Date   
Re: 577 Device Under Test Interlock Switch

Carsten Bormann
 

On 2020-04-24, at 20:29, Dennis Tillman W7PF <@Dennis_Tillman_W7pF> wrote:

Yes, I have forgotten to flip the toggle back to the
middle and I have gotten bitten because of it.
Of course, the unit should emit incessant beeping and blinking while that switch is engaged.
1000 Hz pure tone beeps at 97-112 decibels [1].
Yes, you'll need to wear hearing protection.

Grüße, Carsten

[1]: https://en.wikipedia.org/wiki/Back-up_beeper

Re: 577 Device Under Test Interlock Switch

David Berlind
 

In case you don't have a 577/177 handy to see what this looks like, I took pictures of the front porch on mine. They show the tooth on the plastic cover and the safety button that it engages on the porch's frame. I don't have the push button for disengaging the switch. I must have a newer model.

https://photos.app.goo.gl/6BJLee5k8PhqJvrP8

On April 24, 2020 2:29:56 PM "Dennis Tillman W7PF" <@Dennis_Tillman_W7pF> wrote:

Since the 577 device interlock switch came up in a recent post I thought I
would mention a minor change that was made to the 177 "front porch",
probably by Tek corporate lawyers, to protect the company from lawsuits.

To test a part at collector voltages higher than 100V the part had to be
under a protective plastic cover that activated a safety switch with a small
tab that was part of the safety cover.

This safety cover was a good safety feature in principle if the curve tracer
was used by inexperienced users on a production line for example. But to a
design engineer the safety cover was extremely inconvenient. Usually
something would be jammed into the hole to disable the safety feature
permanently so the safety cover was no longer needed. At this point the
safety cover would be placed somewhere for safe keeping, and it would never
be seen again.

If I am not mistaken the original 177s had a small momentary push button
switch below and to the left of the Left - Off - Right toggle switch. This
push button over rode the safety feature. This way there was no need to jam
something in the hole to disable the safety feature. That push button was a
good solution but it disappeared on later 177s.

I replaced the momentary push button on the 177 I currently use with a small
3 way center off toggle switch. In the down position the safety feature is
disabled. In the center position it is enabled. In the up position which is
momentary the safety feature is disabled for as long as I hold it up. The
advantage of this arrangement is that under occasional use of high voltages
I hold the toggle up with my finger for a few seconds to disable the safety
feature and as soon as I am finished and let go the safety interlock is
activated automatically. When I am testing a lot of HV parts I flip the
toggle down where it stays. When I am done, as long as I remember to flip it
back to the middle the safety interlock will be activated again.

That's the catch. Yes, I have forgotten to flip the toggle back to the
middle and I have gotten bitten because of it. That works to remind me for
the next few months to flip the toggle back to the middle.

Dennis Tillman W7pF

Re: Need Plug In Attenuators for Tek 465 Scope

Timothy Freeze
 

Steve,

I sent you a private email.

Thanks!
--
Tim

Re: Need Plug In Attenuators for Tek 465 Scope

Timothy Freeze
 

Thanks to all for the help. It looks like I'll be able to get the parts. It's so nice to be able to rescue a vintage instrument.

Thanks again,
Tim

577 Device Under Test Interlock Switch

 

Since the 577 device interlock switch came up in a recent post I thought I
would mention a minor change that was made to the 177 "front porch",
probably by Tek corporate lawyers, to protect the company from lawsuits.

To test a part at collector voltages higher than 100V the part had to be
under a protective plastic cover that activated a safety switch with a small
tab that was part of the safety cover.

This safety cover was a good safety feature in principle if the curve tracer
was used by inexperienced users on a production line for example. But to a
design engineer the safety cover was extremely inconvenient. Usually
something would be jammed into the hole to disable the safety feature
permanently so the safety cover was no longer needed. At this point the
safety cover would be placed somewhere for safe keeping, and it would never
be seen again.

If I am not mistaken the original 177s had a small momentary push button
switch below and to the left of the Left - Off - Right toggle switch. This
push button over rode the safety feature. This way there was no need to jam
something in the hole to disable the safety feature. That push button was a
good solution but it disappeared on later 177s.

I replaced the momentary push button on the 177 I currently use with a small
3 way center off toggle switch. In the down position the safety feature is
disabled. In the center position it is enabled. In the up position which is
momentary the safety feature is disabled for as long as I hold it up. The
advantage of this arrangement is that under occasional use of high voltages
I hold the toggle up with my finger for a few seconds to disable the safety
feature and as soon as I am finished and let go the safety interlock is
activated automatically. When I am testing a lot of HV parts I flip the
toggle down where it stays. When I am done, as long as I remember to flip it
back to the middle the safety interlock will be activated again.

That's the catch. Yes, I have forgotten to flip the toggle back to the
middle and I have gotten bitten because of it. That works to remind me for
the next few months to flip the toggle back to the middle.

Dennis Tillman W7pF

Re: Need Plug In Attenuators for Tek 465 Scope

donald collie
 

I purchased several of these attenuators from Sphere Research. They were
available used but good, and new.Cheers!...........Don

On Sat, Apr 25, 2020 at 3:01 AM stevenhorii <sonodocsch@...> wrote:

Tim,

I parted out a several Tek 7000-series plug ins. They were mechanically
damaged, so I pulled parts. Among them are plug-in attenuators.

I have several, but of the ones you mention, I have:

307-1013-01 10X

And

307-1014-01. 100X

Since I could not test the plug ins (cracked circuit boards) I cannot
verify that they are good. However, if you want to try them (and others in
the group say they will fit) you are welcome to them for the shipping cost.
They are small, so they will easily go in a USPS First-class padded
envelope or a small flat-rate Priority Mail box or envelope (with the
padded envelope inside - these can be dropped in a mail box).

Contact me off-list if you want them.

Steve H.

On Fri, Apr 24, 2020 at 10:36 Timothy Freeze <s35pilot@...> wrote:

I bought a 465 from E bay and the plugin attenuators are missing. I've
fixed all the problems and just need these to have a good working
scope. I
believe the art numbers are:

307-1013-00 for the 10X
307-1014-02 for the 100X

I see some on ebay with part numbers 307-1013-04 and 307-1014-01. I
assume these will still work? They are about $15 each including shipping
which is reasonable?

Thanks for any advice.
--
Kindest regards,
Tim





Re: Electrolytic Capacitor Removal NO Desoldering Required

tekscopegroup@...
 

On Tue, Apr 21, 2020 at 03:06 PM, Roy Thistle wrote:

On Tue, Apr 21, 2020 at 01:43 PM, Paul Amaranth wrote
A lot of people seem to like him
Not me... I find him irritating.
Roy
And I find his style sooooo very boooooooring.... the way he talks does not help.
Just my 2 cents.

Re: 465 dot only, no sweep

james_55@...
 

On Sat, Apr 4, 2020 at 05:13 PM, Mlynch001 wrote:


You must have the correct Service Manual. Study the Circuit description
section, starting with the power supplies. After that, all the LV supply
voltages need to be correct voltages. Then and only then can you move to
diagnose the problems with the sweep. Start at the bottom and work up, do not
try to start in the center and work in all directions.

Not sure I have the correct service manual and have been trying to find out which component is pulling the voltage towards ground.

Made a list of all components in the -8v rail and tested each one, however the other day, after the scope had been on for five minutes, it started buzzing and glowing up the two neons under the HV cover.
I assumed it was the -8v rail 3000µF filter cap that had failed, so pulled that, however the buzzing persisted.

It was around then that I found a vid of a 475A with a failing -8v rail, where the fella explained that it had to do with his +5v rail having a defective bridge rectifier...

...which I hadn't realised was related...

So I pulled the +5v 500µF filter cap,

...and the buzzing stopped!

Thing is, the cap seems fine... Measures 8000+µF and doesn't appear to draw any current when connected up to my bench power supply.
I have a Peak Atlas ESR70, a MK-328 and a DMM with capacitor test to do my testing.

So, pulled the +5v rail bridge rectifier but that tested fine too.

My question, is, "why would the +5v filter cap have been making the neons buzz if it is ok?"

Re: 577 curve tracer 177 test fixture current per division troubleshoot

Chuck Harris
 

Ok, I wasn't paying enough attention to the thread.

The yellow light is switched from several sources. The first, and most
obvious is the HV enable signals for the deadly HV ranges... which comes
from the porch.

The second is Q588 on the collector supply board. Notice that Q588
is involved with two 1uf tantalum caps, C586 and C587. You might want
to look at them. THe board is littered with similar tantalum caps that
are by now often found leaking their guts out all over the circuit board.

The electrolyte is sulfuric acid, and very conductive, and very corrosive.

-Chuck Harris

teamlarryohio wrote:

I was speaking of unplugging the whole 177. My DUT cover interlock got
jumpered years ago.
-ls-



Re: Need Plug In Attenuators for Tek 465 Scope

stevenhorii
 

Tim,

I parted out a several Tek 7000-series plug ins. They were mechanically
damaged, so I pulled parts. Among them are plug-in attenuators.

I have several, but of the ones you mention, I have:

307-1013-01 10X

And

307-1014-01. 100X

Since I could not test the plug ins (cracked circuit boards) I cannot
verify that they are good. However, if you want to try them (and others in
the group say they will fit) you are welcome to them for the shipping cost.
They are small, so they will easily go in a USPS First-class padded
envelope or a small flat-rate Priority Mail box or envelope (with the
padded envelope inside - these can be dropped in a mail box).

Contact me off-list if you want them.

Steve H.

On Fri, Apr 24, 2020 at 10:36 Timothy Freeze <s35pilot@...> wrote:

I bought a 465 from E bay and the plugin attenuators are missing. I've
fixed all the problems and just need these to have a good working scope. I
believe the art numbers are:

307-1013-00 for the 10X
307-1014-02 for the 100X

I see some on ebay with part numbers 307-1013-04 and 307-1014-01. I
assume these will still work? They are about $15 each including shipping
which is reasonable?

Thanks for any advice.
--
Kindest regards,
Tim



Re: Troubleshooting and repairing a 7704A instrument

 

On Fri, Apr 24, 2020 at 11:05 AM, Albert Otten wrote:


Ernesto,


Not included is the 155-0078, the big hybrid at the output of the vertical
amplifier. This one
may be still withheld as a trade secret?
? There is a lot of info about 155-0078-xx (M84) versions at Tekwiki and also
a schematic.
Actually, Ernesto made a typo: The "big hybrid at the output of the vertical amplifier" is a 155-0077-xx stud-mounted vertical amplifier, much like the 155-0115-xx (in the 100 MHz 465(B)) and others. Its schematic is shown in the circuit diagram of the vertical output stage in the 7704A's manual.
To my knowledge, not much else has been published about it, unlike the 155-0078-xx, which is very common in various grades, with lots of info on Tekwiki, as Albert indicates.

Raymond

Need Plug In Attenuators for Tek 465 Scope

Timothy Freeze
 

I bought a 465 from E bay and the plugin attenuators are missing. I've fixed all the problems and just need these to have a good working scope. I believe the art numbers are:

307-1013-00 for the 10X
307-1014-02 for the 100X

I see some on ebay with part numbers 307-1013-04 and 307-1014-01. I assume these will still work? They are about $15 each including shipping which is reasonable?

Thanks for any advice.
--
Kindest regards,
Tim

Re: Washing a 7K scope

jim Madden
 

I would buy a pump sprayer from lowes or h depot thar you can pressurize with a few pumps and use desalinated warm water and dawn.jim

Tektronix 466 Probe Recommendation.

wkibler
 

Can someone recommend a good probe for the Tektronix 466 scope?
I would like something that doesn't overshoot the specs too much
and be somewhat vintage or at least looking like it fits the
era of the scope. The manual mentions the P6062A which looks cool.
Are there any other 1X/10X probes with readout pin that would work?

Also, even though the scope is 100Mhz would it be worth it at all to find
an active FET probe with external power supply?

Re: 577 curve tracer 177 test fixture current per division troubleshoot

teamlarryohio
 

I was speaking of unplugging the whole 177. My DUT cover interlock got
jumpered years ago.
-ls-

Re: Fuse's or MOV's? 11A72 and 11A52 fuse question.

wkibler
 

Apologies, I meant TEK, not Tea. Damned auto correct. I swear the Apple autocorrect and predictive type they use on the Mac OS has got more aggressive.

Re: Fuse's or MOV's? 11A72 and 11A52 fuse question.

wkibler
 

This is the exact reason I enjoy repairing vintage Tea gear. There is much to learn that I am able to use in my career.


I recently (last year) used PTCs in a new design - another opportunity for
life long learning ;-)

Cheap manuals alert - eBay

Keith
 

Routine post here - alerting everyone that I see a seller on eBay offering lots of twelve OEM Tek manuals pretty cheap. The cost per manual works out to $3.32 per manual INCLUDING shipping. The seller has many lots posted...again 12 to a lot.

Here is a link to one typical lot. Check their store for the others. Not me, by the way.

https://www.ebay.com/itm/TEKTRONIX-Lot-of-12-Manuals-Lot-T4/202937299096?_trkparms=aid%3D1110006%26algo%3DHOMESPLICE.SIM%26ao%3D1%26asc%3D20131003132420%26meid%3D108fa6e7fc8b40c4b40600b4b1662525%26pid%3D100005%26rk%3D1%26rkt%3D12%26mehot%3Dpf%26sd%3D264538078644%26itm%3D202937299096%26pmt%3D1%26noa%3D0%26pg%3D2047675%26algv%3DSimplAMLv5PairwiseWeb%26brand%3DTektronix&_trksid=p2047675.c100005.m1851

That’s all. Hope it helps someone.

Cheers,
CoolBlueGlow

Re: Troubleshooting and repairing a 7704A instrument

Albert Otten
 

Ernesto,

Not included is the 155-0078, the big hybrid at the output of the vertical amplifier. This one
may be still withheld as a trade secret?
? There is a lot of info about 155-0078-xx (M84) versions at Tekwiki and also a schematic.

What I find is that two transistors in the differential output drive, U4356
and U4366, get very hot, even after having squelched the 50 Mhz oscillation.
I question if this is normal? Time will tell.
The whole area around that output stage gets quite hot. After half an hour with the sweep free running at 1 ms/div I measured about 55-60 C with an IR thermometer and 60 C with a P6058 temperature probe right at the top of the Q4365 an Q4366. P6058 reading not corrected for measurement influence, so slightly >60 C in reality.

Albert

Re: Rail Probes?

K9FFK
 

Dan:

"TSP #76 - Keysight N7020A 2.0GHz Power Rail Probe Review, Teardown and Experiments"

<< https://www.youtube.com/watch?v=d_Ybe6xnMIg&feature=youtu.be >>

Part of this presentation gets into the probe itself. Might be informative.

ymmv

Dick K9FFK

On 4/23/2020 2:03 PM, dnmeeks wrote:
Thanks, yeah I see the data sheet. I was hoping to know exactly how it's made. What's inside. The real scooby.