Tek 2465B Calibration question after RIFA capacitor replacement - Page 1
Forum section: electronics / testgear

author: Bosteve
author_rank: Newbie
timestamp: April 03, 2025, 07:34:35 pm
content: Original post is here:https://www.eevblog.com/forum/testgear/fifa-cap-replacements-for-tektronix-2465b/msg5782503/#msg5782503I've replaced the blown caps and resistors as well as the other four RIFA caps. The crystal was replaced because I had snapped it off when originally reinstalling the case.The unit powers up fine but I get a calibration error. I can still use it to see waveforms, but voltage measurements are off.Im asking if anyone can give me a decent guesstimate what calibration might cost. I certain this is not something I can do. There are a couple places in the Boston area, but with Tektronix I have not had my call returned. Others were in need of a business account.Also curious if there are people on this forum that do calibration. As I said in the opening post I'm a hobbyist, so don't need a high level of calibration.Other options include an inexpensive 2213a available locally, or some digital scope. A good friend that is far above my level strongly suggests staying analog. I have used the 2465B ability to measure voltages, and would like to have that function.

author: tggzzz
author_rank: Super Contributor
timestamp: April 03, 2025, 07:50:42 pm
content: Don't bother to get it calibrated until the cause of the message has been found and rectified. Especially consider the A5 board and the NVRAM battery.There are useful hints in the thread you mention, plus there is the 2465 megathread and TekScopes.What exactly is the message you see?

author: Kwakerman
author_rank: Regular Contributor
timestamp: April 03, 2025, 07:54:04 pm
content: If you have a xtal then I'm assuming you have an early style A5 board (with battery)? If so, it is probably worth considering replacing the battery before getting it calibrated if you don't know when it was last replaced. As you said you don't need a 'traceable' calibration I was going to suggest sending the A5 to me (to reduce postage costs) and I could have put it in one of my scopes and ran it through a Cal, then I realised you were talking Boston in US, not Boston in UK (we have one too).

author: bdunham7
author_rank: Super Contributor
timestamp: April 03, 2025, 10:17:44 pm
content: Quote from: Bosteve on April 03, 2025, 07:34:35 pmWhat serial number is your scope and how far off are the voltage measurements? I'd be concerned that there is some problem with the unit and possibly it needs more than just calibration. If you do have an early version, I'd suggest replacing the battery first. Which error do you get on startup?If it isn't broken I can calibrate it but I'm a long way off and you might be better off finding someone local. It would be impractical and expensive to have it done commercially, you need the "phone a friend" option here, meaning another hobbyist.Edit: I should mention that the last 2465B that I calibrated appeared to be 100% working yet would not complete the calibration until I replaced one of the hybrids. I don't recall which one, but it was not U800. So that's an expensive nothingburger if you go with a commercial cal lab.

author: Bosteve
author_rank: Newbie
timestamp: April 04, 2025, 02:14:33 am
content: Im getting “Test 04 Fail 11” message. I may be wrong about the voltages. I think in my frustration I was making incorrect readings. Im going to check on that tomorrow. As for the battery, Ive had it for seven or eight years. I do not know if it had ever been replaced. Honestly, I had no idea it was needed until reading about repairs. Ive seen a thread about the procedure and will get on it.I recall while replacing the caps that I was going by the early schematic. Attached is the tag from the unit.Thank you for the assistance.

author: bdunham7
author_rank: Super Contributor
timestamp: April 04, 2025, 03:09:25 am
content: Yes, early, needs a battery and then you'll need to recalibrate it to remove the error code. But it probably won't be grossly off in display or readings. If you do see a large error there may be a repair needed.

author: tggzzz
author_rank: Super Contributor
timestamp: April 04, 2025, 12:59:57 pm
content: Quote from: Bosteve on April 04, 2025, 02:14:33 amWhat does the service manual state that is?If, for example, it states there is a bad checksum in the calibration data, then the first question iswhyit hasbecomebad. No point in recalibrating until after the cause has been fixed.

author: Bosteve
author_rank: Newbie
timestamp: April 04, 2025, 03:17:21 pm
content: The owners manual han no info. Idid a search before getting into the service manual. The attached link came up. States Test 04 Fail 11 is a parity error with bad checksum. It also gets in to some of the issues. Interesting, but far beyond my pay grade..https://groups.io/g/TekScopes/topic/2400_series_test_4_fail_3_13/29566030

author: tggzzz
author_rank: Super Contributor
timestamp: April 04, 2025, 04:34:02 pm
content: Quote from: Bosteve on April 04, 2025, 03:17:21 pmThis is a service issue, not a use issue. You need the service manual; see the TekWiki. TekScopes is a good source of information.When you calibrate the 2465, the resulting magic numbers (i.e. calibration constants) are stored non-volatile RAM. If the battery is dead or the RAM is damaged, then you won't get the same number out!