This one did fail the truth table check when it was in the device. VCC is about 15V
which means a HIGH is 15V. Output 3 has a 5V output and does not move from there.
When it should be high it is at 5V when it should be low it is at 5V. In the 501 the
truth table is frequency dependent on the input. As you roll through the frequency
the outputs should do their thing. 1 2 and 4 seem to function as expected.

On 1/5/2020 3:30 PM, KB6NAX wrote:

Watch out! The CD and 74 pinouts are different. You don't what to hack up your
circuit board.

Also, be advised, when troubleshooting IC's in general having the schematic of the
device gives understanding of how inputs and outputs work. For example a tri-state
output could be "off" and not "open." A CMOS input is high impedance so you don't
know if the input stage is blown unless a clamp diode is shorted. The ultimate is
to try the truth table, a lot of work on complex parts. Parts substitution can't
be beat for getting results. I always buy two or more when in that situation.

eBay to the rescue - Item #372418190226

Arden

-----Original Message----- From: Eric
Sent: Sunday, January 05, 2020 6:51 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Trying to bring back a AA501

I did find out that the AA501 does need the VCC of 15V so the HC series
logic is out for sure. I am going to order some of the direct
replacement parts as there is a supply house that has then mouser and
digikey were out. Texas Instrument cross reference says a CD40175BE is a
comparable part as well. I have also confirmed the fault as with this IC
out of circuit the 501 says 100+% distortion on all frequencies also one
of the outputs is open when i check it with my small curve tracer. On
this one pin 14 is dead.


On 1/5/2020 1:08 AM, KeepIt SimpleStupid via Groups.Io wrote:

My GOTO place has it: http://www.utsource.net/sch/MM74C175N
On Saturday, January 4, 2020, 10:31:47 PM EST, Mlynch001
<mlynch002@gmail.com> wrote:
OK, learned something. LSTTL and TTL are different animals? SN74HC175N Will
drive 10 outputs of LSTTL. Just trying to learn how logic works, I will likely
encounter a similar issue in the future.

Thanks!

There are some tests you can do with a partially working scope, but you
are going to be very limited.

1) assuming horizontal sweep problems, you use an external ramp or the
"other" sweep if you have a dual sweep model.

2) if you have a horizontal amplifier problem, using the scope in XY
mode, even with the calibrator, can give you some idea of whether or not
it's the sweep or the amplifier.

3) if you have a dual channel scope, you can use a working channel to
debug the separate part of the vertical amplifier

These generally end up being go/no-go tests and are somewhat crude.

Function generators can make a very crude horizontal sweep. If they're
gated, then a gated ramp might work as a sweep.

Very crude, but better than nothing.

Generally, unless you have a scope specifically designed for self
diagnosis, you're better off with another, completely working, scope.

Even then, a scope designed for self diagnosis makes certain assumptions
about what's working, especially once you get past the "is the CPU
working...."

Harvey


On 1/4/2020 4:29 PM, Panos wrote:

I have read enough service manuals for the oscilloscopes, and till today

I didn't find any of them to mention, that someone can use the same faulty
scope (partially or totally) to repair his self.

But as always we can hope for something like that. After all, don't

they say that hope dies always last? :-)

In my opinion if you have time to play then do it by that way. But if

you want really to repair it, then proceed it with another oscilloscope.

On Sat, Jan 4, 2020 at 8:13 PM William Schuler <guitardad1967@gmail.com>
wrote:

I am in no hurry, so I will give it a try just for fun. It would be
interesting to compare results with my buddy’s functional scope.

Hmmm, you already see the output of the horizontal amplifier - that's what
your CRT shows.
The only thing is that your horizontal output (
https://youtu.be/8dzxGlcErUo?t=10) is differential. By comparing both
sides, you'd be able to see whether this is due to one side pulling or both
- it's a data point at least. I'd bet that you'll find your problem
elsewhere than in the horizontal amp, though. I'm betting on power
supplies, as that's where ~90% of all trouble happens. Is the fan working
OK?
In any case, while I often^Wsometimes miss the most direct way to figure
out what's up, I find the detours are more than worth their while for the
learnin'.

Now to
figure out exactly where that horizontal amplifier is....

You have the service manual (

http://www.ko4bb.com/manuals/download.php?file=Tektronix/Tektronix_-_2245A/Tektronix_2245A_Oscilloscope_Service_Manual.pdf
)?

Have fun!
Siggi

I have read enough service manuals for the oscilloscopes, and till today I didn't find any of them to mention, that someone can use the same faulty scope (partially or totally) to repair his self.
But as always we can hope for something like that. After all, don't they say that hope dies always last? :-)

In my opinion if you have time to play then do it by that way. But if you want really to repair it, then proceed it with another oscilloscope.

Watch out! The CD and 74 pinouts are different.  You don't what to hack up your circuit board.

Also, be advised, when troubleshooting IC's in general having the schematic of the device gives understanding of how inputs and outputs work.  For example a tri-state output could be "off" and not "open."   A CMOS input is high impedance so you don't know if the input stage is blown unless a clamp diode is shorted.  The ultimate is to try the truth table, a lot of work on complex parts.  Parts substitution can't be beat for getting results.  I always buy two or more when in that situation.

eBay to the rescue - Item #372418190226

Arden

-----Original Message----- From: Eric
Sent: Sunday, January 05, 2020 6:51 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Trying to bring back a AA501

I did find out that the AA501 does need the VCC of 15V so the HC series
logic is out for sure. I am going to order some of the direct
replacement parts as there is a supply house that has then mouser and
digikey were out. Texas Instrument cross reference says a CD40175BE is a
comparable part as well. I have also confirmed the fault as with this IC
out of circuit the 501 says 100+% distortion on all frequencies also one
of the outputs is open when i check it with my small curve tracer. On
this one pin 14 is dead.


On 1/5/2020 1:08 AM, KeepIt SimpleStupid via Groups.Io wrote:

  My GOTO place has it: http://www.utsource.net/sch/MM74C175N
     On Saturday, January 4, 2020, 10:31:47 PM EST, Mlynch001 <mlynch002@gmail.com> wrote:
  OK, learned something.  LSTTL and TTL are different animals? SN74HC175N Will drive 10 outputs of LSTTL.    Just trying to learn how logic works, I will likely encounter a similar issue in the future.

Thanks!

I have a couple working 2465s i don't use, but I am not in Continental
USA...so I could maybe scrap out a m'board from 1

I had a University EE Summer Student who did not know how a tube worked so
I broke a 6SN7 and showed him the parts. He then said tubes were no longer
used so I asked him what he thought was in our 100kW RF amp that drove the
Superconducting Cyclotron, and how he would replace it with Solid State. I
then told him his theories MIGHT work but how would Solid State handle the
huge reflected power often sent back to the amplifier, and survive?
I'm not sure how I would test a 4CW200,000 (if I remember the 200kW water
cooled tube number correctly). The HV power supply was bigger than our
kitchen.

On Sun, Jan 5, 2020 at 4:01 PM Dennis Tillman W7PF <dennis@ridesoft.com>
wrote:

Hi Richard,

It may seem that vacuum tubes are history but nothing could be further
from the truth. To my amazement I have sold almost 200 of my little VTCT
Adapter boards. That really surprised me. That gives people a way to

avoid

paying $5,000 for a 570 Tube Tester. It still costs at least a few

hundred

dollars with my adapter because you still need some kind of transistor
curve tracer and a tube tester.

There are many applications that use tubes these days. Vacuum tube
manufacturing never went away and now the Russians are producing a lot of
them. But there are many other companies also doing it. A top of the line
vacuum tube audio amplifier will set you back $100,000 and eventually the
push-pull output tubes will need balancing or replacing. Likewise, rock
guitarists all use tube amplifiers, not solid state. The sound of tube
guitar amplifiers is sweeter and the guitarist can create far more

classic

rock sound effects with tube amps than with solid state amplifiers. Like
with the home audio amplifiers, a lot depends on the push-pull output

tubes

being balanced. Having balanced output tubes is essential to getting the
most from your guitar amplifier.

Testing transmitter tubes is another application for a tube curve tracer.

Dennis Tillman W7PF

-----Original Message-----
From: Richard Solomon
Sent: Sunday, January 05, 2020 9:22 AM
Subject: Re: [TekScopes] Tektronix 570 Vacuum Tube Curve Tracer on eBay

Pardon me if this sounds like
Heresy, but what real world use
would have for one of these ?

I can see the "cool/nostalgia"
factor, but other than that, what
would one do with it ??

Thanks, Dick, W1KSZ

On Sun, Jan 5, 2020 at 8:32 AM Dave Daniel <kc0wjn@gmail.com> wrote:

I have been looking at sales of Tektronix 570s, mostly but not all on
ebay, for a long time now. All of then have had an asking price of
around $4k.

DaveD

Sent from a small flat thingy

On Jan 5, 2020, at 09:45, Eric <ericsp@gmail.com> wrote:

I would love to have a 570 in the lab but not for that that is nuts.

On 1/5/2020 9:36 AM, Mlynch001 wrote:

On Sat, Jan 4, 2020 at 10:48 PM, Dan Cordova wrote:

For less than $200, I put together a Dennis Tillman VTCT board,
and

modified

my Hickok Tube Tester to use with my Tektronix 575 curve tracer.
I

also made

the Daniel Schoo designed triode and pentode adapters for the

Tektronix 576

Curve Tracer at work.
I'm also not sure all my tubes and stereo gear are worth ~$4000
all

together.

;)

I KNOW my stereo gear is not worth that much! I have the stuff to

build Dennis Tillman's VTCT and I have a 576 as well. So even after I
buy a suitable tube tester, I am sure that all told I would have less
than
$1000 in the whole thing. It might not do what the 570 will do, but
likely 95% as much and still test solid state devices as well. You
would need to have a serious desire or even more serious need for this
thing in order to justify paying that price. From the description, it
sounds as though this thing is not quite ready to go as it is. The
elephant in the room is getting it shipped to ones location without it
being destroyed in the process. The seller does have a "Make an
Offer" option as well. This will be interesting to watch.

--
Dennis Tillman W7PF
TekScopes Moderator

I have been looking at sales of Tektronix 570s, mostly but not all on
ebay, for a long time now. All of then have had an asking price of
around $4k.

DaveD

Sent from a small flat thingy

On Jan 5, 2020, at 09:45, Eric <ericsp@gmail.com> wrote:

I would love to have a 570 in the lab but not for that that is nuts.

On 1/5/2020 9:36 AM, Mlynch001 wrote:

On Sat, Jan 4, 2020 at 10:48 PM, Dan Cordova wrote:

For less than $200, I put together a Dennis Tillman VTCT board,
and

modified

my Hickok Tube Tester to use with my Tektronix 575 curve tracer.
I

also made

the Daniel Schoo designed triode and pentode adapters for the

Tektronix 576

Curve Tracer at work.
I'm also not sure all my tubes and stereo gear are worth ~$4000
all

together.

;)

I KNOW my stereo gear is not worth that much! I have the stuff to

build Dennis Tillman's VTCT and I have a 576 as well. So even after I
buy a suitable tube tester, I am sure that all told I would have less
than
$1000 in the whole thing. It might not do what the 570 will do, but
likely 95% as much and still test solid state devices as well. You
would need to have a serious desire or even more serious need for this
thing in order to justify paying that price. From the description, it
sounds as though this thing is not quite ready to go as it is. The
elephant in the room is getting it shipped to ones location without it
being destroyed in the process. The seller does have a "Make an
Offer" option as well. This will be interesting to watch.

So what is a SMU?

SMU Singapore Management University
SMU Southern Methodist University
SMU Saint Mary's University *(Halifax, Nova Scotia; Philippines)* SMU
Solid (Waste) Management Unit SMU Saint Mary's University of Minnesota
SMU Sikkim Manipal University *(India)* SMU Suomen Merimies-Unioni
*(Finnish: Finnish Seamen's Union)* SMU Sindicato Médico del Uruguay
SMU Storage Migrator for Unix SMU Shanghai Maritime University
*(Shanghia, China)* SMU Santa Monica United *(soccer; California)* SMU
Swansea Metropolitan University *(UK)* SMU Sekolah Menengah Umum
*(Indonesian High school)* SMU Special Management Unit SMU Services
Médicaux d'Urgence *(French: Emergency Medical Services)* SMU Southern
Mississippi University SMU Special Mission Unit *(US DoD)* SMU System
Management Utility SMU Smallest Mining Unit SMU Start Me Up SMU
Southeastern Massachusetts University *(formerly used, now Umass)* SMU
Source Measurement Unit SMU Storage Management Utility *(data
storage)* SMU Special Make Up SMU Selective Mining Unit SMU Sociedad
Mexicana de Urología SMU System Managed Undo *(Oracle Databases)* SMU
Sediment Management Unit SMU Supply Management Unit SMU Sassy
Management Unit SMU Small Marching Unit SMU Switch Multiplexer Unit
SMU Secure Mobile Unit SMU Service Meter Unit SMU Scrutin Majoritaire
Uninominal *(French: Single Member Plurality)* SMU Service Management
Unit SMU Strategic Market Unit SMU Switch Multiplex Unit SMU Svenska
Missionskyrkans Ungdomsförbund *(Swedish Christian Youth
Organisation)* SMU Storage Management Unit SMU Secours Médical
d'Urgence
*(French: Emergency Medical Relief; various organizations)* SMU
Subscriber Module Urban SMU Single-Word, Multiple-Bit Upset SMU
Software Maintenance Update *(Cisco)* SMU Speaker/Microphone Unit *(US
NASA)* SMU System Master Unit SMU Sindh Madressah University
*(Karachi, Pakistan)* SMU Shelter Management Unit *(US FEMA)* SMU
Space Management Utility SMU Small and Medium-Sized Undertaking SMU
System Measurement Unit SMU Simple Mail Users SMU Space Self
Maneuvering Unit SMU Secours Mondial d'Urgence *(French: World
Emergency Relief)* SMU Super Module Unit SMU Super Millionaire
University *(fictional, from TV show Gilligan's Island)* SMU Smoke Me
Up SMU Safe Mode Utility SMU Special Maintenance Unit *(India)*

On Sun, Jan 5, 2020 at 10:10 AM Eric <ericsp@gmail.com> wrote:

Is there a modern version of these curve tracers? From what I have
seen the 300 series seems to be about the top end. I know you can get
the same functionality today but you need 2 X $10,000 SMU's, and a
computer, and software so call it a $25,000 setup though given the
catalog price of the 576 and the 300's doesn't sound so bad now that I say it.


On 1/5/2020 6:59 AM, cnc_joker via Groups.Io wrote:

A long time ago in the early 80's the Massachusetts hams ran an
auction

at Honeywell Inc

in Billerica. You could bring your old electronic stuff and they would

auction it off. It was

great fun and always well attended.

Anyway, one guy brought a 370 to be auctioned. As he wheeled it in on

a cart the crowd

chuckled. When it went up for auction it sold for $1 and the

auctioneer had a hard time

getting even that! Between then and now, what a great return on that

investment.

Pete.

My GOTO place has it: http://www.utsource.net/sch/MM74C175N
On Saturday, January 4, 2020, 10:31:47 PM EST, Mlynch001 <mlynch002@gmail.com> wrote:
OK, learned something. LSTTL and TTL are different animals? SN74HC175N Will drive 10 outputs of LSTTL. Just trying to learn how logic works, I will likely encounter a similar issue in the future.

Thanks!