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Martin Jones Sync Pulse Generator: A Layman in Need of Help with a Schematic

Great to see people are still improving this design @rsignal.
If you'd like to go for broke, do you think it would be possible to add the option to accept either CSync or H/VSync input to your model?
 
Diode package is SOD-123. Resistors and ceramic capacitors package is 0805. Be sure to solder the diode with the correct orientation according to the schematic.

Using a 2K pot instead of 1K for RV1 is maybe better. 1K is what I have on hand and it works for me.

This is just an early prototype, it needs some work. Each TTL chip should have a 100nf decoupling ceramic cap.
 
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nam9 said:
Great to see people are still improving this design @rsignal.
If you'd like to go for broke, do you think it would be possible to add the option to accept either CSync or H/VSync input to your model?
Click to expand...
I'm not sure what would be the best way to combine HSync+VSync into CSync, any suggestion? this would be useful for regenerating CSync too. Anyway you could do that with other circuit and plug the output into this circuit input.
 
nam9 said:
And here is an update to the schematic to include H+V sync combiner on the unused gates on IC2

Yes, yes, fix v1 before adding features. (Credit philmurr, UKVAC)

Sync_cleaner.JPG
Click to expand...
@rsignal
 
@nam9 Although I'd like to incorporate a H+V sync combiner my priority is improving the basics first.

I've ordered some pcbs of this new version, will share results once tested. Although I can share the gerbers with anyone interested (just send me a PM)

After doing some tests with 74AHCT1G17 Schmitt buffer with mixed results (works fine with all boards tested except MVS) I've incorporated a 74HC14 buffer as RGB explains followed by a voltage divider in a similar way used in Tim Worthington's AV-Driver, but using common 470R and 75R resistors instead of 475R and 82.5R. This way TTL / 350mV CSYNC is selectable by a jumper.

If this work I'll adjust R1 and R2 for 75ohm impedance matching taking into account the output impedance of the 74HC. I think it's 470R and 87R being 50R the output impedance of 74HC to get ~400mV, but I need to double check this.


The circuit also features a DPDT switch to enable or disable Martin Jones' CSYNC processing, making a total of 4 CSYNC modes.

Bugfix: Unused 74LS86 inputs are now connected to ground.

Update: The circuit is wrong since when "REGEN" is off there are floating TTL inputs. I use the same circuit as in this post but using a 74HC14 buffer.
 
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rsignal said:
Although I can share the gerbers with anyone interested (just send me a PM) I prefer to test before making them public.


After doing some tests with 74AHCT1G17 Schmitt buffer with mixed results (works fine with all boards tested except MVS) I've incorporated a 74HC14 buffer as RGB explains followed by a voltage divider in a similar way used in Tim Worthington's AV-Driver, but using common 470R and 75R resistors instead of 475R and 82.5R. This way TTL / 350mV CSYNC is selectable by a jumper.
Click to expand...
Testing boards before releasing, and showing the schematics is the way to go, great job!

What issues did you experience with the schmitt and MVS?
 
With MVS I get no output signal from the 74AHCT1G17, so I'm looking for alternatives, like 74HC14 used by RGB or 74HC04 as suggested by mikejmoffitt in this thread.

I opened a thread with this specific problem here.
 
anyone hae a parts list for @Hatsune Mike board that worked? @XianXi and I are trying to get it to work but maybe its the parts were using.
 
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Thank you! I'm glad it's useful for you.

I used a Cadillacs and Dinosaurs copy and a Blaupunkt 14" CRT TV. Unfortunately I don't have a Taito F3 to test, but it should work since in previous posts people had success and the only change in the circuit is the 1K pot working as a rheostat - so turning it down it will behave as the original Martin Jones circuit.
 
pacoarcade said:
I've tested the circuit and it works!

syncfix-mount.jpg

BOM

R16K8 0805
R2470R 0805
R315K 0805
C11nF 0805
C2220nF 0805
C322nF 0805
C4, C5100nF 0805
RV1Bourns 3362P-1-102LF
U1SN74LS86
U2SN74LS221
D11N4148 SOD-123
Click to expand...
necrobumping this thread, did you ever share the gerbers for this syncfix pcb? I'd like to try It out with my PFX.
 
hi
I want to make a sync pcb. can you help me? could you send me your wiring diagram?
thanks
pacoarcade said:
I've tested the circuit and it works!

syncfix-mount.jpg

BOM

R16K8 0805
R2470R 0805
R315K 0805
C11nF 0805
C2220nF 0805
C322nF 0805
C4, C5100nF 0805
RV1Bourns 3362P-1-102LF
U1SN74LS86
U2SN74LS221
D11N4148 SOD-123
Click to expand...

I want to make a sync pcb. can you help me? could you send me your wiring diagram?
thanks robert
 
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