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On Wed, Apr 7, 2021 at 12:00 AM, Stephen wrote:

But I think I’m gonna leave it as is (If it’ll even work...), and not
convert it to a later model.

You can't do without any voltage on pin 12. See Satbeginner's message.
A bias voltage of about 150V is needed or all electrons will just land on the grid and die/charge it.
IOW: If the image is fine without a bias, there probably isn't an expansion mesh in your CRT...

Raymond

Thank you Michael! ?

On Tue, Apr 6, 2021 at 11:25 AM, Raymond Domp Frank wrote:

Time to give away another secret:
The wire actually is white, with a brown and a red stripe. Guess why?

Raymond

Because the designer was colorblind?? ??♂?

On Tue, Apr 6, 2021 at 05:05 PM, Stephen wrote:

BTW, you’re talking about “mesh” this, and “mesh” that...
I don’t even know what that is. Could someone please enlighten me?
What does it mean?

Stephen,

Here is a link to an excellent article on the Vintage TEK site. This is by Peter Keller and explains the mesh and its function.



Hope this helps.

--
Michael Lynch
Dardanelle, AR

On Tue, Apr 6, 2021 at 11:58 PM, Dave Peterson wrote:

And the wire is the red striped one in Stephens picture that runs in front of
the R1431 resistor over to the bundle, and then up to the CRT.

Time to give away another secret:
The wire actually is white, with a brown and a red stripe. Guess why?

Raymond

BTW, you’re talking about “mesh” this, and “mesh” that...
I don’t even know what that is. Could someone please enlighten me?
What does it mean?

On Tue, Apr 6, 2021 at 10:44 AM, Dave Peterson wrote:

That's what I was looking for.

Yeah, exactly, the early service manual doesn't include those components, and
those are the components that are supposed to drive pin 12 of the CRT.

Your picture shows your board matches the early service manual and does not
include CR1427, R1428, and VR1428 (note: previous message called out R1427
instead of R1428).

See the picture I just added. Your board doesn't have these. Interesting. Talk
about missing parts!

Dave

So I guess this one is a pretty early model then.
In my other thread, I was asking about “missing parts”, referring to those that had been obviously scavenged, not to those that had never been there to begin with. ?

But I think I’m gonna leave it as is (If it’ll even work...), and not convert it to a later model.
I’ll replace the missing parts and see if the CRT is even working on this thing, who knows...

And the wire is the red striped one in Stephens picture that runs in front of the R1431 resistor over to the bundle, and then up to the CRT.

I see now what they did, and I was distracted by the relocation of the circuitry, not that it was missing. And the CRT tube schematic was updated to be a little more explicit.

And now I'm that much more clear on the early/late difference. And still find it interesting that my scope SN B177xxx is the later layout, not the earlier. Perhaps coinciding with CRT part number change at SN B010500? But that's not necessarily so either.

Dave

Eureka! There it is, right in front of me.

Dave

That's what I was looking for.

Yeah, exactly, the early service manual doesn't include those components, and those are the components that are supposed to drive pin 12 of the CRT.

Your picture shows your board matches the early service manual and does not include CR1427, R1428, and VR1428 (note: previous message called out R1427 instead of R1428).

See the picture I just added. Your board doesn't have these. Interesting. Talk about missing parts!

Dave

Hi all,

A while back I transplanted a 465 CRT to a 2235, and in that one too I needed to add the Pin12 wire and components to provide the appr. 110VDC.

Like Raymond said, just one resistor, diode and capacitor.

Saludos,

Leo

Thanks to all that offered advice on my freezing TEK 2430. I've replaced the RIFA safety caps and all of the less than 50v electrolytics in the low voltage supply.
I'm at the 4 hour mark and everything is still rock stable and running as it should.
I really appreciate having this resource to lean on when things go "south". Great bunch of helpful folks.

John / K7RLD

On Tue, Apr 6, 2021 at 09:55 PM, Dave Peterson wrote:

I was wondering if you can see what's driving the wire to pin 12 of the CRT.
The early 070-1330-00 service manuals do not appear to have the necessary
components in the board diagrams for A9.

Sure it does.
We're talking about VR1434 and C1434 in the CRT schematic.
Figure 7-17 shows them just to the right of the space between the long ceramic combined resistor R1431 and C1404, right above C1404 and CR1404, printed diagonally.

Raymond

C1427, R1427??
I don’t see them on the pictures you posted.... ??♂?
Look at the one I’m posting right now

Hi Stephen,

No, I was asking about components underneath the HV cover on the bottom of the scope. It looks from your pictures that you already have it off - I can see one of the hex stud posts next to Q1566. The last remaining power supply driver that's mounted to the heat sink.

I was wondering if you can see what's driving the wire to pin 12 of the CRT. The early 070-1330-00 service manuals do not appear to have the necessary components in the board diagrams for A9. See the photos I've added to your album (not posting links since they seem to be causing problems and potentially more confusion). This is the rear of the A9 board adjacent to the vertical pre-amp assembly, opposite the power supply side (left and right are confusing depending on orientation of the scope - looking at A9 the scope is upside-down).

I'm curious what your board has. In researching your original question I found that, at least with regards to C1549, your A9 board is constructed per the early service manual board diagram. That made me wonder what the mesh driver circuit on your board looks like, since the early service manual does not include any mesh driver schematic nor board components.

My original and fundamental concern is/was the uniqueness of early 465 CRTs. But it seems the early 465 CRTs should have a mesh, and therefore are interchangeable with later 465 CRTs. My conclusion, based on the location of C1549, was that this appeared to be a very early 465 and that it might not have the mesh/circuits. Presuming that yours does have the components CR1427, R1427, and VR1428 as indicated in the later service manuals, then you have an A9 board that is a hybrid/intermediate variation that includes the "old" C1549 location and "new" CR1427/R1427/VR1428 installations. It would make for an interesting documentation of such a board as it does not seem to be documented in either service manual.

Pardon the thread theft, and I'm sure I've flogged this dead horse enough.
Dave

On Tue, Apr 6, 2021 at 08:20 PM, Siggi wrote:

Rather than going this way, you might try to re-lube the motor. On my 485,
which had a horribly noisy & rattling fan, I did this successfully.

In 465/475 family 'scopes, I've encountered a few motors with worn-out sintered bronze bearings, causing a very unpleasant rumbling noise. I could clearly feel the radial play, mostly in one direction. Fortunately, I had a few donors available, which I treated mostly the way you suggest.

Raymond

On Tue, Apr 6, 2021 at 03:54 AM, Dave Peterson wrote:

When you were asking him about his board part number you seemed to have a
similar board at hand? Do you? How does this earlier board drive pin 12?

I have one board left. It looks very old and is quite dirty. It carries ref. no. 670-2233, like Stephen's.
The HV multiplier has date code 7341, earliest component dates are 7337, latest "originals" are 7431, so it's probably a 250000-plus board.
It has the ganged focus tracking pot and has the mesh components (C/CR/R1427, C/R1428 and C1418/1419 (one dipped tantalum cap 47uF/35V) in the locations as indicated in the 250000-plus SM 070-1861-00.
CRT pin 12 has been in use and connected and probably connected to C1427.

Raymond

On Sat, Apr 3, 2021 at 2:41 PM durechenew via groups.io <durechenew=
[email protected]> wrote:

For those with a 2465A (or maybe B) version; I just received a 2465. Very
clean and good looking inside; probably heavy usage, though, considering
the status of the blower: noisy.
Another thing I noticed (didn't mention that actually works normal - up to
a point) is that adjusting intensity it goes in a de-focus state; partially
adjustable, but you don't want to do that every time you go from low
frequency to higher. Could be a CRT issue or something in the control
circuits; have to do some verification.
The first issue is the one I need some help with: the blower's motor is a
Siemens device that's beyond repair and I'm considering the idea of
changing the whole blower with a regular fan and some mods in the path of
airflow; that if there is a kind soul that could take the trouble to
provide a picture of the fan in a 2465A; from SM I take it might be not a
blower, but a regular fan; I might be also wrong.

I went through the conversion with my 2465, replacing the wonderful
impeller fan with a 60mm case fan. I hated it so much that I bought a new
Siemens motor when one came up on eBay and I reverted the modification.
Note that the back cover on the 2465 doesn't leave as much room as does the
cover for e.g. the 2467 or 2465A, so fitting a slim 60mm case fan was about
the best I could do. Even with a temperature controlled speed reduction,
this was all kinds of whiney and objectionable.
Rather than going this way, you might try to re-lube the motor. On my 485,
which had a horribly noisy & rattling fan, I did this successfully.
I first de-soldered the motor and then removed the thrust bearing at the
back of it. This allowed me access at both ends (bushings) of the motor. I
then flushed the motor with isopropyl alcohol a couple of times
to get decades of ick and crusted up oil out. I then lubed the bearings
with a drop of 30W synthetic motor oil. This seems to have restored it to
wonderful, near-silent operation.

One reason why I stopped shipping scopes.? I never had a problem/failure, but it was only a matter of time.
-Dave

Dave,

I don’t seem to find your last message. But you were asking me something regarding removing the back to take a picture of the CRT pins, correct?
Could you refresh my memory?