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Re: MC1456N replacements for 577

Bill Carns
 

P.S.

Both Semi Source and Classic Components have them in stock and there are a number of offerings on eBay

Bill Carns

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of David M
Sent: Monday, June 17, 2019 9:21 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] MC1456N replacements for 577

On Sun, Jun 16, 2019 at 06:25 PM, DW wrote:


I am looking at swapping out these OP AMPs where could I find
something equivalent to this

MC1456N for 577 curve tracer quantity 3

Thanks
Unicorn Electronics (http://www.unicornelectronics.com/prod.htm) has the MC1456N in stock. Look in the Linear section.

Cheers,
DaveM


Re: MC1456N replacements for 577

Bill Carns
 

You can also look at many places where the original VERY equivalent part is stocked under the original Motorola number MC1456P. This is a very common part. Actually, it was my part when I was the Strategic Marketing Manager of the Motorola Analog Division. That part only got the "N" package designation when it was second sourced by TI and National. The Mot part is the better choice.

Regards,
Bill Carns

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of David M
Sent: Monday, June 17, 2019 9:21 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] MC1456N replacements for 577

On Sun, Jun 16, 2019 at 06:25 PM, DW wrote:


I am looking at swapping out these OP AMPs where could I find
something equivalent to this

MC1456N for 577 curve tracer quantity 3

Thanks
Unicorn Electronics (http://www.unicornelectronics.com/prod.htm) has the MC1456N in stock. Look in the Linear section.

Cheers,
DaveM


Re: MC1456N replacements for 577

 

On Sun, Jun 16, 2019 at 06:25 PM, DW wrote:


I am looking at swapping out these OP AMPs where could I find something
equivalent to this

MC1456N for 577 curve tracer quantity 3

Thanks
Unicorn Electronics (http://www.unicornelectronics.com/prod.htm) has the MC1456N in stock. Look in the Linear section.

Cheers,
DaveM


Re: MC1456N replacements for 577

Craig Sawyers <c.sawyers@...>
 

I am looking at swapping out these OP AMPs where could I find something equivalent to this

MC1456N for 577 curve tracer quantity 3
When I blew my 557 up (don't ask) I bought mine from eBay.

Craig


Re: 7854 with strange intensity/focus problem (to me)

unclebanjoman
 

After a few days of use I have to say that the 7854 works quite well except for one thing.
Turning the readout intensity CW the intensity increases but the characters become progressively more blurred.
This does not happens (or happens in a very minimal manner) with the real-time (SCOPE) trace or the digitized trace (STORED INT)..

Seems that the auto focus circuit does not works very well.
I've performed some component checking on the A20 board but all seems O.K.

Today I performed a complete check/calibration of Z-axis circuit, following all the steps, without success. All waveform and voltages are as per manual, with the exception of the step B10 (manual's page 4-53).
For that step a 067-0587-02 signal standardizer is required. I own the early 067-0587-00, having a max rep. rate of 250 KHz instead of the 1 Mhz required.

I tried anyway, but the result is puzzling me somewhat. Cranking the intensity fully CW (readout off, real trace only) the trace become very unfocused but I'm unable to reach a reasonable focused trace adjusting R63 (Focus Gain).
Turning R63 from one end to the other, my DVM connected at TP83 reads between +123 V and -9V.
According to the manual this voltage could be -12V or even more negative, but I reach only -9V at most. And the trace still remains unfocused. The best result is obtained with R63 fully turned CW obtaining a DVM reading of -9V but in this case, returning to normal intensity, and turning on again the readout intensity it is more blurred, worse than before!

I've checked Q77 and Q83 in-circuit with a VOM (ICE 680R) but they looks fine to me.

Focus Output level R70 works fine: I obtain 123 V as per manual.

II am uncertain whether to think about some problems with the CRT focus grid or problems with the autofocus circuit.

Max


MC1456N replacements for 577

DW
 

I am looking at swapping out these OP AMPs where could I find something equivalent to this

MC1456N for 577 curve tracer quantity 3

Thanks


Re: 7854 display during AQR/AVG command blanks or flickers

unclebanjoman
 

Hi Nenad,
thank you for your reply!

7854 with "blank" screen during AVG command:
S/N B095270
Pressing ID button displays: TEK/7854,V79.1,01.03,8K

7854 with "flickering" readout during AVG command:
S/N B063304
Pressing ID button displays: TEK/7854,V79.1,01.03,8K

ID command seems to display same firmware version. The thing become mysterious....

The Operator manual stated (page 5-10) that:

"....(omissis) Return to the DISPLAY mode by pressing STORED.
Press AVG100.
During command execution: the BUSY indicator is lit ; the previously stored waveform is maintained on the display; and the AVG mnemonic, BUSY message, and number of averages to be completed are displayed in t he bottom division (line #16) of t he graticule."

Max


Re: 7854 display during AQR/AVG command blanks or flickers

Nenad Filipovic
 

Hi Max,

At first glance I can't help you much, but I'm curious. I have a late model
7854, during AVG it behaves much like your second unit - real time waveform
update can be seen clearly (a very nice feature), but the flickering
readout is barely readable (but still somewhat usable).

Could you please check the firmware versions of your two units? Just press
the "ID" button near top right corner of the mainframe front panel.

Best Regards,
Nenad Filipovic


Re: 7A13 relay substitution report

tomford717@...
 

I've added some pics of the 7A13 relay and variable cap repair.

https://groups.io/g/TekScopes/album?id=91736

Tom Ford


Re: 7A13 relay substitution report

tomford717@...
 

Yes Al,

What you described is exactly what I found when I removed the original broken air variables
in my 7A13, the compression rings were all cracked. My best solution for replacement was to remove
most of the old cap, only leaving the grounded ring shaped support in place on the pcb. One lead
of a new variable cap was soldered to the original grounded ring section. It served as an electrical
and mechanical connection to support the replacement cap. The free hanging new cap lead was then
soldered to the proper nearby components to complete the install.

I did a complete relay replacement too and have some low res pics to illustrate my solution. I don't
know how to post pics of the relay and variable cap fix, but would like to share it with the group since
others are dealing with the same problem.

Tom Ford


Re: 7A13 relay substitution report

Allan Jamison
 

Regarding the failure of the air trimmer capacitors in the 7A22 and other plug-ins, I believe the cause is that the brass collar that is force fitted on the end of the rotor and normally compresses the spring washer to centre the rotor plates, fails metallurgically.

The failure mode is a single almost invisible crack in one side which relieves the force fit stress and allows the collar to then fall off.

I think this just happens after time. Perhaps the collar material was not properly heat treated but it seems to be a common failure after many years. New collars could be made but would require a precision hole and a press to install them. They have to be a tight fit to maintain pressure to compress the contact washer.

Al Jamison


Re: Waveform calculator keyboard spotted for sale at an electronics fair

David Kuhn
 

" https://www.electronicsfleamarket.com"

That is too cool. I wish we had something liked that around central, PA.

Dave

On Thu, Jun 13, 2019 at 2:24 PM Rajesh VS <rajeshvs@gmail.com> wrote:

Dave, I think it is the electronics flea market

https://www.electronicsfleamarket.com

Was heartbroken to see a 585 and a 545 being dragged away by tube
scavengers/parts sellers in the june one.
I was late by few minutes and could not rescue them.

Regards
Rajesh

Rajesh


On Thu, Jun 13, 2019 at 6:58 AM David Kuhn <Daveyk021@gmail.com> wrote:

An electronics flee market? Never been to one or seen one (other than
Ham
Fests in my youth, but not much like that happens around central PA
anymore). On the truck it says "Sunny Vale, CA", to I suspect this was
in
California somewhere. Too cool.

On Sat, Jun 8, 2019 at 6:06 PM cheater cheater <cheater00@gmail.com>
wrote:

Since those are somewhat hard to find, I thought I would let you guys
know.
I am not sure where exactly this is, but the author of the photo can be
reached.

https://mobile.twitter.com/Foone/status/1137383704521633795








Re: 2246 no display/odd behavior

Matt
 

Successfully replaced CR2701-04 with 1N4936RLG - no change in behavior. Not worse, not better.

For anyone else who may wonder: The diodes definitely have the legs bent under the board. I first cut the diode out close to each side of the body. Then I flowed each remaining leg and wiggled out with tweezers. Then wicked the remaining solder which left a clean via to work with. Installation was about a 4 second heat application at 600 F tip temp.

Anyway - still open to further suggestions.


Re: Oregon Public Broadcasting "Oregon Experience - The Spirit of Tek"

Michael
 

Yes Jim, I was in my office back in the 70s when their sales rep showed up. Of course he tried to imply I was disloyal for not buying Raytheon scopes. We both know there was no scope better, even HP scopes. I was spoiled and would not have wanted to see anything in our shop but 465s. Maybe you could ask around talking to old timers to see if they remember this. My guess is that this branch of Raytheon could not have lasted more than a few months. Who in their right mind would buy one? Clearly it was a terrible decision. Raytheon has the money to handle this kind of failure.

O.T. BTW, I hope your work environment is as good as I had. My boss let me do whatever I wanted as long as our office made money. I did get some flack when I sold complete new electronics to 9 Iranian destroyers after their revolution. Made a great month for me. But my boss said if we were caught the publicity would cost more money than we made that month. Complete electronics meant surface and air search radar, sonar, fathometers, IFF, and radios. They were updating old US destroyers they had purchased. I realized at the time there might be a problem, but wisely got the money up front in cash. Scared me to death walking to my car on the pier with suitcases full of money. It was not until 1980 that Manchester noticed the large sale and purchaser. We regularly serviced Soviet ships for cash up front. Never any credit offered. The design of their radars was suspiciously very like our own Raytheon radars and so they came to us for service. We had the parts and technicians. Seemed like most of the officers spoke English. It was a wonderful time in my life fixing so many different things and meeting people from all over the planet. Now down to repairing transceivers and stereos, sigh.........


Re: PG506 standard amplitude output rise-time?

Adrian Nicol
 

Mine is a B04 something and yes, I can trigger on the noise in that way too!

On 6/14/2019 12:02 PM, Albert Otten wrote:
my PG506 is B03something. With suitable setting of the scope time base unit you can trigger on the spikes in the signal


Re: PG506 standard amplitude output rise-time?

Albert Otten
 

Adrian,

There have been several posts here about that switching noise. Maybe the B04-up version performs better in this respect, I don't know, my PG506 is B03something. With suitable setting of the scope time base unit you can trigger on the spikes in the signal, with the square wave appearing as noise.

Albert


Re: PG506 standard amplitude output rise-time?

Adrian Nicol
 

Thanks Siggi & Albert,

Yes, that was my point and I think Albert is correct, lifting one end of C315 makes the fast noise worse at very low amplitude outputs, although hanging a .05 uF ceramic cap in it's place seems to pretty much get it back where it was in terms of noise but with a much improved rise time. Of course that may just be telling me the noise is way worse than it should be and I need to look at the state of supplies etc - will prod around some more!

Adrian

On 6/14/2019 9:18 AM, Albert Otten wrote:
That's true Siggi, but it doesn't explain the presence of C315 0.22uF across the output.
The 10V-and-below goes down to 0.2 mV. At that low amplitudes spikes produced by the switching power supply appear in the output signal and can be larger than the signal amplitude. I guess C315 serves to reduces these spikes.


Re: PG506 standard amplitude output rise-time?

Albert Otten
 

That's true Siggi, but it doesn't explain the presence of C315 0.22uF across the output.
The 10V-and-below goes down to 0.2 mV. At that low amplitudes spikes produced by the switching power supply appear in the output signal and can be larger than the signal amplitude. I guess C315 serves to reduces these spikes. In earlier versions there was no C315 but the output was filtered by an LC network in the path to the BNC connector. The filter was by-passed in the 20-50-100V positions.

Albert

On Thu, Jun 13, 2019 at 11:51 PM, Siggi wrote:


The standard amplitude output is driven in two different ways - the
20/50/100V output is voltage driven with a current limit, whereas the lower
voltages are current driven for a 50Ohm load. There's a discussion of this
in the Theory of Operation section.

On Thu, Jun 13, 2019 at 1:58 PM Adrian <Adrian@nicol1.org.uk> wrote:

The 1kHz standard amplitude waveform was a curious shape, traced to a dead
or dying opto-coupler driving the 'standard' amplifier stages, fixed by
replacing it.

I then noticed that the output waveform rise time was noticeably faster
(~1us) at outputs of 20V and above than at 10V and below (~23us) this seems
to be due to the 0.22uF in parallel with a 10k5 resistor that is present
across the output connector when these lower voltage ranges are selected.

I realise that this doesn't really matter as it is the amplitude accuracy
that is important in this application but I have failed to find mention of
the purpose of this filter in the service manual, can anyone enlighten me?

Thanks in advance,
Adrian




Re: PG506 standard amplitude output rise-time?

Siggi
 

The standard amplitude output is driven in two different ways - the
20/50/100V output is voltage driven with a current limit, whereas the lower
voltages are current driven for a 50Ohm load. There's a discussion of this
in the Theory of Operation section.

On Thu, Jun 13, 2019 at 1:58 PM Adrian <Adrian@nicol1.org.uk> wrote:

The 1kHz standard amplitude waveform was a curious shape, traced to a dead
or dying opto-coupler driving the 'standard' amplifier stages, fixed by
replacing it.

I then noticed that the output waveform rise time was noticeably faster
(~1us) at outputs of 20V and above than at 10V and below (~23us) this seems
to be due to the 0.22uF in parallel with a 10k5 resistor that is present
across the output connector when these lower voltage ranges are selected.

I realise that this doesn't really matter as it is the amplitude accuracy
that is important in this application but I have failed to find mention of
the purpose of this filter in the service manual, can anyone enlighten me?

Thanks in advance,
Adrian




Re: PG506 standard amplitude output rise-time?

Mlynch001
 

Is it possible this is for load matching?
--
Michael Lynch
Dardanelle, AR

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