Questions about schematics/pcbs

[mrkmpn]

My 1st question is regarding PCB markings:

Some components marked on the PCB are prefixed with a 'p', so for example, rather than c101 it might be 'pc101', or r101 - 'pr101', etc... so what does the addition of the 'p' on these components indicate?

My next question is regarding component values on the schematics:

SC10U25V3MX-GP
It looks like this capacitor is 10uf 25v, but I'm not sure what else is indicated here. What does "s" at the beginning, and the 3mx at the end indicate? I'm assuming that since everything in the schematics ends in "gp" that can be ignored.


3D9R3-GP
If I'm following things correctly, based on the boardview, this resistor on the board has 3.9 printed on top. (or would have to be 6.E). But from what I've read, the letter R is usually used to indicate a decimal (like 3R9). So I'm confused about the value above indicated on the schematic for this resistor.

[ktmmotocross]

Re: Questions about schematics/pcbs

3D9R3-GP - 3.9ohm

SC10U25V3MX-GP - 10u 25V

[mon2]

Re: Questions about schematics/pcbs

SC10U25V3MX-GP

Yes, 10uf @ 25V capacitor. Very likely the p/n supplied by the vendor of the part used for the PCBA (PCB assembly). Probably an electrolytic or tantalum capacitor so will have a polarity. The above full part number should be linked to some vendor but could be buried in the many many many manufacturers in Asia.

-GP = General Purpose

3D9R3-GP

As per above but since you have observed 3.9 = 3R9 (is the style we like to use for our product design as my eyes are not as they used to be. Steve Austin, astronaut... days are in the past so it is easy to miss out on the decimal place when we are cross checking the designs before prototypes are built).

3R9 = 3.9 ohms.

-GP = General Purpose

[mrkmpn]

Re: Questions about schematics/pcbs

Yes, 10uf @ 25V capacitor. Very likely the p/n supplied by the vendor of the part used for the PCBA (PCB assembly). Probably an electrolytic or tantalum capacitor so will have a polarity. The above full part number should be linked to some vendor but could be buried in the many many many manufacturers in Asia.

-GP = General Purpose


As per above but since you have observed 3.9 = 3R9 (is the style we like to use for our product design as my eyes are not as they used to be. Steve Austin, astronaut... days are in the past so it is easy to miss out on the decimal place when we are cross checking the designs before prototypes are built).

3R9 = 3.9 ohms.

-GP = General Purpose

Thanks for the reply, on the capacitor it is an 0805 size smd cap. I've tried searching the numbers on google, but all of the results are for other schematics from various manufacturers' boards using the same label for capacitors. This is the only component (so far) that I know needs to be replaced.

I'm still confused on the resistor. Is 3D9 interchangeable with 3R9, and if so what is the next R and 3 for? I don't need to replace this resistor, I'm just trying to understand how to decode the information on the schematics for future situations where I might not be able to read the top of the resistor.

[mon2]

Re: Questions about schematics/pcbs

With experience, you will hunt these parts down like Dog the Bounty Hunter.

Can you share a picture of the part? What is the body color?

If it is flesh / cream color, then the part is an 0805 ceramic non-polarized capacitor. Check Samsung / Walsin brands, etc.

If you see a '+' or band on the part, then it is polarized and ideally should be replaced with a similar. Pretty sure you are up against a generic ceramic cap in 0805 size.

Check Mouser and Digikey for these.

I have not seen 3D9 used but have seen 3R9 which may have started from Europe as a convention.

[mrkmpn]

Re: Questions about schematics/pcbs

With experience, you will hunt these parts down like Dog the Bounty Hunter.

Can you share a picture of the part? What is the body color?

If it is flesh / cream color, then the part is an 0805 ceramic non-polarized capacitor. Check Samsung / Walsin brands, etc.

If you see a '+' or band on the part, then it is polarized and ideally should be replaced with a similar. Pretty sure you are up against a generic ceramic cap in 0805 size.

Check Mouser and Digikey for these.

I have not seen 3D9 used but have seen 3R9 which may have started from Europe as a convention.

From what I've seen it does appear to be a ceramic capacitor. The one that's bad is burnt, but according to the schematics the two nearest capacitors are identical and don't appear to have any signs of polarization marks.

Thanks again.

[petehall347]

Re: Questions about schematics/pcbs

Some components marked on the PCB are prefixed with a 'p', so for example, rather than c101 it might be 'pc101', or r101 - 'pr101', etc... so what does the addition of the 'p' on these components indicate?
could be the p is a certain part of the circuit . power supply maybe ..

[Stevedb]

Re: Questions about schematics/pcbs

P is in my knowledge PR power resistor and Power condensator PC. If I am wrong somebody please correct me.

Regards
Steve

[mrkmpn]

Re: Questions about schematics/pcbs

P is in my knowledge PR power resistor and Power condensator PC. If I am wrong somebody please correct me.

Regards
Steve

I finally found a list of abbreviations that that included the information.

PC :POWER CAPACITOR
PD :POWER DIODE
PL :POWER INDUCTOR
PQ :POWER TRANSISTOR
PR :POWER RESISTOR
PU :POWER INTEGRATED CIRCUIT

[mrkmpn]

Re: Questions about schematics/pcbs

In case anyone else comes across this with questions about the component labels on schematics..., and because googling them showed results for schematics from multiple manufacturers, I thought I'd share this. I found the information on page 2 of the schematics... (noob mistake not looking there I guess)

Resistors:
The naming rule is value + R + size + tolerance
For the value, it can be read by the number before R. (R means resistor)
For the tolerance, it can be read from the last letter.
For the rating, we don't show on the symbol name.
For the size, R2=>0402, R3=>0603, R5=>0805,...
Rating, 0402=> 1/16W, 25v, 0603 => 1/16W, 75V, 0805 => 1/10W, 100V
Tolerance (J: 5%, F: 1%, D: 0.5%, B: 0.1, No letter means J)

For example: 33D3R5 = 33.3 Ohm / 0805 package 5% tolerance
1KR3F = 1K Ohm / 0603 package 1% tolerance

Capacitors:
The naming rule is
Capacitor type + value + rating + size + tolerance + material
SCD1U10V2MX-1
SC=> SMT Ceremic, TC=> POS cap or SP cap
D1U => 0.1uF
10V => the voltage rating is 10V
2=> 0402, 3=>0603, 5=>0805
M=>tolerance M, K, Z (M: +/-20, K: +/-10, Z: +80/
size (2=>0402, 3=>0603, 5=>0805, 6=>1206, 0=>1210)
X=> X7R/X5R, Y=> Y5V
-1 => symbol version, nonsense to EE characteristic