Tek 453 - Q913 Part Number


nu7f <jbstamper@...>
 

I have an early (Serial 009869) Tek 453 scope with no trace. Q913
on the Z Axis board appears to be the only transistor in this unit
that is not original. Can someone give me the correct tek part
number or sub for Q913? I'm hoping it is just the transistor before
I go digging into the HV side.

Thanks,
John


Rex W. Athey <mister_twister@...>
 

Q913 - Tek pn 151-0220-00 Silicon 2N4122 for Type 453 oscilloscope

part of HV regulator circuit - Q914, Q913, Q923 - Q 930 is the HV osc transistor that drives the HV transformer. F937 2 Amp fuse for the circuit.

Hope this helps.

Rex W. Athey


ROLYNN PRECHTL K7DFW
 

Q913 - Tek pn 151-0220-00 Silicon 2N4122 for Type 453 oscilloscope
===========================

Now I'm confused.

My manual, with SN 4395 written in, shows 913 as a 0133-00 which is a
selected 2N3251 (a PNP) and the schematic shows it as a PNP.

That 2N4122 is a NPN.

K7DFW

..._._


Howard Matthews
 

Repeating my private post (I guess, I'm still learning how the posts
work on Yahoo)...

The serial number given indicates the proper part number for Q913 is
the "selected" 2N3251, PN 151-0133-00. At SN 12680 this circuit was
redesigned and Q913 became PN 151-0220-00, a 2N4122 with no
indication that it was specially selected. My parts list is very
clear about this, my schematic is less clear, but shows a PNP.

If you have the right part in your scope, you can get a general idea
whether Q913 and it's surrounding parts work by measuring: Base=-
0.24V, Emitter=-0.18V, Collector = -3.8V. (Hmm, I'm guessing that's
a Germanium because of the .06V base-emitter voltage. That seems
low even for Germanium, but that is what the schematic says.)

But before you blame the Z-axis for lack of trace, check the
horizontal and vertical deflection pins on the CRT. They should all
be, or Horz/Vert centering should adjust to, about 47-48V. A
failure in either the horizontal or vertical amp boards can drive
the trace off the face, and appear as though there is no trace. I
know, I just fixed a "no trace" 453 with a bad transistor in the
vertical amp. It's a real smiley face experience to replace a
transistor in a $19 "parts scope" and suddenly get a decent trace!

Good luck,
-Howard

--- In TekScopes@yahoogroups.com, "Rolynn PRECHTL K7DFW"
<k7dfw@c...> wrote:



Q913 - Tek pn 151-0220-00 Silicon 2N4122 for Type 453
oscilloscope
===========================

Now I'm confused.

My manual, with SN 4395 written in, shows 913 as a 0133-00 which
is a
selected 2N3251 (a PNP) and the schematic shows it as a PNP.

That 2N4122 is a NPN.

K7DFW

..._._


Howard Matthews
 

Checking the NTE cross reference, both the 2N3251 and the 2N4122 are
PNP, and are crossed to NTE 159.

Combine that with the fact that although the parts list for Q913
listed the two different transistors for different serial number
ranges, the schematic showed no substantial changes at the same SN
break point, I've come to this tentative conclusion:

Tek got tired of selecting 2N3251s, and found that 2N4122s did the
job better. So, I believe the 2N4122 would be the prefered
replacement for any Tek 453 Q913, SN 100 to 19,999 (and also SN >
20K) - unless you have an early model that you *absolutely must*
restore to *factory mint* condition.

I'm new at this repair game, so if my detective work is wrong, I
would like to be corrected. :]

-Howard

--- In TekScopes@yahoogroups.com, "Rolynn PRECHTL K7DFW"
<k7dfw@c...> wrote:



Q913 - Tek pn 151-0220-00 Silicon 2N4122 for Type 453
oscilloscope
===========================

Now I'm confused.

My manual, with SN 4395 written in, shows 913 as a 0133-00 which
is a
selected 2N3251 (a PNP) and the schematic shows it as a PNP.

That 2N4122 is a NPN.

K7DFW

..._._


ROLYNN PRECHTL K7DFW
 

Checking the NTE cross reference, both the 2N3251 and the 2N4122 are
PNP, and are crossed to NTE 159.
============================
Darn, it appears I was hornswaggled by the internet again.

Got the info from here......
<http://www.reprise.com/host/tektronix/reference/transistor.asp>
where it's claimed to be a NPN......

"Transistor type 2N4122 has been assigned the following Tektronix part
numbers:
Tek Part Number Remarks
151-0493-00 NPN, SI"

I should know better and consult my Tek semiconductor catalog instead of
trusting the www.

K7DFW

..._._


Miroslav Pokorni
 

Do not blame Walter, that might be his or Tek's mistake. God knows manuals
have more than a fare share of typos and various other mistakes.

As for detective work, there is something to be desired in drawing
conclusion: 'if both transistors cross reference to the same NTE number,
then those transistors must be same' . Let us keep in mind what is purpose
of NTE numbers: to supply TV repair shops and as a side line a supplier for
home brew projects.

It is true that National Semiconductor makes both transistors on the same
process (#66) and gain seems to be similar for several currents shown in
listing. However, the package is different and transit frequency and turn
off times are quite different:

Package fT toff

2N3251 TO-18 300 250

2N4122 TO-92 450 150



Regards

Miroslav Pokorni

----- Original Message -----
From: "Rolynn PRECHTL K7DFW" <k7dfw@clatskanie.com>
To: <TekScopes@yahoogroups.com>
Sent: Friday, November 14, 2003 9:58 PM
Subject: Re: [TekScopes] Re: Tek 453 - Q913 Part Number




Checking the NTE cross reference, both the 2N3251 and the 2N4122 are
PNP, and are crossed to NTE 159.
============================
Darn, it appears I was hornswaggled by the internet again.

Got the info from here......
<http://www.reprise.com/host/tektronix/reference/transistor.asp>
where it's claimed to be a NPN......

"Transistor type 2N4122 has been assigned the following Tektronix part
numbers:
Tek Part Number Remarks
151-0493-00 NPN, SI"

I should know better and consult my Tek semiconductor catalog instead of
trusting the www.

K7DFW

..._._




zenith5106 <zenith@...>
 

--- In TekScopes@yahoogroups.com, "nu7f" <jbstamper@c...> wrote:
I have an early (Serial 009869) Tek 453 scope with no trace. Q913
on the Z Axis board appears to be the only transistor in this unit
that is not original. Can someone give me the correct tek part
number or sub for Q913? I'm hoping it is just the transistor
before
I go digging into the HV side.

Thanks,
John
----------
My microfiche RPR (replaceable parts record) says that 151-0133-00 is
replaced by 151-0220-00 at all occurrences in 453, all S/N's, except
for Q423, Q753, Q754, Q775 and Q785 where no replacement is listed.
You can find a scan of this page at
http://w1.871.telia.com/~u87138090/
/Zenith