Date   
Interested in comments on Chinese oscilloscopes

John Williams
 

Hi. This may be totally off topic and may even upset some of you. I hope not so here goes.

I am wondering if anybody has any experience with the Chinese oscilloscopes such as the Uni-T 2025 family. I am thinking of bringing one in to evaluate and compare to tektronix models of similar specs. I would be grateful if someone had experience with this type of equipment and would comment. If they are junk I would like to know or if they are useful that would be the sort of thing I would like to know. Thanks. John

Re: Portable scope Tek /Sony.

Paul Amaranth
 

The 335 does not have attached probes, you might be thinking of the 2xx series.
Look at the 212, for example. One of that series included an onscreen readout
for a DMM (the 213) Those are not Sony, however.

The Tek/Sony 335 is a bigger scope and has a higher bandwidth. I have one of those
and, except for the concentric ch1/ch2 attenuator and the AC/Gnd/DC coupling
switches, I really like it. The 336 doesn't have that problem and has digital
storage as well; that would be a nice scope.

Both of those are pretty compact and something of a challenge to fix if something
goes wrong.

Paul

On Tue, Feb 05, 2019 at 12:12:46PM -0800, Phillip Potter wrote:
I have a 335 Sony/Tektronix scope that is very portable and runs on 120 volt
mains or 12v to 24v from an external battery... Awesome unit. I love mine!

If not something else, you might consider looking at one.

Best,

Phil


On 2/5/2019 11:01 AM, vaclav_sal via Groups.Io wrote:
I like to replace my broken 464 with a small portable scope made by Tek and I believe with Sony.
About 40 years plus ago.
Do not remember the number , but it was two channel scope with attached probes , and same  hardware format as a multimeter they made.
I think it was battery operated , but not sure.




!DSPAM:5c59ee74218181533255956!
--
Paul Amaranth, GCIH | Manchester MI, USA
Aurora Group, Inc. | Security, Systems & Software
paul@... | Unix & Windows

Re: 7854 - yet another problem

Chuck Harris
 

Same family, but likely physically bigger.

-Chuck Harris

n4buq wrote:

Same chip used in the TI-99/4A?

Thanks,
Barry - N4BUQ

The 7854 is based on a ti-9900 16 bit minicomputer emulating
microcomputer. Bank in the vernacular of the time, a "real time
clock" was a counter driven off of the power line. I can't think
of a reason for a 7854 to have such a clock, but I haven't studied
it extensively.

-Chuck Harris

Re: Portable scope Tek /Sony.

EricJ
 

I'm guessing that's the one he's talking about. Neat little unit for sure.--EricSent from my Samsung Galaxy smartphone.

-------- Original message --------From: Phillip Potter <p.potter@...> Date: 2/5/19 2:12 PM (GMT-06:00) To: TekScopes@groups.io Subject: Re: [TekScopes] Portable scope Tek /Sony. I have a 335 Sony/Tektronix scope that is very portable and runs on 120 volt mains or 12v to 24v from an external battery... Awesome unit. I love mine!If not something else, you might consider looking at one.Best,PhilOn 2/5/2019 11:01 AM, vaclav_sal via Groups.Io wrote:> I like to replace my broken 464 with a small portable scope made by Tek and I believe with Sony.> About 40 years plus ago.> Do not remember the number , but it was two channel scope with attached probes , and same  hardware format as a multimeter they made.> I think it was battery operated , but not sure.>>

Re: 7854 - yet another problem

n4buq
 

Same chip used in the TI-99/4A?

Thanks,
Barry - N4BUQ

The 7854 is based on a ti-9900 16 bit minicomputer emulating
microcomputer. Bank in the vernacular of the time, a "real time
clock" was a counter driven off of the power line. I can't think
of a reason for a 7854 to have such a clock, but I haven't studied
it extensively.

-Chuck Harris

David C. Partridge wrote:
The problem was simple once it got bad enough that I could hear the
crackle/hiss of EHT leakage - I removed the CRT (easier said than done),
thoroughly cleaned the cable and around the seal where it connected to the
PDA mesh (even though there was little if any sign of carbon tracking),
and put it back together. Since then (so far) it has behaved perfectly .

PS I think the "real time clock" problem may have been related as it hasn't
recurred. I think the real time clock refers to a problem with the "50Hz"
signal from the Readout Acquire circuit (schematic <31>). Strangely the
actual frequency in this scope was close to 70Hz (even though the timing R
& C connected to pin 6 of U2510 were pretty much spot on value).
Strangely U2510 isn't shown in the parts list for the Display Board
(A29).
It's a 155-0021-01 timing generator and swapping it with one from another
readout board made no change.

David

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of
fred@...
Sent: 05 February 2019 15:21
To: TekScopes@groups.io
Subject: Re: [TekScopes] 7854 - yet another problem

The 7854 I'm trying to resurrect has a problem where the readout starts to
flicker a lot after it has been on for a short while.

Hi David,
if you store a waveform, is it flickering as well? I had a similar problem
with the -15V supply on my 7854. It showed OK DC values by got ripple
after a short time running. It was a 330uF filter cap in the powersupply.

Re: Portable scope Tek /Sony.

Phillip Potter
 

I have a 335 Sony/Tektronix scope that is very portable and runs on 120 volt mains or 12v to 24v from an external battery... Awesome unit. I love mine!

If not something else, you might consider looking at one.

Best,

Phil

On 2/5/2019 11:01 AM, vaclav_sal via Groups.Io wrote:
I like to replace my broken 464 with a small portable scope made by Tek and I believe with Sony.
About 40 years plus ago.
Do not remember the number , but it was two channel scope with attached probes , and same  hardware format as a multimeter they made.
I think it was battery operated , but not sure.

Re: 7854 - yet another problem

Chuck Harris
 

The 7854 is based on a ti-9900 16 bit minicomputer emulating
microcomputer. Bank in the vernacular of the time, a "real time
clock" was a counter driven off of the power line. I can't think
of a reason for a 7854 to have such a clock, but I haven't studied
it extensively.

-Chuck Harris

David C. Partridge wrote:

The problem was simple once it got bad enough that I could hear the crackle/hiss of EHT leakage - I removed the CRT (easier said than done), thoroughly cleaned the cable and around the seal where it connected to the PDA mesh (even though there was little if any sign of carbon tracking), and put it back together. Since then (so far) it has behaved perfectly .

PS I think the "real time clock" problem may have been related as it hasn't recurred. I think the real time clock refers to a problem with the "50Hz" signal from the Readout Acquire circuit (schematic <31>). Strangely the actual frequency in this scope was close to 70Hz (even though the timing R & C connected to pin 6 of U2510 were pretty much spot on value). Strangely U2510 isn't shown in the parts list for the Display Board (A29).
It's a 155-0021-01 timing generator and swapping it with one from another readout board made no change.

David

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of fred@...
Sent: 05 February 2019 15:21
To: TekScopes@groups.io
Subject: Re: [TekScopes] 7854 - yet another problem

The 7854 I'm trying to resurrect has a problem where the readout starts to
flicker a lot after it has been on for a short while.

Hi David,
if you store a waveform, is it flickering as well? I had a similar problem with the -15V supply on my 7854. It showed OK DC values by got ripple after a short time running. It was a 330uF filter cap in the powersupply.

Re: Portable scope Tek /Sony.

Harvey White
 

On Tue, 5 Feb 2019 19:01:33 +0000 (UTC), you wrote:

I like to replace my broken 464 with a small portable scope made by Tek and I believe with Sony.
About 40 years plus ago.
Do not remember the number , but it was two channel scope with attached probes , and same  hardware format as a multimeter they made.
I think it was battery operated , but not sure.
Tektronix 200 series, 212, 213, 214 depending on accessories. I think
that the 213 is the one you'd want.

Bear in mind that the scope's bandwidth is quite limited. You may want
to try something in the 220 series, which is digital and 10 Mhz or 60
Mhz (but expensive).

You'd likely need to replace batteries in the scope, depending on age.

Harvey





Re: Portable scope Tek /Sony.

Jim Ford
 

Hey, look it up on TekWiki (www.w140.com/tekwiki/).
Jim Ford 


Sent from my Verizon, Samsung Galaxy smartphone

-------- Original message --------From: "vaclav_sal via Groups.Io" <vaclav_sal=yahoo.com@groups.io> Date: 2/5/19 11:01 AM (GMT-08:00) To: TekScopes@groups.io Subject: [TekScopes] Portable scope Tek /Sony.
I like to replace my broken 464 with a small portable scope made by Tek and I believe with Sony.
About 40 years plus ago.
Do not remember the number , but it was two channel scope with attached probes , and same  hardware format as a multimeter they made.
I think it was battery operated , but not sure.

Portable scope Tek /Sony.

vaclav_sal
 

I like to replace my broken 464 with a small portable scope made by Tek and I believe with Sony.
About 40 years plus ago.
Do not remember the number , but it was two channel scope with attached probes , and same  hardware format as a multimeter they made.
I think it was battery operated , but not sure.

Re: 7854 - yet another problem

 

The problem was simple once it got bad enough that I could hear the crackle/hiss of EHT leakage - I removed the CRT (easier said than done), thoroughly cleaned the cable and around the seal where it connected to the PDA mesh (even though there was little if any sign of carbon tracking), and put it back together. Since then (so far) it has behaved perfectly .

PS I think the "real time clock" problem may have been related as it hasn't recurred. I think the real time clock refers to a problem with the "50Hz" signal from the Readout Acquire circuit (schematic <31>). Strangely the actual frequency in this scope was close to 70Hz (even though the timing R & C connected to pin 6 of U2510 were pretty much spot on value). Strangely U2510 isn't shown in the parts list for the Display Board (A29).
It's a 155-0021-01 timing generator and swapping it with one from another readout board made no change.

David

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of fred@...
Sent: 05 February 2019 15:21
To: TekScopes@groups.io
Subject: Re: [TekScopes] 7854 - yet another problem

The 7854 I'm trying to resurrect has a problem where the readout starts to
flicker a lot after it has been on for a short while.

Hi David,
if you store a waveform, is it flickering as well? I had a similar problem with the -15V supply on my 7854. It showed OK DC values by got ripple after a short time running. It was a 330uF filter cap in the powersupply.

--
Best regards,

Fred S.

Re: Wanted: knurled nut for earth terminal on 7K scope

 

Hi David,
I have one I can spare.
It shouldn't cost more than a few dollars to send it to you.
Keep me in mind if you can't find one locally.
Dennis

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of David
C.
Partridge
Sent: Tuesday, February 05, 2019 4:11 AM
To: TekScopes <Tekscopes@groups.io>; TekScopes2@groups.io
Subject: [TekScopes] Wanted: knurled nut for earth terminal on 7K scope

The earth terminal at the right hand end of the centre section of the
front
panel on the 4 bay 'scopes is threaded, and there's a knurled nut that
screws onto it. Part number is 200-0103-00.

I'm missing one - does anyone (ideally in UK/EU) have a spare one?

Thanks
David



--
Dennis Tillman W7PF
TekScopes Moderator

Re: 7854 - yet another problem

Fred S.
 

The 7854 I'm trying to resurrect has a problem where the readout starts to
flicker a lot after it has been on for a short while.

Hi David,
if you store a waveform, is it flickering as well? I had a similar problem with the -15V supply on my 7854. It showed OK DC values by got ripple after a short time running. It was a 330uF filter cap in the powersupply.

--
Best regards,

Fred S.

Re: Inappropriate language

Dale H. Cook
 

At 01:07 PM 2/4/2019, Dennis Tillman wrote:

Recently a message was posted with inappropriate language that is not a reflection of the other 7,500 members of TekScopes.
Dennis -

Thank you. Civility in public conversation is steadily coming to resemble the dodo. It is good to see that it is still the norm in TekScopes.

Dale H. Cook, GR/HP/Tek Collector, Roanoke/Lynchburg, VA
https://plymouthcolony.net/starcity/radios/index.html

Re: 7A26 attenuator compensation problem

Fabio Trevisan
 

Apologies to everyone, I sent the message before finishing... Resuming now:

On Mon, Jan 28, 2019 at 06:16 PM, Nenad Filipovic wrote:

Thank you all for your hints, but still no go.
Yes, 10mV and 20mV are pass-through...
Hello Nenad,
Arrived a little bit later to this, but I see there might be a confusion or misunderstanding that can ruin all the process down the road.
I do own a 7A26 myself and 10 and 20mV ARE NOT the ranges where all the high impedance attenuators are BYPASSED.
They're 5mV and 10mV / div, being that 10mV/div is the attenuation that shares the same preamplifier GAIN with all the other (higher) attenuation factors, while the 5mV/div setting stands alone on its own, as it employs no input attenuation (just as the 10mV does) and doubles the gain of the pre-amplifier.
If you're performing the preamplifier's LF and HF response adjustments at 10mV/div you're fine but, if you're performing them using the 20mV range, believing this range is a BYPASS range, then you will be compensating on the preamplifier's AC response adjustments, whatever deviation your X2 attenuator block might have, and this is not right.

So - risking to digress from Tektronix a little bit - basically what you would want is:
1. Go through the checks of the DC attenuation factors, to rule-out that there might be some bad contacts on the attenuator blocks and/or the contact leaves.
2. Using a low impedance source (e.g. going through a 50 Ohm past-through terminator), and using the 10mV range (and not the 5mV range in my opinion), perform all the preamp AC adjustments (LF and HF step response).
3. Changing over from the 50Ohm terminator to the 1M Input normalizer, adjust the pre-amlipfier's input capacitance (C130 alone or C130 and C134, depending on the serial number of your 7A26).
4. Then perform each attenuator block's Frequency compensations and Input capacitances in the following order:
4a. Change from 1M Input normalizer to 50Ohm terminator, Set range to 20mV, Set generator's amplitude accordinglly, adjust C106 (this is x2 att.'s freq. compensation).
4b, Change from 50Ohm term. to 1M Input normalizer, leave everything else untouched, adjust C107 (this is x2 att's input capacitance).
4c. Change from 1M Input normalizer to 50Ohm terminator, Set range to 50mV, Set generator's amplitude accordinglly, adjust C110 (this is x5 att.'s freq. compensation).
4d, Change from 50Ohm term. to 1M Input normalizer, leave everything else untouched, adjust C111 (this is x5 att's input capacitance).
4e. Change from 1M Input normalizer to 50Ohm terminator, Set range to 100mV, Set generator's amplitude accordinglly, adjust C114 (this is 1st x10 att.'s freq. compensation).
4f, Change from 50Ohm term. to 1M Input normalizer, leave everything else untouched, adjust C115 (this is 1st x10 att's input capacitance).
4g. Change from 1M Input normalizer to 50Ohm terminator, Set range to 1V, Set generator's amplitude accordinglly, adjust C118 (this is 2nd x10 att.'s freq. compensation).
4h, Change from 50Ohm term. to 1M Input normalizer, leave everything else untouched, adjust C119 (this is 2nd x10 att's input capacitance).

Some might disagree from me, about keeping changing over between 50Ohm terminator and 1M Input normalizer, but the net result is the same, and by doing the frequency compensation adjustments always from a low impedance source, helps preventing that the input capacitance from the block being adjusted (which is not yet calibrated up to each step) will interfere in the compensation adjustment itself, even if it's grossly off.

Of course that this method implies that your generator is capable of sourcing at least 10Vpp on 1M load, and 5Vpp on 50Ohm (for an optimal 5 div display at 1V/div).

Doing this way has always yielded predictable results for me.

Rgrds,

Fabio

Re: 7A26 attenuator compensation problem

Fabio Trevisan
 

On Mon, Jan 28, 2019 at 06:16 PM, Nenad Filipovic wrote:

Thank you all for your hints, but still no go.
Yes, 10mV and 20mV are pass-through...
Hello Nenad,
Arrived a little bit later to this, but I see there might be a confusion or misunderstanding that can ruin all the process down the road.
I do own a 7A26 myself and 10 and 20mV ARE NOT the ranges where all the high impedance attenuators are BYPASSED.
They're 5mV and 10mV / div, being that 10mV/div is the attenuation that shares the same preamplifier GAIN with all the other (higher) attenuation factors, while the 5mV/div setting stands alone on its own, as it employs no input attenuation (just as the 10mV does) and doubles the gain of the pre-amplifier.
If you're performing the preamplifier's LF and HF response adjustments at 10mV/div you're fine but, if you're performing them using the 20mV range, believing this range is a BYPASS range, then you will be compensating on the preamplifier's AC response adjustments, whatever deviation your X2 attenuator block might have, and this is not right.

So - risking to digress from Tektronix a little bit - basically what you would want is:
1. Go through the checks of the DC attenuation factors, to rule-out that there might be some bad contacts on the attenuator blocks and/or the contact leaves.
2. Using a low impedance source (e.g. going through a 50 Ohm past-through terminator), and using the 10mV range, perform all the preamp AC adjustments (LF and HF step response).
3. Changing over from the 50Ohm terminator to the Input normalizer, adjust the pre-amlipfier's input capacitance (C130 alone or C130 and C134, depending on the serial number of your 7A26).
4. Then perform each attenuator block's Frequency compensations and Input capacitances in the following order:

Re: Best practices for working on a ceramic hybrid front-end board (TDS3032)

Brendan
 

On Tue, Feb 5, 2019 at 04:14 AM, benj3867 wrote:


Hi,

As the saga of fixing my TDS3032 continues, I am now faced with the need to
remove one of the relays from the ceramic board/hybrid front-end module of
channel 1 in order to gain access to one of the laser-trimmed resistors
printed underneath it on the ceramic substrate.

My question is:
what is the best way to desolder and re-solder the relay (as well as how to
eventually replace the blown printed resistor) without causing the pads
printed on the ceramic substrate to disintegrate and disappear?

So please guys, share your experience and best practices for reworking these
ceramic hybrids!

My own experience can be summarized as follows.
The ceramic strips used in tube-era Tektronix instruments are not the subject
of this post. Indeed, following the recommended use of silver bearing solder I
have never had any problem with these. However, the one time I have worked on
a modern ceramic hybrid was different. I had to replace an op-amp on an LEM
current sensor, and desoldering this DIP-8 chip using a desoldering braid
removed about 30% of the pads material printed on the ceramic substrate as
well. After soldering the new chip in (using silver bearing solder), and
removing it one more time (don't ask why I had to do that :-)) two of the 8
pads were completely gone from the ceramic substrate. Unlike a regular epoxy
PCB where pads may delaminate if one applies too much heat, her the pads were
simply slowly disappearing together with the removed solder.

I have no idea if the ceramic hybrid used in the TDS3032 front-end (and many
other modern Tek scopes) are more robust than the LEM hybrid I have worked on,
but I would hate to find out that they are the hard way.
On my TDS320 I cut the leads and ordered a new relay from Mouser. For the TDS320 the relays were under $2

Wanted: knurled nut for earth terminal on 7K scope

 

The earth terminal at the right hand end of the centre section of the front
panel on the 4 bay 'scopes is threaded, and there's a knurled nut that
screws onto it. Part number is 200-0103-00.

I'm missing one - does anyone (ideally in UK/EU) have a spare one?

Thanks
David

Best practices for working on a ceramic hybrid front-end board (TDS3032)

benj3867
 

Hi,

As the saga of fixing my TDS3032 continues, I am now faced with the need to remove one of the relays from the ceramic board/hybrid front-end module of channel 1 in order to gain access to one of the laser-trimmed resistors printed underneath it on the ceramic substrate.

My question is:
what is the best way to desolder and re-solder the relay (as well as how to eventually replace the blown printed resistor) without causing the pads printed on the ceramic substrate to disintegrate and disappear?

So please guys, share your experience and best practices for reworking these ceramic hybrids!

My own experience can be summarized as follows.
The ceramic strips used in tube-era Tektronix instruments are not the subject of this post. Indeed, following the recommended use of silver bearing solder I have never had any problem with these. However, the one time I have worked on a modern ceramic hybrid was different. I had to replace an op-amp on an LEM current sensor, and desoldering this DIP-8 chip using a desoldering braid removed about 30% of the pads material printed on the ceramic substrate as well. After soldering the new chip in (using silver bearing solder), and removing it one more time (don't ask why I had to do that :-)) two of the 8 pads were completely gone from the ceramic substrate. Unlike a regular epoxy PCB where pads may delaminate if one applies too much heat, her the pads were simply slowly disappearing together with the removed solder.

I have no idea if the ceramic hybrid used in the TDS3032 front-end (and many other modern Tek scopes) are more robust than the LEM hybrid I have worked on, but I would hate to find out that they are the hard way.

Re: TDS 500 600 700 series calibration

 

It's a bit of a nasty clean-up to get the gel gone. I didn't try a strong solvent like acetone, although tempted. A good 99% alcohol and plastic scraper gets it. Then put the glass back on using the same gap. There will be enough nubs of RTV to set the gap. I sealed it up with a bead of black RTV.
I've found that Goo Gone (and how appropriate that name is!) works great on dissolving that gel. Just scrape off the majority with a soft plastic scraper first.

Jay