Date   

Re: Tektronix 2465B Square wave noise on active readout. #photo-notice

Ozan
 

On Thu, May 20, 2021 at 06:38 AM, @Antonio90 wrote:


Sorry if It's obvious, but is it normal to have around 42 ohms across the 5 &
-5 volt rails and ground?
I was just checking continuity on the damaged area around U650, and the
ceramic caps in the 5v power distribution, (in particular C675) appear as
~42R, with the resistance going up as I measure caps further away in the same
rail. Also, pins 12 and 5 of J119 give out around 42R.
I vs V transfer function of the supplies will be nonlinear because of many active devices on the supplies; however, measuring 42-ohm is not a concern by itself.

The resistance across the supplies should measure about the same on all points of the rail unless you are crossing one of the supply filtering inductors shown on sheet <11>.

Ozan


Re: Challenging 2465 PS repair

Ozan
 


My weird mind has a question: the service manual says to use 2 pcs of 2 ohm
resistors to load the 5VD output, however, the manual does not say whether
they should be in series or parallel?
I put them in parallel, because if they needed something like 4 Ohm, they just
would have used a 3.9 Ohm resistor.
--
Hi Leo,
In 2465 schematic 5VD has a 5A fuse so 2//2=1ohm would be too small (too much current for the supply). Interestingly 2467B has a similar PSU and the load instructions say: "TEST LOAD. Connect a 2-ohm, 25 watt resistor (Tektronix part number 308-0205-00) from the +5 VD pins of J303 and J232 (on the Inverter Board) to ground.". Almost the same instructions as 2465 but "a 2-ohm" instead of "two 2-ohm".

A single 2-ohm might be intended if this is a typo; however, it is better to start with two 2-ohms in series to be safe,
Ozan


Adding Option 14 to a TDS380 - Plug & Play?

Richard Peterson
 

I picked up a parts donor TDS380 that has Option 14 installed. As I swap parts over to my current TDS380, I'd like to move that as well, but I'm wondering if there are any software/firmware issues i need to be aware of. Can i simply move the hardware, plug it in and close it back up?

Thanks.


465 Electrolytic Capacitor replacement done

Bill
 

Got all the electrolytics in the power supplies replaced. I used the capacitor adapter discs from CUOG on EBAY. They made the soldering job very easy. All low voltage power supply voltages are correct now. Got the traces back on both channels. Replaced a few Tantalums and small electrolytics while I was at it. Also replaced all the bridge rectifiers since they were all original and with the old electrolytics removed it was a much easier job to do.

Now I have to clean the Volts/Div switches. They are a little flaky but with some gentle tapping still work.

Thanks to all for your suggestions and sharing your experiences.

Bill


Re: "Chats"

Vince Vielhaber
 

On 05/20/2021 02:28 PM, Roy Thistle wrote:
On Thu, May 20, 2021 at 09:31 AM, Vince Vielhaber wrote:


chats is that they're not searchable
Search worked for:
Question: Understanding a scope probe
2430A scope problem
using the groups.io search engine, and were also indexed on Google.

Some of the older chats did not turn up with the Groups.io search... or Google... so groups.io may have just started indexing them. (Or the indexing may be something you get when you pay for a groups.io subscription.)
I was able to join some of the oldest chats on TekScopes... so they are still active. That means they are indexed somehow on groups.io.
Ok, JOIN one of the chats and search for something from within it. It's the contents that aren't searchable, I thought what I meant was a given, guess not.

Vince.
--
K8ZW http://www.metalworkingfun.com http://www.hamradio.fun


Re: 556 advertised on Facebook

 

All of which is why I repeatedly encouraged the seller to post here directly. The seller said that they saw this thread, and thanked me for it, and gave me that permalink (which most people can't use), but obviously hasn't posted here. I don't know why, but maybe the scope has already found a home. There were several people making noises like they were interested, and were near enough to pick it up.

-- Jeff Dutky


Re: 556 advertised on Facebook

 

Bernie,

Man that sucks! We were told that the group was going private due to a Facebook policy change, which sounds plausible enough, because Facebook sucks too, but kicking you off as admin sounds like a real jerk move.

I like the group, but it feels like a ghost town, even though it has thousands of members. There's very little expertise on display, not many replies to requests for help, especially compare to this group, and only a few posts per day. Also, because it's Facebook, it's basically walled off from the internet, which makes it a significantly less useful resource, even if it were a repository of significant expertise.

-- Jeff Dutky


Re: CFG253 vs CFG250 schematic

Tom Lee
 

If it works on some ranges but not others, I’d suspect switches first. So before diving too deeply into the debug, first do the Deoxit dance. That might fix up the range-setting dependent sine distortion as well.

Of course, check the supplies, etc. to make sure that bypass caps are doing what they’re supposed to do, and the regulators are regulating, etc. But it sounds like this should be a pretty easy fix.

Cheers,
Tom

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

On May 20, 2021, at 1:17 PM, Chris Elmquist <chrise@pobox.com> wrote:

I recently received a CFG253 function generator that is kinda cute and
goes along with the CMC250 frequency counter I've had for eons.

Unfortunately, the CFG253 has some issues-- namely, no oscillations on
the 100, 10 and 1 ranges and some distortion in sine mode on other ranges.
So, I'd like to fix it up.

I can't find a schematic for CFG253 but I did for CFG250. Can anyone
comment on how different they may really be? I suspect very similar
with only some component differences to achieve the higher frequency
capability in the '253??

If anyone knows a source for a CFG253 schematic, that would be greatly
appreciated too. I have found a Service Bulletin that discusses some
alignment operations but no actual schematic with component values so far.

Chris
--
Chris Elmquist NØJCF






CFG253 vs CFG250 schematic

Chris Elmquist
 

I recently received a CFG253 function generator that is kinda cute and
goes along with the CMC250 frequency counter I've had for eons.

Unfortunately, the CFG253 has some issues-- namely, no oscillations on
the 100, 10 and 1 ranges and some distortion in sine mode on other ranges.
So, I'd like to fix it up.

I can't find a schematic for CFG253 but I did for CFG250. Can anyone
comment on how different they may really be? I suspect very similar
with only some component differences to achieve the higher frequency
capability in the '253??

If anyone knows a source for a CFG253 schematic, that would be greatly
appreciated too. I have found a Service Bulletin that discusses some
alignment operations but no actual schematic with component values so far.

Chris
--
Chris Elmquist NØJCF


FS: Tek Type 134 Current Probe Package - Complete

Liam Perkins
 

I have a Type 134 Current Probe Package for sale for $US300.00 complete.
I'll tidy my many pix into a .zip and post later today.

In the meantime you can pull down a slew of info here:

https://www.pearl-hifi.com/06_Lit_Archive/15_Mfrs_Publications/35_Tektronix/Tek_Type_134_Current_Probe_Amplifier/Tek_Type_134_Current_Probe_Amplifier.zip

noting that this one's SN is 01328 meaning its Type 134 amplifier will
handle only the P6019 and P6020 probes.

It has been tested working on the cal' current loop of a 7844.

The kit is -complete- in the original case with power supply, P6019 probe
w/5ft. cord, P6019 passive termination PN 011-0078-00 and of course the
Type 134 Current Probe Amplifier, with which the included P6019 will work
w/o the termination.

Pls. ping off list if interested 'sales at pearl-hifi dot com'

Liam


Re: "Chats"

pdxareaid
 

PM is available.
I see quite a bit of humanity in the posts already.
My concern is that technically valuable info will migrate to chats and be harder to come by.
But i will be fine with whatever Dennis decides.
BTW: groups.io is really deficient compared to other forums that segregate topics and have stickies etc.
I think the switch from yahoo to groups.io was to allow the email option for those that use it (i don't) and mimic the simplicity
of yahoo groups, which many members seem to like. Chats will begin to diverge from that model.


Re: "Chats"

 

So where do you go if you just want to find out how everyone's day has been?

We're not robots after all. Some human connection would be nice.

On Thu, May 20, 2021 at 8:44 PM pdxareaid <public_email2@frontier.com> wrote:

I think it is valuable to keep in mind that not all groups.io groups use the facilites in the same way.
In some groups, chats might be the appropriate place for individual help that we frequently
encourage in the main forum. A segregated chats section is appropriately provided there.

The way we use groups.io, we would wind up having 2 places to follow what should be contained in one place.
I even find OT to be a valuable learning diversion and prefer it to be amongst the various help threads.
I don't see the purpose of splitting something off to chats and then having to police its proper use, which
will inevitably be violated.
Having one place to post seems the best option for the intent of the this group. It is not broken.
Disabling chats would prevent its misuse, I think.





Re: "Chats"

pdxareaid
 

I think it is valuable to keep in mind that not all groups.io groups use the facilites in the same way.
In some groups, chats might be the appropriate place for individual help that we frequently
encourage in the main forum. A segregated chats section is appropriately provided there.

The way we use groups.io, we would wind up having 2 places to follow what should be contained in one place.
I even find OT to be a valuable learning diversion and prefer it to be amongst the various help threads.
I don't see the purpose of splitting something off to chats and then having to police its proper use, which
will inevitably be violated.
Having one place to post seems the best option for the intent of the this group. It is not broken.
Disabling chats would prevent its misuse, I think.


Re: 556 advertised on Facebook

widgethunter <tubesnthings@...>
 

Yup - the deadbeat piece of shit group owner made the group private and kicked me to the curb after I spent 2 yrs as the senior admin, building the group to over 2k members.Bernie Schroder

-----Original Message-----
From: Vince Vielhaber <vev@michvhf.com>
To: TekScopes@groups.io
Sent: Thu, May 20, 2021 9:20 am
Subject: Re: [TekScopes] 556 advertised on Facebook

Not only do you need to be on FB, you need to be a member of that FB
group to see it.  The group is private.

Vince.

On 05/20/2021 10:20 AM, Jeff Dutky wrote:
Here is a link to the facebook post from the seller: https://www.facebook.com/groups/oldtekscopes/permalink/939543180167188/?sale_post_id=939543180167188




--
  K8ZW  http://www.metalworkingfun.com   http://www.hamradio.fun


Re: "Chats"

Roy Thistle
 

On Thu, May 20, 2021 at 09:31 AM, Vince Vielhaber wrote:


chats is that they're not searchable
Search worked for:
Question: Understanding a scope probe
2430A scope problem
using the groups.io search engine, and were also indexed on Google.

Some of the older chats did not turn up with the Groups.io search... or Google... so groups.io may have just started indexing them. (Or the indexing may be something you get when you pay for a groups.io subscription.)
I was able to join some of the oldest chats on TekScopes... so they are still active. That means they are indexed somehow on groups.io.
--
Roy Thistle


14 x 10^9 miles OT but too interesting to let go by

Liam Perkins
 

NASA's Voyager 1, the farthest spacecraft from Earth, said farewell to the
solar system almost a decade ago, passing through an invisible door some 11
billion miles from Earth and crossing into interstellar space. Since then,
it's tacked on another 3 billion miles and it's still sending home data,
allowing scientists to probe the space between stars. In a paper published
in the journal Nature Astronomy on Monday, researchers examined data beamed
back by Voyager 1's Plasma Wave System over its journey, but particularly
after it passed through over the solar system's border.

The border is a messy "edge" where the sun's influence disappears and the
interstellar medium begins. The medium is typically characterized as empty,
desolate and dark, but the PWS on Voyager 1 has detected a low, constant
pattering against its detector, space raindrops gently falling on a window.
Those drops signify plasma waves -- or interstellar gas -- is constant
company for the spacecraft.

"We're detecting the faint, persistent hum of interstellar gas," said
Stella Koch Ocker, a doctoral student at Cornell University who led the
research. "It's very faint and monotone, because it is in a narrow
frequency bandwidth."
==============
And there's this:
https://www.theregister.com/2020/09/18/voyager_1_14_billion_miles/
where we read that:

"NASA's extraordinarily long-lived Voyager 1 probe this week passed 14
billion miles from Earth.
It takes light nearly 21 hours to reach the spacecraft, making commanding
it increasingly tricky."

I'd love to know how they lock onto that signal.

Liam


Re: 2230 PSU Replacement Component Choices

alastair.knights@...
 

I thought I ought to answer my original question in case it helps others. Back in March 2021, I asked for advice about suitable replacement parts for a 2230 PSU and based on tests, the answers seem to be:

Q935, ‘Thyristor, SCR 8A, 200V sens gate - I tried using a ST Micro TS820-600T as a replacement, but it triggered unexpectedly and burn out, so this device may be too sensitive. So, I kept the old GE C10682 part in service.

Q946 and Q947, ‘Transistor NPN, 50V, 150mA, 200mW, inverter’ - I tried using On Semi MJE15032G as replacements, but the inverter would not oscillate reliably or continuously. It seems likely that hFE and possibly capacitance are major factors in whether the inverter oscillates. My MJE15032Gs have an hFE=96 while the original transistors are only hFE=48. Once again the original transistors were retained.

Q9070, ‘MOSFET, N-channel, TO-220’ - I used a Toshiba TK10E60W as a replacement and this worked fine. I also bolted a small finned heatsink onto the back of the main mounting plate using the Q9070 fixing screw and this lowered the temperature of the mounting plate by around 10 degrees C (max temp was 46C after 30mins).

(VR935, ‘Zener, 51V, 5%’, SZG35009K7 (1N978B), There was no need to replace this as it only needs replacing to make room for the revised SCR location described in Tek Product Modification 060-2239-03.)

CR907 (and CR906) - I used a MUR460 as a replacement but the leads are too large to fit in the holes on the PCB. However, binding the thick MUR460 leads onto the stumps of the old diode is a simple fix (please don't drill out the THP hole!)

Apart from the RIFA caps in the Line Input Filter, the only other component that I felt needed replacing was C907, which has to pass very high ripple currents of many amps. Despite the original being a high-quality TRW film capacitor, given its 35 years of service and critical location, I replaced it with a 630V Panasonic ECQE6105JF cap.

Hope this helps someone as previous postings have helped me.

Alastair Knights


Re: "Chats"

Vince Vielhaber
 

On 05/20/2021 11:46 AM, Roy Thistle wrote:
On Thu, May 20, 2021 at 01:57 AM, dave G8SFU wrote:


...disable the chat facility. If a discussion needs to go out of mainstream it can go to pm.
I reckon, Chats ought not to be a place to start a discussion about the culinary advantages of rutabagas versus turnips. Rather is would be about "tekscopes" which is mainstream on TekScopes ... I reckon.
The big problem I'm seeing with chats is that they're not searchable. Never mind the fact that you have to join them to see what's going on. If someone has a problem and it gets solved in the chat, how will anyone else be able to find it?

Seems to me Chats should be left for threads that get so off topic that they don't belong on the list and whoever wants to continue the conversation can move/join it there.

Vince.
--
K8ZW http://www.metalworkingfun.com http://www.hamradio.fun


Re: 556 advertised on Facebook

Vince Vielhaber
 

Not only do you need to be on FB, you need to be a member of that FB group to see it. The group is private.

Vince.

On 05/20/2021 10:20 AM, Jeff Dutky wrote:
Here is a link to the facebook post from the seller: https://www.facebook.com/groups/oldtekscopes/permalink/939543180167188/?sale_post_id=939543180167188




Free 050-0473-00 Mod kit for 547 scopes, Tek 465B spares

 

I found a mod kit for this older scope, involves new sweep steering diodes.
if any use to somebody, I can drop it in an envelope to you. contact me off list please.

Also, lots of Tek 465B spares going onto the stuff page later today here:
https://www.sphere.bc.ca/test/stuffday.html#tekfans

all the best,
walter (walter2 -at- sphere.bc.ca)
sphere research corp.

5601 - 5620 of 188129