Date   

Re: Powering up after long storage

Dave Seiter
 

I agree with Chuck's comment; I've always just checked for anything wonky, cleaned anything that looked questionable, and turned them on.   I would never use a variac on anything with a switching PS.  My experience with tube gear is that it either works or it doesn't; a variac wouldn't have made any difference. 
When I got my initial 2 pallets of Tek gear, I was going to build a test load so I could work on all the ticking 7704A PSUs, but I never got around to it.  Most of the problems turned out to be Ta caps in the mainframes.
-Dave

From: "stingray666@rocketmail.com [TekScopes]" <TekScopes@yahoogroups.com>
To: TekScopes@yahoogroups.com
Sent: Sunday, August 6, 2017 9:25 AM
Subject: Re: [TekScopes] Powering up after long storage

  Well, I'm suitably flabbergasted by this comment. I'd been given to understand one had to slowly wind up the supply voltage on the variac whilst monitoring the current drawn by the oscilloscope, keeping that current down to below 100mA at the outset and monitoring for it falling slowly back as the caps 'healed' up whereupon it would be safe to increment the supply volts again. And so on.
Now you say this is worse than just plugging the thing in and giving it full voltage from the get-go. Would it be any better to isolate the PSU section of the scope, place it under a dummy load and then going through the above process secure in the knowledge that the rest of the instrument will not be damaged?

[Non-text portions of this message have been removed]

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Re: WTB: Tek 475 Spares - (UK)

Rob Angell
 

Hi All,

Just a quick note to say; many thanks to everyone who responded; either directly, or via the list, much appreciated.

A kind list member is packaging up some spares for me, so hopefully my 475 will live another day.


All the best,


Rob Angell.


Re: Powering up after long storage

Paul B.
 

Well, I'm suitably flabbergasted by this comment. I'd been given to understand one had to slowly wind up the supply voltage on the variac whilst monitoring the current drawn by the oscilloscope, keeping that current down to below 100mA at the outset and monitoring for it falling slowly back as the caps 'healed' up whereupon it would be safe to increment the supply volts again. And so on.
Now you say this is worse than just plugging the thing in and giving it full voltage from the get-go. Would it be any better to isolate the PSU section of the scope, place it under a dummy load and then going through the above process secure in the knowledge that the rest of the instrument will not be damaged?


Re: Powering up after long storage

Chuck Harris
 

Actually, most of those that know, know that isn't
the case.

Variacs won't help. They are frequently fatal when
applied to switching power supplies, or scope supplies
with time delay relays...

Failed electrolytics will get hot, but rarely will they
blow up right away. There is usually time for you to
evaluate their condition as part of the after you turn
the scope on ritual of checking power supplies for
correct voltage and ripple.

Variacs to reform electrolytics, won't. They have too
low of an impedance, and as such, the minor shorts that
happen as the oxide layer takes its two steps forward
and one step back journey while reforming, will simply
get blown away and damage the capacitor. Reforming
requires serious current limitation to work effectively.

Check the scope for stray parts, bugs, missing parts,
physical abuse, plug it in, and turn it on. Measure the
power supply voltages, check their ripple, and then turn
it off and check the filter caps for heating. Be mindful
that electrolytic cap's cases are sometimes electrically
hot wrt ground.

That is about the best you can do.

-Chuck Harris

stingray666@rocketmail.com [TekScopes] wrote:

Hi all, I believe most people know that if you power an old scope up that's been
lying around for years doing nothing, then you can expect a *bang* and lots of
smoke, usually from an electrolytic that was caught having a nap. Is there a
generally agreed procedure for bringing an old scope back to life safely and if
so, what is it? I've used a variac in the past but still ran into trouble at
times, probably because I wound it back up too quickly. Any tips? Thanks!


Powering up after long storage

Paul B.
 

Hi all,
I believe most people know that if you power an old scope up that's been lying around for years doing nothing, then you can expect a *bang* and lots of smoke, usually from an electrolytic that was caught having a nap.
Is there a generally agreed procedure for bringing an old scope back to life safely and if so, what is it? I've used a variac in the past but still ran into trouble at times, probably because I wound it back up too quickly. Any tips?
Thanks!


Re: 2230 numerical readout error and power supply noise

 

On 04 Aug 2017 23:52:19 +0000, you wrote:

But the readout of volt/div is wrong on some settings; always going to the next higher reading according to the analog voltage level supplied by the voltage divider. In other words 2mV/div almost always reads .2V/div which is the next higher voltage range the divider provides to the digital section. 2mV measures 2.267V (which is within the proper range 2.104 to 2.340) but the readout displays .2V (which is the next range 2.340 to 2.502).
Does it do this on both channels? Is it only the volt/div readout
which is affected?

Then I scoped the switch output and found a 20ish KHz spike very noisy about 20mV. My theory now is this spike is fooling the digital decoding. Yes?

Going to the power supply all the positive supplies have some level of the 20Khz noise. The negative supplies not so much.
20kHz is from the inverter.

The 100V supply has a 250mV spike. 30V supply a 50mV spike. I replaced both filter caps (C954 and C956) with no change. The 8.6V supply a 30mV and the 5V supply a 20mV. Replacing caps made no difference.

I will keep plugging away. All power supply measurement has been at the final filter cap for that supply (diagram 9)

Isn't this in fact way too much noise on the supplies? Whether or not the cause of the bad display readouts.

Thanks
John
I do not think the connection between the readout divider and the
multiplexor could cause it to read high but the multiplexor itself
could have failed. The 2230 uses 4051 CMOS multiplexors shown on
schematic 19 and I have noticed before that they seem to have more
reliability problems.

There is a +5 volt reference marked +5VREFa, +5VREFb, and +5VREFc
depending on where it is used for which the origin is shown on
schematic 21. This should be checked for accuracy.

If you have done that much work on the power supply, then I would
change the rest of its aluminum electrolytic capacitors. They are
certainly all worn out.


Re: S52 pulse head standalone wiring/trigger? S4 for sale.

 

Tektronix made the Type 285 power supply for operating a single S-50
series head. The manual includes details and schematic:

<http://w140.com/tekwiki/wiki/285>

On 04 Aug 2017 23:28:32 +0000, you wrote:

Hi All:
I picked up a 17 psec S52 from EBAY and I am trying to figure out the way to power it up and give it a trigger.

Can anyone point me in the right direction please?

Also, got an S4 sampler in near mint condition (package deal) if anyone needs one before I put it back on EBay.


Re: Lots of corrosion on my new (newly aquired) Type 576 Curve Tracer

Chuck Harris
 

The 5V filter is something like 11Kuf, and it dries out,
letting the 5V logic signals dance wildly. This will affect
most everything in the curve tracer.

The 3uf 150V, C719, is parth of the -75V regulator's
frequency compensation, and it can cause all of the voltages
to dance about if it is going bad. Mostly however, it likes
to leak sulfuric acid onto the board. It is essential
that it be a very low leakage capacitor, or it will cause
the voltages to drift. I replace them with a 3uF 200V mylar.
It is way too big, so with some creative lead bending, you
can fit it under the LV regulator board using the same holes
as the original. A little lead insulation is in order.

-Chuck Harris

Brent Watson brentleew2003@yahoo.com [TekScopes] wrote:

Thanks Chuck,I'll plan to change them immediately I don't suppose they could cause
the step inop. Brent


On Friday, August 4, 2017, 9:14:29 PM PDT, Chuck Harris cfharris@erols.com
[TekScopes] <TekScopes@yahoogroups.com> wrote:


Before you go too far, there are two capacitors that are always bad in the 576.
The 5V filter cap, and a 3uf 150V wet tantalum cap.

-Chuck Harris


576 Curve Tracer no Steps

brentleew2003@...
 

There are two 2000uf caps in the rectifier circuit for the 50v supply, this is where I found a damaged diode from corrosion. They are in parallel and rated at 75v. I want to replace them with a single 4700uf 100v cap. Is there a reason they used two caps here. Space perhaps. Is this slight over-rating acceptable? It's within the tolerance given in the parts list.+75 -10% I would leave the old caps in place and fit these below where there is space, as removing the originals looks to be rather intensive and risky.

Cheers,
Brent


Re: New 547 owner

Adrian Nicol
 

Indeed - especially when one has the bad habit of reading threads from the latest post backwards....................!


On Saturday, August 5, 2017 6:10 PM, "'Craig Sawyers' c.sawyers@tech-enterprise.com [TekScopes]" <TekScopes@yahoogroups.com> wrote:


  >Tek used to offer plastic slip-on
covers; you could also use condoms.
Now there is a sentence you could take several ways ;-)

Craig

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Re: P6035B Repair

Robert Simpson
 

Found the problem. One end of the center conductor came loose from its connection on the little compensation board PCB. With careful soldering using a custom tip, I was able to reattach that very tiny wire and now the probe works again.


Bob


Re: New 547 owner

Craig Sawyers <c.sawyers@...>
 

Tek used to offer plastic slip-on
covers; you could also use condoms.
Now there is a sentence you could take several ways ;-)

Craig


Re: Tektronix 454

Roger Evans
 

Probably with the switch half way out each pole of the switch is open circuit. Do you have any way of checking Q164 and Q174? You can do basic open circuit and short circuit checks with just a multimeter.

Roger


Re: New 547 owner

 

There is a writeup on the washing process; look on the Vintage Tek web site, or on Stan Griffiths' site.Avoid spraying any cardboard, chassis-mounted electrolytic caps.Tek used to offer plastic slip-on covers; you could also use condoms.Avoid spraying adjustment pots; Tek had covers for those too.Let it dry for several days after blowing out as much water as you can before turning it on.
 HankC, Boston WA1HOS

[Non-text portions of this message have been removed]


Re: Lots of corrosion on my new (newly aquired) Type 576 Curve Tracer

Brent Watson <brentleew2003@...>
 

Thanks Chuck,I'll plan to change them immediately
I don't suppose they could cause the step inop.
Brent

On Friday, August 4, 2017, 9:14:29 PM PDT, Chuck Harris cfharris@erols.com [TekScopes] <TekScopes@yahoogroups.com> wrote:

 
Before you go too far, there are two capacitors
that are always bad in the 576. The 5V filter cap,
and a 3uf 150V wet tantalum cap.

-Chuck Harris

Brent Watson brentleew2003@yahoo.com [TekScopes] wrote:

After a day of cleaning and lubing switches and contacts on the 576, it's not as bad as I thought. I used a small artists' brush and lightly coated a few circuit board traces with DeOxit. Using De-ox on all the controls made a big difference. I was able to go through the familiarization procedure up to #51 with optimum results.Replaced a few rusted screws and went through initial test-set up to #51 with optimum results.

Step 47 is the Step Generator.
After inserting an NPN transistor and getting a minimum step amplitude, I can't get any steps. I believe I saw some briefly yesterday, but can't get anything today. I got as far as putting my meter on step generator IC U75 pins 9,1,3,5, which respond to the "Number of Steps" switch. But have not been able to follow the path further.
I was hoping there might be someone here who knows these well enough to suggest where to suspect a problem. adapter doesn't support it, but didn't think it . I'm using an 013-069 adapter because that's what I have. Here's a short video showing the issue.
https://www.youtube.com/watch?v=FdC9qWejY2M&feature=youtu.be


Cheers,
Brent

On Thursday, August 3, 2017, 12:29:15 AM PDT, 'Craig Sawyers' c.sawyers@tech-enterprise.com [TekScopes] <TekScopes@yahoogroups.com> wrote:


Mosyt instability is due to
the Display Invert and Display Offset Zero and Cal switched being super dryed out I checked
voltages
and ripple.
Is there any easy way to get at the controls for lubrication. I have the manual, but it looks
like you strip
the knobs and pull the front off.
It looks like I'll need a lot of contract cleaner. Perhaps a larger container of De-Ox.
The push button switches are notorious on the 576 and other instruments on which they are used. I
was lucky enough to get a 576 free from a guy who worked in the BBC Technical Centre in the UK. It
had a characteristic problem with the older 576 of epoxy potting on the HT transformer (yours is a
late instrument after Tek had gone across to silicone potting, so you're OK there). The BBC were
going to put it in the skip, so this guy hauled it home intending to fix it, never got around to it
and gifted it to me.

Anyhow, to cut a long story short, this 576 had had a really nice life in a dry air conditioned
environment. But the push switches were all intermittent.

To get to one set, you have to take out all some, or all horizontal and vertical boards. You have to
take the knobs off these and undo the switch securing nuts, then a screw at the back. You have to
unplug a great number of wires (use your phone to take lots of close up photos so you can put them
back correctly). If you have the manual there are clear diagrams which show which colour wires go
where too.

Once you get them out, you will see a board with the offending switches on it. Using the flexible
nozzle on a deoxit can you get a good squirt down the inside of each switch. Exercise each one a
lot, then a final squirt. Reassemble.

Good luck - these curve tracers are well worth saving!

Craig




[Non-text portions of this message have been removed]



------------------------------------
Posted by: Brent Watson <brentleew2003@yahoo.com>
------------------------------------


------------------------------------

Yahoo Groups Links





[Non-text portions of this message have been removed]


Re: Lots of corrosion on my new (newly aquired) Type 576 Curve Tracer

Chuck Harris
 

Before you go too far, there are two capacitors
that are always bad in the 576. The 5V filter cap,
and a 3uf 150V wet tantalum cap.

-Chuck Harris

Brent Watson brentleew2003@yahoo.com [TekScopes] wrote:


After a day of cleaning and lubing switches and contacts on the 576, it's not as bad as I thought. I used a small artists' brush and lightly coated a few circuit board traces with DeOxit. Using De-ox on all the controls made a big difference. I was able to go through the familiarization procedure up to #51 with optimum results.Replaced a few rusted screws and went through initial test-set up to #51 with optimum results.

Step 47 is the Step Generator.
After inserting an NPN transistor and getting a minimum step amplitude, I can't get any steps. I believe I saw some briefly yesterday, but can't get anything today. I got as far as putting my meter on step generator IC U75 pins 9,1,3,5, which respond to the "Number of Steps" switch. But have not been able to follow the path further.
I was hoping there might be someone here who knows these well enough to suggest where to suspect a problem. adapter doesn't support it, but didn't think it . I'm using an 013-069 adapter because that's what I have. Here's a short video showing the issue.
https://www.youtube.com/watch?v=FdC9qWejY2M&feature=youtu.be


Cheers,
Brent

On Thursday, August 3, 2017, 12:29:15 AM PDT, 'Craig Sawyers' c.sawyers@tech-enterprise.com [TekScopes] <TekScopes@yahoogroups.com> wrote:


Mosyt instability is due to
the Display Invert and Display Offset Zero and Cal switched being super dryed out I checked
voltages
and ripple.
Is there any easy way to get at the controls for lubrication. I have the manual, but it looks
like you strip
the knobs and pull the front off.
It looks like I'll need a lot of contract cleaner. Perhaps a larger container of De-Ox.
The push button switches are notorious on the 576 and other instruments on which they are used. I
was lucky enough to get a 576 free from a guy who worked in the BBC Technical Centre in the UK. It
had a characteristic problem with the older 576 of epoxy potting on the HT transformer (yours is a
late instrument after Tek had gone across to silicone potting, so you're OK there). The BBC were
going to put it in the skip, so this guy hauled it home intending to fix it, never got around to it
and gifted it to me.

Anyhow, to cut a long story short, this 576 had had a really nice life in a dry air conditioned
environment. But the push switches were all intermittent.

To get to one set, you have to take out all some, or all horizontal and vertical boards. You have to
take the knobs off these and undo the switch securing nuts, then a screw at the back. You have to
unplug a great number of wires (use your phone to take lots of close up photos so you can put them
back correctly). If you have the manual there are clear diagrams which show which colour wires go
where too.

Once you get them out, you will see a board with the offending switches on it. Using the flexible
nozzle on a deoxit can you get a good squirt down the inside of each switch. Exercise each one a
lot, then a final squirt. Reassemble.

Good luck - these curve tracers are well worth saving!

Craig








------------------------------------
Posted by: Brent Watson <brentleew2003@yahoo.com>
------------------------------------


------------------------------------

Yahoo Groups Links




Re: Tektronix 454

erik erickson
 

Also just found out trace appears if I leave invert switch halfway out but no functions work when the trace appears.

Sent from my iPhone

On Aug 4, 2017, at 6:18 AM, David davidwhess@gmail.com [TekScopes] <TekScopes@yahoogroups.com> wrote:

I encourage you not to give up on your 454. It has a fabulously
bright and sharp CRT.

I have to ask some of the same questions:

1. Does the trace drift off screen when the input coupling is set to
ground?

2. Does the trace drift off screen when the input coupling is set to
DC and the input is shorted?

One thing that can cause the trace to drift off of the screen is if
the DC circuit path to the grid of V113 shown on schematic 2 is open.
This could include an open R110.

The variable control is R167 and could not cause the trace to drift
off of the CRT by itself.

What does the channel 2 INVERT switch do? It would cause problems if
the switch was bad.

Since only channel 2 is affected, the problem is on either schematic 2
or schematic 3 before the delay line driver.

On Tue, 1 Aug 2017 11:24:52 -0700, you wrote:

Hey I'm very sorry for taking so long to respond. I've been very busy at work and in going out of town soon. I reseated the transistors on the channel 2 vertical preamp. The trace most of the time isn't on the screen so I can't be sure. I haven't seen a trace on channel two in a while. Channel one seems to work fine. Only problem is the red knob on the volts/division doesn't work.

Sent from my iPhone

On Jul 21, 2017, at 8:03 PM, David davidwhess@gmail.com [TekScopes] <TekScopes@yahoogroups.com> wrote:

Which transistors did you reseat?

Does the trace drift off screen when the input coupling is set to
ground?

Does the input response normally while it is on screen?

On Wed, 19 Jul 2017 22:06:56 -0700, you wrote:


Hey everyone my tektronix 454 channel two doesn't work. It worked for about 20 seconds when I reseated all the transistors and then slowly went off the screen. Sometimes it works but will always stop working within 20 seconds. The position knob would not bring it back. I'm new to this so all help will be greatly appreciated. I have the manual and I've been reading it.
Sent from my iPhone


Re: Tektronix 454

erik erickson
 

I just checked the invert switch and when I pull it the trace flashes on the screen and then disappears instantly.

Sent from my iPhone

On Aug 4, 2017, at 6:18 AM, David davidwhess@gmail.com [TekScopes] <TekScopes@yahoogroups.com> wrote:

I encourage you not to give up on your 454. It has a fabulously
bright and sharp CRT.

I have to ask some of the same questions:

1. Does the trace drift off screen when the input coupling is set to
ground?

2. Does the trace drift off screen when the input coupling is set to
DC and the input is shorted?

One thing that can cause the trace to drift off of the screen is if
the DC circuit path to the grid of V113 shown on schematic 2 is open.
This could include an open R110.

The variable control is R167 and could not cause the trace to drift
off of the CRT by itself.

What does the channel 2 INVERT switch do? It would cause problems if
the switch was bad.

Since only channel 2 is affected, the problem is on either schematic 2
or schematic 3 before the delay line driver.

On Tue, 1 Aug 2017 11:24:52 -0700, you wrote:

Hey I'm very sorry for taking so long to respond. I've been very busy at work and in going out of town soon. I reseated the transistors on the channel 2 vertical preamp. The trace most of the time isn't on the screen so I can't be sure. I haven't seen a trace on channel two in a while. Channel one seems to work fine. Only problem is the red knob on the volts/division doesn't work.

Sent from my iPhone

On Jul 21, 2017, at 8:03 PM, David davidwhess@gmail.com [TekScopes] <TekScopes@yahoogroups.com> wrote:

Which transistors did you reseat?

Does the trace drift off screen when the input coupling is set to
ground?

Does the input response normally while it is on screen?

On Wed, 19 Jul 2017 22:06:56 -0700, you wrote:


Hey everyone my tektronix 454 channel two doesn't work. It worked for about 20 seconds when I reseated all the transistors and then slowly went off the screen. Sometimes it works but will always stop working within 20 seconds. The position knob would not bring it back. I'm new to this so all help will be greatly appreciated. I have the manual and I've been reading it.
Sent from my iPhone


Re: Lots of corrosion on my new (newly aquired) Type 576 Curve Tracer

Brent Watson <brentleew2003@...>
 

After a day of cleaning and lubing switches and contacts on the 576, it's not as bad as I thought. I used a small artists' brush and lightly coated a few circuit board  traces with DeOxit. Using De-ox on all the controls made a big difference. I was able to go through the familiarization procedure up to #51 with optimum results.Replaced a few rusted screws and went through initial test-set up  to #51 with optimum results.

Step 47 is the Step Generator.
After inserting an NPN transistor  and getting a minimum step amplitude, I can't get any steps.  I believe I saw some briefly yesterday, but can't get anything today. I got as far as putting my meter on  step generator IC U75 pins 9,1,3,5,  which respond to the "Number of Steps" switch. But have not been able to follow the path further.
I was hoping there might be someone here who knows these well enough to suggest where to suspect a problem. adapter doesn't support it, but didn't think it . I'm using an 013-069 adapter because that's what I have.  Here's a short video showing the issue.
https://www.youtube.com/watch?v=FdC9qWejY2M&feature=youtu.be


Cheers,
Brent

On Thursday, August 3, 2017, 12:29:15 AM PDT, 'Craig Sawyers' c.sawyers@tech-enterprise.com [TekScopes] <TekScopes@yahoogroups.com> wrote:

 
Mosyt instability is due to
the Display Invert and Display Offset Zero and Cal switched being super dryed out I checked
voltages
and ripple.
Is there any easy way to get at the controls for lubrication. I have the manual, but it looks
like you strip
the knobs and pull the front off.
It looks like I'll need a lot of contract cleaner. Perhaps a larger container of De-Ox.
The push button switches are notorious on the 576 and other instruments on which they are used. I
was lucky enough to get a 576 free from a guy who worked in the BBC Technical Centre in the UK. It
had a characteristic problem with the older 576 of epoxy potting on the HT transformer (yours is a
late instrument after Tek had gone across to silicone potting, so you're OK there). The BBC were
going to put it in the skip, so this guy hauled it home intending to fix it, never got around to it
and gifted it to me.

Anyhow, to cut a long story short, this 576 had had a really nice life in a dry air conditioned
environment. But the push switches were all intermittent.

To get to one set, you have to take out all some, or all horizontal and vertical boards. You have to
take the knobs off these and undo the switch securing nuts, then a screw at the back. You have to
unplug a great number of wires (use your phone to take lots of close up photos so you can put them
back correctly). If you have the manual there are clear diagrams which show which colour wires go
where too.

Once you get them out, you will see a board with the offending switches on it. Using the flexible
nozzle on a deoxit can you get a good squirt down the inside of each switch. Exercise each one a
lot, then a final squirt. Reassemble.

Good luck - these curve tracers are well worth saving!

Craig


Re: 2465A Filter, Implode shield, gray knob

mosaicmerc
 

Ok, will compare it to my 2465a shield for dimensions.

42561 - 42580 of 181317