Please help with identifying/troubleshooting this transistor - Page 1
Forum section: electronics / repair

author: highcap
author_rank: Contributor
timestamp: June 06, 2024, 07:54:26 pm
content: This is within an 91' CRT monitor (dumb terminal)It is having a copper radiator, but it's running very hot like you can't touch it (unlike the other similar transistors on the board), in just 2-3 minutes after powering up.My issue is this is within a terminal monitor, so the terminal board underneath seems to switch itself off and no more text is displayed on the screen, within about 1 minute since powering up the monitor. (The more it stays powered off, the more it can hold on at the next power up, and the opposite)Also, I can't find any info online about this transistor by its marks, it might be the culprit?Thank you for any help!

author: watchmaker
author_rank: Unknown
timestamp: June 07, 2024, 12:25:47 am
content: https://pdf.datasheetcatalog.com/datasheet/sgs-ates/BD282-BD284-BD286.pdf

author: fzabkar
author_rank: Super Contributor
timestamp: June 07, 2024, 01:12:36 am
content: Quote from: highcap on June 06, 2024, 07:54:26 pm91 feet? :-)Can you show us a photo of that area of the PCB? Do you know what the circuit is doing in that area?

author: Whales
author_rank: Super Contributor
timestamp: June 07, 2024, 01:26:48 am
content: Where is this transistor in the circuit? What does it do? Can you provide photos of the circuit board?The transistor overheating is probably a symptom, not a cause. Something elsewhere might be bad.

author: highcap
author_rank: Contributor
timestamp: June 08, 2024, 11:17:11 am
content: Quote from: Whales on June 07, 2024, 01:26:48 amQuote from: fzabkar on June 07, 2024, 01:12:36 amFrom year 1991I'm accompanying this post with a pic of the terminal board underneath and more CRT board pics.Note that the CRT tube remains powered on after the text is disappearing, it seems there's an issue with powering up the terminal board, but maybe I'm wrong...Thank you for your inputs!

author: highcap
author_rank: Contributor
timestamp: June 08, 2024, 11:23:47 am
content: And just added a video with what's actually happening.To be more precise, I have also measured voltages of the DB15 out connector from the CRT board to the terminal board, and it seems like some voltages are progressively dropping (since powering up) from 5.12 volts to around 0.3 volts. That may indicate a power issue on the CRT board that needs to sustain the terminal board.https://youtu.be/4CZuLlBMe_o

author: tooki
author_rank: Super Contributor
timestamp: June 08, 2024, 05:25:50 pm
content: Quote from: highcap on June 08, 2024, 11:17:11 amThe apostrophe replaces the omitted letters or numbers, so91’would be “91nnn”, wherennnis any number of digits — it cannot mean 1991. In other words, to abbreviate 1991, you need to write’91. Or just write 1991 to make it clear it’s a year — it’s literally only one more character!

author: highcap
author_rank: Contributor
timestamp: June 08, 2024, 07:54:22 pm
content: True, I was too focused on the issue I placed the apostrophe the other side.

author: kevin.gibbs
author_rank: Regular Contributor
timestamp: September 18, 2024, 11:23:16 am
content: Looks like the transistor power is not enough for a monitor with a diagonal of almost 30 meters )))))