Tektronix 2465B, I can’t seem to remove the power supply boards... - Page 1
Forum section: electronics / repair

author: gtr
author_rank: Contributor
timestamp: August 13, 2025, 03:42:45 pm
content: Hello everyone,I can’t seem to remove the power supply boards from the Tektronix 2465B to replace the Rifa capacitors. There must be one or more screws that I’m not seeing. Are there any screws underneath that need to be removed, or something else?Thank you!

author: chilternview
author_rank: Frequent Contributor
timestamp: August 13, 2025, 04:42:21 pm
content: IIRC there are 3 screws that hold the heatsink to the bottom chassis, as well as the 2 at the back. But it is a tight fit even when all are undone.

author: gtr
author_rank: Contributor
timestamp: August 13, 2025, 05:48:07 pm
content: Quote from: chilternview on August 13, 2025, 04:42:21 pmThank you very much! I also needed to remove the power connector. It’s true that it’s very tight and difficult to take out. Now all I have left is to replace the Rifa capacitors, even though they’re still in fairly good condition.Thank you! :-)

author: Kwakerman
author_rank: Regular Contributor
timestamp: August 14, 2025, 09:03:14 am
content: I normally loosen the screws that hold the backplate on by a couple of turns, that gives a bit more room to wiggle it out. I assume you also disconnected the 4 wires from the 115/230 volt switch and fuse holder (they are on spade terminals)?

author: gtr
author_rank: Contributor
timestamp: August 14, 2025, 05:38:58 pm
content: Quote from: Kwakerman on August 14, 2025, 09:03:14 amThanks for the info. Yes, I unplugged the fuse and the power cord, which I removed because it took me several tries to realize that these connections were preventing me from taking off the plates. Once I had finished replacing the capacitors and screwed the plates back on tightly, I looked to my left… and realized I had forgotten to put back the three clips that hold the plates together. Damn… So I had to take everything apart again. But hey, everything works fine now. Thanks again! :-)

author: Kwakerman
author_rank: Regular Contributor
timestamp: August 15, 2025, 07:41:46 am
content: While the pcbs were apart did you look under the metal shied (held on with three screws)? Most of the time there are three RIFAs under there, one hidden by the thermal switch. They also suffer from cracks but don't seem to have the same catastrophic failures that the two on the other pcb.I say 'most of the time' as I have had PSUs where some or all of the RIFAs have been replaced with other brands as part of the original build. Haven't worked out if that change is by model, date or manufacturing location.

author: tggzzz
author_rank: Super Contributor
timestamp: August 15, 2025, 07:47:33 am
content: Have you read the service manual? Free at the usual sites.The condoraudio PDF also contains a lot of useful information.Condoraudio also sells complete capacitor kits on fleabay.

author: gtr
author_rank: Contributor
timestamp: August 17, 2025, 05:38:44 pm
content: Quote from: Kwakerman on August 15, 2025, 07:41:46 amHello,Yes, I replaced these three capacitors, making a total of five Rifa capacitors to replace. They weren't in that bad of a condition. Even the 0.01uf capacitor looks like it was new, but from a newer Rifa model, but I replaced it anyway.Thank you! :-)

author: gtr
author_rank: Contributor
timestamp: August 17, 2025, 05:56:15 pm
content: Quote from: tggzzz on August 15, 2025, 07:47:33 amHello,Yes, I have the manual, which I had already found online because I don't buy an old device or an old oscilloscope without making sure I find it first. However, I'm French-speaking and I use a translator here, and I'm going to translate the manual to help me. I can get by a bit in some English manuals at times, but I get stuck on certain passages at times.I had already downloaded version 2 of Condoraudio here and watched the videos on the 2465B as well.My 2465B was apparently a 1991-1992 version with firmware B.02 (1993). The NVRAM is dead because when I hold down the Self button while turning on the oscilloscope to see the diagnostics, I immediately get the error message "Test 02 Fail 42," which tells me the battery is dead. It's still usable and gives me very accurate measurements. But I'll probably replace the Dallas DS1225Y-200 NONVOLATILE SRAM 9417E 043437 NVRAM in my oscilloscope.The rest seems fine.Thanks! :-)

author: W3KW
author_rank: Contributor
timestamp: August 25, 2025, 11:27:36 pm
content: I just bought 2 chips at mouser. Mine are a different part number than you listed however. Not sure why, but here is the link:https://www.mouser.com/c/?q=DS1225AD-150%2BThe -AD version preserves the battery until power up of the chip for the first time, thereby ensuring a fresh start and long life.

author: gtr
author_rank: Contributor
timestamp: August 28, 2025, 05:40:06 pm
content: Quote from: W3KW on August 25, 2025, 11:27:36 pmThank you for sharing.However, here is what I found:Timing differences: a critical point to noteA notable difference between these versions is the reset timeout:The “-Y” versions (like the DS1225Y) have a shorter reset timeout, generally on the order of a few milliseconds.The “-AD” versions (like the DS1225AD) have a delay of approximately 125 ms, which is longer.This means that upon power-up, your Tektronix must wait at least 125 ms before attempting to access memory. Otherwise, premature accesses could occur, leading to corruption or malfunctions.

author: chilternview
author_rank: Frequent Contributor
timestamp: August 30, 2025, 02:38:16 pm
content: I used the DS1225AD-150+ and it worked just fine on my 2465B.

author: gtr
author_rank: Contributor
timestamp: August 31, 2025, 05:37:35 pm
content: Quote from: chilternview on August 30, 2025, 02:38:16 pmI finally ordered the DS1225AD-200+ to be the closest match to my original DS1225Y-200.