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

nam9 said:
In that case i’d drop chris (at) martin-jones an email (from his About and Contact page) and ask...
I’ve emailed him before...
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I reached out through the site about a month and a half ago, no response.
 
Do you guys think the tolerances on the caps (+/-5%) and resistors (+/-1%) I selected are the problem?
 
I’ll have to review my schematic - the circuit I assembled worked without any issues.

How does it look on the scope?
 
Frank_fjs said:
Increased through hole diameter for resistors and caps. Changed caps to suit poly caps. Fixed R1 silkscreen value. Beefed up copper pads.

Sync Pulse Generator.png
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Does your design use a GROUND plane?From picture of produced PCBs and Gerber viewer I can't see GROUND traces on top and bottom layers and netiher a plane.Perhaps this is why it doesn't work.
 
Yes, there's a ground plane on the bottom layer.
 
I've given it a cursory look and can't find any inconsistencies between the schematic and PCB. I'll keep checking though...
 
Hatsune Mike said:
I’ll have to review my schematic - the circuit I assembled worked without any issues.

How does it look on the scope?
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I don't have scope or know how to use one.

Out of curiousity, do you still have the Digikey or Mouser parts list for your version? I am wondering if my resistors and cap tolerances are the problem.
Frank_fjs said:
I've given it a cursory look and can't find any inconsistencies between the schematic and PCB. I'll keep checking though...
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Yeah, looking at your work and the schematic has helped me piece together how to read a schematic. Looks fine in my laymen eyes.

Thanks for your help, btw. It must be the components I used.
 
Resistor values in your photos are correct. Just checked the colour codes.
 
Diode is orientated correctly, as are ICs.

Can you check with a multimeter the DC voltage of sync in and sync out please?
 
  • Sync-in = 3.22-to-3.25
    • Measured at the connector going into the PCB
  • Sync-out = 3.1
    • Measured at the connector going out of the PCB
 
Well at least a signal of some form is being output.

Can you test with different games and/or a different monitor?
 
Different games, yes. Different monitor is going to be difficult however since I will have to splice in connectors.

Let me try different games first.
 
Shit. Could be JLC produces bad stuff then if everything else seems to be in order. If everyone that is an expert confirms Frank's design is legit, might as well make an order at OSH Park I suppose.What do you guys think?
 
Considering @XianXi had the same result with a breadboard, I would suspect the schematic. Might be worth reaching out to some other video guru to double check it.
 
Frank_fjs said:
Can you test with different games and/or a different monitor?
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Same results with a Sega C2 and CPS2 which are both known to work fine with a Sanwa PFX: 'No Signal' message on screen.

Can't yet test on a different monitor.
nem said:
Considering @XianXi had the same result with a breadboard, I would suspect the schematic. Might be worth reaching out to some other video guru to double check it.
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Schematic is good. I have in hand Hatsune Mike's version which is soldered onto a JAMMA finger/extension board, and it works. How about this, @XianXi, out of curiosity, what vendor did you have your PCB's fabbed with? If the answer is JLC, maybe that is the problem? If so, why don't I make a small order with Osh Park for Frank's and Mike's versions? I'd say XianXi's too but his is designed for SMD, which I have no parts for.

@Hatsune Mike, would you mind digging up your gerber files and shooting them over (via PM. I won't make them public without your permission).
 
I don’t use JLC, I’ve always used Seeed for my all my stuff. My scope is in storage unfortunately. But all I can say is with my probe is that it pulses on input but no pulsing on output(that the probe can detect).
 
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