Date   

Re: DM502 with problems

Harvey White
 

This is a multiplexed display.  There's a switch/transistor applying power to each of the displays in turn.  That same switch changes the input of a single decoder to the various counters, likely through a multiplexer.

There's a counter that selects a digit and the appropriate input.  If that counter doesn't run, you get whatever input there is to the decoder and the single digit much brighter than normal. Scanning averages out the peak current (selected) to the average current desired, hence the digits would be dimmer.

FIrst there needs to be a scanning clock.  Secondly, the counter and decoding circuit that selects the digits needs to work.

If it's a 555, they're easy to come by.  RadioShack/Tandy sold them, as did/does Jameco, etc.

If you had a signal generator that put out TTL pulses, I'd suggest pulling the 555 and patching a 1 Khz (roughly) output into the former output of the 555 timer and see how it goes.  What their exact frequency is will be in the manual.

Depending on what state the decoding circuitry comes up in, you could be looking at any one of the counter outputs.

Analyze the circuit starting at the oscillator and go from there.

Harvey

On 7/16/2021 7:36 PM, Richard Peterson wrote:
Sorry for hijacking this discussion, but i'm working on a DM502 as well and wonder if you all could help. The unit powers on and has +5V and +/- 12V (step 1 of the check/adjustment procedure) but I don't have a clock signal - step 2. I'm guessing the NE555 timer IC is fried, but before i start randomly replacing parts, I checked out as much as i could. Voltages at various other points i tested seem OK and the resistors, capacitors and transistors within the display drive circuit all test OK as well. When the unit is powered up, i get a '0' on the display no mater what setting the switch is on with the decimal point showing up on a couple of the switch settings. Sometimes the display will go dark after being on for a while but not always. The sn7447 and LD110 ICs both feel very warm but not too hot to touch - maybe OK?

I tried Roger's suggestion to pull, clean and reseat the ICs but that didn't change anything. So . . . should i try just changing the NE555 to see if it comes back on line. Replace all the ICs? Are there other tests I can try to isolate the root cause of the problem? possibly a dirty switch?

Mouser has the NE555, the SN7447 and the SN7416N but the LD110 and LD111 appear to be approaching extinction although there is one seller on the fleabag selling sets.

Thanks for your help.

Rich





Re: Members in Germany, Brussels, and the Netherlands affected by the floods

Jim Ford
 

+1, Thomas!              Jim Ford (unfortunately living in an earthquake zone)Sent from my Verizon, Samsung Galaxy smartphone

-------- Original message --------From: Thomas Garson <tgarson@auraltek.com> Date: 7/16/21 1:41 PM (GMT-08:00) To: TekScopes@groups.io Subject: Re: [TekScopes] Members in Germany, Brussels, and the Netherlands affected by the floods For Real.....Step 3: Stop building homes and factories on historic flood plains, in areas prone to earthquake or landslides, and on sea coasts that have been under water as recently as 10,000 years ago, a minuscule amount of time from a geological perspective.Step 4: Stop ignoring the fact that climate change is inevitable and has been ongoing for 4 billion years and live accordingly.Step 5: Don't blame your neighbors for causing the problem while your government, and you, have not got the guts to call out one of the largest, and most populous, countries on the planet which is responsible for generating as much as 1/3 of the human attributable greenhouse gasses that may be contributing to current climate changes.Hint: It's neither the US, Russia nor the EU, none of whom are blameless but do, at least, acknowledge that responsible use of available resources and treatment of the environment as desirable goals.(I believe the Russians are more afraid of them than of any other country!)Hence forth, I will refrain from any discussions on topics other than those pertaining to Tektronix products.Thomas GarsonAural Technology, Ashland, ORBy my calculation, the  dynamic range of the universe is roughly 679dB,which is approximately 225 bits, collected at a rate 1.714287514x10^23 sps.On 7/16/21 9:03 AM, Marian Beermann wrote:> The usual ceremony> > step 0. woah climate change is looking pretty bad right about now!> step 1. talk about doing green things and being green and totally against> climate change> step 2a. If you are a private person, adjust lifestyle and consumption> precisely not at all> step 2b. If you are a corporation, proclaim new growth targets to hit> > Gets too depressing if you think about it for too long, so don't.> > not-so-cheerful> Marian> > > > > > >


Wanted: 154-0731-04 or 154-0676-19

Mark Vincent
 

I am looking for either of these CRTs for a 465. If you have one, let me
know.

Mark


Re: DM502 with problems

Richard Peterson
 

Sorry for hijacking this discussion, but i'm working on a DM502 as well and wonder if you all could help. The unit powers on and has +5V and +/- 12V (step 1 of the check/adjustment procedure) but I don't have a clock signal - step 2. I'm guessing the NE555 timer IC is fried, but before i start randomly replacing parts, I checked out as much as i could. Voltages at various other points i tested seem OK and the resistors, capacitors and transistors within the display drive circuit all test OK as well. When the unit is powered up, i get a '0' on the display no mater what setting the switch is on with the decimal point showing up on a couple of the switch settings. Sometimes the display will go dark after being on for a while but not always. The sn7447 and LD110 ICs both feel very warm but not too hot to touch - maybe OK?

I tried Roger's suggestion to pull, clean and reseat the ICs but that didn't change anything. So . . . should i try just changing the NE555 to see if it comes back on line. Replace all the ICs? Are there other tests I can try to isolate the root cause of the problem? possibly a dirty switch?

Mouser has the NE555, the SN7447 and the SN7416N but the LD110 and LD111 appear to be approaching extinction although there is one seller on the fleabag selling sets.

Thanks for your help.

Rich


Re: Tektronix RAMS (Surplus) Store - Odd hours?

Harvey White
 

My wife has two bedrooms her own, for knitting, gourds, and whatever she wants.  I have one for a lab.  I also have the (shared) library for my books, TV, and recliner.  She has the family room for her TV and recliner.  The garage is full of combined stuff, the shop has an area for her, we're sharing what's left (although the kitchen is mostly mine) and we have ABSOLUTELY NO ROOM for guests.....

unless they want to sleep in a recliner.

Works for us..... <grin>

Harvey

On 7/16/2021 5:27 PM, Jim Ford wrote:
I feel your pain, Dan!  If it weren't for my wife, my house would be full floor to ceiling with test equipment and musical gear!  OTOH, if it weren't for me, the wife would have it full of scrapbooking supplies and holiday decorations!  Either way it would be a no-brakes situation.  Good luck!           Jim FordSent from my Verizon, Samsung Galaxy smartphone
-------- Original message --------From: "Daniel Koller via groups.io" <kaboomdk=yahoo.com@groups.io> Date: 7/16/21 6:04 AM (GMT-08:00) To: tekscopes@groups.io, TekScopes@groups.io Subject: Re: [TekScopes] Tektronix RAMS (Surplus) Store - Odd hours? Hey, just out of curiosity, what sorts of things does one find these days at the RAMS store?  Any vacuum tube stuff that someone dug up from storage, or retirees offices? What are the prices like?Is there a web page so one can see what it looks like in there?  These are not just idle questions.  My wife and I are seriously considering visiting some family in the Portland area, but unfortunately, in August, not after Sept. 1.  On the other hand, that's a good thing.  I should not be allowed in surplus stores, flea markets, or junk yards. (The catch is they are my wife's relatives, so if I bring anything home, I will not be visiting Portland any more).   Dan    On Friday, July 16, 2021, 12:53:15 AM EDT, Magic_Smoke <jsymonds@gmail.com> wrote: I got to answer my own question today, it's the 3rd Thursday of the month and I had the day off so I swung by. I found a sign next to the door that reads: RAMS Country Store is currently closed due to COVID-19Please check back September 1, 2021Very exciting! I'm really looking forward to this bit of normalcy returning.



Re: Tektronix RAMS (Surplus) Store - Odd hours?

Jim Ford
 

I feel your pain, Dan!  If it weren't for my wife, my house would be full floor to ceiling with test equipment and musical gear!  OTOH, if it weren't for me, the wife would have it full of scrapbooking supplies and holiday decorations!  Either way it would be a no-brakes situation.  Good luck!           Jim FordSent from my Verizon, Samsung Galaxy smartphone

-------- Original message --------From: "Daniel Koller via groups.io" <kaboomdk=yahoo.com@groups.io> Date: 7/16/21 6:04 AM (GMT-08:00) To: tekscopes@groups.io, TekScopes@groups.io Subject: Re: [TekScopes] Tektronix RAMS (Surplus) Store - Odd hours? Hey, just out of curiosity, what sorts of things does one find these days at the RAMS store?  Any vacuum tube stuff that someone dug up from storage, or retirees offices? What are the prices like?Is there a web page so one can see what it looks like in there?  These are not just idle questions.  My wife and I are seriously considering visiting some family in the Portland area, but unfortunately, in August, not after Sept. 1.  On the other hand, that's a good thing.  I should not be allowed in surplus stores, flea markets, or junk yards. (The catch is they are my wife's relatives, so if I bring anything home, I will not be visiting Portland any more).   Dan    On Friday, July 16, 2021, 12:53:15 AM EDT, Magic_Smoke <jsymonds@gmail.com> wrote: I got to answer my own question today, it's the 3rd Thursday of the month and I had the day off so I swung by. I found a sign next to the door that reads: RAMS Country Store is currently closed due to COVID-19Please check back September 1, 2021Very exciting! I'm really looking forward to this bit of normalcy returning.


Re: Members in Germany, Brussels, and the Netherlands affected by the floods

n7qmm25
 

My 2 cents. Politics does not belong on the TEK web site.

On 7/16/2021 11:09 AM, cheater cheater wrote:
There is no way to avoid progressing global warming unless the largest
single polluters are brought to justice - including jail time for
everyone involved. This means the full executive and top engineering
rosters of the largest corporations. Call me a socialist, but there's
no way this correction will happen in a fully free market. The mere
notion of free markets requires ignoring issues that happen not on the
market itself - such as pollution, global warming, etc.

On Fri, Jul 16, 2021 at 6:03 PM Marian Beermann <public@enkore.de> wrote:
The usual ceremony

step 0. woah climate change is looking pretty bad right about now!
step 1. talk about doing green things and being green and totally against
climate change
step 2a. If you are a private person, adjust lifestyle and consumption
precisely not at all
step 2b. If you are a corporation, proclaim new growth targets to hit

Gets too depressing if you think about it for too long, so don't.

not-so-cheerful
Marian






Re: Members in Germany, Brussels, and the Netherlands affected by the floods

Thomas Garson
 

For Real.....
Step 3: Stop building homes and factories on historic flood plains, in areas prone to earthquake or landslides, and on sea coasts that have been under water as recently as 10,000 years ago, a minuscule amount of time from a geological perspective.
Step 4: Stop ignoring the fact that climate change is inevitable and has been ongoing for 4 billion years and live accordingly.
Step 5: Don't blame your neighbors for causing the problem while your government, and you, have not got the guts to call out one of the largest, and most populous, countries on the planet which is responsible for generating as much as 1/3 of the human attributable greenhouse gasses that may be contributing to current climate changes.
Hint: It's neither the US, Russia nor the EU, none of whom are blameless but do, at least, acknowledge that responsible use of available resources and treatment of the environment as desirable goals.
(I believe the Russians are more afraid of them than of any other country!)

Hence forth, I will refrain from any discussions on topics other than those pertaining to Tektronix products.

Thomas Garson
Aural Technology, Ashland, OR
By my calculation, the dynamic range of the universe is roughly 679dB,
which is approximately 225 bits, collected at a rate 1.714287514x10^23 sps.

On 7/16/21 9:03 AM, Marian Beermann wrote:
The usual ceremony
step 0. woah climate change is looking pretty bad right about now!
step 1. talk about doing green things and being green and totally against
climate change
step 2a. If you are a private person, adjust lifestyle and consumption
precisely not at all
step 2b. If you are a corporation, proclaim new growth targets to hit
Gets too depressing if you think about it for too long, so don't.
not-so-cheerful
Marian


Re: [HP-Agilent-Keysight-equipment] OT: Looking for a Pentium M765 (or maybe M780 - not sure it that will work)

 

That's why I linked you to a card that slots into a PCI slot and
provides you with a PC/104+ connector.

At which point the sky's the limit with inexpensive, powerful motherboards.

On Fri, Jul 16, 2021 at 9:41 PM David C. Partridge
<david.partridge@perdrix.co.uk> wrote:

Problem this scope *needs* the PCI/104 ...

-----Original Message-----
From: TekScopes@groups.io <TekScopes@groups.io> On Behalf Of cheater cheater
Sent: 16 July 2021 18:49
To: TekScopes@groups.io
Subject: Re: [TekScopes] [HP-Agilent-Keysight-equipment] OT: Looking for a Pentium M765 (or maybe M780 - not sure it that will work)

This might help you

http://www.sensoray.com/products/623.htm

it's much easier to find PCI motherboards than PC/104+ ones.






Re: 7904A compress sweep

Harvey White
 

I would guess that the horizontal drivers are bottoming (or topping) out.  This suggests a power supply voltage is off.  That it suddenly goes "good" then back again suggests that the *effective* power supply to the horizontal (or vertical, too) amp is changing.

I'd measure the power supply voltages both on the deflection driver boards and the supply itself.  Problems could be bad connections, a filter capacitor acting up, an odd filter resistor (if any).

It could be just as easy as a transistor (in the input circuitry) with an intermittent contact.  I'd be checking the static voltages with the intensity turned down to zero and no sweep.

Harvey

On 7/16/2021 3:53 PM, Tom Phillips wrote:
I need some advice on where to start looking to track down a compressed sweep issue on a 7904A I was given.

The sweep is compressed by about one division on each end and it does not matter what plugins or channel combinations are used. The readout seems slightly compressed as well.

Very rarely it will suddenly appear normal width and readout seems to slightly expand but then seems to revert shortly after.

Its a very nice scope in otherwise excellent condition.






7904A compress sweep

Tom Phillips
 

I need some advice on where to start looking to track down a compressed sweep issue on a 7904A I was given.

The sweep is compressed by about one division on each end and it does not matter what plugins or channel combinations are used. The readout seems slightly compressed as well.

Very rarely it will suddenly appear normal width and readout seems to slightly expand but then seems to revert shortly after.

Its a very nice scope in otherwise excellent condition.


Re: OT: Looking for a Pentium M765 (or maybe M780 - not sure it that will work)

 

AFAIK both the M765 and M780 are socket 478 which is what this board has.

-----Original Message-----
From: TekScopes@groups.io <TekScopes@groups.io> On Behalf Of DaveH52
Sent: 16 July 2021 19:11
To: TekScopes@groups.io
Subject: Re: [TekScopes] OT: Looking for a Pentium M765 (or maybe M780 - not sure it that will work)

If you're going to replace the CPU only, make sure you get the correct socket-type for the replacement CPU.


Re: [HP-Agilent-Keysight-equipment] OT: Looking for a Pentium M765 (or maybe M780 - not sure it that will work)

 

Problem this scope *needs* the PCI/104 ...

-----Original Message-----
From: TekScopes@groups.io <TekScopes@groups.io> On Behalf Of cheater cheater
Sent: 16 July 2021 18:49
To: TekScopes@groups.io
Subject: Re: [TekScopes] [HP-Agilent-Keysight-equipment] OT: Looking for a Pentium M765 (or maybe M780 - not sure it that will work)

This might help you

http://www.sensoray.com/products/623.htm

it's much easier to find PCI motherboards than PC/104+ ones.


Re: OT: Looking for a Pentium M765 (or maybe M780 - not sure it that will work)

 

The CPUs in question only come in one socket type!

On Fri, Jul 16, 2021 at 8:10 PM DaveH52 <ac2gl.dave@gmail.com> wrote:

If you're going to replace the CPU only, make sure you get the correct socket-type for the replacement CPU.





Re: Tektronix RAMS (Surplus) Store - Odd hours?

 

Yes, I'm enabling.

On Fri, Jul 16, 2021 at 8:12 PM cheater cheater
<cheater00social@gmail.com> wrote:

You forgot you can buy the thing, put it in a box, and mail it out via
FedEx to a neighbor.

On Fri, Jul 16, 2021 at 3:05 PM Daniel Koller via groups.io
<kaboomdk=yahoo.com@groups.io> wrote:

Hey, just out of curiosity, what sorts of things does one find these days at the RAMS store?
Any vacuum tube stuff that someone dug up from storage, or retirees offices?
What are the prices like?
Is there a web page so one can see what it looks like in there?
These are not just idle questions. My wife and I are seriously considering visiting some family in the Portland area, but unfortunately, in August, not after Sept. 1. On the other hand, that's a good thing. I should not be allowed in surplus stores, flea markets, or junk yards. (The catch is they are my wife's relatives, so if I bring anything home, I will not be visiting Portland any more).
Dan
On Friday, July 16, 2021, 12:53:15 AM EDT, Magic_Smoke <jsymonds@gmail.com> wrote:

I got to answer my own question today, it's the 3rd Thursday of the month and I had the day off so I swung by. I found a sign next to the door that reads:
RAMS Country Store is currently closed due to COVID-19
Please check back September 1, 2021

Very exciting! I'm really looking forward to this bit of normalcy returning.










Re: Tektronix RAMS (Surplus) Store - Odd hours?

 

You forgot you can buy the thing, put it in a box, and mail it out via
FedEx to a neighbor.

On Fri, Jul 16, 2021 at 3:05 PM Daniel Koller via groups.io
<kaboomdk=yahoo.com@groups.io> wrote:

Hey, just out of curiosity, what sorts of things does one find these days at the RAMS store?
Any vacuum tube stuff that someone dug up from storage, or retirees offices?
What are the prices like?
Is there a web page so one can see what it looks like in there?
These are not just idle questions. My wife and I are seriously considering visiting some family in the Portland area, but unfortunately, in August, not after Sept. 1. On the other hand, that's a good thing. I should not be allowed in surplus stores, flea markets, or junk yards. (The catch is they are my wife's relatives, so if I bring anything home, I will not be visiting Portland any more).
Dan
On Friday, July 16, 2021, 12:53:15 AM EDT, Magic_Smoke <jsymonds@gmail.com> wrote:

I got to answer my own question today, it's the 3rd Thursday of the month and I had the day off so I swung by. I found a sign next to the door that reads:
RAMS Country Store is currently closed due to COVID-19
Please check back September 1, 2021

Very exciting! I'm really looking forward to this bit of normalcy returning.










Re: Members in Germany, Brussels, and the Netherlands affected by the floods

 

Glad you're alright. I'm sure the scopes will survive. They're built
to last. I wish you the best. Is there anything we can do to help you?

On Fri, Jul 16, 2021 at 4:24 PM Dr. Manfred K. Zeller via groups.io
<drmanfredzeller=googlemail.com@groups.io> wrote:

Yes my, I leave in Cologne- 15 Tek Scopes under water. But it could be
worse. About 100 people lost their live and others missing.Thanks to the
group in participating.
Greetings
Manfred
--
Dr.-Ing. Manfred K. Zeller
Hahnwaldweg 47A
50996 Köln-Hahnwald
Deutschland





Re: OT: Looking for a Pentium M765 (or maybe M780 - not sure it that will work)

DaveH52
 

If you're going to replace the CPU only, make sure you get the correct socket-type for the replacement CPU.


Re: Members in Germany, Brussels, and the Netherlands affected by the floods

 

There is no way to avoid progressing global warming unless the largest
single polluters are brought to justice - including jail time for
everyone involved. This means the full executive and top engineering
rosters of the largest corporations. Call me a socialist, but there's
no way this correction will happen in a fully free market. The mere
notion of free markets requires ignoring issues that happen not on the
market itself - such as pollution, global warming, etc.

On Fri, Jul 16, 2021 at 6:03 PM Marian Beermann <public@enkore.de> wrote:

The usual ceremony

step 0. woah climate change is looking pretty bad right about now!
step 1. talk about doing green things and being green and totally against
climate change
step 2a. If you are a private person, adjust lifestyle and consumption
precisely not at all
step 2b. If you are a corporation, proclaim new growth targets to hit

Gets too depressing if you think about it for too long, so don't.

not-so-cheerful
Marian





Re: [HP-Agilent-Keysight-equipment] OT: Looking for a Pentium M765 (or maybe M780 - not sure it that will work)

 

This might help you

http://www.sensoray.com/products/623.htm

it's much easier to find PCI motherboards than PC/104+ ones.

On Fri, Jul 16, 2021 at 6:18 AM David C. Partridge
<david.partridge@perdrix.co.uk> wrote:

Not a dumb question, but changing the mobo in a Waverunner Xi is apparently somewhat of a challenge.

It also needs to work with XP embedded.

David
-----Original Message-----
From: TekScopes@groups.io <TekScopes@groups.io> On Behalf Of cheater cheater
Sent: 16 July 2021 03:47
To: HP-Agilent-Keysight-equipment@groups.io
Cc: TekScopes <Tekscopes@groups.io>
Subject: Re: [TekScopes] [HP-Agilent-Keysight-equipment] OT: Looking for a Pentium M765 (or maybe M780 - not sure it that will work)

This might be a dumb question, but why not get a different motherboard?





5581 - 5600 of 189865