

11-03-2005, 19:20

Sure there are IC's containing video buffers. I do not have practical experience with them. It is lineair electronics, so dont count on less components than the discrete transitor based circuits Smile

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