Capacitor value on a SA1 Snes pcb?

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Markfrizb
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Capacitor value on a SA1 Snes pcb?

Post by Markfrizb »

Would anyone know the cap value of C12 on the 1L5B-20 SA1 pcb?
All the other caps look to be about .01uF but C12 is such a small value that my cap meter can’t measure it.

I’m trying out this reproduction SA1 board and ran into this issue.
Yes, I can just grab that C12 from the donor and move it to the repo, but that still leaves an information void.

Thanks
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TmEE
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Re: Capacitor value on a SA1 Snes pcb?

Post by TmEE »

It should be few tens of pF at most, it appears to be a filter cap on a clock line. I don't have this hardware at hand to actually do any measurements but it will be difficult to measure capacitances that low anyway.
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Ben Boldt
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Re: Capacitor value on a SA1 Snes pcb?

Post by Ben Boldt »

I have one of these (USD $14 - 15):

https://www.aliexpress.com/item/3256803319171250.html

It actually works REALLY darn well for testing low inductance and capacitance. You have to zero it out regularly. To zero it correctly, you hold the zero button down a while until it says "saved" or something. It looks kind of junky but I highly recommend it.
Markfrizb
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Re: Capacitor value on a SA1 Snes pcb?

Post by Markfrizb »

Ben Boldt wrote: Tue Jun 07, 2022 2:25 pm I have one of these (USD $14 - 15):

https://www.aliexpress.com/item/3256803319171250.html

It actually works REALLY darn well for testing low inductance and capacitance. You have to zero it out regularly. To zero it correctly, you hold the zero button down a while until it says "saved" or something. It looks kind of junky but I highly recommend it.
Look like a nifty tool. I ordered one but it’s not expected to be delivered until August?! Still hoping someone might know (or measure) what that cap value is, I’ll eventually get the answer.
Thanks for the lead.
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Ben Boldt
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Re: Capacitor value on a SA1 Snes pcb?

Post by Ben Boldt »

It usually takes 3-4 weeks from AliExpress to USA but it can take the full time sometimes.
Markfrizb
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Re: Capacitor value on a SA1 Snes pcb?

Post by Markfrizb »

Well, I got the tool in the mail. If I am to believe the tool, C12 is 33pF…and that sounds reasonable…. But when I test bigger caps (2200uF, 220uF, 47uF), I get a very reliable 356nF for each cap value. I did zero it out. My trust in this device is not very high unfortunately. The tool didn’t come with any instructions.
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TmEE
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Re: Capacitor value on a SA1 Snes pcb?

Post by TmEE »

33pF is in the ballpark for the clock filter purpose that this cap should be used for. (and it is a standard capacitance value too)
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Ben Boldt
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Re: Capacitor value on a SA1 Snes pcb?

Post by Ben Boldt »

With large caps, you have to use the Hi.C mode. In general, use low C for ceramics and Hi C for electrolytic. There is a manual for this thing that gives the ranges of each mode.

For zeroing low-c mode, hold the zero button with the leads completely disconnected and not touching anything except the zero button. Then attach the capacitor in a way where you also do not have to touch anything during the measurement. The capacitor should be removed from the original circuit. It measures picofarad ceramics really great this way.

It is a very accurate tool despite its cheap appearance. Sort of quirky; you have to learn its quirks. In general if you did something wrong, it tells you so by giving you a way wrong value, as you have observed with large caps in low-C mode. Give it a chance and let me know if you need help.
Markfrizb
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Re: Capacitor value on a SA1 Snes pcb?

Post by Markfrizb »

Thanks Ben
I’ll tinker with it some more tomorrow. Can you send a link to the operations manual?
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Ben Boldt
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Re: Capacitor value on a SA1 Snes pcb?

Post by Ben Boldt »

Markfrizb wrote: Tue Jun 28, 2022 8:40 pm Thanks Ben
I’ll tinker with it some more tomorrow. Can you send a link to the operations manual?
I had printed a hardcopy and not saved the original, but I did find it again here:

https://www.mpja.com/download/33374te%2 ... manual.pdf

There are very useful tables listing the ranges of each mode and the combinations of buttons. Note the "Invalid" combination! It apparently does not ignore the "Hi-L" button in L/C = C mode! Like I say, quirky.
Also, the manual wrote:Automatic measuring ranges, it is easy to operate
Neither of which are true!
Markfrizb
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Re: Capacitor value on a SA1 Snes pcb?

Post by Markfrizb »

Much appreciated. When I wrap up this project, I’ll post the share link incase anyone wants to make their own. The original file set I got from OSHpark had errors and the author has been unresponsive to my emails alerting him to the errors and OSHpark doesn’t even manufacture 1.2mm thick Pcbs. So getting OSHpark to make this design would be a mistake…. Pcb would be either too thick or too thin.
So I fixed the errors (in gerber!) and I’ll post the design on pcbway in a few weeks.
Markfrizb
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Re: Capacitor value on a SA1 Snes pcb?

Post by Markfrizb »

Much appreciated.
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Yolt1
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Re: Capacitor value on a SA1 Snes pcb?

Post by Yolt1 »

Markfrizb wrote: Tue Jun 07, 2022 8:58 am I’m trying out this reproduction SA1 board
Hey there,

I didn't know these PCBs existed. Nice!
I've already done several SA1 repros, but the "traditionnal" way :
using a donor cartridge, ripping of the orignial maskrom and replacing it with mine.

But i would be interested in one such PCB. Mainly for building up a Test Cartridge.

I've seen the price on OSHpark and it is holding me back... 55$ per unit, yikes.

So i was wondering, did you order several ones? Do you have any spare PCB you would not be using?
I would be glad if i could make a deal somehow.

see you soon
Markfrizb
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Re: Capacitor value on a SA1 Snes pcb?

Post by Markfrizb »

OSHpark does NOT manufacture 1.2mm Pcbs. So if you were to order it from them, you would be very disappointed. Also the design (as I stated earlier in this thread) has some errors. I repaired the errors and I will post it on a different pcb sharing site for any and all. I’ve just been lazy lately. I don’t have any spares laying around. They are all used. I swapped the parts from the 1L3B carts. I will post links to this thread when I get it up.
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Yolt1
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Re: Capacitor value on a SA1 Snes pcb?

Post by Yolt1 »

Hey there,

Thanks for the quick answer.
OK I get it (Sorry i didn't read about the errors)
So, for the time beeing there isn't a fully working SA1 remplacement PCB.
I will be waiting for your feedabck on it.
Cheers
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