465 Missing a Few Components


Stephen
 

Thanks Toby!


Stephen
 

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...


Stephen
 

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


 

On Fri, Apr 9, 2021 at 01:46 AM, Stephen wrote:


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...
You are correct, Stephen, they are reversed. My parts donor board contains an MJE2801. Its base and emitter are reversed in comparison with the TIP35. The emitters on the board are closer to the rectifier/buffer part of the mainboard, the bases are closer to the HV section.

Raymond


 

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


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

https://docs.telegraphics.com.au/Tektronix_070-1330-00_465_Oscilloscope_Service_Instruction_Manual.tif

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

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

You had uploaded it, Toby. It's the fourth manual in the 465 SM lineup.
ITM, I have OCR'ed it and added it as the fifth SM, in PDF format. I left your doc. in for the moment but am happy to remove it if desired.

Raymond


Tom Lee
 

Thanks very much to both of you!

—Cheers,
Tom

Sent from my iThing, so please forgive typos and brevity.

On Apr 8, 2021, at 5:29 PM, Raymond Domp Frank <hewpatek@gmail.com> wrote:

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


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

https://docs.telegraphics.com.au/Tektronix_070-1330-00_465_Oscilloscope_Service_Instruction_Manual.tif

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

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

You had uploaded it, Toby. It's the fourth manual in the 465 SM lineup.
ITM, I have OCR'ed it and added it as the fifth SM, in PDF format. I left your doc. in for the moment but am happy to remove it if desired.

Raymond





toby@...
 

On 2021-04-08 8:28 p.m., Raymond Domp Frank wrote:
On Fri, Apr 9, 2021 at 12:58 AM, <toby@telegraphics.com.au> wrote:


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

https://docs.telegraphics.com.au/Tektronix_070-1330-00_465_Oscilloscope_Service_Instruction_Manual.tif

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

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

You had uploaded it, Toby. It's the fourth manual in the 465 SM lineup.
ITM, I have OCR'ed it and added it as the fifth SM, in PDF format. I left your doc. in for the moment but am happy to remove it if desired.
No problem at all. I was too lazy to check. I'm just happy it's on
Tekwiki, that's the ideal destination for my scans.

thanks
--Toby


Raymond





Stephen
 

On Thu, Apr 8, 2021 at 01:11 PM, Raymond Domp Frank wrote:

You are correct, Stephen, they are reversed. My parts donor board contains an
MJE2801. Its base and emitter are reversed in comparison with the TIP35. The
emitters on the board are closer to the rectifier/buffer part of the
mainboard, the bases are closer to the HV section.

Raymond
The problem is that the manual, as well as the cross reference document, both mention that these pass elements can by substituted for MJE2801, without mentioning any modifications.
And when I looked at the data sheets online, both for the MJE2801, and the TIP35C, their pinouts looked identical. Hence my mistake. But maybe I didn’t look correctly...
Or maybe Tektronix had a special run with the reversed pinout? If so, why not warn the service person to watch for the correct pinout...?
Maybe I just didn’t read the data sheet correctly.


 

On Fri, Apr 9, 2021 at 10:46 AM, Stephen wrote:


The problem is that the manual, as well as the cross reference document, both
mention that these pass elements can by substituted for MJE2801, without
mentioning any modifications.
As I said, my donor board contains a part clearly marked as Motorola MJE2801, date code 7411, with correct connections for the A1 board and therefore, reversed as compared with TIP35.

You'd think that datasheets on MJE 2801 are incorrect...but they are not:
As it turns out, there are two functionally identical siblings: the MJE2801 and the MJE2801K
The MJE2801 is encapsulated in a (as Motorola calls it) "Style 2" case, "90-05", whereas the MJE2801K lives in a "Style 1" case, "199-04".
The MJE2801 is "ECB" from left to right, front view, legs down, the MJE2801K is "BCE".
The MJE2801K is pin-compatible with the TIP35C (and that layout is the most common style), whereas the MJE2801 is reversed and the latter (MJE2801) does indeed fit the 465 A1 mainboard.
So, there you have it. Source: Motorola Discrete Products Data Book, Volume 3, series A, 1974

Raymond


Stephen
 

Duly noted Raymond, thank you for the explanation.
I will reverse the leads.

PS: BTW, it’s the A9 board, not the A1 board.


 

On Fri, Apr 9, 2021 at 02:01 PM, Stephen wrote:


PS: BTW, it’s the A9 board, not the A1 board.
Of course it is, Stephen. Often, the mainboard is A1 and I didn't look it up. As is so often the case, extra (and wrong) data only contributed to increased confusion. At least, one of us was awake (as was I, at 5 AM today, and up again at 10 AM).

Good luck going on with this project. Very little to use, a lot to gain.

Raymond


 

On Fri, Apr 9, 2021 at 03:08 PM, Raymond Domp Frank wrote:


Very little to use, a lot to gain.
Correction: "Very little to lose, a lot to gain".

Raymond


Stephen
 

Raymond,

I know you knew that, and that it was an honest mistake.
I just pointed this out so future people that will be eventually interested in this restoration, won’t get confused, and try to locate these parts on the A1 board.

Yes, nothing to loose really (but a little time), only gain... Particularly if it turns out to be indeed a quite early European made example with an interesting serial number for a 465 (700465). I think it ought to be preserved, and restored. With that in mind, I’m doing my best.


BTW, I finally got a replacement for my dead Variac. 😉


 

On Fri, Apr 9, 2021 at 03:44 PM, Stephen wrote:


Yes, nothing to loose really (but a little time), only gain... Particularly if
it turns out to be indeed a quite early European made example with an
interesting serial number for a 465 (700465). I think it ought to be
preserved, and restored. With that in mind, I’m doing my best.

BTW, I finally got a replacement for my dead Variac.
Stephen,
The gained experience in itself is worth the effort, not much money lost if it doesn't work out.
The serial number is nothing special for a Heerenveen (NL) -produced Tek. Non-US serial numbers often are like it. Both my 7854's are Guernsey-numbers below 200.

Use your variac! Initially, forget about my earlier recommendations and start by applying your variac. Start at a voltage as low as around 6 or 10VAC and see how all unregulated voltages behave at that one setting, then the regulated ones. Should be easy and very informative first steps. One remote possibility is a defective mains transformer though...

Raymond


Stephen
 

I just think that the fact that it’s serial number 465, which is the same as the model number, is kinda neat. Other than that, nothing special. It’s just a serial number... 🤷‍♂️

I’ll use the Variac when it’ll actually get here. In transit at the moment. 😉
It’s not a very big one, just 5A.

Meanwhile, I’m going to power the scope with a 12VAC. That’s all I have available at this point, along with a 24VAC one, until the Variac gets here.


Dave Peterson
 

Guys,

I'm curious to know how "rare" these early scopes are any more. Tek seems to have made these early changes fairly quickly, even before the actual SN B250K. I currently posses a B177K and it seems to mostly be made up of later components. The A9 is late, and the A5 (vertical amp) seems to be somewhat later: non-IC discrete components matching the change schematic, but the post B250K four digit component numbers. It includes components on the earlier change schematic that aren't present on the later board.

And as Raymond noted, the first SN starts at B010100?

So I wonder if there are few surviving examples?

I know 465s are like the VW Beetle of oscilloscopes. But even early "split window" Bugs are pretty valuable now. It seems appropriate to try to preserve surviving examples. But I'm biased.

Stephen seems to be in possession of of a true early scope. Stephen, is the A5 board a discrete component or IC version? Does it have a surviving time/div know without "LOCK KNOBS"? And a simple "A" HORIZ DISPLAY button? What other notable differences are there on the early pre SN B250K scopes?

Dave

On Friday, April 9, 2021, 07:39:48 AM PDT, Stephen <stephen.nabet@gmail.com> wrote:

I just think that the fact that it’s serial number 465, which is the same as the model number, is kinda neat.  Other than that, nothing special.  It’s just a serial number...  🤷‍♂️

I’ll use the Variac when it’ll actually get here.  In transit at the moment.  😉
It’s not a very big one, just 5A.

Meanwhile, I’m going to power the scope with a 12VAC.  That’s all I have available at this point, along with a 24VAC one, until the Variac gets here.


 

Interleaved


On Fri, Apr 9, 2021 at 04:39 PM, Stephen wrote:


I just think that the fact that it’s serial number 465, which is the same as
the model number, is kinda neat. Other than that, nothing special. It’s just
a serial number... 🤷‍♂️
Oh yes, I completely forgot that. Of course it's very special!


I’ll use the Variac when it’ll actually get here. In transit at the
moment. 😉
It’s not a very big one, just 5A.
Absolutely big enough for all Tek 'scope work!


Meanwhile, I’m going to power the scope with a 12VAC. That’s all I have
available at this point, along with a 24VAC one, until the Variac gets here.
That is fine, start with 12VAC.

Raymond


 

On Fri, Apr 9, 2021 at 05:06 PM, Dave Peterson wrote:


I'm curious to know how "rare" these early scopes are any more. Tek seems to
have made these early changes fairly quickly, even before the actual SN B250K.
I currently posses a B177K and it seems to mostly be made up of later
components. The A9 is late, and the A5 (vertical amp) seems to be somewhat
later: non-IC discrete components matching the change schematic, but the post
B250K four digit component numbers. It includes components on the earlier
change schematic that aren't present on the later board.
Interesting, Dave. I think you already know more about the 465's history than I, with my more general knowledge.
Please keep us informed.

Raymond


Stephen
 

Interleaved.

On Fri, Apr 9, 2021 at 04:06 AM, Dave Peterson wrote:

Stephen seems to be in possession of of a true early scope. Stephen, is the A5
board a discrete component or IC version?
If by IC version you mean U440, it’s there.

Does it have a surviving time/div
know without "LOCK KNOBS"?
How do you mean? I don’t see any differences between this scope and my other 465, or my 475A, or my 465B as far as the Time/Div knob(s).

And a simple "A" HORIZ DISPLAY button?
Same as above.

What other notable differences are there on the early pre SN B250K scopes?
The only noticeable difference that I see is that the CRT bezel isn’t held by checkered and captive screws like the others, but with regular non-captive philips screws.


Feel free to ask more questions if you need to.


Dave


Stephen
 

Dave,
Maybe this last picture will answer some of your questions:
« https://groups.io/g/TekScopes/photo/262670/3204540?p=Created,,,50,2,0,0 »