Date   

Re: 130 LC meter

Jean-Paul
 

I have found it in 3rd basement, untouched since 2004 or before. Refugee from Lawrence Livermore scrap yard, cost was $0.30 /lb....

Inside perfect clean, date codes on tubes 1963.

Gradual line with a variac, caps are old and deformed.

Worked but thought has to be out of cal.

The fixed OSC should be 140 kHz, tested at 140,650 Hz.

Found some mica caps, and got a few in series to get ~ 300 pF as measured on a pair of HP 4332A LCR meters and the old Wayne Kerr 3245 analyzer. All agreed to 307 pF.

On the 130 LC, 300 pF scale PERFECT!

Tested a few other cap ranges and on some small inductors, all were very close to correct values.

AMAZING! Perfect after 58 years......

Vive Tektronix! Jon


Re: Scope

Thomas Dodge
 

Hi Dave,
Thanks for your quick reply. I know I would use a high voltage probe for
the high voltage spots, but I don't plan to get into that area, but just
for my information, what high voltage probe would I use for that? Is there
anyone in my area who works on Tektronix scopes? I guess if I had to, I
could send it somewhere to be repaired, but I really want to do it myself
with someone who is experienced. Do you know of any places around that
could repair this if I sent it out? Thanks Dave.

Tom Dodge

On Fri, Dec 11, 2020 at 11:56 AM Dave Casey <polara413@gmail.com> wrote:

Tom -

The HV is all over on the display driver board that sits next to the CRT.
The board on top is the processor board (or an option board if so
equipped). Tek is very good about warning you where the HV may be
encountered and shielding accordingly. You can also refer to the service
manual disassembly procedures which are also very good about advising when
precautions are necessary.

Dave Casey

On Fri, Dec 11, 2020 at 1:51 PM Thomas Dodge <tdodge2404@gmail.com> wrote:

Hi all,
I have a question. I have written before about the scopes that I have. I
have a TDS684A, which is my best one. The issue that it has is this. I
bought it from a surplus place, and it had been there for quite a while,
but I always wanted to pick it up. When I bought it and took it home, and
powered it on, the panel lights came on initially, but that's all. I
turned
it off and on again a few times, and finally the relays started to
initialize, and it ran the self test, and it was fine. I turned it off
and
on again, and it was fine. I turned it on recently, and the panel lights
came on, but no display at all. I connected an external monitor from the
rear connector, but no signal. I looked at the troubleshooting flowchart
in
one of the manuals for the 684A, and it is very helpful. II know the
scopes
carry a significant anode voltage, so I am very aware of that. I live in
Glendora, Calif. and just wanted to know if there is someone in my area,
who has a lot of experience repairing these scopes? I want to do it
myself,
but I would want to work with someone who has Tektronix experience to
show
me the ropes. I really want to get experience working on these. But one
question I do have. With the scope cover removed, is there any high
voltage
present on the board on top? I appreciate any input any one of you might
have. My 684A is in really good condition. Thanks very much.

Tom Dodge










Re: Scope

Dave Casey
 

Tom -

The HV is all over on the display driver board that sits next to the CRT.
The board on top is the processor board (or an option board if so
equipped). Tek is very good about warning you where the HV may be
encountered and shielding accordingly. You can also refer to the service
manual disassembly procedures which are also very good about advising when
precautions are necessary.

Dave Casey

On Fri, Dec 11, 2020 at 1:51 PM Thomas Dodge <tdodge2404@gmail.com> wrote:

Hi all,
I have a question. I have written before about the scopes that I have. I
have a TDS684A, which is my best one. The issue that it has is this. I
bought it from a surplus place, and it had been there for quite a while,
but I always wanted to pick it up. When I bought it and took it home, and
powered it on, the panel lights came on initially, but that's all. I turned
it off and on again a few times, and finally the relays started to
initialize, and it ran the self test, and it was fine. I turned it off and
on again, and it was fine. I turned it on recently, and the panel lights
came on, but no display at all. I connected an external monitor from the
rear connector, but no signal. I looked at the troubleshooting flowchart in
one of the manuals for the 684A, and it is very helpful. II know the scopes
carry a significant anode voltage, so I am very aware of that. I live in
Glendora, Calif. and just wanted to know if there is someone in my area,
who has a lot of experience repairing these scopes? I want to do it myself,
but I would want to work with someone who has Tektronix experience to show
me the ropes. I really want to get experience working on these. But one
question I do have. With the scope cover removed, is there any high voltage
present on the board on top? I appreciate any input any one of you might
have. My 684A is in really good condition. Thanks very much.

Tom Dodge






Scope

Thomas Dodge
 

Hi all,
I have a question. I have written before about the scopes that I have. I
have a TDS684A, which is my best one. The issue that it has is this. I
bought it from a surplus place, and it had been there for quite a while,
but I always wanted to pick it up. When I bought it and took it home, and
powered it on, the panel lights came on initially, but that's all. I turned
it off and on again a few times, and finally the relays started to
initialize, and it ran the self test, and it was fine. I turned it off and
on again, and it was fine. I turned it on recently, and the panel lights
came on, but no display at all. I connected an external monitor from the
rear connector, but no signal. I looked at the troubleshooting flowchart in
one of the manuals for the 684A, and it is very helpful. II know the scopes
carry a significant anode voltage, so I am very aware of that. I live in
Glendora, Calif. and just wanted to know if there is someone in my area,
who has a lot of experience repairing these scopes? I want to do it myself,
but I would want to work with someone who has Tektronix experience to show
me the ropes. I really want to get experience working on these. But one
question I do have. With the scope cover removed, is there any high voltage
present on the board on top? I appreciate any input any one of you might
have. My 684A is in really good condition. Thanks very much.

Tom Dodge


Re: 1S1 sampling bridge GaAs diodes: What alternatives?

toby@...
 

On 2020-12-11 1:21 p.m., snapdiode via groups.io wrote:
No idea, but they need to withstand 2 volts reverse bias. Then they need to conduct with 2 volt forward bias from the pulse network. In about 350 ps.

Naively applying I=CdV/dT, you get a large number for dV/dT, around 11.5E9. So if you swing 2pF 4 volts in 350ps, you need about 20mA from the pulse network.

The 1N5711 is specified at 2pF junction capacitance, but that is at 0 volts. With 2 volts reverse bias, I am guessing from the graph it's more like 1pF. In any case, it's lower.

"But Snapdiode", I hear you say, "the 1N5711 is only rated for 15mA current!" But that's continuous, the 1S1 blasts this current pulse for probably much less than 350pS and at a quite low PRR.

Now Tek says the diode quad was "matched". In the days of hand-made diodes I assume this was to select for diodes with similar capacitance.

I'm going to theorize that modern manufacturing processes for the 1N5711 make them all very nearly identical.

But still, that 15mA number bugs me. Does anyone have 25 cents to spare to give this a try?
The cheap ones are 15mA.

https://www.mouser.ca/datasheet/2/389/1n5711-1848799.pdf

Digikey sells a 33mA _average_ current version for much more.
https://www.digikey.ca/en/products/detail/microsemi-corporation/1n5711-1/4899004

--Toby







Re: Looking for parts for 212 portable scope.

Greg Muir
 

There is frequently a radical difference between “contact cleaners” and cleaner/lubes for potentiometers. And in this case it appears that this product would primarily be found in automotive shops used by mechanics or other mechanically-oriented businesses who simply need to clean the oil. dirt and debris out of switches and such. The name “Overhaul Cleaner” definitely alludes to this type of application.

I have had little success informing others regarding use of only those products that are specifically targeted towards sensitive electronics rather than off-the-shelf cleaners utilized for a myriad of other purposes. I keep my harsh mechanical-oriented cleaner in the garage, the true electronic cleaners and lubes in the lab. If the item does not specifically state for use on things like potentiometers, it goes to the garage where it belongs.

Remember – generic contact cleaners are safe on contacts which are normally made of metal and cannot be damaged without some effort (except for elastomeric types which should NEVER be exposed to cleaners and lubricants). Therefore they can contain some very nasty ingredients with no effect except if the contacts are housed in materials that may be sensitive to aggressive chemicals.

It pays to be safe or pay the penalty.

Greg


Re: 1S1 sampling bridge GaAs diodes: What alternatives?

snapdiode
 

No idea, but they need to withstand 2 volts reverse bias. Then they need to conduct with 2 volt forward bias from the pulse network. In about 350 ps.

Naively applying I=CdV/dT, you get a large number for dV/dT, around 11.5E9. So if you swing 2pF 4 volts in 350ps, you need about 20mA from the pulse network.

The 1N5711 is specified at 2pF junction capacitance, but that is at 0 volts. With 2 volts reverse bias, I am guessing from the graph it's more like 1pF. In any case, it's lower.

"But Snapdiode", I hear you say, "the 1N5711 is only rated for 15mA current!" But that's continuous, the 1S1 blasts this current pulse for probably much less than 350pS and at a quite low PRR.

Now Tek says the diode quad was "matched". In the days of hand-made diodes I assume this was to select for diodes with similar capacitance.

I'm going to theorize that modern manufacturing processes for the 1N5711 make them all very nearly identical.

But still, that 15mA number bugs me. Does anyone have 25 cents to spare to give this a try?


Re: Looking for parts for 212 portable scope.

Miguel Work
 

To repair my 214 intensity pot, I bought a similar pot with different axe, and I changed only the carbon track. You can use pier pot too, and glue original axe.

https://www.tme.eu/es/details/pt15nv-1m/potenciometros-tht-de-una-revolucion/piher/pt15nv02105a2020s/?brutto=1&gclid=Cj0KCQiAzsz-BRCCARIsANotFgPiNwQ8wHbGufy120PCggiZKGin5hslVRVKzhqf_yhd30k1h6SWWr0aAspHEALw_wcB





-----Mensaje original-----
De: TekScopes@groups.io [mailto:TekScopes@groups.io] En nombre de Roy Thistle
Enviado el: viernes, 11 de diciembre de 2020 18:42
Para: TekScopes@groups.io
Asunto: Re: [TekScopes] Looking for parts for 212 portable scope.

On Fri, Dec 11, 2020 at 05:25 AM, Colin Herbert wrote:


Looking at the website and the description "Overhaul Cleaner"
There's Z-294 and Z-294-L... the Z-294 MSDS say's it has 30% cyclohexane (death to polycarbonate... but compatible with most plastics.) If those pots were a plastic/carbon track, or carbon ink track... the cyclohexane might have attacked that. There is also ethanol, and "petroleum solvents" in the Z-294.







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Re: Looking for parts for 212 portable scope.

Roy Thistle
 

On Fri, Dec 11, 2020 at 05:25 AM, Colin Herbert wrote:


Looking at the website and the description "Overhaul Cleaner"
There's Z-294 and Z-294-L... the Z-294 MSDS say's it has 30% cyclohexane (death to polycarbonate... but compatible with most plastics.)
If those pots were a plastic/carbon track, or carbon ink track... the cyclohexane might have attacked that. There is also ethanol, and "petroleum solvents" in the Z-294.


Re: Looking for parts for 212 portable scope.

Roy Thistle
 

On Fri, Dec 11, 2020 at 05:25 AM, Colin Herbert wrote:


Surely not just greed on the part of the manufacturers.
greed applies!


Re: 1S1 sampling bridge GaAs diodes: What alternatives?

Kurt Rosenfeld
 

Do we know the original selection criteria Tek used for the diodes used in the sampling bridge?


Re: 1S1 sampling bridge GaAs diodes: What alternatives?

snapdiode
 

Sadly all my 1S1s are basically bookends these days. I'd love to give it try too but it's not in my plans right now.


Re: 1S1 sampling bridge GaAs diodes: What alternatives?

Dave Wise
 

Which circuit numbers?

Dave Wise
________________________________________
From: TekScopes@groups.io <TekScopes@groups.io> on behalf of snapdiode via groups.io <snapdiode=yahoo.com@groups.io>
Sent: Thursday, December 10, 2020 9:50 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] 1S1 sampling bridge GaAs diodes: What alternatives?

I love the 1N5711. I've replaced several of the GaAs diodes in the 1S1 memory circuit with 1N5711s and it works fine.


Re: Looking for parts for 212 portable scope.

Colin Herbert
 

Looking at the website and the description "Overhaul Cleaner" this seems to be for disassembly and cleaning of mechanical items, though the use on a pcb in the last picture might make you think otherwise. Keep it away from any pots and switches - caveat emptor. There has to be a reason why well-thought-of stuff like Deoxit and Electrolube are a bit on the pricey side, doesn't there? Surely not just greed on the part of the manufacturers.
Colin.
Colin.

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Jared Cabot via groups.io
Sent: 11 December 2020 12:38
To: TekScopes@groups.io
Subject: Re: [TekScopes] Looking for parts for 212 portable scope.

On Fri, Dec 11, 2020 at 09:10 PM, David C. Partridge wrote:


The brand to be avoided is very useful information ...
It's the Japanese brand Hozan, Z-294 Overhaul Cleaner.

https://www.hozan.co.jp/catalog/Maintenance_Tools/Z-294.html

And it's total rubbish...... >:(


Re: Looking for parts for 212 portable scope.

Jared Cabot
 

On Fri, Dec 11, 2020 at 09:10 PM, David C. Partridge wrote:


The brand to be avoided is very useful information ...
It's the Japanese brand Hozan, Z-294 Overhaul Cleaner.

https://www.hozan.co.jp/catalog/Maintenance_Tools/Z-294.html

And it's total rubbish...... >:(


Re: Looking for parts for 212 portable scope.

 

The brand to be avoided is very useful information ...

-----Original Message-----
From: TekScopes@groups.io <TekScopes@groups.io> On Behalf Of Jared Cabot via groups.io
Sent: 11 December 2020 12:02
To: TekScopes@groups.io
Subject: [TekScopes] Looking for parts for 212 portable scope.

Hi all.
I have a 212 portable scope here I was restoring, and it seems the contact cleaner I used wasn't compatible with the pots and stripped the carbon traces clean out of them....


Looking for parts for 212 portable scope.

Jared Cabot
 

Hi all.
I have a 212 portable scope here I was restoring, and it seems the contact cleaner I used wasn't compatible with the pots and stripped the carbon traces clean out of them....
Needless to say, that cleaner has gone straight into the bin and that brand will never be used again.......

So now I'm on the hunt for either the A1 input circuit board in its entirety, or a full set of pots.
Anyone out there got an old 212 scope they can part out to save this one from the scrap pile?


Thanks!
Jared


Re: Yet another use for a curve tracer

Jean-Paul
 

Rebonjour,

No TEK adapters exist For lamp and LED testing.
We made binding post adapters for the test fixtures, two male banana plugs and two small pieces are acrylic plastic, in a sandwich separated by stand-offs.

The 576 is huge and dominantes a bench, It is a fine instrument for power electronics and lighting control development. Only service in 25 years, replaced the gratiticule or fiber optic display lamps.

Ever see the SCR turnoff time test adapter?

Bon journée
Jon


Re: Yet another use for a curve tracer

Miguel Work
 

Yes, I use my 576 to check led backlight

And my 176 to test fake xinese transistors and mosfets to 200A

-----Mensaje original-----
De: TekScopes@groups.io [mailto:TekScopes@groups.io] En nombre de Jean-Paul
Enviado el: viernes, 11 de diciembre de 2020 10:51
Para: TekScopes@groups.io
Asunto: Re: [TekScopes] Yet another use for a curve tracer

Hello all: We have a fine 576 with the pulsed high current test fixture and many adapters.

One unusual use has been testing gas discharge lamps, Telecom protection spark gaps, neon, etc, Set on AC, 0.5 or 2.3 W, up to 1500V No base connection needed. Gas Breakdown voltage and ON impedance are easily checked.

Another use is checking LEDs,
There are some that are very high power and others that are prototype tubular filament LED.
Like a diode but with many series junctions, so voltage forward can be 30-100V.

Enjoy,

Jon







Scanned by McAfee and confirmed virus-free.
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Re: Yet another use for a curve tracer

Jean-Paul
 

Hello all: We have a fine 576 with the pulsed high current test fixture and many adapters.

One unusual use has been testing gas discharge lamps, Telecom protection spark gaps, neon, etc,
Set on AC, 0.5 or 2.3 W, up to 1500V
No base connection needed. Gas Breakdown voltage and ON impedance are easily checked.

Another use is checking LEDs,
There are some that are very high power and others that are prototype tubular filament LED.
Like a diode but with many series junctions, so voltage forward can be 30-100V.

Enjoy,

Jon

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