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Yes Dave, I’m good.
Don’t bother. And Thank you!!

Hmmm ?
When I look at the data sheet for the MJE2801 (Q1534,Q1546, Q1566), it has exactly the same pinout as the TIP35C I used.
However, now that I have a better and clearer view of the board layout, (thanks to the different links), I realize that, although the part number used by Tekronix is replaceable by an MJE2801, the board silkscreen says that the Base and Emitter are reversed from what I see on the data sheet... I couldn’t clearly see that before, not even on my unit.
That will definitely need to be addressed.

Can someone double check and confirm? It’s a bit confusing...

Thanks Toby!

On Fri, Apr 9, 2021 at 12:58 AM, <toby@...> wrote:

And I've personally scanned a clear one, not sure if it's the right SN
range for you.



(note, multipage tif, but most system viewers are fine with it)

I would have thought I'd uploaded this to Tekwiki.

That's the same as 070-1330-00465Service.pdf on

Raymond

On 2021-04-08 6:41 p.m., Stephen wrote:

On Thu, Apr 8, 2021 at 11:26 AM, Ozan wrote:

Hi Stephen,

The schematic from
TekWiki is not very good. It’s near impossible sometimes to make out the
parts numbers.

Did you look at the SMs at :
(2)/
and


Ozan

And I've personally scanned a clear one, not sure if it's the right SN
range for you.



(note, multipage tif, but most system viewers are fine with it)

I would have thought I'd uploaded this to Tekwiki.

--Toby

Much, much better! Thank you Ozan. ?

On Thu, Apr 8, 2021 at 11:26 AM, Ozan wrote:

Hi Stephen,

The schematic from
TekWiki is not very good. It’s near impossible sometimes to make out the
parts numbers.

Did you look at the SMs at :
(2)/
and


Ozan

Much, much better! Thank you Ozan. ?

On Fri, Apr 9, 2021 at 12:30 AM, n4buq wrote:

If this is the Siemens motor version, HP also used this motor in the 8640B
signal generator so searching for replacement parts for that might reveal some
possibilities.

AFAIK, the same one is used in the HP 8620 main frame. These are sometimes offered at low prices. I have two but just one plugin. The fan in both is fine.

Raymond

On Thu, Apr 8, 2021 at 11:19 PM, Raymond Domp Frank wrote:

Check by connecting current-limited DC across each of the buffer caps
separately, starting from a few volts.
If no shorts observed, check individual diodes in diode bridges.
All this in-circuit but *with mains plug disconnected*.

This would be a good occasion for using a variac. I remember you didn't have one a few months ago, Stephen, and didn't plan on getting one yet. "Get a variac when I can" just scored one point today...

Raymond

If this is the Siemens motor version, HP also used this motor in the 8640B signal generator so searching for replacement parts for that might reveal some possibilities.

Thanks,
Barry - N4BUQ

Hi Stephen,

The schematic from
TekWiki is not very good. It’s near impossible sometimes to make out the
parts numbers.

Did you look at the SMs at :
(2)/
and


Ozan

On Thu, Apr 8, 2021 at 11:19 PM, Raymond Domp Frank wrote:

If no shorts observed, check individual diodes in diode bridges.

I meant to say "If no shorts elsewhere observed, check individual diodes in diode bridges".
Since you're looking for shorts (not PN junctions) in individual diodes in the bridges, that's usually possible with the bridges in.

Raymond

Systems are not working well today. I'm not getting messages until much later than they are posted, so apologies if they are out of sync.
Dave

I believe someone mentioned that the 465/475/485 family used the same fan motor. This got me scared, so I pulled out my 465B Service Manual to compare. I finally found the fan and the motor is listed as Tek #290-0536-00, Mfg Code 90201 (Mallory Capacitor!) part #TDC106M025FL (465B SM, rev E, May 1980). I don't know how similar it is, but it has 13 pins arranged in a circle.

That referenced AntiqueRadios article called out Tek parts 670-7390-00 or 670-7390-01, completely different series. I wonder if that means the 2465 motors were custom made, as copies of the earlier motors, after Mallory declined to make more.

A question: What are the chances that any of these motor bearings could be oiled, before they got too worn. A stitch in time....

BTW, I don't recommend ordinary motor oil for applications like this. You don't really want detergent oil in something that doesn't have a pump and filter, and SAE 50 sounds WAY too heavy. Non-detergent or STM (Straight Mineral Oil) in SAE 20 or 30 are probably better choices.

How is it broken?

If it's a plastic part and it's not grossly deformed, it can likely be
repaired to like-new condition at least when it comes to the
functionality.
If it's metal, probably as well, with more work. Plastic is easier to restore.

One thing I wonder about.

Why not just get a new motor? It doesn't have to be that exact one, right?

On Thu, Apr 8, 2021 at 8:16 PM durechenew via groups.io
<durechenew@...> wrote:

Thanks to all for the great interest this has started and for more than interesting information presented. Great, great article at antiqueradios; whoever's ready for that work, good luck!
Not going to work for me, as part of the bushing holder is broken and I think that's no repairable. I believe somebody mentioned the fan for 2465A(B?) or 2467 with driver circuit with an NTC; I didn't find than NTC in schematic, maybe I don't have the right one... The idea of a regular fan with that (thermal) controller (or another, maybe from a 2465 modified for the need) is attractive (I have some fans of high reliability).
Thanks all for thoughts
TT

On Thu, Apr 8, 2021 at 10:41 PM, Dave Peterson wrote:

If the main fuse you're going to have to see if you can identify the short in
the power rails. Do any of the power test points measure 0 ohms to ground?

Shorts in the power rails after the buffer circuits usually aren't able to cause blowing of the mains fuse.
That's why I suggested checking the circuits as in my message about half an hour ago.

Raymond

BTW, you’ll notice that I’ve replaced the 2 missing pass transistors with TIP35C’s.
I checked the pinout, ans it seems to be the same as the MJE2801.

Yes Raymond,

This is the fuse I’m talking about.
Good pieces of advice, as usual. Thank you ?

On Thu, Apr 8, 2021 at 09:41 AM, Dave Peterson wrote:

Interleaved,

Stephen,

I don't quite have the equipment to scan the pre SN B250000 11x17 pages, but I
can take photos and look up specifics for you.

That would be awesome, thank you.

The A9 board has many board layout pages in the book. Each one highlights
components from different sections: Horizontal Amp, CRT, Power Supply, etc.

I’m sure...

Please let me know what you need and I'll upload pictures. It's kind of a
run-around to take and upload pictures, so a blanket dump would take a while.
My phone takes pics that are several Meg in size, so I resize them down to
something more on the order of several 100k. But it takes a bit of shenanigans
to do. I don't want to blow up the groups disk space.

Of course, I understand. Can you send them to me full size, privately maybe?

When you say the fuse blows, are you talking about the main fuse, or F1419?

I’m talking about the main fuse, the 0.750mA one outside the unit (the scope is set to 230V, I’m in Europe)

F1419 is the one on the board that drives the HV transformer. Quite common
that C1419 shorts and causes that.

F1419 is fine. Although C1419 was testing good, I replaced it anyways because I happened to have a brand new one just if front of me. I guess it was C1419 (can’t make out the number), the large 47uF/25V tantalum underneath the high voltage cover shield, in the corner.

If the main fuse you're going to have to
see if you can identify the short in the power rails. Do any of the power test
points measure 0 ohms to ground?

Nope... The 15V rail was shorted to ground before I even powered up the scope, and I fixed that already.
None of the low voltage test points are shorted to ground now.

As you know, some of the A9 board diagrams are already in your TekScopes photo
album. Let me know what's not covered that you think will help. Same with
schematic pages.

Yes, But I’d like, if possible, to have as much as I can with the parts labeled.
I’m posting a few pictures of my A9 board after it’s been cleaned up quite a bit.
Look at the first 3 pictures in the album to get an idea of what board version we’re talking about.
Note the lack of that big resistor between the filter caps, and the slightly different layout when compared to newer units.

/g/TekScopes/album?id=262670

Thanks Dave.

Dave

Hello Joe,

I use a capacitor checker from Mr. Carlson's Lab, and that works very well. As far as your list of capacitors goes, I have had very good luck with Good-All capacitors! I have checked many of them and they were doing very well with no leakage. However, I have yet to find 1 Bumble Bee that is not leaky. I still test those but most likely they are replaced. High voltage capacitors, well, my checker can test them for leakage, but if the are the disc type, those should be fine. I have found the the Black Sprague capacitors goes, there are 2 different colors. And in my experience, the black caps with the yellow writing tend to be very leaky while the ones with the red writing don't have the leakage issues. I have one of those Chinese testers myself, does a rather pretty good job for a go-no go test!

Seleniums on the other hand tend to scare me. It's only a matter of time before those will fail, and I had one blow out that nasty smoke and believe me, was not pleasant to deal with. My whole house reeked for a long time before it cleared out. I actually have a conversion kit pulled from an old 531 scope sitting around somewhere, but I don't know if that would work with a 575. That is one piece of Tektronix equipment that I would love to have.....for a reasonable price that is.

Brenda

On Thu, Apr 8, 2021 at 10:30 PM, Stephen wrote:

Now that I’ve replaced what I could so far, I turn the unit on, and the line
fuse blew instantly.

I guess by line fuse you mean mains fuse. Assuming that's correct, I'd start by looking at the usual suspects for this 'scope family:
See schematic dwg 12, ckt. layout in fig. 7.21: Bridge rectifiers, buffer caps, overvoltage protection circuit (around Q1514). VR1515 being shorted is a candidate. Check with current-limited voltage across Q1514 but only for a short moment, because C1512 will be reverse-biased. Just tap the test voltage for a second or so. 10V to 20V usually makes a bad circuit trip (shorted Q1514 or VR1515).
Check by connecting current-limited DC across each of the buffer caps separately, starting from a few volts.
If no shorts observed, check individual diodes in diode bridges.
All this in-circuit but *with mains plug disconnected*.

Raymond