Replacing the transistor in the power supply from the microscope

Here you can discuss DIY adaptations to the microscope.
Post Reply
Message
Author
alexgor26
Posts: 2
Joined: Thu Jul 28, 2022 8:58 pm

Replacing the transistor in the power supply from the microscope

#1 Post by alexgor26 » Thu Jul 28, 2022 9:29 pm

Hi all! The old power supply from the microscope is out of order. I decided to disassemble and fix it, as I understand a little about it. I tested and found that the BC547 transistor does not work. I looked for a replacement on the Internet and here https://chipdatasheet.com/transistor/bc ... ent-specs/ subtracted that the modern equivalent in terms of specs and BC547 pinout is BC550. I'm thinking of putting in a new one or looking for the same BC547.

User avatar
blekenbleu
Posts: 299
Joined: Tue Feb 25, 2020 5:55 pm
Location: South Carolina low country
Contact:

Re: Replacing the transistor in the power supply from the microscope

#2 Post by blekenbleu » Thu Jul 28, 2022 11:27 pm

alexgor26 wrote:
Thu Jul 28, 2022 9:29 pm
the modern equivalent in terms of specs and BC547 pinout is BC550.
I'm thinking of putting in a new one or looking for the same BC547.
They are in the same family:
https://www.mouser.com/datasheet/2/308/ ... 310266.pdf

The BC547 tolerates a higher Emitter−Base Voltage (6V) than the BC550 (5V),
which may not matter in your application. The BC546 is more tolerant...
Small signal transistors typically do not fail unless something else provokes them,
e.g. a leaky capacitor.
Metaphot, Optiphot 1, 66; AO 10, 120, EPIStar, Cycloptic

jfiresto
Posts: 342
Joined: Fri Feb 15, 2019 8:19 am
Location: Northern Germany

Re: Replacing the transistor in the power supply from the microscope

#3 Post by jfiresto » Fri Jul 29, 2022 6:11 am

I do not know where you are, but currently, TME has a tolerable few BC547 variants in stock. You may not even have to form the leads.
Last edited by jfiresto on Fri Jul 29, 2022 6:13 am, edited 1 time in total.
-John

DrPhoxinus
Posts: 316
Joined: Mon Jan 28, 2019 5:17 pm
Location: Rochester Hills, MI

Re: Replacing the transistor in the power supply from the microscope

#4 Post by DrPhoxinus » Fri Jul 29, 2022 6:12 am

As a ham operator I can attest that electrolytic capacitors fail. Replace the capacitors

Dubious
Posts: 426
Joined: Sun May 09, 2021 7:55 pm

Re: Replacing the transistor in the power supply from the microscope

#5 Post by Dubious » Fri Jul 29, 2022 4:54 pm

DrPhoxinus wrote:
Fri Jul 29, 2022 6:12 am
As a ham operator I can attest that electrolytic capacitors fail. Replace the capacitors
Yes, generally the first to go in a power supply; and when one goes, others are probably not far behind. I like the screen proportions of my older Princeton monitor, so when one of the electrolytics failed a year ago, rather than tossing the monitor, I replaced all the electrolytic capacitors in its power supply circuit. Working fine since.

Post Reply