Explanation of schematic values

[SpareRibs]

Hello,
      You guys recently walked me through a problem I thought was overwhelming. It wasn't as bad as it
seemed. I tackled it successfully. Now after being exposed to the schematics I have a question about a
few of the ways the values are marked.
       Caps marked such as C8 10/50. What does each number mean? I think it may have something to
with the fact that the circuit has AC and DC voltage running through it. Also on the pots some have a
marking like 100KL, what does the L mean?
        Thank you in advance for any information provided.

[Enzo]

Capacitors have various specifications, two are most important to us.  The first is its capacitance, generally specified in units that are parts of farads, so microfarad or picofarad are common units.  But it also matters a lot what voltage a cap can withstand, so they all have a voltage rating.

I don't know what schematic you refer to, but when I see 10/50, to me it means 10uf at 50 volts.

Often a schematic has notes in a corner, and one common note will say something like "all capacitor values in microfarads unless otherwise noted."  So 10/50 means 10uf "uf" means microfarad) and not 10pf (picofarad).  If it were to be a 10pf, it would have the whole "10pf" printed there.

Potentiometers - pots - such as volume controls have resistance, measured in ohms.  So 100k means 100k ohms, which just means 100,000 ohms.   But as you turn the control, the resistance from the center terminal to the end terminals varies.   Some vary resistance in a linear fashion.   Half way up is half the resistance, 1/4 way up is 1/4 the resistance.   But for purposes of the design, we sometimes want the rate of change to vary as well, so if we plot the resistance against the percentage of rotation, instead of a straight line, we get a curve.

The pot is labelled with its resistance, but we also need to know about such curves, which we call tapers.   As in the resistance tapers off.  So we have labels.   Most common are the letters B for linear, and A for audio taper.   SOme drawings will label a linear pot with an L instead of a B, such as yours.   Problem with that is that the L could also mean "logarithmic" taper, a curved taper.  SO I myself would not use L.   As a tech, I can usuyally tell from the circuit context which taper a pot needs to be.

[SpareRibs]

Hello,
      Thank you Enzo, I am looking at the Fender Squier 15 I posted about in my first post. I started just
looking at the schematic and thought to myself, it's not really that complicated if I could understand a
little more about the values and such. I am not deluding myself into thinking I can become a tech over night. However I can now tell the pre amp, amp, and power source apart, before it was just a big jumble.
       So I will just keep lurking and as I do I think I will pick up things here and there. I think as I tackle
small projects things will start coming together for me. Thanks again!!!

[Roly]

Just to add that the pot taper thing has turned into an unholy mess with everybody doing their own thing.  It has got so bad that the only thing I really trust these days is "log", "lin", or measure the damn thing at mid point.

A major clue here is that we know the Master pot will be an audio taper or log pot, and it's marked "50KL", so in the context of this particular circuit we can take the "L" to mean Log.  It would also make sense that the tone controls are also Log, but what about the Volume control "50KA" and Gain control "50KRA"?

As far as I can tell these are also log pots, but from a different manufacturer.  The "RA" most likely means a reverse log taper given it's position in the op-amp feedback network (there  is no such thing as a reverse linear).  Sadly pot taper codes are now such a mess that we all have to use a bit of enlightend guesswork.

http://www.resistorguide.com/potentiometer-taper/

Jeri Ellsworth - Secret to Learning Electronics - Fail and Fail Often
www.youtube.com/watch?v=xhQ7d3BK3KQ

This is the Squire 15 circuit that some claim Fender says "doesn't exist".   :lmao:

[SpareRibs]

Hello,
      Thank you for your reply Roly. It is difficult for me to grasp all of this, but small bits of information like you,and Enzo have just added in this post have brought quiet a few things to my attention. I know
you are aware of the fact that you can look at some things many, many times and not see things until they are pointed out to you. After time it comes to a point you can just look at the overall picture and
get an idea of what is going on. I am a very long way from that. But I guess it is a matter of time.
       Anyway Thanks again !!!!!!