Tektronix TDS210 VERTICAL lines on display - Page 1
Forum section: electronics / repair

author: Mr Lurpak
author_rank: Contributor
timestamp: September 23, 2025, 11:21:20 am
content: Hiya. Does anyone has experience or seen this fault? Scope starts and works but display has vertical lines as in picture.It is NOT:- Display (tried another one)- Firmware or Eprom Replaced and newest FW installed- RAM (thought as display share RAM with CPU it might be that so changed that)- Q144 (original display was blank and missing 24 ish Volt on display connector that was fixed but replacing Q144)Any ideas?

author: squadchannel
author_rank: Frequent Contributor
timestamp: September 23, 2025, 11:44:00 am
content: lines appear at regular intervals, one of the data lines going to the LCD seems faulty.STN LCDs are typically8-bit, I suspect D1 and D5 is the problem.PS:LM32P07 is 4bit parallel. and MSB first. so,D2is the problem.Quote from: Mr Lurpak on September 23, 2025, 11:21:20 amDid you check the data line with the scope?

author: Mr Lurpak
author_rank: Contributor
timestamp: September 23, 2025, 12:21:56 pm
content: No didn't check data lines as - but with this info it makes senseFor some reason I had the idea is was serial to the display so did not think about this. That is why forums like this is great.

author: Mr Lurpak
author_rank: Contributor
timestamp: September 23, 2025, 01:47:49 pm
content: Spot on!I found the data sheet for the display and yes D2 is dead/noise. Traced it back to the MM9527-VCE. Does anyone knows if that chip has a replacement variant available as it seems to be pretty hard to find? Even data sheet?Cheers

author: squadchannel
author_rank: Frequent Contributor
timestamp: September 23, 2025, 02:52:54 pm
content: It's a custom ASIC. it's hard to find.But i think not that IC would fail just that pin.Do you have photos of the entire board? Both front and back. Let's trace the traces.Trace the data lines other than D2 from the connector; they should lead to some IC. My guess is the trace is broken somewhere.I've never worked with TDS210, but I heard a rumor that the board corrodes with some kind of acid?

author: TERRA Operative
author_rank: Super Contributor
timestamp: September 23, 2025, 05:01:22 pm
content: I have a spare board here that I can pull that chip from if you end up needing it.I was always planning to strip the board down and make up a schematic, so I can pull chips off to look underneath and trace out things if you need too.

author: Mr Lurpak
author_rank: Contributor
timestamp: September 23, 2025, 08:50:36 pm
content: Unfortunately, the pin 4 on CRT connector, and all the way to display, is connected and checked with scope and continuity check - Pin 4 goes directly to U201 so think the MM9527-VCE is bad.

author: Mr Lurpak
author_rank: Contributor
timestamp: September 23, 2025, 08:56:42 pm
content: Yes, same board I have. The MM9527-VCE seems to be National Semiconductors chip and not a TEK one, so hoping to see if I can find replacement/equivalent - need to do some more research. But at least I NOW know that D2 to display is causing the fault.

author: Mr Lurpak
author_rank: Contributor
timestamp: September 23, 2025, 09:00:10 pm
content: BTW have watched several of your videos on YOUTUBE - good stuff man. I recently picked up electronics again after years away from it and just found a passion in old Oscilloscopes and test equipment. So came across your videos on Tek 2235 and some Philips scopes.