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The oscilloscope seems to work correctly, the self test reports no problems. To avoid future problems, given that I recently replaced the entire power supply unit, is it advisable to restore the electrolytic capacitors of the A1 board?

Giovanni,

Yes.

Mark

What do you mean "restore"

To REFRM or to REPLACE?

Avoid complet recapping , beware the 15V cap screen error in manuals.

Jon

Replace. Once the various electrolytic caps have been replaced, will the calibration of the instrument be lost?

Jean-Paul, could you be a little more specific about error?

Giovanni: Searhc here, EEVblog, for Tektronix 2465 A1 silkscreen error electrolytic caps
see notes at Condor Audio, and Q service on warnings of replacement/recapping A1.

Two lytic caps are reversed on silkscreen, leads to wrong voltage caps after replace.

Do it ONE at a Time NOT all at once.

Bon chance,

Ciao!


Jon

I keep seeing this reference to mislabeled silkscreen but after a search I
have yet to see exactly which boards and capacitors they refer to.
I repaired a 2465 and checked every capacitor on the power supply boards.
The capacitors themselves were not clearly marked with the usual black
stripe or + but the boards seemed OK and had square holes to mark the
positive. My 2465 is working fine for months.
I don't believe that A1 is a power supply board.
I watched a video that showed that two capacitors were swapped on the
manual layout.
Are there more than one error on the boards and in the manual?

AFAIK, the silkscreen error is not on the main board (A1), but on the inverter board (A3) where C1132 and C1115 are swapped, I believe

Hello yes I mixed A1 main bd with A2 PSU, I meant the PSU of course.

Main board: I have NEVER found ANY bad caps on A1 no heard of any replacements/recapping on A1.

If it anit broke dont fix it


Jon

As you can see from the photo in the link, the coil next to U600, the support has cracked, but the wire is not interrupted, can it create problems?

Giovanni
Is the scope working ?

Typically these,colis,are,damages by cover removing carelessly
Brittle plastic.

Please DO NOT touch, or replace or fix these,coils unless the,vertical transient or BW is way bad.

To change anything in vertical output, you must have equipment and experience for a vertical calibration.

Suggest that you close your scope up, enjoy and just stop tweaking and fiddling

You will cause ,more problems

Ciao.

Jon

I have had a fair few 2400 series through my hands . I have never replaced any caps on any A1 /main boards , just the Power supply and most importantly the Electrolytics on the A5 boards that have them . Replace your Dallas with an FM16W08-SG and put the covers on, or the backup Battery on earlier boards. On even earlier boards , put a socket on your ER1400 chip and read the data into your programmer and program a spare . Then put the covers on and walk away .

I'm going to jump in here.
Replacing the caps on the A1 is NOT a big deal, and is no more complicated than doing any of the other PCB's.

The only so-called "obstacle" is the disassembly/reassembly -
1. You need to partially release the front and rear panels, and unsolder the BNC's to free the PCB,
2. Be super careful when disconnecting/connecting the CRT wiring to not crack the CRT's glass,
3. Watch for the coiled-up delay cable underneath the PCB that it doesn't unravel.

Some owners have reported a substantial improvement in the waveform sharpness after recapping, and others have reported little improvement. May I presume that the greatest improvements will be seen on a well-used scope?

Because you're going to invest more time and effort in the disassembly/reassembly of the A1, then don't waste your money on sub-standard caps.
If you're making the decision to invest in the effort to do the A1, then a few extra $ on the highest-quality parts is well-spent, in order to the job right once only, the first time.

In short, if you're competent, then there's absolutely nothing to be afraid of, and especially if you have an older scope with many hours, then expect a visible improvement in the waveform quality.

Menahem Yachad
CondorAudio

It would be interesting vto take a 10,000 hr 2465B and document all the voltage /ripple on all the main rails and voltages on the va1 board and then document the trace quality etc. Then replace all the caps on the A1 board and document the result . But the thread starter asked on whether we thought it was necessary . The answer must be that it would depend on whether you are happy with the trace quality and measuring ability . As Menahem says there is nothing to fear if you are competent . Your decision !

I reassembled everything and the oscilloscope works quite well, except for the intensity potentiometer. When I turn the knob the intensity does not change gradually. Is there a way to repair it or do I necessarily have to replace the entire group of potentiometers? By the way, replacing the caps on the A1 card has certainly improved the quality of the track.

Giovanni,
I don't think an instrument's calibration, typically, can be lost by
replacing electrolytic capacitors (nor have I ever seen it). These types of
capacitors are never precision types, and they consistently perform their
sought function over a range of values.
Personally, with instruments I both want to keep and/or are of a certain
age, I may go ahead and replace them all. Or if a complex and large unit -
such as, for instance, my recent project with a Fluke 5440A - and I have it
open anyway, then I replace all those I have access to.
I never "reform" electrolytics as a procedure, but oftentimes I've had
older units start barely working to substantially recover with the run
time. I think at least part of that is biased electrolytics improving their
condition.
Radu.

To reassure yourself test all the capacitors you replaced on the A1 board on a decent tester and report here the values and ESR etc . This will give an indication of the validity of the work .

Typically the HV pots get scratchy, and are NOT fly by wire encoders.

Locate the focus, astig, and intensity pots

Get a good control lube and cleaer,

Spray and exercise.

Should fix the issues


We use ONLY 99% isopropyl alcohol to flush and clean and control lube .

DO NOT use WD-40 or petroleum distilates, nor acetone, etc!!!!!

Jon

Jean-Paul - What do you mean by “good control lub and clear”, can you be a little more precise please? An example?

Not entirely sure of HV applications, but the typical product used on
controls would be DeoxIT FaderLube (F5).
Radu.

On Thu, Apr 18, 2024, 9:41 AM Giovanni via groups.io <hasdist=
[email protected]> wrote:

Jean-Paul - What do you mean by “good control lub and clear”, can you be a
little more precise please? An example?