Date   

Re: Logic families

KB6NAX
 

It was just a quickie off of Google.

Arden

-----Original Message-----
From: Mlynch001
Sent: Saturday, January 04, 2020 7:33 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Logic families

Arden,

THANKS! much appreciated.

--
Michael Lynch
Dardanelle, AR


Re: Tektronix 570 Vacuum Tube Curve Tracer on eBay

Dan Cordova <danny_cordov@...>
 

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.    ;)

On Saturday, January 4, 2020, 08:25:27 PM PST, Roy Morgan <k1lky68@gmail.com> wrote:

Gee.  Only ten bucks less than four thousand dollar$. Too bad he doesn't have two - one for spare.

Roy Morgan
K1LKY Western Mass

On Jan 4, 2020, at 11:02 PM, John Williams <books4you@telus.net> wrote:

https://www.ebay.com/itm/Tektronix-570-Vacuum-Tube-Curve-Tracer-w-manual/333465990412?hash=item4da41f350c:g:~hMAAOSwpj1eETIK



Re: Tektronix 570 Vacuum Tube Curve Tracer on eBay

Jamie Ostrowski
 

When the prices get that high, at some point you need to ask yourself how
much it would cost to build one from scratch!

On Sat, Jan 4, 2020 at 10:25 PM Roy Morgan <k1lky68@gmail.com> wrote:

Gee. Only ten bucks less than four thousand dollar$. Too bad he doesn't
have two - one for spare.

Roy Morgan
K1LKY Western Mass

On Jan 4, 2020, at 11:02 PM, John Williams <books4you@telus.net> wrote:


https://www.ebay.com/itm/Tektronix-570-Vacuum-Tube-Curve-Tracer-w-manual/333465990412?hash=item4da41f350c:g:~hMAAOSwpj1eETIK





Re: Tektronix 570 Vacuum Tube Curve Tracer on eBay

Roy Morgan
 

Gee. Only ten bucks less than four thousand dollar$. Too bad he doesn't have two - one for spare.

Roy Morgan
K1LKY Western Mass


Re: Logic families

Mlynch001
 

Covers the very modern series of logic families. It seems to be a little short on the older families. I don’t see many of these listed. Those families are the ones that I am more interested in. I have an older TI Logic Cross reference that crosses over many of the older Logic IC’s. I still appreciate any information where logic is concerned. There are so many sub-divisions within TTL alone, understanding them all is confusing to say the least. I appreciate any lessons that I can learn.
--
Michael Lynch
Dardanelle, AR


Re: Logic families

Dean Davidson
 

On 5/01/2020 13:58, KB6NAX wrote:
Here's a comprehensive overview of the various logic families (long URL):
https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=19&cad=rja&uact=8&ved=2ahUKEwjBrqSQuevmAhVoB50JHRjTC4MQFjASegQIBxAC&url=http%3A%2F%2Fwww.ti.com%2Flit%2Fsdyu001&usg=AOvVaw25lGF9wfK6uX4gPjvyvJpf
No that very comprehensive. What about DTL & RTL???
Dean


Tektronix 570 Vacuum Tube Curve Tracer on eBay

John Williams
 


Re: Logic families

Mlynch001
 

Arden,

THANKS! much appreciated.

--
Michael Lynch
Dardanelle, AR


Re: Trying to bring back a AA501

Mlynch001
 

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!
--
Michael Lynch
Dardanelle, AR


Re: TDS694C 50 Ohm Overload

Reginald Beardsley
 

On Sat, Jan 4, 2020 at 05:30 PM, EricJ wrote:


A lot of SPC fails on TDS scopes seem to be related to contact resistance in
the switching relays on the hybrid acquisition boards. I have a TDS754D that
had that problem. Changing the relays solved it.

--Eric

On Jan 4, 2020 4:00 PM, "Reginald Beardsley via Groups.Io"
<pulaskite=yahoo.com@groups.io> wrote:




If it works on the higher setting, the problem is in the input section
ahead of the ADC.  I'd look for a burned 50 ohm resistor. Or perhaps a
cracked solder joint.

I saw several of these on ebay with the SPC fail, but had been unable to
find any information about what might be wrong with such a unit.  How did
you get the input damage information?

Reg





How hard is it to get replacement relays and what do they cost?

Is there a blog post about reviving these things?

And what do you ask an ebay seller to do to find out the status of an item?

Thanks,
Reg

Reg


Re: Does anyone know Ynvge Von Spalden's current email address?

 

Hi Goran,
Yes, you are correct.
Somedays I can't do anything right.
Dennis Tillman W7PF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Göran Krusell
Sent: Saturday, January 04, 2020 2:42 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Does anyone know Ynvge Von Spalden's current email address?

Perhaps it should be Yngve? That is the way I would spell it. Göran

Den lör 4 jan. 2020 23:29Dennis Tillman W7PF <dennis@ridesoft.com> skrev:

I'm trying to reach Ynvge von Spalden, a member of TekScopes.

Does anyone know his current email address?
If so contact please contact me off list at dennis at ridesoft dot com.

The email address I have been using as recently as August 2019 just
bounced back to me as an unknown address.
Dennis Tillman W7PF

----
Final-Recipient: rfc822; dvs@xxxxxxxxxxxx.de (I deliberately crossed
out most of his email address)
Action: failed
Status: 0.0.0 (Unknown class - no additional status information
available)
Diagnostic-Code: smtp; 550 5.1.1 Unknown recipient



--
Dennis Tillman W7PF
TekScopes Moderator







--
Dennis Tillman W7PF
TekScopes Moderator


Logic families

KB6NAX
 


Re: Trying to bring back a AA501

KB6NAX
 

Meh, I said "Hz" when I meant MHz. Oh, also, high speed logic designs require much more rigorous power and ground rail decoupling because the faster the logic the noisier the environment. But still you may be OK with the 74HC part.

Arden

-----Original Message-----
From: KB6NAX
Sent: Saturday, January 04, 2020 6:32 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Trying to bring back a AA501

Eric, the 74C157 and 74HC157 are the same logic functions but are members of
two distinctly different semiconductor processes. The 74C157 belongs to the
metal gate family, the first of the CMOS families. It's maximum toggle
speed is in the neighborhood of 5 - 10 Hz and it's operating voltage ranges
from 3 - 15V. The 74HC157 belongs to the later silicon gate high speed CMOS
family. It toggles at up to around 35MHz. It’s operating voltage maxes at
6 volts. So the rub is knowing what the rail voltage is in the 501. If
it's 5 volts the "HC" part may work OK, but it's not guaranteed if the logic
in the 501 is susceptible to timing issues with much faster through gate
transmission times.

Arden

-----Original Message-----
From: Eric
Sent: Saturday, January 04, 2020 6:03 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Trying to bring back a AA501

I have found a bad IC in the 501 it is the MM74C175N from On
semiconductor. It also seems this part is obsolete. Would I be safe in
subbing a 74HC175N from Texas Instruments. I am not sure if the
difference in C and HC logic will matter?

On 12/31/2019 9:33 PM, Eric via Groups.Io wrote:
OK a little more digging and something I can dig in to at least not sure if this is the only issue but it is a start. I was looking around U1410 on the main board and ran through the truth table. It turns out Pin15 on U1410 has a constant output of about 5VDc. The others go to 14.5V when they should be high. Also when pin 15 should be high the distortion levels look in the ball park when Pin 15 should be low the distortion goes to +100% distortion and the function output from the aa501 is a sign wave as opposed to the distortion elements. The frequency it can’t get past is 959 Hz which is when Pin 15 should go low.

On 12/31/2019 9:35 AM, Eric via Groups.Io wrote:
Well it looks like the AA501 is not as bad off as I though. I got a service manual still need to go over it in detail however it looks like the fault is isolated to “higher frequency”, anything ~1Khz it looks like I am getting numbers that are at least in the realm of sanity. Anything over that and I get 100%+ distortion. I am starting to suspect ½ and opamp has gone out.




Re: Trying to bring back a AA501

KB6NAX
 

Both operate at TTL levels ....
Sorry, Michael, but you are wrong. The input true and false thresholds are different for CMOS and TTL. Only a 74HCT (notice "HCT" for TTL interface compatibility) part may be used with TTL parts only because its input thresholds are offset to meet TTL output levels.

Arden

-----Original Message-----
From: Mlynch001
Sent: Saturday, January 04, 2020 6:33 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Trying to bring back a AA501

It appears to me that the MM74C175N has a VCC (max. operating) of 15V and the 74HC175N VCC operating range is -.5V - 7.0V. Otherwise they appear to be similar. Both operate at TTL levels. Quad Flip Flops with common clock and clear to all 4. As long as your operating VCC was compatible, it looks like the 74HC175N could sub in.

--
Michael Lynch
Dardanelle, AR


Re: Trying to bring back a AA501

KB6NAX
 

Eric, the 74C157 and 74HC157 are the same logic functions but are members of two distinctly different semiconductor processes. The 74C157 belongs to the metal gate family, the first of the CMOS families. It's maximum toggle speed is in the neighborhood of 5 - 10 Hz and it's operating voltage ranges from 3 - 15V. The 74HC157 belongs to the later silicon gate high speed CMOS family. It toggles at up to around 35MHz. It’s operating voltage maxes at 6 volts. So the rub is knowing what the rail voltage is in the 501. If it's 5 volts the "HC" part may work OK, but it's not guaranteed if the logic in the 501 is susceptible to timing issues with much faster through gate transmission times.

Arden

-----Original Message-----
From: Eric
Sent: Saturday, January 04, 2020 6:03 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Trying to bring back a AA501

I have found a bad IC in the 501 it is the MM74C175N from On
semiconductor. It also seems this part is obsolete. Would I be safe in
subbing a 74HC175N from Texas Instruments. I am not sure if the
difference in C and HC logic will matter?

On 12/31/2019 9:33 PM, Eric via Groups.Io wrote:
OK a little more digging and something I can dig in to at least not sure if this is the only issue but it is a start. I was looking around U1410 on the main board and ran through the truth table. It turns out Pin15 on U1410 has a constant output of about 5VDc. The others go to 14.5V when they should be high. Also when pin 15 should be high the distortion levels look in the ball park when Pin 15 should be low the distortion goes to +100% distortion and the function output from the aa501 is a sign wave as opposed to the distortion elements. The frequency it can’t get past is 959 Hz which is when Pin 15 should go low.

On 12/31/2019 9:35 AM, Eric via Groups.Io wrote:
Well it looks like the AA501 is not as bad off as I though. I got a service manual still need to go over it in detail however it looks like the fault is isolated to “higher frequency”, anything ~1Khz it looks like I am getting numbers that are at least in the realm of sanity. Anything over that and I get 100%+ distortion. I am starting to suspect ½ and opamp has gone out.




Re: Trying to bring back a AA501

Mlynch001
 

It appears to me that the MM74C175N has a VCC (max. operating) of 15V and the 74HC175N VCC operating range is -.5V - 7.0V. Otherwise they appear to be similar. Both operate at TTL levels. Quad Flip Flops with common clock and clear to all 4. As long as your operating VCC was compatible, it looks like the 74HC175N could sub in.

--
Michael Lynch
Dardanelle, AR


Re: Trying to bring back a AA501

Eric
 

I have found a bad IC in the 501 it is the MM74C175N from On semiconductor. It also seems this part is obsolete. Would I be safe in subbing a 74HC175N from Texas Instruments. I am not sure if the difference in C and HC logic will matter?

On 12/31/2019 9:33 PM, Eric via Groups.Io wrote:
OK a little more digging and something I can dig in to at least not sure if this is the only issue but it is a start. I was looking around U1410 on the main board and ran through the truth table. It turns out Pin15 on U1410 has a constant output of about 5VDc. The others go to 14.5V when they should be high. Also when pin 15 should be high the distortion levels look in the ball park when Pin 15 should be low the distortion goes to +100% distortion and the function output from the aa501 is a sign wave as opposed to the distortion elements. The frequency it can’t get past is 959 Hz which is when Pin 15 should go low.

On 12/31/2019 9:35 AM, Eric via Groups.Io wrote:
Well it looks like the AA501 is not as bad off as I though. I got a service manual still need to go over it in detail however it looks like the fault is isolated to “higher frequency”, anything ~1Khz it looks like I am getting numbers that are at least in the realm of sanity. Anything over that and I get 100%+ distortion. I am starting to suspect ½ and opamp has gone out.



Re: Tektronix 2245a Flickering Trace

Siggi
 

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


465M Restoration Completion

KB6NAX
 

It seems my junker 465M has pulled through four days of surgery and hopefully will become useful help for someone (disclaimer - I'm not offering it for sale here). The only thing I need now is a top cover for Junker. If anyone has a top cover for a 465M that is missing a purpose I would like to buy it. If interested send me your coded e-mail address. Thanks.

Arden


Re: Tektronix 2245a Flickering Trace

William Schuler
 

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

On Sat, Jan 4, 2020 at 2:29 PM Panos <sadosp@gmail.com> 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.



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