Date   
Re: Tektronix 475 Possibly DM or other optional board ???

Jim Olson <v_12eng@...>
 

Just double checked by manual it does say 670-2239-24 like your board and has a line under the part # stating it is a option 7 only board.

Jim O

On October 19, 2018 at 8:09 PM Craig Cramb <@Manfromtrane mailto:@Manfromtrane > wrote:


Thanks Jim,
My manual is a B25000/up rev Apr 1982. I see the -24, but the part number is changed for this extension it shows the manual 670-2339-24 which is maybe a typo. But in my manual from -12 and up the part number is changed. The board actually has the part # 670-2239-24 printed on it.

Craig


Craig,
I have a listing for that board in the service manual I have it is an option 7 only main board for the B250000 and up 475 scopes. So if you need any specific parts #'s I can supply them.

Jim O


Re: vintageTEK museum microfiche index

Vincent Trouilliez
 

Looking good !

I am glad I donated for the scanner funding... the museum is making good use of it and processing all that data really fast, and now even offers on request manual scans, and for a reasonable amount too.

I see that there is some modern semiconductor and even digital stuff, the most wanted TDS 300/400/500/600/700/800 series, greaaaaaat !
Though it looks like general family information rather than actual service manual for specific models. Maybe we will find the service manuals in the other half of the cabinet...

Can't wait for the index to be complete to see what's available... then another round on all those fiches to look into all the duplicates, put them together in the same place in the cabinet, see if they are indeed duplicates or if they have different or updated contents... then check every document one by one to figure out what type of content it contains exactly : service manual or user manual, calibration procedure and what not...


Lots of work ahead, but looking super promising already, very excited !! :-D




Vincent Trouilliez

THS720 to THS720A/THS720P Upgrade...

maxim.vlasov@...
 

Dear forum members!

I have THS720 and just wonder whether by a "not so simple" FW change THS720 could be upgraded to THS720A or THS720P? The functional difference is in having for later models the external trigger input. I wonder whether someone already tried anything like that? HW seem to be almost the same between A and not-A models.
Also it's known that the flash IC in question contains the calibration data too. It's a 680x0 (683xx) based machine. It would be interesting to check whether there is a some sort of ISP function built-in into the FW. I don't believe that Tek service guys had to unsolder anything to re-program the new version of the FW.

Thank you!

Maxim

Re: THS720 to THS720A/THS720P Upgrade...

 

On Sat, Oct 20, 2018 at 10:59 AM, <maxim.vlasov@...> wrote:


I have THS720 and just wonder whether by a "not so simple" FW change THS720
could be upgraded to THS720A or THS720P?
I don't believe that Tek service guys had to unsolder anything to re-program the new
version of the FW.
All the original non-windows TDS's except the 200, 300 and 3000 series
had their F/W updated through the GPIB connector. To update the 300's
a special pod was connected to a connector on the main board. The other
end of the pod was connected to a PC with both GPIB and RS232. It was
powered by an 18 VAC adapter. The pod P/N was 067-1436-00.
The THS's used the same pod plus a cable adapter to connect to a connector
under the keyboard. To update a special DOS software in conjunction with
the F/W data files was used.

According to the info I have the THS non-A and A are not compatible.

/Håkan

Re: THS720 to THS720A/THS720P Upgrade...

maxim.vlasov@...
 

On Sat, Oct 20, 2018 at 05:05 AM, zenith5106 wrote:


According to the info I have the THS non-A and A are not compatible.

/Håkan
Thank you Håkan,

I see. So, since the connector has the 680x0 bus on it, likely the pod had the complete programmer putting the main THS CPU in the Hi-Z mode on the bus and taking the controls over the THS internals.
By analyzing the board of my THS720 and the schematics of THS720a, I could assume that likely the FW will work, but the external calibration routing will fail when checking the external trigger. I have no circuitry for the extenal trigger at all. The rest seems to be identical apart from quite a few common mode chokes.
Have anyone actually tried to boot the 1.14-1.16 FW on the THS710/720 scope?
As you say the legit tools wouldn't support this, however.

Thank you,

Maxim

Clearing error log in THS720A

 

The recent topic about the THS720/THS720A encourages me to submit an issue that I've had with my THS720A for some time.
The instrument is in pristine condition, both cosmetically and technically. Unfortunately, some time ago I could not resist the temptation to "upgrade" it to a THS730A by moving a few resistors, as described somewhere on the 'net.
Basically, it sort-of worked (both bandwidth and samples/sec) but it slowly filled the error log so I restored it to its original state as a THS720A.
Since then, it has been fine except for the old entries in the error log, which I haven't been able to clear. It's ugly but not a real problem of course.

I'm wondering if the error log can be cleared independently, i.e. without calibrating first (it doesn't need any adjustments) and if so, how, and if not, is calibration of the 'scope-part i.e. leaving the DVM as-is possible and sufficient? I don't have any of the special DC voltage generators needed and I'm not looking forward to set the voltages ad hoc on a normal voltage source.

Thanks in advance for any info!

Raymond

Re: Random noise on LV power rails

Brendan
 

On Wed, Oct 17, 2018 at 07:54 PM, lop pol wrote:


On Wed, Oct 17, 2018 at 07:16 PM, <skv1958@...> wrote:


While trying to figure out what is going on with my 468 I decided to monitor
the -8V and 15V supply DC coupled. When the trace starts to jitter there is
noise on both of them. Not ripple, it almost looks like a digital signal. What
would cause that? This has been a pretty cool trouble shooting experience.

Just loud thinking...when jitter starts in some circuit, sudden current draw
changes may cause sudden voltage changes, which may appear as noise. What
are
the amplitudes of these noises on power rails? You may also want to check
ripple specifications and bypass capacitors. My two cents on this problem,
apart from the mention of some failing pots earlier...

Shailendra
I ordered new filter caps today. I'm unable to get any capacitance reading
from C926 15V unregulated line. I'm hoping that will cure the issues. The caps
will be here Friday. I already have the old caps out, while I was in there I
replaced all the bridge rectifiers also. I replaced all the small caps in the
storage power supply today and will do the big caps when they come. Figured I
may as well give it the full treatment.
Ok this is what I have figured out so far. I replaced all the filter caps on both power supplies. Replaced the bridge rectifiers on the main power supply. F4009 was blown have no idea how or why. Still has horizontal jitter. Now here is the kicker. I live in Arizona its always hot so my central air conditioner is almost always on. The last few days it has been cool enough to have it off for long cycles. Long story short the jitter happens mostly when the air conditioning kicks on I measured the voltage drop when the air kicks on its only about a volt. I have many other scopes that are not affected in the same way. When the air kicks on I can even hear the fan pitch change. I'm now at a loss in what to do. Could this have anything to do with the EMI line filter?

Re: Random noise on LV power rails

Harvey White
 

On Sat, 20 Oct 2018 17:08:56 -0700, you wrote:

On Wed, Oct 17, 2018 at 07:54 PM, lop pol wrote:


On Wed, Oct 17, 2018 at 07:16 PM, <skv1958@...> wrote:
<SNIP>

Ok this is what I have figured out so far. I replaced all the filter caps on both power supplies. Replaced the bridge rectifiers on the main power supply. F4009 was blown have no idea how or why. Still has horizontal jitter. Now here is the kicker. I live in Arizona its always hot so my central air conditioner is almost always on. The last few days it has been cool enough to have it off for long cycles. Long story short the jitter happens mostly when the air conditioning kicks on I measured the voltage drop when the air kicks on its only about a volt.
Sounds like something is not regulating. What it sounds like is that
you're getting coupling from the AC line into the power supply output.

First thing I'd do is to (if you have a variac available) run the
supply voltage up and down by a bit and see what the power supply
voltages are doing.

Secondly, I'd look at the noise on the AC line, and see if it
correlates to the jitter on the scope. Definitely want to see what
the noise is on the power supplies. It suggests to me that a number
of the bypass capacitors could be bad (as a thought, that's just noise
coupling).

Now, if the regulator can't regulate fast enough (and they're supposed
to be pretty good about some of that), then it's possible that the
noise on the AC line is coupled through the regulator to the load. It
is possible, but it requires something to be not working.

If the regulator doesn't have enough headroom (what's the voltage
setting on the scope and the line?), then it can drop out of
regulation. That lets lots of noise get through.

What does the line do when that AC is on? How much noise and what is
the voltage?


Harvey

I have many other scopes that are not affected in the same way. When the air kicks on I can even hear the fan pitch change. I'm now at a loss in what to do. Could this have anything to do with the EMI line filter?


Re: Random noise on LV power rails

Brendan
 

On Sat, Oct 20, 2018 at 05:56 PM, Harvey White wrote:


On Sat, 20 Oct 2018 17:08:56 -0700, you wrote:

On Wed, Oct 17, 2018 at 07:54 PM, lop pol wrote:


On Wed, Oct 17, 2018 at 07:16 PM, <skv1958@...> wrote:
<SNIP>

Ok this is what I have figured out so far. I replaced all the filter caps on
both power supplies. Replaced the bridge rectifiers on the main power supply.
F4009 was blown have no idea how or why. Still has horizontal jitter. Now here
is the kicker. I live in Arizona its always hot so my central air conditioner
is almost always on. The last few days it has been cool enough to have it off
for long cycles. Long story short the jitter happens mostly when the air
conditioning kicks on I measured the voltage drop when the air kicks on its
only about a volt.

Sounds like something is not regulating. What it sounds like is that
you're getting coupling from the AC line into the power supply output.

First thing I'd do is to (if you have a variac available) run the
supply voltage up and down by a bit and see what the power supply
voltages are doing.

Secondly, I'd look at the noise on the AC line, and see if it
correlates to the jitter on the scope. Definitely want to see what
the noise is on the power supplies. It suggests to me that a number
of the bypass capacitors could be bad (as a thought, that's just noise
coupling).

Now, if the regulator can't regulate fast enough (and they're supposed
to be pretty good about some of that), then it's possible that the
noise on the AC line is coupled through the regulator to the load. It
is possible, but it requires something to be not working.

If the regulator doesn't have enough headroom (what's the voltage
setting on the scope and the line?), then it can drop out of
regulation. That lets lots of noise get through.

What does the line do when that AC is on? How much noise and what is
the voltage?


Harvey

I have many other scopes that are not affected in the same way. When the air
kicks on I can even hear the fan pitch change. I'm now at a loss in what to
do. Could this have anything to do with the EMI line filter?


No variac :(
I have not looked at the mains with a scope (because I'm scared to do it)
The low/high switch his set to high and the voltage on the line before the air conditioner kicks on is 120-122V and drops to about 119V when its on. I plugged the scope into a APC 1500 UPS and that SEEMS to almost totally correct the issue. The issue is so random one time the air will kick on and the scope will display no issues the next time it will. There is no way I have found to reliably induce the symptoms. I think I need a variac. I have spent 10 hours a day for about a week trying to figure this out.

A (safer) way to look at the mains.....

Dale Chayes
 

Noise on the “mains” are often an issue on modern “all electric” ships where I have spent way too much time and with the advent of so many poorly designed switching power supplies and drive systems they can appear anywhere.

The THD from those switchers is a continuing to grow issue. It can cause all kinds of obscure behaviors.

When I have to do this, I used to start with a 10:1 transformer - to get down to 12 (or 22, or 44 or 60) volts AC in front of my scope probe, even though I usually carry a high voltage probe for troubleshooting sonar system power supplies.

Depending on the transformer it will/may have some impact, on the signal but it’s a decent place to start.

I eventually graduated to a Fluke 43b

As always, be thoughtful and careful when poking around any high voltage stuff.

-Dale

On Oct 20, 2018, at 18:00 , lop pol via Groups.Io <the_infinite_penguin=yahoo.com@groups.io> wrote:

On Sat, Oct 20, 2018 at 05:56 PM, Harvey White wrote:


On Sat, 20 Oct 2018 17:08:56 -0700, you wrote:

On Wed, Oct 17, 2018 at 07:54 PM, lop pol wrote:


On Wed, Oct 17, 2018 at 07:16 PM, <skv1958@...> wrote:
<SNIP>

Ok this is what I have figured out so far. I replaced all the filter caps on
both power supplies. Replaced the bridge rectifiers on the main power supply.
F4009 was blown have no idea how or why. Still has horizontal jitter. Now here
is the kicker. I live in Arizona its always hot so my central air conditioner
is almost always on. The last few days it has been cool enough to have it off
for long cycles. Long story short the jitter happens mostly when the air
conditioning kicks on I measured the voltage drop when the air kicks on its
only about a volt.

Sounds like something is not regulating. What it sounds like is that
you're getting coupling from the AC line into the power supply output.

First thing I'd do is to (if you have a variac available) run the
supply voltage up and down by a bit and see what the power supply
voltages are doing.

Secondly, I'd look at the noise on the AC line, and see if it
correlates to the jitter on the scope. Definitely want to see what
the noise is on the power supplies. It suggests to me that a number
of the bypass capacitors could be bad (as a thought, that's just noise
coupling).

Now, if the regulator can't regulate fast enough (and they're supposed
to be pretty good about some of that), then it's possible that the
noise on the AC line is coupled through the regulator to the load. It
is possible, but it requires something to be not working.

If the regulator doesn't have enough headroom (what's the voltage
setting on the scope and the line?), then it can drop out of
regulation. That lets lots of noise get through.

What does the line do when that AC is on? How much noise and what is
the voltage?


Harvey

I have many other scopes that are not affected in the same way. When the air
kicks on I can even hear the fan pitch change. I'm now at a loss in what to
do. Could this have anything to do with the EMI line filter?


No variac :(
I have not looked at the mains with a scope (because I'm scared to do it)
The low/high switch his set to high and the voltage on the line before the air conditioner kicks on is 120-122V and drops to about 119V when its on. I plugged the scope into a APC 1500 UPS and that SEEMS to almost totally correct the issue. The issue is so random one time the air will kick on and the scope will display no issues the next time it will. There is no way I have found to reliably induce the symptoms. I think I need a variac. I have spent 10 hours a day for about a week trying to figure this out.



Re: Random noise on LV power rails

EricJ
 

Oh yes, you do. Every electronics hobbyist should have a variable transformer. They are extremely handy for all sorts of things.
--Eric
Sent from my Samsung Galaxy smartphone.

-------- Original message --------From: "lop pol via Groups.Io" <the_infinite_penguin=yahoo.com@groups.io> Date: 10/20/18 9:00 PM (GMT-06:00) To: TekScopes@groups.io Subject: Re: [TekScopes] Random noise on LV power rails
On Sat, Oct 20, 2018 at 05:56 PM, Harvey White wrote:


On Sat, 20 Oct 2018 17:08:56 -0700, you wrote:

On Wed, Oct 17, 2018 at 07:54 PM, lop pol wrote:


On Wed, Oct 17, 2018 at 07:16 PM, <skv1958@...> wrote:
<SNIP>

Ok this is what I have figured out so far. I replaced all the filter caps on
both power supplies. Replaced the bridge rectifiers on the main power supply.
F4009 was blown have no idea how or why. Still has horizontal jitter. Now here
is the kicker. I live in Arizona its always hot so my central air conditioner
is almost always on. The last few days it has been cool enough to have it off
for long cycles. Long story short the jitter happens mostly when the air
conditioning kicks on I measured the voltage drop when the air kicks on its
only about a volt.

Sounds like something is not regulating.  What it sounds like is that
you're getting coupling from the AC line into the power supply output.

First thing I'd do is to (if you have a variac available) run the
supply voltage up and down by a bit and see what the power supply
voltages are doing.

Secondly, I'd look at the noise on the AC line, and see if it
correlates to the jitter on the scope.  Definitely want to see what
the noise is on the power supplies.  It suggests to me that a number
of the bypass capacitors could be bad (as a thought, that's just noise
coupling).

Now, if the regulator can't regulate fast enough (and they're supposed
to be pretty good about some of that), then it's possible that the
noise on the AC line is coupled through the regulator to the load.  It
is possible, but it requires something to be not working.

If the regulator doesn't have enough headroom (what's the voltage
setting on the scope and the line?), then it can drop out of
regulation.  That lets lots of noise get through.

What does the line do when that AC is on?  How much noise and what is
the voltage?


Harvey

I have many other scopes that are not affected in the same way. When the air
kicks on I can even hear the fan pitch change. I'm now at a loss in what to
do. Could this have anything to do with the EMI line filter?


No variac :(
I have not looked at the mains with a scope (because I'm scared to do it)
The low/high switch his set to high and the voltage on the line before the air conditioner kicks on is 120-122V and drops to about 119V when its on. I plugged the scope into a  APC 1500 UPS and that SEEMS to almost totally correct the issue. The issue is so random one time the air will kick on and the scope will display no issues the next time it will. There is no way I have found to reliably induce the symptoms. I think I need a variac. I have spent 10 hours a day for about a week trying to figure this out.

Re: Random noise on LV power rails

Harvey White
 

On Sat, 20 Oct 2018 19:00:20 -0700, you wrote:

On Sat, Oct 20, 2018 at 05:56 PM, Harvey White wrote:


On Sat, 20 Oct 2018 17:08:56 -0700, you wrote:

On Wed, Oct 17, 2018 at 07:54 PM, lop pol wrote:


On Wed, Oct 17, 2018 at 07:16 PM, <skv1958@...> wrote:
<SNIP>

Ok this is what I have figured out so far. I replaced all the filter caps on
both power supplies. Replaced the bridge rectifiers on the main power supply.
F4009 was blown have no idea how or why. Still has horizontal jitter. Now here
is the kicker. I live in Arizona its always hot so my central air conditioner
is almost always on. The last few days it has been cool enough to have it off
for long cycles. Long story short the jitter happens mostly when the air
conditioning kicks on I measured the voltage drop when the air kicks on its
only about a volt.

Sounds like something is not regulating. What it sounds like is that
you're getting coupling from the AC line into the power supply output.

First thing I'd do is to (if you have a variac available) run the
supply voltage up and down by a bit and see what the power supply
voltages are doing.

Secondly, I'd look at the noise on the AC line, and see if it
correlates to the jitter on the scope. Definitely want to see what
the noise is on the power supplies. It suggests to me that a number
of the bypass capacitors could be bad (as a thought, that's just noise
coupling).

Now, if the regulator can't regulate fast enough (and they're supposed
to be pretty good about some of that), then it's possible that the
noise on the AC line is coupled through the regulator to the load. It
is possible, but it requires something to be not working.

If the regulator doesn't have enough headroom (what's the voltage
setting on the scope and the line?), then it can drop out of
regulation. That lets lots of noise get through.

What does the line do when that AC is on? How much noise and what is
the voltage?


Harvey

I have many other scopes that are not affected in the same way. When the air
kicks on I can even hear the fan pitch change. I'm now at a loss in what to
do. Could this have anything to do with the EMI line filter?


No variac :(
I have not looked at the mains with a scope (because I'm scared to do it)
Reasonable enough. As was suggested, a filament transformer or other
transformer designed for AC line use would work well. Even one of
those little AC supply wall warts would be reasonable. Not the best,
but reasonable.


The low/high switch his set to high and the voltage on the line before the air conditioner kicks on is 120-122V and drops to about 119V when its on.
Fairly reasonable....

I plugged the scope into a APC 1500 UPS and that SEEMS to almost totally correct the issue. The issue is so random one time the air will kick on and the scope will display no issues the next time it will. There is no way I have found to reliably induce the symptoms. I think I need a variac.
It could help, but the absolute line voltage may not be the problem.
Noise may be.

You know that UPS supplies can have filtering in them?

You may want to just see if you can find a filtered outlet strip,
borrow it, and see what it does for you.

I have spent 10 hours a day for about a week trying to figure this out.
not surprising, you want a good hard repeatable failure every time.

You don't get them.

Harvey




Re: 7834 High Voltage Board

ef804s tubes
 

On 10/16/18 10:55, ef804s tubes wrote:

On Mon, Oct 15, 2018 at 09:09 AM, Craig Sawyers wrote:

What you seem to be saying is that the main power supply works fine when the
coax inputs to T2010 are
not connected, but when you connect them the main supply goes into tick mode?

Is that correct?

Craig

Hi Craig,
that's correct.

Fred

My apologies for not quoting the question

Hi Craig,
that's correct.

Fred

So, what's the verdict?

Fred

Re: 7834 High Voltage Board

Craig Sawyers <c.sawyers@...>
 

Next thing to try is disconnecting the input wire to the x4 voltage multiplier. Then connect the two
coax feeds. If the main supply then comes up OK, the fault is with the multiplier. If it is still in
tick mode it is likely the transformer.

Craig. The old crumbly one that has been on the list for 16 years, to avoid confusion with any other
Craigs

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of ef804s tubes
Sent: 21 October 2018 08:19
To: TekScopes@groups.io
Subject: Re: [TekScopes] 7834 High Voltage Board


On 10/16/18 10:55, ef804s tubes wrote:

On Mon, Oct 15, 2018 at 09:09 AM, Craig Sawyers wrote:

What you seem to be saying is that the main power supply works fine when the
coax inputs to T2010 are
not connected, but when you connect them the main supply goes into tick mode?

Is that correct?

Craig

Hi Craig,
that's correct.

Fred

My apologies for not quoting the question

Hi Craig,
that's correct.

Fred

So, what's the verdict?

Fred

Re: 7834 High Voltage Board

Mark Wendt
 

On 10/21/18 03:34, Craig Sawyers wrote:
Next thing to try is disconnecting the input wire to the x4 voltage multiplier. Then connect the two
coax feeds. If the main supply then comes up OK, the fault is with the multiplier. If it is still in
tick mode it is likely the transformer.

Craig. The old crumbly one that has been on the list for 16 years, to avoid confusion with any other
Craigs
Chuckle.  There's a bunch of us "old crumbly one's" here.  I believe the correct pithy term is curmudgeon.  ;-)


Mark

Output use of PG 508 Pulses

John Ferguson
 

I bought a PG 508 to use to configure some model airplane servos whose actions are determined by Pulse Width Modulated signals.

I have one question about the CAL pots on some of the controls on the PG 508 panel. If there is any counsel in the manual on how these work, I couldn't find it.  It looks as though turning the knobs fully counterclockwise is the way to get the pulse-width (duration) shown on the panel-mine seems to work this way.  Is this correct?

I don't have a number for the power consumption of the signal input of the servos but suspect it isn't much.

So the second question:

Am I risking damage to either my 2445b or the PG 508 if I connect the output of the PG 508 to the servo and to channel one of the scope?

If this does look risky, I suppose answer is to make a transistor switch to make the the pulse signals going to the servo keeping the PG 508 and Scope on the control side of the transistor.

Is there something dumb in what I have in mind?  If so, what would you recommend?

john

Re: Output use of PG 508 Pulses

Kurt Rosenfeld
 

Connecting the PG508 to the scope and the servo in parallel should be fine. I would connect it to the scope first to get the PWM voltage right, since the PG508 is capable of voltages outside of what most servos are expecting. After you have the PG508's output voltage set, then add the servo. I wouldn't expect the servo to significantly load the 50-ohm output of the PG508. Also beware of driving the servo with a weak power supply. It can make for flaky behavior. (How do I know this?)

Re: Output use of PG 508 Pulses

John Ferguson
 

On 10/21/18 1:59 PM, Kurt Rosenfeld wrote:
Connecting the PG508 to the scope and the servo in parallel should be fine. I would connect it to the scope first to get the PWM voltage right, since the PG508 is capable of voltages outside of what most servos are expecting. After you have the PG508's output voltage set, then add the servo. I wouldn't expect the servo to significantly load the 50-ohm output of the PG508. Also beware of driving the servo with a weak power supply. It can make for flaky behavior. (How do I know this?)
U2?

Re: 7834 High Voltage Board

ef804s tubes
 

Next thing to try is disconnecting the input wire to the x4 voltage multiplier. Then connect the two
coax feeds. If the main supply then comes up OK, the fault is with the multiplier. If it is still in
tick mode it is likely the transformer.

Craig. The old crumbly one that has been on the list for 16 years, to avoid confusion with any other
Craigs

I disconnected the multiplier and the other high voltage secondaries. Still the power supply shuts down.

Fred

Re: Clearing error log in THS720A

 

On Sun, Oct 21, 2018 at 01:18 AM, Raymond Domp Frank wrote:


I'm wondering if the error log can be cleared independently
If you connect a PC running a terminal program to the serial port of the THS
you can try sending first PASSWORD PITBULL and then ERRLOG CLEAR.
It doesn't clear any RS232 errors but it resets the numbers of power up and
most likely power on errors (mine has no errors so I can't say for sure).
/Håkan