Reading SMT capacitor values

[displaced]

Hi all,

I'm building a logic board capacitor list for the Gossamer motherboard (beige G3). Now, I usually work on older machines -- this is the first time I've considered replacing SMT caps from the late 1990s. Don't worry -- I've practiced on a junk board (the control board from my old hot-water boiler -- no Macs were harmed!).

I'm used to reading through-hole electrolytic values ('cos it's easy!), but I'm a neophyte when it comes to these caps. I've had a google, but it seems these caps are old enough not to use the current-standard markings.

So, these caps have three values written on them. The first appears to be a 'series':

e.g. J2, J3, L4, Z4, GQC. Would anyone have a clue what these indicate?

Then, there's presumably the capacitance: 47 and 100. is that 47uF? I mean, I can answer that myself by desoldering and measuring, but wouldn't mind confirmation.

And lastly, the voltage, which is self-explanatory.

Thanks for any help you can provide! I'm also ordering a few through-hole caps for the VRM board, and I'll replace those first to see if it helps my board's power-up problems. But I might as well get caps for the board itself too whilst I'm making an order!

 

[3lectr1c]

post a picture of the caps in question. You seem to have hit it on the nose though, M7 or whatever would be the series, first number down is the capacitance, second is the voltage. This is the case for just about every one of those trash cans.

 

[displaced]

Here’s an example!

I’m struggling to map those ‘series’ values to anything currently available (I’m looking at uk-rs-online.com). Should I worry too much about that, or just go for replacements which are the correct capacitance/voltage and physical size?

 

[3lectr1c]

47uf 16v - a very standard spec on these Mac boards. I wouldn't worry about matching a series, I'd even go tantalum if I were you. Matching the series matters with something extra-sensitive like a PSU or analog board, but not much on a motherboard with tiny values like these.

 

[displaced]

Excellent -- thank you very much for your help. I'll get ordering!