SLG3000 Scanline Generator performs

[bigsanta]

Thank you Telis and Bigsanta for answer. I didn't read ニユ－マン's post carefully, sorry.

I'm currently investigating my slg3000, it has a Texas Instruments ship (red circle on picture) which seems to have same function as the HD74LS74 if I'm not wrong. It has 3 more ICs labelled "JATR" (green circles). I'm not sure of the TI IC's reference, I think it is CDHC73MG4. I haven't found datasheet for the 3 more little ICs yet.

CD74HC73
The 7474 is just a positive edge dual D type flip flop , where as the slg3000 flip flop seems to be a dual JK negative triggered one .I think only 1 flip flop is being used .But if the slg3000 is using an analog switch which needs E to be active when high and thus Y and Z = on state ,then how come are Y and Z being read as  a closed switch instead of open/off  ,when the slg3000 is not connected to anything ?

Because the 74LVC1G66 is an active high switch ,so the 3 in the slg3000 must be an active low version,using something like the 384 version (74LVC1G384)of the same family  .

[gojirien]

Which scaler are you using, the 2 VGA or one VGA model?  I ask as my 2VGA model puts horizontal lines on the image with this scanline mod when using the VGA out that's close to the edge of the board, but it fine when using the middle vga out.  (I haven't investigated this further yet, it might just be the placement of the scanline board when I stuck it on the underside of the scalers board)

Pete

I'm using the 2 vga one, I've tried the 2 outputs and each make same result for scanlines, so the problem might be with the scanlines circuit. I have to build another one, with sockets for 74's ICs.

Bigsanta, thanks for all info, very interesting.

Another little thing, two days ago I put a LM1881N (usually I'm used to stick it under the cga vga scaler) directly in the scart socket.

[bigsanta]

IC1A changes state with every HSync pulse, so one line is untouched and the next one is blanked (or vice-versa).
The switch (S1) selects if the blanking circuit (IC2) has to erase the even or the odd lines.
When IC2 is active the RGB lines are grounded and you see a black line.

Well, instead of tying the (active low)buffer's 3 inputs to ground ,why can't a pot be on those lines instead,allowing us to control the VGA's RGB levels peak to peak voltage (black =0/Vss  -0.7 Vcc = full intensity)

[NeWmAn]

I'm not sure if I understand what you want to do with that. Please post a schematic of your suggested modification.

[bigsanta]

Example

[NeWmAn]

I don't think it will work, unless you change the 74*125 with an analog switch.

From Wikipedia:
A TTL input signal is defined as "low" when between 0 V and 0.8 V


And even if you use a suitable device, the circuit (as it is) will not work as you wish:
The video signals always go through the 3xPOT,  but you want this to happen only when needed.

[bigsanta]

Oops ,made a few mistakes with that first eagle.sch
Maybe use something like a 4016 ,to replace  the quad buffer.

[NeWmAn]

TTL parts wont work, CMOS (or 74HC) parts may work, but the signal will probably need to be amplified.
Best solution (apart from copying the SLG3000) would be to use dedicated parts, like this video switch:
http://www.maxim-ic.com/datasheet/index.mvp/id/5872
or maybe this:
http://www.maxim-ic.com/datasheet/index.mvp/id/6469/t/al

[bigsanta]

Here's a 90% complete eagle.sch of the slg3000.It's missing the  terminal block for connecting a spst switch and enabling the slg3000 to work in vga pass through mode.The Vcc and Vss points for connecting an external psu.Also missing are the two capacitors ,(the 47 uf@25v and the 0805 size 100 nf  smdc cap that seem to be there for filtering, when the external psu is used,along with another 0805 size smd 10k ohm resistor(pull up ) (labled as 1002).Also the reset pin on the SO 74HC73m flip flop ,it is actually connected to on of the pins of the terminal block that's there for connecting a spst switch.It then goes to the 10K  ohm pull up resistor that's next to  the LED's 220 ohm resistor(2200 ) ,the other pin goes to Vss/gnd(,enabling a low input to be sent to the 7473's reset pin ,from a connected spst switch.

Also, the bi lateral switches IC2,3,4 ,these are still not a certainty  to be the correct types as in my schematic,they could be active low enabled (or something completely different ),so  don't take it as gospel .The pots are 500 ohm each(those in the schematic i've used a 3/triple gang pot instead of the single pots that are on the pcb).The 7473 used in the schematic/slg3000 is infact an m version,not a D(this was down to eagle's library missing the 74hc73m version)

Switch 1 is numbered incorrectly .On the slg 1=switch 4 and 2 =switch 5.(on the latest version of the slg).

All smd resistors ,the LED and all but 1 of the capacitors are size 0805

[gojirien]

Oh, very interesting Bigsanta !

So for my problem with my diy scanlines circuit, I think I know the origin of the problem : I didn't understand that 74LS74 and 74LS125 needed capacitors...Stupid I am^^. Will try with the capacitors, anyone could tell me their value, and the pins locations on Ics where to solder them ?

[bigsanta]

I used these cmos ICs to make a working diy adjustable slg ,but i think the rgb levels go a bit too dark when the scanlines are set to  fully on,but i had been messing with my contrast levels earlier in the week ,so i'll let someone else tell me, if they make one.R4 isn't needed,just tie the reset pin to Vcc instead.

I used much smaller pots (not value) and the dip switches ,i changed them to a side/right angle type of dip switch.Maybe you could remove the analog pots and substitute 3 digital ones like the x9c1025's and operate them with just two switches ,one on  the inc and up/down pins (all inc tied together and all up/down tied together and pulled high )?As in my unfinished schematic below?

IC'5 pins's are numbered wrong.IC5C  should be numbered as follows;
IC5C  (c=1  a=2  b=13 )
IC5B  (c=3  a=4  b=5  )
IC5A  (c=9  a=8  b=6)

I removed the remaining R1 and R2 resistors and it fixed the problem of getting too dark. There's no need for any resistors ,just remove them all from the adjustable diy scan line maker.

[rendermatt]

How would you double the horizontal lines from an s-video connection and convert it to VGA, in order to use a scan line generator like this? What device(s) would you guys recommend? Thanks,

Matt