Getting specific frequenzy

>>1023526
If you can find another xtal that is a multiple of that frequency then you can use a divider to get it down to the frequency that you want.

Imagine a high frequency crystal triggering a binary counter. Every time the counter outputs a 4, for example, then you use that pulse as your frequency, reset the counter, and wait for it to reach 4 again. Of course, you need logic chips that are fast enough to keep up with the actual xtal that you are using. Pretty simple really.

>>1023530
I'm actually having a hard time even finding a crystal slightly above the required frequency. But I also read that the sega master system divides this frequency by 15 for the cpu and 12 for the video out. So maybe I could just get two crystals feeding those frequencies to the chips that need them.

>>1023534
That would work to. It all comes down to what frequency crystals you can actually find, and if they are multiples of what you need. Where have you been looking for xtal so far? Digikey? Mouser? Arrow?

>>1023539
It looks like the closest standard is 53.1250Mhz. I wonder if that would be close enough, because there are tons of those avaliable for like $1/each.

>>1023543
According to my calculator, that's a difference of less than 0.2%, and I think most timers are specified for a tolerance of 1%, so the widely available 53.1250Mhz would probably work for you. Can anyone else verify/refute this?

>>1023526
Googling around, it appears there are tonnes of SMSfags in the same boat. Theres also plenty of homebrew solutions for people who cannot source crystals. Naturally, you have followed the advice of our sticky, googled around and investigated the many options out there, right..?

>>1023548
In this case even if he hasn't googled it I feel like it was an appropriate question for diy

>>1023526
>>>/vr/ might have some sauce. But yeah, they seem rare as rockinghorse shit.

>>1023547
Yeah. I've replaced the same system, with that same crystal. If it's +/- %1 then it is no bueno. %.2? Op will be fine

>>1023547

No, there is no "most timers". The requirements for electronics communications varies depending on the tolerance of your receiving device and/or message length. This can be anywhere from milliseconds worth of deviation for unusually slow, short-length transmissions between devices with poor clock sources, to the more typical networking and PC accessories requiring 20ppm (0.002%) crystals or thereabouts. Plus, of course, the clocks that are required to be absurdly accurate like the atomic standards in GPS satellites.

That being said, my cursory Googling would indicate that this particular clock isn't overly sensitive and would be okay with a 0.2% difference. Take that with a grain of salt because, again, I didn't dig all that deep.

>>1023569

Also, I should mention that you want to look for a crystal specified for the same capacitance as the one you're replacing. Loading a crystal with too much or too little capacitance will throw off its resonant frequency if the difference is extreme enough.

You can also use this effect to "tune" a crystal to a frequency close to its intended one. This might help if it turns out the system isn't okay with the new frequency.

FXO-HC730-532
53.2MHz
60ppm off spec, should be more than good enough for your purposes

>>1023539
Been just browsing the online store for my local electronics store, they have pretty much anything I've ever needed, tried ebay also

>>1023543
>>1023547
Thanks, will look into.

>>1023548
Naturally, I've had plenty of trust in my google fu previously but apparently its still lacking if you managed to find anything about my issue.

>>1023661
Will check these out.

I'd guess thr SMS isn't really that frequency dependant since I've seen post from people where they overclock their systems with different crystals, the only thing I'm worried about is the clock to the video encoding IC, I'm guessing that it's rather sensitive to ensure proper PAL50 signal.

>>1023526
You can use trim capacitors or inductor to adjust a crystal oscillator that is close to the desired frequency. I used to do this years ago when working on CB radios.
Google "crystal oscillator pulling"

/vr/ person here.

I think this is what you're looking for OP: http://www.digikey.com/product-detail/en/cts-frequency-controls/CB3LV-2I-53M203425/CB3LV-2I-53M203425-ND/5230498

It runs at 53.203425MHz

>>1023526
find it hard to believe the crystal is dead. i'd think the chip its connected to is dead (in most cases the cpu).

>>1025395
Well I've replaced all the electrolytic caps, probed the board for gnd and vcc to every IC, replaced the voltage regulator and any non custom switches. When testing around any of the ICs that need xtal with a frequency tester I don't get any signal at all so either it's the crystal, something in the oscillator circuit or the logic that divides the crystals clock by 12 and 15 that is broken. I do however have another Z80 lying around but it's not the exact same model, would it still work as a replacement?

>>1025395
I've replaced a good few dead xtals in my 20 plus years of repair. Not in video games but other items.

i have a dead PAL megadrive 2 in the loft you might get a crystal from.

>>1025704
Does the megadrive use the same crystal? It is a different gen console after all.

>>1025704
no idea. i assumed it would because if not the games would run too fast or slow. many games i rented were compatible witrh both consoles.

>>1026029
Yeah I found some info on it and it does indeed use the same crystal. I did not however know about games being cross compatible, that's nice! Maybe I could score a dead mega drive somewhere here in Finland for not too much.

>>1026378
post up an email and i'll send you the crystal or the whole sega megadrive 2 if you cover the postage.

>>1026465
Really? Thanks anon!

[email protected]

Where are you from? Just wondering how much that postage is gonna be.

>>1026988
republic of ireland. i burned out the video in it by hooking it to a cats ears to make a short range transmitter when i was too young to know any better.

>>1027099
btw i have a working sega megadrive 1 here also.