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  • My two cents: In the last year I used to buy good 27C322 EPROMS from QIAOMAER seller (link) and I've found only 2 bad from 30 or so. I also got other other eproms from this seller with good results (specifically 27C160 and 27C800) and other chips like 6116 motorola rams, these ones were good in a 8/10 ratio or so.

  • MINI DIN 8 to SCART Adapter

    rsignal - - Project Sentinel

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    I've asembled my remaining PCB from RGB's Oshpark and I confirm that it fits perfectly in the TME SCART connectors. This time I've soldered it once placed into the plastic case as suggested by Frank_fjs

  • Crime Fighters 1 and 2 (also known as Vendetta) are great too. Aliens may be another one although I have not played it on real hardware yet

  • I've connected the scope to the CSYNC coming from the MVS and I see a DC offset of 2V. Adding a 10K resistor to ground did not change anything I can appreciate, but adding a 100nF ceramic capacitor in series did the trick and the image is stable! With a Double Dragon 2, though, the image doesn't sync except when I connect the 10k resistor to ground. I'll continue my tests using 74HC04 and 74HC14 instead.

  • Quote from invzim: “Speaking from experience, you need a scope when dealing with stuff - doesn't have to be a fancy one. For fun, you can try to put a 10k resistor to gnd on csync before the schmitt to see if it makes a difference. ” Very true! In my opinion, me and anyone that really loves arcade stuff a really good reason is detecting ill signals from RAMs, TTLs etc... instead of brute force repairing I take note of the 10k resistor to GND, thanks! I'm looking to buy some cheap old analog scop…

  • 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.

  • @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-…

  • Fixed! the problem was caused by a bad opamp. I've recapped the board anyway (some capacitors were out of spec)

  • Welcome!

  • Hi, I came across a Double Dragon 2 copy. It works fine but the music sounds heavily distorted, specially in some tunes, and there is an annoying background buzzing noise. Maybe the YM3012? the opamp? bad caps? vocaroo.com/buAtVK1qOIZ vocaroo.com/hJsa5aomlfl

  • Hi from shmups land

    rsignal - - Introduce Yourself!

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    Welcome!

  • I'm using a THS7373 as video buffer for my supergun to connect arcade boards to SCART TV sets or maybe an OSSC. In Tim's AV Driver CSYNC is DC-coupled while RGB signals are AC-coupled... and now this article makes me consider if DC-couple all the signals is the best for this amp. I found another document that favors the idea of DC coupled output: Quote from Maxim Integrated: “Despite these complications, video signals must be AC-coupled at the point where the voltage domains change. Connecting t…

  • Hi! I've found this article and I'm a bit confused about what's the best option: To AC couple or not to AC couple? That's the question! I'm doing some tests with different TV sets and games and it works with both AC coupled and DC coupled outputs. Is it really convenient or adequate to AC couple the video signal with modern ICs like THS7373? or it's better to DC couple in sake of signal integrity? Inputs are AC-coupled using 100nF capacitors to get rid of the DC offset.

  • Not sure if this is may be the cause, but Panasonic FR have way too low ESR so I wouldn't use them as replacement for general purpose caps. I ran into problems twice recapping Sega Mega Drive consoles with these capacitors and the problem dissapeared when I replaced them with general purpose caps. My problem was video noise after ~1h running, probably due to oscillations in the 7805.

  • MINI DIN 8 to SCART Adapter

    rsignal - - Project Sentinel

    Post

    Quote from Frank_fjs: “I see it now. Doesn't look like it's over by much, could have possibly carefully filed the PCB down a little? ” Good point.. I'll assembly my third unit with the PCB inserted in the SCART plastic.

  • MINI DIN 8 to SCART Adapter

    rsignal - - Project Sentinel

    Post

    The generous pad size makes it very easy to align and solder the pins. Great job! I take note about 2mm thick pcbs, it's a good idea. Maybe the plastic is a bit brittle... like all SCART connectors I used. I didn't notice any weird smell. Quote from Frank_fjs: “That looks fantastic. Where does a few mm need to be trimmed? ” At the left of the HAS logo in the photo and upwards the "by RGB" text.

  • MINI DIN 8 to SCART Adapter

    rsignal - - Project Sentinel

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    I took a photo... the case broke when reassembling, so definitely it would be very nice to cut a few milimeters from the pcb, at least for these connectors from tme.eu. md8toscart.jpg Once installed the step-up circuit covers the HAS logo.

  • I connect CSYNC directly from JAMMA edge to input pin (pin 2) of 74AHCT1G17 and after the output (pin 4) I use a voltage divider consisting in 470R and 75R resistors.

  • MINI DIN 8 to SCART Adapter

    rsignal - - Project Sentinel

    Post

    I'll take photos tomorrow. I'd maybe cut one or two mm at the left to make it fit better in the SCART case.

  • MINI DIN 8 to SCART Adapter

    rsignal - - Project Sentinel

    Post

    I'm using RGB's MD8 to SCART PCB and it works fine! I've tested it with and without Step up pcb. I've not tried to connect stereo sound, though, but it disconnects audio when I plug an audio cable