Date   

Re: A6302/P6302 current clamp questions and parts.

Jared Cabot
 

Looks the same as mine except my plug is chrome plated. :)
That inner metal collar piece around the rubber boot will also unscrew allowing you to withdraw the whole assembly (with a little push to the pins to ease the pin assembly out).

So far it looks identical to the way my plug is, but I'm not sure about what's supposed to be going on deeper inside. I won't ask you to go deeper unless you are comfortable though. :)


Re: chinese witches hats for old probes help

dave G8SFU
 

Hi all..
This is my report on the chinese witches hats.
First my thanks to all who replied. No-one was able to say for certain if they would fit my probes.

I ordered six of the widely advertised ones
(6 New Probe Hook (Gray) for Tektronix Probes, P6139A, P6138A, P6109, P6105)
from seller sharpseller2000. The price was £11.26 delivered.
Ordered on 19 March, delivered in two packages, first on 29 March and the other a couple of days later.

I have no genuine Tek ones to compare.
They are made of two plastic parts, the metal hook and a spring.
There is no earthing part inside. I expect the genuine ones to continue the probe earth sleeve some way inside the hat.

The fit to all the probes listed in my original query below is satisfactory. The inner plastic sleeve fits on the earth sleeve of the probe quite firmly.

I dont think they would have lasted many days on Jim Williams' bench but they are going to be good enough for me for now.
I recognise and understand their limitations and am happy with my purchase.

I hope this helps others.

Dave G8SFU

On 10/03/2021 17:01, dave G8SFU via groups.io wrote:
Hi. I'm looking for a bit of guidance here please.
Since moving house a couple of years ago I am only just getting some test gear set up.
I find I have 4 good genuine Tek probes to go with the 4 Tek scopes.
(466, 468, 475 and 2246)
Other scopes make do with inferior probes.
The Tek probes are P6062B, P6101A, P6053B, and P6011.
All seem to be in good order, but none of them have witches hats,(sprung hook clips).
All seem to be the same fitting around the tip area with the earth sleeve diameter being 4.4 mm diameter or just a bit larger.
I had a good look on the site for chinese ones, but they are all specified for newer probe models, so I was not sure enough to order any.
Each of the Tek par numbers for the witches hats is slightly different but they look to me as if they would all take the same hat.
Can anyone who has bought from china give me any guidance please.
I realise the quality will be what it is, but it seems they would be worth a punt if anyone can confirm the size.
thanks for reading   Dave    G8SFU


Re: A6302/P6302 current clamp questions and parts.

Albert Otten
 

Here is another attempt. Tekwiki again. Picture of plug with cap removed and strain relief pulled out a few mm. I didn't take the risk to dismantle the plug any further. The thicker rubber cannot go further in then halfway the inner metal part with the flats. I think the rubber is long enough to get compressed when the cap is screwed on. It might be that the thicker rubber is not part of the sleeve itself, difficult to see.
I made a test plug with an original Amphenol 185-9 plug. There a short rubber bus goes in followed by a short metal bus. The metal bus gets pressed in by the cap and then compresses the rubber. (This is at least the way I thought it was intended.)

Albert

On Wed, Mar 31, 2021 at 08:57 PM, Albert Otten wrote:


Ah yes, I was too quick because I remembered that photo I took years ago. I
made the special test plug but that was without the strain relieve. I guess
the inner part of the official strain relieve gets compressed (to less inner
diameter) when the end ring is screwed inward.
Albert

On Wed, Mar 31, 2021 at 07:58 PM, Jared Cabot wrote:


Thanks for that but it's actually the big metal plug that attaches to the
AM503 module that I'm looking for photos of.

Jared.


Re: Tektronix 2247A not starting

Andrey Ulyanchenko
 

The problem has changed a bit. Sometimes there is a start. calibrated perfectly. and with warming up for about 5-10-15 minutes, the input test signal is turned off. The measurement symbols remain on the screen. Re - power on- indicates the chip 160-3493-00. startup is unstable. This is a definite problem. The output transistors heat up to no more than 53 Celsius. Please advise who could solve this problem. Added a photo (please see).


Re: Odd 453A on ebay UK

ChrisBeee
 

Hey,
FYI: this is a typical over-sensible behavior when drugs are involved and to be honest, I would not be surprised if that's actually the case. I am pretty well sure that this crackhead does not realize what BS he is talking. So, better stay away from this seller, whatever stuff he is offering!
Besides that: I am wondering what would happen if all forum members would go and ask him about the CRT... Mushroom cloud? =D
Chris


Re: Persuading a 7S12 to play nice with a 7934.

Albert Otten
 

On Wed, Mar 31, 2021 at 04:07 PM, Albert Otten wrote:


I measured about 0.5 mV more positive level of A17 during the active parts of
interdot blanking. That doesn't look impressive, but the effect of 0.5 mV
change in Z-axis is very well visible.
Sorry, it was 5 mV, not 0.5 mV. Albert.


Re: 2nd life for a 575 after resting for 30+ years in the attic #photo-notice

Renée
 

I have always believed in the wisdom told to me eons ago- the best test bed is the equipment itself, if the circuit works leave it alone. most circuits were designed to work just fine at 50% tube functionality...so far that has held true..there are always exceptions...but then the circuit was not working.....
Renée

On 3/31/21 4:37 PM, Michael W. Lynch via groups.io wrote:
On Wed, Mar 31, 2021 at 04:28 PM, Brenda wrote:

The only thing that I would say is not to rely on your tube tester for testing
tubes. Tektronix says it over and over in the manuals for the scopes that I
have, I don't know the quote right off-hand, but manuals do say not to rely on
tube testers, replace only when that tube is actually causing a problem,
otherwise leave it alone.
In contrast to most audio gear, most tubes in TEK instruments do not need to be at the pinnacle of their operational function to work as designed. Tektronix made sure that a tube that might test "weak" in a tester will still operate acceptably in their instruments. Laughably, those people who scavenge tubes from this old gear probably do not realize that many of these tubes are not in the best condition. I guess that they think since the tubes are in that pretty TEK Blue Cabinet, that this imparts "magical powers" to said tubes.


Re: 2nd life for a 575 after resting for 30+ years in the attic #photo-notice

Michael W. Lynch
 

On Wed, Mar 31, 2021 at 04:28 PM, Brenda wrote:


The only thing that I would say is not to rely on your tube tester for testing
tubes. Tektronix says it over and over in the manuals for the scopes that I
have, I don't know the quote right off-hand, but manuals do say not to rely on
tube testers, replace only when that tube is actually causing a problem,
otherwise leave it alone.
In contrast to most audio gear, most tubes in TEK instruments do not need to be at the pinnacle of their operational function to work as designed. Tektronix made sure that a tube that might test "weak" in a tester will still operate acceptably in their instruments. Laughably, those people who scavenge tubes from this old gear probably do not realize that many of these tubes are not in the best condition. I guess that they think since the tubes are in that pretty TEK Blue Cabinet, that this imparts "magical powers" to said tubes.

--
Michael Lynch
Dardanelle, AR


Re: 7D15 internal trigger not working

Mark Vincent
 

Steve,

Check R2409. I suspect it is high or open by the voltages you measured. A bad IC will also make the voltages off. Good you will get a replacement 0022. If bad, use a 1/2W resistor with the size about 3,5x10mm. The original is 1/8W. More wattage is being dissipated than the resistor is rated, ,133W dissipation of a ,125W resistor. I am glad you found your 7D15 is working. That is a nice plug-in.

Raymond Frank is exactly right! Do NOT hot-swap the plugins. This advice should be observed on the 5000 and 11000 series as well.

Mark


Re: 2nd life for a 575 after resting for 30+ years in the attic #photo-notice

Brenda
 

Hello Joe,

First off, I just want to say that's great that you got that 575 up and running! The only thing that I would say is not to rely on your tube tester for testing tubes. Tektronix says it over and over in the manuals for the scopes that I have, I don't know the quote right off-hand, but manuals do say not to rely on tube testers, replace only when that tube is actually causing a problem, otherwise leave it alone. I have several tubes in my Tektronix 535A and both of my 561A's that have issues, but I use them because they are not causing any problems. With tubes getting harder to find NOS, in my personal opinion, use that tube until it does create a problem.

Brenda


Re: 2nd life for a 575 after resting for 30+ years in the attic #photo-notice

Harvey White
 

In 1961, I'd call tube technology "mature".  Barring new designs (nuvistor, etc), Tubes were well understood.  Transistors were not, and certainly the manufacturing process was still young.

Harvey

On 3/31/2021 3:38 PM, Keith wrote:
Love this story! This is so typical of how comparatively well tube gear ages. I’ve seen this over and over with various tube vs. solid state hi-if and studio gear. The tube stuff - which we were told by industry experts was “unreliable” compared to the fancy new transistor stuff they were pushing on us - has in practice outlived and out-valued the transistor stuff. I love the irony of it all.

You just have to have hung on to the transistor stuff long enough to see the failures happen.

For example, I have on display at our production facility a circa 1961 Roberts 770x (all tube) and a circa 1962 Roberts 771x reel to reel. Both are virgin mint condition pieces that have been babied their whole life. Guess which one still works? 🤓

Of course I know in my heart that Tek could never have done the cool stuff we love and depend upon these days without modern transistor designs.
But I also know from some decades of personal experience that my really old tube stuff tends to come on and work no matter the age, while my really old transistor stuff does not so much exhibit this same robustness.





Re: P6137...id button not working

Harvey White
 

The ID button shorts the ring to ground, the X10 setting is a fixed resistor that sets the scale factor.

You should be able to see if the probe is working properly easily enough  If not, then it's possibly a bad connection from the pin to the ring.

Harvey

On 3/31/2021 4:19 PM, Giuseppe Marullo wrote:
Got one used from Ebay, seems to work.except for the ID.

Is that useful to cause me to return the probe?

It would take forever and of course maybe the seller does not have one
available. I guess is not easily fixable.


I got also the el-cheapo P6150 and they trigger the ID based on how I do
rotate the base on the BNC, of couse the 10x is triggered on/off as well.

Any advice? Should I simply forget about the function(s)?


I was planning to use the P6150 as standard probe on the 485, but also on it
the 10x led goes on and off based on how I do rotate the BNC. Hopefully I am
doing something wrong or it is just something fixable on the ring. On two
scopes I have weird behavior so I am not too optimistic.


TIA


Giuseppe Marullo

IW2JWW - JN45RQ







Re: 2nd life for a 575 after resting for 30+ years in the attic #photo-notice

 

On 31. Mar 2021, at 21:38, Keith <coolblueglow@gmail.com> wrote:

Love this story! This is so typical of how comparatively well tube gear ages...
Transistors vs. tubes.

I know another story: mechanical vs. electromechanical vs. computers... in railway signalling!

Here in Germany, but actually all over the world, you still see many mechanical interlockings in operation (in english its called signal boxes, sometimes). In the 30ies up to the 70ies came relay technology, and computer technology beginning in the 80ies.

Guess what: the mechanical ones live forever (i.e. since more than 100 years), as long as there is someone with a hammer, a lime and an oil can. The relay ones continue their service, weakest point I know of is the cabling between relay groups where wires with red or brown isolation become brittle. Relays are still in production, so they can be repaired without problems. Yet the first computer interlockings turned out to be a pain in the ass to keep running when the semiconductor industry decided to no longer make an 8085 processor. You have to redesign the hardware and parts of the software with all the safety certification stuff, which is coming close to a complete redevelopment. Today this problem is addressed by an "obsolescence department". Yeah!!

Safety-wise computer and relay interlockings are comparable. A bit better than mechanical interlockings as they ease workload from the signaller. Nevertheless today, every manager in railway industry seems totally drunk when boasting a new generation of "digital interlockings". They forgot that mechanical interlockings were already fully digital...

cheers
Martin


Re: 2nd life for a 575 after resting for 30+ years in the attic #photo-notice

Bert Haskins
 

On 3/31/2021 3:38 PM, Keith wrote:
Love this story! This is so typical of how comparatively well tube gear ages. I’ve seen this over and over with various tube vs. solid state hi-if and studio gear. The tube stuff - which we were told by industry experts was “unreliable” compared to the fancy new transistor stuff they were pushing on us - has in practice outlived and out-valued the transistor stuff. I love the irony of it all.

You just have to have hung on to the transistor stuff long enough to see the failures happen.

For example, I have on display at our production facility a circa 1961 Roberts 770x (all tube) and a circa 1962 Roberts 771x reel to reel. Both are virgin mint condition pieces that have been babied their whole life. Guess which one still works? 🤓

Of course I know in my heart that Tek could never have done the cool stuff we love and depend upon these days without modern transistor designs.
But I also know from some decades of personal experience that my really old tube stuff tends to come on and work no matter the age, while my really old transistor stuff does not so much exhibit this same robustness.
Ya pays your money, ya takes your choice.

Both my really old tube stuff and my really old transistor stuff are all going strong.
I have moved into my eighth decade of working with electronics and the only tubes that I feel any affection for are CRTs.

What is it in the 771x reel to reel that can't be fixed?




Re: Sampling head remove/install with scope power on?

Tom Lee
 

If the manual does not say specifically that hot-plugging is supported, assume that it is not.

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

On Mar 31, 2021, at 12:56 PM, Charles <charlesmorris800@centurytel.net> wrote:

True, unless specifically designed for it, which is why I asked.





P6137...id button not working

Giuseppe Marullo
 

Got one used from Ebay, seems to work.except for the ID.

Is that useful to cause me to return the probe?

It would take forever and of course maybe the seller does not have one
available. I guess is not easily fixable.



I got also the el-cheapo P6150 and they trigger the ID based on how I do
rotate the base on the BNC, of couse the 10x is triggered on/off as well.

Any advice? Should I simply forget about the function(s)?



I was planning to use the P6150 as standard probe on the 485, but also on it
the 10x led goes on and off based on how I do rotate the BNC. Hopefully I am
doing something wrong or it is just something fixable on the ring. On two
scopes I have weird behavior so I am not too optimistic.



TIA



Giuseppe Marullo

IW2JWW - JN45RQ


Re: 2nd life for a 575 after resting for 30+ years in the attic #photo-notice

Joe
 

Keith,

the same thoughts apply to "musical instruments". In my living room we have got a Rock Ola 434 "Concerto" juke box circa 1969 tube with tube amplifier (4x 6BQ5 PP). Once you have listened to the old 7" vinyls on this one you are sure nothing else compares to it!

Well I have found out in that Tek 575 there is at least one weak emission 6AU6 tube in the sweep amplifier. I am going to check all the tubes on a tube tester, maybe I will have to put in some new ones. Up to now I haven't seen one that I would classify as "impossible to find" as NOS. I would not want to use Chinese or Russian substitute tubes, just for the reason that this was not original.

Joe


Re: 7D15 internal trigger not working

 

On Wed, Mar 31, 2021 at 09:50 PM, Steve Nossen wrote:


I have read that these ICs are subject to damage doing hot swaps.
The 7000 series do not support hot swapping. A warning to that effect is shown on many plugins.

Raymond


Re: Sampling head remove/install with scope power on?

 

True, unless specifically designed for it, which is why I asked.


Re: 7D15 internal trigger not working

Steve Nossen
 

I had a chance to get back to the 7D15 after a new grandchild arrived. Following group suggestions (mount -5V supply perpendicular to board), I measured the voltages on the 7D15 internal trigger amplifier while in the second vertical slot and all matched the voltages on the schematic. Looking at the scope I realized all of my observations were with the 7B53 in the right H slot (B) and 7D15 in the left H slot (A). I swapped the equipment and the counter now triggers and the timebase does not! The 7D15 trigger seems OK. Measured voltages on the main frame trigger select ICs, U2404 and U2424, 155-0022-00. The voltages were not the same on pin 4 of the two ICs under the same conditions. I swapped the chips and the problem and voltage measurements followed the chip. I could get a trigger to occur with the bad chip intermittently and dependent on the setting of both slot A and slot B trigger select switches, both had to be in vertical mode position. The voltage on pin 4 of the good chip is the same if the right slot is selected as trigger independent of how the right slot is selected. For the bad chip the voltage is dependent on how the right slot is selected, right slot or mode and vertical mode right. That combination changes if pin 4 is driven through the transistor, Q2090, or though the resistor, R2093. Additionally, the voltage on pin 11 is -1.3 volts instead of -4.1 volts.

I located a trigger board from a parted 7603 that claimed to have a failed CRT and am waiting on delivery to harvest the IC. Any thoughts on the IC failure are appreciated. Anything else I should be concerned with in replacing the IC? Other than trying a few plugins in this particular scope I don't have any history with this 7704A so I don't know if this is a preexisting condition or something that happened on my watch. I have read that these ICs are subject to damage doing hot swaps.

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