Date   

Re: An informative web site for test equipment repairs

Tom Lee
 

Thanks, Brad, for finding this. I have enjoyed the little bit that I’ve read so far. Even his Tek rants.

— Cheers,
Tom

Sent from my iThing, so please forgive typos and brevity.

On Jan 29, 2021, at 5:58 PM, Brad Thompson <brad.thompsonaa1ip@gmail.com> wrote:

Hello--

I just finished spending a couple of enjoyable hours reading through this web site...

https://emperoroftestequipment.weebly.com/

...In which the author describes experience acquired while repairing assorted test equipment,
most of which had multiple problems. Like many (most?) of us test equipment
collectors, the author looks for equipment described as "not working, doesn't power up"
that's priced accordingly.

Have fun!
73--

Brad AA1IP






Re: An informative web site for test equipment repairs

Bob Albert
 

I won't argue.  He does however back down on his rating of Tek at one point.
We are all entitled to opinions and he was patently exercising his entitlement.  More authoritative than most, as he has had a lot of hands on experience.
Nevertheless I enjoyed the read.
Bob On Friday, January 29, 2021, 10:13:23 PM PST, Bob Albert via groups.io <bob91343=yahoo.com@groups.io> wrote:

I read through most of that.  At the appropriate place he mentions buying an HP 5245L that had been erroneously described as a 5345 and when he complained he got his money back and kept the counter.  I was probably the guy who made the costly error and refunded his money but didn't want to add to my losses by paying for return shipping.
I had another 5245L that I finally got rid of to a friend and now have a 5328A that I pieced together from three bad units, luckily including the 10811 ovenized oscillator.
Bob K6DDX

On Friday, January 29, 2021, 07:21:21 PM PST, John Williams <books4you4@mail.com> wrote:

I had a quick look and may be some interesting stuff there for someone. However he just spent too much verbiage on berating Tektronix. People like that piss me off. I always wonder what they contributed to the world. So I can’t recommend the site to members of the forum. Just mt nickels worth.


Re: An informative web site for test equipment repairs

Bob Albert
 

I read through most of that.  At the appropriate place he mentions buying an HP 5245L that had been erroneously described as a 5345 and when he complained he got his money back and kept the counter.  I was probably the guy who made the costly error and refunded his money but didn't want to add to my losses by paying for return shipping.
I had another 5245L that I finally got rid of to a friend and now have a 5328A that I pieced together from three bad units, luckily including the 10811 ovenized oscillator.
Bob K6DDX

On Friday, January 29, 2021, 07:21:21 PM PST, John Williams <books4you4@mail.com> wrote:

I had a quick look and may be some interesting stuff there for someone. However he just spent too much verbiage on berating Tektronix. People like that piss me off. I always wonder what they contributed to the world. So I can’t recommend the site to members of the forum. Just mt nickels worth.


Tek 2782

Steve Lindberg
 

I have a dead 2782 spectrum analyzer. I had a wierd screen and was looking around the video stuff. When I tilted it on it's side and it shut off and won't power up anymore.


Re: Sloppy front panel BNC connector - 475

saipan59 (Pete)
 

Some pix of the the 2465 issue. In one image, on the far left you can see the set screw in the frame.
https://groups.io/g/TekScopes/album?id=260014

Pete


Re: Sloppy front panel BNC connector - 475

saipan59 (Pete)
 

On Fri, Jan 29, 2021 at 05:54 PM, Torch wrote:


I can't see any sign of a set screw. Unless it is hidden under the mounting
nut.
Hi, not sure who you're replying to, but in case it's me (regarding the similar issue on my 2465):
On the 2465, there is no nut for the BNC. Rather, there is a 'collar' that includes a set-screw, and it is only accessible when the attenuator module is removed. I think (not sure) that if the set screw were removed, then the BNC would either slide out or screw out of the attenuator frame.
In my case, the set screw was tight, and the only thing I could see to give mechanical support to the center conductor was the solder joint.

Pete


Re: Tektronix 492BP

 

It said:
FREQUENCY OUT OF RANGE AFTER STEP.
What board should I chage?


Re: TM50X DC ripple?

Harvey White
 

You may have missed the ripple specs, but for any power supply, especially when we're looking at your results, suggests that the ripple on the TM506 is excessive.  A bit of logic suggests that the ripple on the TM504 *is* correct, or acceptable.  Have you compared them?

Your diagnosis seems reasonable.

Harvey

On 1/29/2021 9:04 PM, Michael W. Lynch via groups.io wrote:
I have TM506 that I have had for some time.

I have a PG506 that works but it shows terrible distortion on the top and bottom of the square wave when installed in any compartment the TM506. Just as a test, I inserted the PG506 into both the TM504 and TM501 and it works perfectly, the distortion is gone.

I am attributing this to excess ripple in the DC Supplies of the since the 506 shows a 500-900mV @ 120Hz (unloaded). The distortion on the PG506 square wave looks like a miniature version of the ripple waveform that you read in the TM506. The TM504 and 501 both check with much less ripple that the 506.

Am I diagnosing this correctly or is my observation and reasoning faulty?

The service manuals do not show a specification for ripple that I can find. Have I just missed it or is the spec just not there? What would be an acceptable level of ripple?

Thanks!


Re: An informative web site for test equipment repairs

John Williams
 

I had a quick look and may be some interesting stuff there for someone. However he just spent too much verbiage on berating Tektronix. People like that piss me off. I always wonder what they contributed to the world. So I can’t recommend the site to members of the forum. Just mt nickels worth.


Re: TM50X DC ripple?

 

In going through the vintageTEK Museum's TM500 power modules, the most common problem is filter capacitors, which produces excess ripple. The supplies should have less than a volt of ripple with a 1 amp load. Which supply shows the ripple you quote unloaded? Does the PG506 behave differently in the rightmost (high-power) slot than the others?

--
Bob Haas


Re: What are the differences between the P6302 and A6302 current probes?

Stephen
 

On Fri, Jan 29, 2021 at 01:19 PM, Steve Lindberg wrote:


Try Tek Probes group. I was in Tek probes engineering for 7 years so started
the group.
Thank you. Done.


Re: 7854 revived with a new CRT - how to correctly calibrate Z circuit (was: #157693 - https://groups.io/g/TekScopes/message/157693)

Dan G
 

On Fri, Jan 29, 2021 at 09:39 AM, unclebanjoman wrote:

Question: what is "baseline"? The bottom portion of the waveform? If this is
the case, R135 has no effects on the level of bottom portion.
"baseline" is the bottom portion of the waveform. The service manual is right,
but the confusion may have come from the labels on the A21 PCB: there
are TWO trimpots labeled "OUTPUT LEVEL". One is in the lower right
corner of the board -- that's R70, and the other is near the center of
the board -- that's R135.

I have just replicated the adjustment procedure from the manual, using
a 7B92A as the time base in Horizontal Slot B, and a 7A26 in Left
Vertical Slot (adjusted to make sure the trace is as far off the screen
as possible!).

R135 (the correct one!) does indeed directly control the level of the
bottom portion of the waveform, as expected. In my case, the levels
were already correct (10V baseline, 70V p-p), so there was no need
to adjust.


I hope this helps,
dan


Re: Tek 7T11A issues

n49ex
 

Dang, you are right!!!! Thank you, I guess I didn't pay attention to the state of the button, and never used the locate function before! That was it! Works just fine after pushing the button in, it must have gotten inadvertently pushed somewhere along the way and I didn't notice. Now, if I could find an "operator error" to fix my 7T11A!

Despite many years of using/collecting/fixing my Tek scopes, I finally found and joined this group - absolutely outstanding info and folks here!
Thanks again!


Re: 465 - Successfully Replaced HV multiplier

 

Get an ESR meter and find and replace the bad caps before power applied.

Regards

On 1/29/2021 9:21 PM, Garth Daddy wrote:
Whats the recommended method with SMPS then? remove connections to main switching caps and regenerate them?



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Re: 465 - Successfully Replaced HV multiplier

 

The HV oscillator is fed from the unregulated 15 supply so if you start out with low line voltage, the oscillator will be starved of its supply. Since it is a regulated supply and hence a constant power device, it will demand a very high starting current. This could put a larger stress on the oscillator driver. It might even pop the fuse in that supply (a 1.5 amp fast blow fuse).

On 1/29/2021 7:12 PM, n4buq wrote:
I may be wrong as well, but since the HV multiplier is fed from an oscillator, once the voltage is sufficient and the oscillator kicks in, then there wouldn't much difference between that point and when full line voltage is applied. Is that incorrect?

Thanks,
Barry - N4BUQ

----- Original Message -----
From: "Jeff Dutky" <jeff.dutky@gmail.com>
To: TekScopes@groups.io
Sent: Friday, January 29, 2021 5:34:29 PM
Subject: Re: [TekScopes] 465 - Successfully Replaced HV multiplier

randolphbeebe wrote:
I had both a 465 and a 465M have the same failure after a day or two of
purchasing them.
Both had been unused for a long time. I am wondering if, just as a
precaution it might help
powering up and old scope gradually with a variac might help.
Maybe I'm completely off-base here, but if the problem was that power was
applied too quickly (and which would have been either remedied or revealed
by gradual power up on a variac) wouldn't we expect the failure to be
immediate, rather than happen after a couple of days?

I understand that gradual power up is a common tactic when working with
certain kinds of old electronics, and I even used it myself (based purely on
internet hearsay, not on personal experience or wisdom), but I also
understand (also on hearsay) that gradual power up can harm more recent
equipment that uses switch mode, rather than linear power supplies (I don't
think that this applies to either the 465 or 465M, but I'm not intimately
familiar with either scope, so again, maybe off-base).

Also, wouldn't the HV multiplier suffer MORE stress, not less, being powered
from a lower input voltage?

If a variac would have helped I would have expected the failure to be
essentially immediate. Am I wrong about this?

-- Jeff Dutky






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Re: 465 - Successfully Replaced HV multiplier

Garth Daddy
 

Whats the recommended method with SMPS then? remove connections to main switching caps and regenerate them?


User Experience of Sampling Scopes

 

I've spent a few fruitless hours looking for videos of people actually using Tek sampling scopes (e.g. a 7000-series with the 7S11/7T11 plugins) just to see what it's like to use them. Is the user experience any different from using a non-sampling scope (e.g. my trusty 475)? If so, does anybody have a video showing what it's like to use such a scope?

-- Jeff Dutky


TM50X DC ripple?

Michael W. Lynch
 

I have TM506 that I have had for some time.

I have a PG506 that works but it shows terrible distortion on the top and bottom of the square wave when installed in any compartment the TM506. Just as a test, I inserted the PG506 into both the TM504 and TM501 and it works perfectly, the distortion is gone.

I am attributing this to excess ripple in the DC Supplies of the since the 506 shows a 500-900mV @ 120Hz (unloaded). The distortion on the PG506 square wave looks like a miniature version of the ripple waveform that you read in the TM506. The TM504 and 501 both check with much less ripple that the 506.

Am I diagnosing this correctly or is my observation and reasoning faulty?

The service manuals do not show a specification for ripple that I can find. Have I just missed it or is the spec just not there? What would be an acceptable level of ripple?

Thanks!
--
Michael Lynch
Dardanelle, AR


An informative web site for test equipment repairs

Brad Thompson
 

Hello--

I just finished spending a couple of enjoyable hours reading through this web site...

https://emperoroftestequipment.weebly.com/

...In which the author describes experience acquired while repairing assorted test equipment,
most of which had multiple problems. Like many (most?) of us test equipment
collectors, the author looks for equipment described as "not working, doesn't power up"
that's priced accordingly.

Have fun!
73--

Brad  AA1IP


Re: broken coupler

 

DaveH52 wrote:

(eBay link)
None available - all gone
That's too bad (though the price was nothing to get excited about) but searching on "flexible coupler" turns up all kinds of apparently suitable modern alternatives, all also available through Amazon (and other retailers), many at extremely reasonable prices. While I'm a bit obsessive about getting authentic parts for external dress on Tek products, I'm much less concerned when the replacements are out of public view.

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