Date   

Re: The 74L72 IC

Jeff W <vwthingy@...>
 

I agree with John, and if I was the original poster, I would first
check the function of this flip-flop and what drives the inputs, and
see if the standard 7472 TTL part would work. It could be that Tek
went with the L version just to save power, and the standard TTL part
would work just fine. If I recall, John is absolutely correct in the
power dissipation ratio between the two families (10:1, 10mW per gate
for TTL, 1 mW per gate for L TTL), however I don't recall that the
input drive current was significantly different between the two. (I
could be waaay wrong on this as it has been 20 years since I last
designed anything with TTL!)

Jeff

John Doran wrote:
Still, I cannot imagine
that one hotter logic chip would load the 'scope's power supply
excessively. The more likely problem is that whatever drives the
74L72's inputs might not be able to handle standard TTL.


The 74L72 IC

John Doran <johnd@...>
 

Howdy! I thought I'd add my two bits to the discussion of this
IC.

Miroslav was being generous--standard TTL actually requires
*ten times* as much power as L TTL! Still, I cannot imagine
that one hotter logic chip would load the 'scope's power supply
excessively. The more likely problem is that whatever drives the
74L72's inputs might not be able to handle standard TTL.

I'd bet that you could substitute an LS TTL part with no problems,
but--total bummer--the 7472 was an old design that, as far as I know,
was only made in standard, L, and H TTL variants (H TTL requires
twice the power of standard TTL).

There appear to be no direct, pin-compatible replacements
for the 74L72 in any more recent logic family. Further, it's not
just a flip-flop; it has gated J and K inputs. It seems to me that
there are only two solutions here; you must find the same part or
you must wire up an equivalent circuit (I'd use 74 HCT) on
some sort of kluge-board.

Oh, one more thing--you can use a 54L72 (military version).

-John


Re: need IC

Michael Dunn <mdunn@...>
 

At 12:51 PM -0800 2003/11/6, Miroslav Pokorni wrote:
can use either package material. However, watch out that you do not get
ceramic flat pack; the 74L72 was also made in that style. Also watch that
you do not get regular TTL, 7472 (no L). They draw double current, roughly,
and can possibly cause problem with a small scope like 212.
I'm not sure about the '72, but if I remember correctly, a lot of L TTL had (oddly enough) different pinouts from the other varieties. I have a vague memory of wiring up some 40085s once (some company's name for a 74C85, which I assumed to have a standard 74_85 pinout), and having the circuit not work too well until I rewired them as 74L85s!

Of course, if you end up subbing and rewiring, a 74HC(T) series part might work well too...

Michael


HC01 and HC02 Hard Copy Unit Manuals

Dennis Tillman <Dennis@...>
 

Hi everyone,

Does anyone know where I can buy a copy of the manual for an HC01 or HC02 Video Hard Copy Unit.

Tek sold them from 1987 through at least 1991.

In reality Tek OEM'd a Mitsubshi P61U Video Copy Processor unit.

The Tek unit is identical in appearance and specs to the Mitsubishi unit.

So a copy manual for the Mitsubishi P61U unit would be just as useful.

Thanks, Dennis
dennis AT silicondesigns DOT com


Re: need IC

Miroslav Pokorni
 

Do a search on Google and you will get few sources, among them
http://www.hobid.com/inventory/7/12.html and
http://www.sphere.bc.ca/test/hpparts.html . Parts will probably not be
cheap; I would guess several bucks a piece. The last letter in part number
specifies package and it can vary with manufacturer; the N is TI's
designation for plastic DIP, while their ceramic DIP is designated J. You
can use either package material. However, watch out that you do not get
ceramic flat pack; the 74L72 was also made in that style. Also watch that
you do not get regular TTL, 7472 (no L). They draw double current, roughly,
and can possibly cause problem with a small scope like 212.

You can also use 54L72, what is military temperature range, basically same
part just tested for that temperature range and parameters adjusted to hold
over that range.

Regards

Miroslav Pokorni

----- Original Message -----
From: "Dan Tulloss" <dtulloss@ntecusa.com>
To: <TekScopes@yahoogroups.com>
Sent: Thursday, November 06, 2003 7:17 AM
Subject: [TekScopes] need IC


Hello,

I am having a problem finding a replacement IC for a Tektronix 212 scope.
The Tek part
number is 156-0280-00 and the MFR part number is SN74L72N. Does anyone
have
one or know where I can get this part?

Thanks,
Dan Tulloss


plug ins

Richard Oglebay <richardoglebay@...>
 

Dear Chuck: I want to thank you for the referal on the man in ohio, He already contacted me on my request and does have one of the things I need. yours truly Richard Oglebay




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Re: need IC

Craig Sawyers <c.sawyers@...>
 

Standard low power TTL, yes. However, very obscure part; single J-K
flip flop. Out of production by the majors. So Digikey, Mouser, and
the like will not have it. Suggest you go to the surplus houses
looking for it.
Or do what I've done in the past to replace an obsolete TTL part - shoehorn
in a modern part. If it is a JK, use instead a dual JK such as an LS73.
Solder or plug in power and ground, then cross wire the other pins into the
original '72 connections. Might have to be careful with preset and clear
connections - but beyond that it should be possible to stitch something
together that works.

Last thing I resurrected this way was my HP5328A counter.

Craig


Re: need IC

John Miles <jmiles@...>
 

Couple of vendors on www.findchips.com show it in stock. Their
minimum-order fees may be prohibitive, though.

-- jm

-----Original Message-----
From: Jeff W [mailto:vwthingy@cox.net]
Sent: Thursday, November 06, 2003 10:09 AM
To: TekScopes@yahoogroups.com
Subject: [TekScopes] Re: need IC


Standard low power TTL, yes. However, very obscure part; single J-K
flip flop. Out of production by the majors. So Digikey, Mouser, and
the like will not have it. Suggest you go to the surplus houses
looking for it.

You may have more luck with the straight SN7472N part. I doubt that
it will affect the operation of the circuit; you should check it out
to be sure.

I know the local surplus place here in San Diego, Gateway, carries
the SN7472N, but not the L version.

Jeff



Re: need IC

ROLYNN PRECHTL K7DFW
 

Dan,

Use this tool......
http://www.findchips.com/avail

No luck with SN74L72N.
Got a hit using SN7472N.

K7DFW

..._._


Re: need IC

Bruce Lane
 

Hi, gang,

*********** REPLY SEPARATOR ***********

On 06-Nov-03 at 18:09 Jeff W wrote:

Standard low power TTL, yes. However, very obscure part; single J-K
flip flop. Out of production by the majors. So Digikey, Mouser, and
the like will not have it. Suggest you go to the surplus houses
looking for it.

You may have more luck with the straight SN7472N part. I doubt that
it will affect the operation of the circuit; you should check it out
to be sure.
Suggestion: If the original chip is socketed, it would probably be pretty easy to construct an adapter to allow the use of a more modern replacement, such as a 74L or LS76.


-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
Bruce Lane, Owner & Head Hardware Heavy,
Blue Feather Technologies -- http://www.bluefeathertech.com
ARS KC7GR (Formerly WD6EOS) since 12-77 -- kyrrin@bluefeathertech.com
"Quando Omni Flunkus Moritati" (Red Green, aka Steve Smith)


Re: need IC

Jeff W <vwthingy@...>
 

Standard low power TTL, yes. However, very obscure part; single J-K
flip flop. Out of production by the majors. So Digikey, Mouser, and
the like will not have it. Suggest you go to the surplus houses
looking for it.

You may have more luck with the straight SN7472N part. I doubt that
it will affect the operation of the circuit; you should check it out
to be sure.

I know the local surplus place here in San Diego, Gateway, carries
the SN7472N, but not the L version.

Jeff


Robert Morein wrote:
THe part number is standard low power TTL.
Possibly Digikey.
Hello,

I am having a problem finding a replacement IC for a Tektronix
212 scope.
The Tek part
number is 156-0280-00 and the MFR part number is SN74L72N. Does
anyone have
one or know where I can get this part?


Re: need IC

Robert Morein <morepub@...>
 

THe part number is standard low power TTL.
Possibly Digikey.

----- Original Message -----
From: Dan Tulloss
To: 'TekScopes@yahoogroups.com'
Sent: Thursday, November 06, 2003 10:17 AM
Subject: [TekScopes] need IC


Hello,

I am having a problem finding a replacement IC for a Tektronix 212 scope.
The Tek part
number is 156-0280-00 and the MFR part number is SN74L72N. Does anyone have
one or know where I can get this part?

Thanks,
Dan Tulloss


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need IC

DANNN31
 

Hello,

I am having a problem finding a replacement IC for a Tektronix 212 scope.
The Tek part
number is 156-0280-00 and the MFR part number is SN74L72N. Does anyone have
one or know where I can get this part?

Thanks,
Dan Tulloss


Which scope to buy?

rollsroyce1_92394
 

I've been looking at older Tek 465, 475, 485 series scopes on EBay,
and have a question for those of you in the know. I want to use the
scope to precisely adjust G2 voltages on my Mitsubishi widescreen
TV. The service manual procedure calls for adjusting them to 190V
using a scope set to 50V/div vertically and 2msec/div horizontally.
The manual further specifies the use of 10:1 probes. Before I cough
up the money for something that might not do the job and then turn
out to be nonreturnable, can one of the Tektronix scopes I mentioned
above do what I need? The specs I've seen don't really cover the
50V/division part of the requirement.

If these won't work, what older (read: inexpensive used) scope(s)
would?

Thanks for any help you can give me.

Royce


Re: Tek 310 and Looking for Advice

Craig Sawyers <c.sawyers@...>
 

The ripple values in the +300, +100, and -150 are 3 mV, 1 mV, and 3 mV,
respectively.
***Wow! That's pretty low ripple but the lower the better.
I've been fooled by this too - the numbers that Tek quote on the schematic
are peak-peak values, whereas what is measured on a meter is the rms value.
Perhaps that expains the difference?

Craig


Re: Tek 310 and Looking for Advice

Stan & Patricia Griffiths <w7ni@...>
 

OK Stan,

I have inserted some more comments below:

----- Original Message -----
From: "stan mcintosh" <mcintosh@triad.rr.com>
To: "Stan & Patricia Griffiths" <w7ni@easystreet.com>; "TekScopes"
<TekScopes@yahoogroups.com>; <morriso@vifm.org>
Sent: Tuesday, November 04, 2003 6:11 PM
Subject: Re: [TekScopes] Tek 310 and Looking for Advice


I have one more in a box, but I decided that an 83.5 volt drop
tube would work for checking out a few of the other items.
***That's probably close enough to make it work . . . I have a bunch of
5651's if we need one that's closer.

Are the power supplies "regulating"? That is, do the voltages remain
the
same as the line voltage is varied from 105 to 125 VAC? If you don't
have
a
metered variable line voltage source, now is the time to get one.
Here is where we see some differentiation. From 105-125VAC input: the
+100
V regulates right at 59V, the -150 regulates at -139, and the +300 swings
from 270 to 290. I don't have a metered line voltage source, but I do
have
a voltmeter for making such measurements when using a Variac input.
***A Variac with an outboard meter attached is good enough. You can vary
the line voltage and you know about how much it is. That's all you need.

How much "ripple" is on each supply? Is is about the amount stated in
the
manual calibration procedure? (10 millivolts)
The ripple values in the +300, +100, and -150 are 3 mV, 1 mV, and 3 mV,
respectively.
***Wow! That's pretty low ripple but the lower the better. It seems a
little strange to me that you could have such low ripple on the +300 supply
and it still varies from 270 to 290 when you vary the line voltage from 105
to 125 VAC . . .

As you try to set the -150 volt power supply on -150, can you vary it at
all
with the adjustment control or is it just at -140 all the time?
The adjustment does affect the -150 output voltage.
***But apparently you can't bring it up (or down) to -150. The next thing I
would check are the precision resistors on both ends of the -150 adjustment
pot. This would be R609 (56.5K) and R611 (68K). These need to be close to
those values. You should also check R669 (1meg) and R670 (490K) in the +300
supply for 1% accuracy and they need to be right on.

Bear in mind that the -150 and +300 supplies depend on each other and they
must both work for either one of them to work. Concentrate your efforts on
these two supplies and make them both work before you look anywhere else for
other problems. The +100 will not work unless both the -150 and +300 are
working but the +100 does not need to work for the -150 or +300 to work.

I'm going to have a cold one and pore over the power supply schematic,
again. However, I'm hoping that you'll effortlessly say, "Ah-Ha! You
obviously failed to check ..."

Again, thanks for all of the help. If this scope didn't have so much
character, and if I didn't really want it to be part of my bench, I'd go
back to working on my superhet.

Sincerely,
stan
***Well, Stan, the 310 and 310A are both gems in my opinion and well worth
the trouble to make them work.

Stan
w7ni@easystreet.com


Re: Question: R7903 Cap Rectifier Board 130v supply

Miroslav Pokorni
 

No, it was not MPS918, I got reference number wrong and from there part
number was wrong, too. The lamp driver that I started from is Q469, generic
number MPS6521, but this one is not a very sturdy device, either. The
continuos collector current is 100 mA, not very much for an incandescent
lamp cold filament surge. The basic device has gain between 150 and 600. I
wonder whether it was higher gain that was selection criteria.

Regards

Miroslav Pokorni

----- Original Message -----
From: "Denton, Adam (Exchange)" <adenton@bear.com>
To: <tekscopes@yahoogroups.com>
Sent: Wednesday, November 05, 2003 9:09 AM
Subject: RE: [TekScopes] Question: R7903 Cap Rectifier Board 130v supply


I find it mind boggling that transistors for driving lamps
are selected from a standard transistor type,
e.g. Q238 in 7904 is selected from MPS918.
Are you serious?!! MPS918 is used as a LAMP DRIVER??!!
My god, MPS918 is a rather delicate RF transistor
(VCEo = 15V, fT = 600MHz, Ic = 50mA). Just about the
LAST part I would ever choose to drive a lamp. Ouch!

To my mind that shows a lack of adult supervision in design
department.
Scary. Did they employ the same lackey in the design of
the now-infamous 24xx U-800? :-O

-Adam

From: Miroslav Pokorni [mailto:mpokorni2000@yahoo.com]
Sent: Friday, October 31, 2003 10:42 PM
To: tekscopes@yahoogroups.com; Joe Sleator
Subject: Re: [TekScopes] Question: R7903 Cap Rectifier Board 130v supply

***********************************************************************
Bear Stearns is not responsible for any recommendation, solicitation,
offer or agreement or any information about any transaction, customer
account or account activity contained in this communication.
***********************************************************************


Re: Question: R7903 Cap Rectifier Board 130v supply

John Miles <jmiles@...>
 

Read as a memo from some PHB at Tek: "We ordered WAY too many of those
darned MPS918s. Find a use for them."

-- jm

I find it mind boggling that transistors for driving lamps
are selected from a standard transistor type,
e.g. Q238 in 7904 is selected from MPS918.
Are you serious?!! MPS918 is used as a LAMP DRIVER??!!
My god, MPS918 is a rather delicate RF transistor
(VCEo = 15V, fT = 600MHz, Ic = 50mA). Just about the
LAST part I would ever choose to drive a lamp. Ouch!

To my mind that shows a lack of adult supervision in design
department.
Scary. Did they employ the same lackey in the design of
the now-infamous 24xx U-800? :-O

-Adam


Re: Question: R7903 Cap Rectifier Board 130v supply

Denton, Adam (Exchange)
 

I find it mind boggling that transistors for driving lamps
are selected from a standard transistor type,
e.g. Q238 in 7904 is selected from MPS918.
Are you serious?!! MPS918 is used as a LAMP DRIVER??!!
My god, MPS918 is a rather delicate RF transistor
(VCEo = 15V, fT = 600MHz, Ic = 50mA). Just about the
LAST part I would ever choose to drive a lamp. Ouch!

To my mind that shows a lack of adult supervision in design
department.
Scary. Did they employ the same lackey in the design of
the now-infamous 24xx U-800? :-O

-Adam

From: Miroslav Pokorni [mailto:mpokorni2000@yahoo.com]
Sent: Friday, October 31, 2003 10:42 PM
To: tekscopes@yahoogroups.com; Joe Sleator
Subject: Re: [TekScopes] Question: R7903 Cap Rectifier Board 130v supply

***********************************************************************
Bear Stearns is not responsible for any recommendation, solicitation,
offer or agreement or any information about any transaction, customer
account or account activity contained in this communication.
***********************************************************************


Re: CRT Needed Tek # 154-0667-02...

Greyhawk <greyhawkeng@...>
 

Hello, It Was A Late Night, I Should Have Said The Tube Is Used In Tek 1502/1503/305/326

----- Original Message -----
From: greyhawkeng
To: TekScopes@yahoogroups.com
Sent: Tuesday, November 04, 2003 21:45
Subject: [TekScopes] CRT Needed Tek # 154-0667-02...


Looking For A Used Tube In Fair Condition Under $75.00 It Is Used In
Tektrinix Models 1502/1504/305/326. TIA


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