SMT Identification "W6" or "W6P"

[bl4ckw1d0w]

I am trying to identify Q81 in a Skar RP-4500. I believe its part of the remote or protection circuit. I dont know what to replace it with.

I believe the identifier is W6 and the P is the date code. I dont know which manufacture uses this style of date code marking. It appears to be the same transistor used in Q275. See attached.

I believe it is a pnp because I have tested in diode check off board.

black probe on base red probe on collecor =.701v

black probe on base red probe on emitter = .012v

in resistance mode its showing 25 ohms between the base and emitter.

 

[Capt Grogg]

W6 BZX84-C3V3 Phi C SOT23 0.3W zener 3.3V±5%

 

[twilliar]

By looking at the configuration of the traces and connected components.

Perhaps,

 

[bl4ckw1d0w]

I pulled Q275 off the board and there is no connection to the emitter pin of a standard sot-23 so my guess is it is a zenner. I will just check the one without the short with a 1k resistor and 9v battery to confirm and report back.

 

[bl4ckw1d0w]

Only showing .8 volts.

 

[Perry Babin]

Was there an independent trace going to the open leg?

Some amps have started using a JFET in locations marked Q81 and Q275.

Is it possible that Q81 is OK and Q275 is defective?

 

[bl4ckw1d0w]

It is possible seeing as i have no signs of life and the relay doesn't engage and i believe Q275 is part of the remote circuit but i am unsure.

Q275 pin 1 is directly connected to ground.

Pin 3 of Q275 is connected to the base of Q225 (2sc2412k).

Pin 3 of Q275 to ground i measure 99.7kΩ

 

[Perry Babin]

Does Q81 check to be a jfet?

 

[bl4ckw1d0w]

Starting with resistance mode.

Red on pin 1.

Black on pin 2: OL

Red on 1 Black on pin 3: starts at 45Ω and decreases to 25Ω with a time span of about 20 seconds.

Black on 1 Red on 2: 6.6MΩ

Black on 1 red on 3: starts at 45Ω and decreases to 25Ω with a time span of about 20 seconds.

Diode Mode:

Red on 1 Black on 2: OL

Red on 1 Black on 3: Starts at .040v and drops down to .015

Black on 1 red on 2: .703v

Black on 1 red on 3: .015V

 

[Perry Babin]

Are you using the following pin configuration?

 

[bl4ckw1d0w]

Is it possible that its the part in the attached datasheet? That has a code of 6P. Maybe the W is a date code.

 

[bl4ckw1d0w]

No your pin3 is my pin 2. I did it in a left to right fashion. I will retest.

 

[Perry Babin]

The prefix codes are often location of production.

The diagrams that use this diagram (I can't post them) simply has 111 as the part description.

no need to repost.

 

[bl4ckw1d0w]

Drain to source resistance of the MMBFJ111 is 30 ohms and I was at about 25 ohms. This would explain a lot. Q275 is open drain to source and Q81 checks out fine.

Boy was this a learning experience for me. I have to read more on Jfets now.

 

[Perry Babin]

The rated value is the maximum. You will generally see something a bit lower.

 

[bl4ckw1d0w]

Good to know. I appreciate the help!