diyAudio (
-   Parts (
-   -   Transistor Identification (

jetbat 21st October 2011 03:02 AM

Transistor Identification
1 Attachment(s)
Hi. I'm trying to identify this surface mount transistor that is part of a piezo buffer circuit. The markings on it are P1KMA. If I search using the first three, P1K, I find the transistor PMBT6428. If I search using the next three, 1KM, I find the transistor PMBT6428L. It looked like this was the transistor but when I looked at the pinout it was incompatible with the way the circuit is wired. The transistor has a single pin on one side and two on the other. The single pin connects to the piezo and needs to be a high impedance connection.

I am comparing two piezo buffer circuits, a old and a new. On the new, the transistor is a Jfet which makes sense because the piezo needs to see a very high impedance. The pinout for this Jfet works with the circuit correctly with the single pin as the gate. The PMBT6428 is a BJT that the pinout would put the single pin as the collector and would put the base to +V. This does not seem right.

If anyone can help it would be appreciated. Attached it a picture of the transistor.

Enzo 22nd October 2011 12:53 AM

Perhaps if you told us the make and model of what it is used in...

jetbat 22nd October 2011 02:20 AM

It's a piezo system by L.R.Baggs that is used in some PRS Guitars. The surface mount componantes are the piezo buffer circuit that is on a pcb mounted under the bridge.

jitter 22nd October 2011 03:46 AM

With SMD-codes you need to differentiate between lower and upper case. Inconveniently, different manufacturers use the same code for different products.
The last letter(s) usually refer to country of origin.

From: SMD marking codes P

p1K = Philips (NXP) PMBT6428
P1 on a SOT23 Philips transistor = BFR92 (also a BJT)
the Philips datasheet mentions only marking P1p (sometimes there are more possibilities if a component is manufactured in more than one country).

P1 on a SOT23 Temic-Atmel transistor = SST201 a n-channel jfet
In the context of this thread I would guess that's the one. MA on your transistor might mean Malaysia.

P1K doesn't appear in the SMD codebooks.

jetbat 23rd October 2011 02:47 PM

Thank you.
Yes I did find p1K instead of P1k.

SST201 sounds like a winner. The new piezo circuit has transistor 62P which is MMBFJ201. So both the old and new circuits use the same 201 jfet but from different manufacturers with different codes.

All times are GMT. The time now is 10:00 PM.

Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 18.75%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio