Fixing up an old Stylophone 350S, and some of these these transistors need replacing. Can't find anything on the internet so far, is this before standardization in the coding? Markings say: E5383. Is this the same as a 2N5383? Any help would be appreciated!
I wouldn't like to say if they are the same as a 2N but I would say its a certainty that any suitable generic type will be OK as a replacement. The 2N5383 stands out as having a very low maximum IC rating so unless you were sure I wouldn't use that on the off chance.
Are you sure they are PNP is the first question ? Hard to believe all four are faulty 🙂 Can you identify the pinouts ? If not, then as long as you know they are PNP it is relatively easy to id the pinouts on the PCB by measuring the voltages present without the devices fitted and looking for clues such as a pin that goes to supply (positive ground on something this old ??) which would be the emitter.
Are you sure they are PNP is the first question ? Hard to believe all four are faulty 🙂 Can you identify the pinouts ? If not, then as long as you know they are PNP it is relatively easy to id the pinouts on the PCB by measuring the voltages present without the devices fitted and looking for clues such as a pin that goes to supply (positive ground on something this old ??) which would be the emitter.
Not sure if they are PNP, a lot of the old stylophone schematics label the transistors as PNP, along with the "Texas" heading along with the strange E#### coding (none of these are the same E5383s). Still no source of the 350S schematic anywhere.
Standardized number systems came along way before the TO92 package. I'd wager my lunch money that those are house numbers - Stylophones number for some generic part.
What is wrong with them, my impression is like Mooly's. If they are JFETs and you test them as bipolars, they will seem bad. And vice versa.
But really, most any general purpose transistor ought to work.
What is wrong with them, my impression is like Mooly's. If they are JFETs and you test them as bipolars, they will seem bad. And vice versa.
But really, most any general purpose transistor ought to work.
If you can find a BRC Colour TV schematic from 1974, they were used in the power supply but I can't remember what sex they are or the parameters, sorry.
If it is impossible to identify and therefore find a direct replacement, I'd substitute by specs. Assuming it's a bipolar (not FET), first determine if PNP or NPN (diode test function on a DMM will help). Then find the hFE/Beta/Gain of a few of the ones that still work well. Determine the minimum required VCE rating, determined mostly by the power supply rails. Find a suitable replacement based these numbers. hFE should be close (say 1/2 to 2x of original), VCE at least, say, 1.5x the power supply rails, and probably use an audio or general purpose type (not high speed RF/UHF etc.). Most types in a TO-92 or TO-18 case should have suitable power dissipation and IC ratings, but don't pick something with really low ratings on either of those since you should err on the high side. You may want to look for something with low noise, but that's up to you. Hopefully the instrument doesn't depend on some strange characteristic of the original transistor, such as by operating it in a highly non-linear region in order to develop certain harmonics.
- Status
- Not open for further replies.