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Next step taken on my beloved TEK 2432A:
I replaced the Li battery by a new one, also replaced the bad X2 caps in the PS, and replaced 2 elcos in the PS that measured NOK (once removed these measured OK but I replaced them anyway), all the other elcos in the PS look & measure fine, probably because this scope has only 4400 operating hours.
No CHKSUM NVRAM fail any more, a nice PASS.

But I still have 3 FAIL messages:
7000 (CCD),
8000 (PA),
9000 (TRIGS).

FAIL details:
7200 CCD-GAIN -> 7210...40 fail,
8220 PA-POS GAIN CH2 & 8410...50 PA-GAIN & 8510...50 PA-INV GAIN fail,
9210 TRIGS-GAIN A TRIG & 9220 TRIGS-GAIN B TRIG fail,

Although it showed PASS at startup, from the test results menu I tested the RAM chips one by one, all PASS. Can I conclude that the battery backed up SRAM chips are OK now or do I need to replace these 2 chips?

From the menu I erased the memory, no effect.

Scope is UNCALD, so I tried to calibrate:
SELF CAL: does not pass, shows me the 3 same FAIL messages (7000 / 8000 / 9000) as above.
EXT CAL: I can only do the REPET test which passes, the other ones are locked ('All selections except REPET are locked, see service manual').

Then I wanted to try a Cold Start but the entire menu with COLD START, CCD SIDE, CCD ADJ, CAL PATH, FORCE DAC is 'Disabled - See manual'.

CH1 works pretty OK up to about 10KHz sinewave, correct voltage level, above 10KHz there is a lot of aliasing.
CH2 shows a sinewave that is much too low in voltage.
Trigger seems to work on CH1.

I'm now really getting stuck, calling out for help, any suggestions pls.?

Okay, so I played with the scope a little using my 2445 and the 2465s channel 2 out. I still haven't completely gone about the check of the preamp settings on the 2465. So with the 2465 set at 2 mV and the 10x'd 850 MHz waveform displayed on the 2465 with no probe connected I noticed a couple things. One is that the waveform does not show on the 2445 other than a fuzzy trace with a "check" in the left hand side of the trace like this -^√----- (sorry best I can do without pics), but the 2445 WILL display a calibrator trace if I connect a probe to the 2465 and connect it to calibration lug. Also I noted that on the waveform in question on the 2465, when I move the ?T markers across the waveform it distorts the waveform as I move across the center of the screen, and the waveform disappears as I use the vertical position control to move the trace towards the upper readout values. Does that ring any bells to anyone here? Keep in mind also this is a 2465 with the DMM/TV/CTT options if it's possible those options could be doing something screwy.

Is section 11 of service manual what you have in mind:


Ozan

Hi Gary,

I'm trying to do the same calibration and get the same error.
Did you find a solution?

Kind regards,

Daan

Not a big fan of Facebook (but I'm interested in Meta AI...so...)
Anyway, this was posted, recently, in the "Vintage Electronic Test Equipment" VETE forum/group, on Facebook.

Anyway... if it was me... and even though I'd like to get it... it's not going to be.
I'd offer him a few bucks for it... especially if he has to USPS it.

Remember, it's on Facebook, it in AR, and it's heavy.


--
Roy Thistle

I would like to replace the graticule lamps in my 2465b. I thought I had seen a exploded view
of the front panel assembly somewhere but can't seem to find it now.

Any suggestions?

Thanks for the advice.

Here's the datasheet for the CRT - it may help.

I have exactly the same issue as you & have checked everything I can think of, I'm sure there's more going off here than a bust CRT. I've not had this issue before with my 545B & 585A so think it's something to do with the 547 circuitry, this is my gut feeling but could be wrong.

I've not worked on mine for a while but was going to try tacking on a resistor/pot combination off R857 IE the cathode supply instead of the current intensity pot to g1. We only need a -65v to -95v difference between cathode and control grid to vary brightness. Crude but worth a try before righting off the CRT.

Andy.

Thanks for looking into this—good to know that those are fuses.

He should definitely hang onto those—almost every 7A19 I’ve acquired either has no spare fuse, or no working fuses.

He’s found the mother lode!

Tom
Sent from an iThing; please forgive the typos and brevity

On May 9, 2025, at 23:36 , Tom Lee via groups.io <tomlee@...> wrote:

There are three attenuator modules in the 7A19, with 10x, 5x, and 2.5x attenuation factors (gain factors are then 0.1, 0.2 and 0.4, which probably explains the "0.2" seen on the pic of the modules you linked to in your OP).

I was curious enough to pull out my mostly-working 7A19 and take a family photo of the fuses and two of the attenuator modules. The two spare fuses and the installed fuse are all marked 0.2 18, so I think John's bag of attenuators is correctly marked!

/g/TekScopes/photo/302392/3914925?p=Name%2C%2C%2C20%2C1%2C0%2C0

I didn't feel like removing a screw to take out the other attenuator module. The 7A19 attenuator is easier to work on than the 7A29, but the plugin sits in a drawer because the coupling switch is flaky and I'm afraid of absentmindedly blowing a fuse.

Adam

I recommend not to pull off the plastic knobs as the service manual says and instead slide off the bezel and the button panel off the pots. The knobs get brittle and break off easily. Otherwise service manual steps are very thorough. Here is an album to explain it better with pictures.

/g/TekScopes/album?id=259435

Ozan

They are all spoken for. Thx!

I have a 2465B with a broken Volts/VAR shaft and am asking for second opinion on replacing
The shaft.
My first thought is to pull the front panel out following service manual.
Then proceed to the POT module removal process as described in service manual to
Gain access to the broken shaft for removal from the actual variable pot.
Install a replacement shaft, then reassemble everything.

I have a dead 2465A for parts doner that I plan on practicing on first.

Is there a simpler solution for what I need to do?
After the shaft is replaced, I plan on recapping the LVPS and then replacing the surface mount electrolyte capacitors and DS chip on the A5 board.

Hey Jason,

If you're diagnosing this scope from scratch, then the first port of call
is to look at all the supplies at J119 on the main board. There's a table
with acceptable voltages and ripple somewhere in the service manual.
You don't need to use an isolation transformer, but you may want to plug
both scopes into the same outlet or extension strip to minimize the ground
differential. Make sure you perform power supply measurements under the
20MHz bandwidth limit.
If you haven't read this document before:
, now is probably a
good time :).

Depending on where in the world you live, 950MHz could be a frequency used
by a mobile network. These scopes are quite capable of showing waveforms up
to a GHz, though the amplitude is way down, and the triggering gets iffy
with my 2467 from ~800MHz.

Good luck,
Siggi

I'll have to get back to you on that while I check all that out sometime tonight hopefully. I do know that I also see the ripple on channel one, but nowhere near the same amplitude. When I plug a probe in channel 2 the ripple drops down to the same amplitude as channel one. I WISH I could post a pic on here of what I'm seeing. Where would a 850ish MHz signal be at inside the scope? Unless it's picking up something like a RF transmission nearby? If that were so then it should be on both channels? I have so many questions on what's happening. All I can think of to do is clean the attenuators and remove, clean and replace the hybrids and see if that changes anything. That and go through the diagnostic waveforms shown in the service manual and see if anything is off there. Do I need to plug the 2465 into an isolation transformer before doing those tests? I didn't see anywhere in the service manual that says to, but I know that doesn't necessarily mean anything, it could be assumed?

Gordon,

By getting the voltage you say using a meter, you are making a complete circuit from the negative supply, through the crt acting like a diode in this case, to ground. The rest of the circuit was on the rest of the pins. Pin 6 goes to the focus so you would get an infinite resistance between pin 3 and the focus with pin 3 disconnected from the circuit.

There are good crts available online. Get one to make sure you have a good one. Do not part the scope out yet. This model is too good to junk.

Mark

Hi Mark & Morris:

Update - I isolated pin 3 of the crt by unsoldering the wire at the junction of R830/C829 & C830 and measured the voltage on the wire. It was around -1070V even though it was not connected to anything. Maybe this is expected, I don't know. Unfortunately, I don't know of anyone with a crt checker.

Also checked for continuity between pin 3 and the cathode at the junction of R857 and C858 - open circuit. Then checked for continuity between pin 3 and the wiper of focus pot R846 - also open circuit. It doesn't seem to be an internal short in the crt, but it's still strange that the grid at pin 3 is at -1070V when not connected to anything.

I think this is now beyond my capabilities, so I may have to consider parting it out :(

Gordon

On 5/10/25 00:36, Tom Lee via groups.io wrote:

sometimes the attenuators will burn out first to protect the fuse. ?

maybe that's why these parts were kept in an envelope in a scope-mobile drawer with a 7904A on it!
The 7A19 must have been nearby at one time too...

Hi John,

The 7A29 has no input fuses (thankfully), but the 7A19 does (along with two spares). The 7A19's fuses and attenuator modules share the same form factor. so that they can be inserted into the signal path with the same minimal perturbation of microstrip line impedance. The attenuators don't have fuses (intentionally) integrated with them, but sometimes the attenuators will burn out first to protect the fuse. :(

There are three attenuator modules in the 7A19, with 10x, 5x, and 2.5x attenuation factors (gain factors are then 0.1, 0.2 and 0.4, which probably explains the "0.2" seen on the pic of the modules you linked to in your OP).

-- Cheers
Tom


--
Prof. Thomas H. Lee
Allen Ctr., Rm. 205
420 Via Palou Mall
Stanford University
Stanford, CA 94305-4070

On 5/9/25 12:19, Adam R. Maxwell via groups.io wrote:

John, those look like 7A19 fuse or attenuator elements. See photos on Tekwiki, or I can take one apart when I get home from work.

Looks similar, except some different circuitry on the flat side. The box it was in was labeled as fuses.
Is the fus *IN* the attenuator? Are there five or ten kinds?