Date   

Re: Any experience with ELECTRONIC LOADS would be appreciated

J. L. Trantham
 

Nigel,

Thanks for the schematic.

I'm a bit puzzled by BR1, the rectifier on the 20 VCT power transformer. Should it be 'rotated' 90 degrees counter clockwise?

Thanks again.

Joe

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of NigelP
Sent: Sunday, January 28, 2018 10:22 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Any experience with ELECTRONIC LOADS would be appreciated

I've had several requests for schematics; I think I've uploaded two files, a PDF scan and a DSN file which is the output of ISIS Schematic Capture (not sure if it is compatible with anything else). Note my actual unit has 4x BDX60 Hometaxial transistors in it (when you work for a semiconductor company you tend to use their products!!!).

Also note to ignore the date shown on the schematic; I had a mad tidying up of all my ancient paper-drawn equipment circuit diagrams recently and the program doesn't let me back-date the file :-(.


Re: 2465B no screen readout

 

When crap like that happens, I swallow my ego (after all, I'm the smartest technician in the world), and go back to where the machine was before my silly fingers touched it.
You said it was working, right?
And all you did was fiddle and play (expertly, I might add) with the PSU, right?
So, you probably, against all odds, screwed up right there.

Bad soldering, or you got some capacitors mixed up - C1132 and C1115 maybe ;-) ?
Wouldn't be the first time that a tech diligently followed the Tek Service manual, and stopped his machine working right there.

EVEN THOUGH the voltages are apparently OK, as you say.

So, take out the PSU (again, I know), and go back and triple-check your work.
Now is NOT the time to start suspecting other PCB's, which you claim that you didn't touch.

Basics in troubleshooting our own screw-ups - works for PSU PCB's and works for jet engines.

LOL

Menahem Yachad
www.condoraudio.com
Israel


Re: New file uploaded to TekScopes@groups.io

Richard Solomon <dickw1ksz@...>
 

Thanks for uploading the file,
but, the values are hard to read,
very light.

Perhaps converting the colors
to black and white would help
and making the values darker or
bolder.

I would do it here if I had a pdf editor.

Thanks, Dick, W1KSZ

On Sun, Jan 28, 2018 at 9:16 AM, TekScopes@groups.io Notification <
TekScopes+notification@groups.io> wrote:

Hello,

This email message is a notification to let you know that a file has been
uploaded to the Files area of the TekScopes@groups.io group.

*File:* Dynamic Load Schematic.PDF

*Uploaded By:* NigelP

*Description:*
Dynamic Load Schematic

You can access this file at the URL:
https://groups.io/g/TekScopes/files/Dynamic%20Load%20Schematic.PDF

Cheers,
The Groups.io Team



Re: Any experience with ELECTRONIC LOADS would be appreciated

NigelP
 

I've had several requests for schematics; I think I've uploaded two files, a PDF scan and a DSN file which is the output of ISIS Schematic Capture (not sure if it is compatible with anything else). Note my actual unit has 4x BDX60 Hometaxial transistors in it (when you work for a semiconductor company you tend to use their products!!!).

Also note to ignore the date shown on the schematic; I had a mad tidying up of all my ancient paper-drawn equipment circuit diagrams recently and the program doesn't let me back-date the file :-(.


New file uploaded to TekScopes@groups.io

TekScopes@groups.io Notification <TekScopes+notification@...>
 

Hello,

This email message is a notification to let you know that a file has been uploaded to the Files area of the TekScopes@groups.io group.

File: Dynamic Load.DSN

Uploaded By: NigelP

Description:
Dynamic Load Schematic

You can access this file at the URL:
https://groups.io/g/TekScopes/files/Dynamic%20Load.DSN

Cheers,
The Groups.io Team


New file uploaded to TekScopes@groups.io

TekScopes@groups.io Notification <TekScopes+notification@...>
 

Hello,

This email message is a notification to let you know that a file has been uploaded to the Files area of the TekScopes@groups.io group.

File: Dynamic Load Schematic.PDF

Uploaded By: NigelP

Description:
Dynamic Load Schematic

You can access this file at the URL:
https://groups.io/g/TekScopes/files/Dynamic%20Load%20Schematic.PDF

Cheers,
The Groups.io Team


Re: 2465B no screen readout

bradley.kimbrough@...
 

Leo,

I do have a separate readout board. I did not remove it when I worked on the power supply boards. In trying to troubleshoot my problem I have removed and inspected the board.
No visually obvious problems. I may need to get an additional readout board for troubleshooting.

Thanks,

Brad


Re: Any experience with ELECTRONIC LOADS would be appreciated

Kevin Oconnor
 

I have no complaints. Mine was branded Kunkin. I was skeptical to be sure. It has all the control you’d expect. Goes to full load on both channels simultaneously. Volt and current meters as accurate as you can expect for 2 decimals. Use it all the time for batteries and ps. Of course your mileage may vary.

Sent from kjo iPhone


Re: 2465B no screen readout

satbeginner
 

Hi,

If you remove the power supply, usually you have to remove the separate readout board, alongside the powersupply.
Usually I remove the readout board before removing the power supply.

It happened to me once that I misplaced the flatcable connection from the readout board to the A1 board when putting it back in :-(

You do have the separate readout board? (if you have the SMD version of the A5 board, the readout functionality is integrated on the SMD A5)

Just my two cents,

Leo


Re: 2465B no screen readout

bradley.kimbrough@...
 

Hello Joe,

I appreciate your response. I gave your suggestion a try, but still no output. I'll keep investigating.

Thanks,

Brad


Re: almost free (postage) TM500 plugin extender pcbs

Erik Hultine
 

My apologies. Definitely take the fee from the transferred amount.

Thanks,

Erik


“The snake which cannot cast its skin has to die.”- Friedrich Nietzsche

-----Original Message-----
From: "John Griessen" [john@ecosensory.com]
Date: 27/01/2018 23:55
To: TekScopes@groups.io
Subject: Re: [TekScopes] almost free (postage) TM500 plugin extender pcbs

These are gone. Please don't send paypal payments before agreeing to a sale. The paypal fees are not refundable.


almost free (postage) TM500 plugin extender pcbs

John Griessen
 

These are gone. Please don't send paypal payments before agreeing to a sale. The paypal fees are not refundable.


Re: 2465B no screen readout

Joe Laffey
 

I don't remember precisely, but I seem to recall one of the scopes needing you to turn the readout intensity back and forth *twice* to display the readout. I think this had something to do with the intensity for use with the camera attachment and single shot trigger mode.

So try turning the intensity knob for the readout all the way counter clockwise and then all the way clockwise and then all the way counter clockwise again, and then up to the desired level. Worth a try....


--
Joe Laffey

On Jan 27, 2018, at 11:24 PM, bradley.kimbrough@gmail.com wrote:

Hello All,

I recently overhauled my 2465B power supply. Prior to the power supply work, the scope was functioning properly. Following repair, the scope will start up, the trace is working, but there is no screen readout. All voltages are in specification. The readout intensity is turned all the way clockwise for scale factors on.

Could it be a faulty A4 board?

Any suggestions would be greatly appreciated.

Regards,

Brad



2465B no screen readout

bradley.kimbrough@...
 

Hello All,

I recently overhauled my 2465B power supply. Prior to the power supply work, the scope was functioning properly. Following repair, the scope will start up, the trace is working, but there is no screen readout. All voltages are in specification. The readout intensity is turned all the way clockwise for scale factors on.

Could it be a faulty A4 board?

Any suggestions would be greatly appreciated.

Regards,

Brad


Former my 2465A died suddenly

ti8jlh
 

Hello to everybody. I am still fighting with the power supply of my 2465A scope. I began last year and now I don´t know what to do.
I was following inverter troubleshooting procedure. Everything was ok before but now the voltage at the cathode of CR1023 stay low. I connected a power supply to the junction of R1020 and CR1022 and slowly rised the voltage to 28V.
I checked Q1021, Q1022 and Q1040 with my AS4002 semiconductor analyzer and the transistors showed no problem. The same with VR1020.(I got a new one). I unsoldered all resistors and capacitors to check them out of the pcb.
U1030 oscillates when it got 12V. When I connect -- direct to the emitter of Q1022 (shorting VR1020), the votlage on the cathode of CR1023 is the same than of the PS I am using minus the 0,5V.
Does anybody had a similar problem or could somebody please help me out giving me an advise.
Thank´s to all and gratulation for new forum.
Joachim


Re: Tektronix 454

erik erickson
 

I spoke to soon, when I switch to .1 volts/div, 2 volts/div, 10 mV volts/div, and 5 mV volts/div the trace disappears. I though maybe adjusting the step attenuator balance may work but when I do that the trace shows up for 5 mV but disappears on all others. Also for a trace to even appear you have to almost put the position switch all the way to the right. The beam finder does bring up the trace though when it’s gone. Any thoughts or should I use channel 1 as a reference and just see.

Sent from my iPhone

On Jan 27, 2018, at 6:41 PM, erik erickson via Groups.Io <the_truth_is_out_there=yahoo.com@groups.io> wrote:

Thanks for all the help. For some reason channel two is working perfectly right know. Trace shows with invert switch on or not but it moves down from the center, one horizontal line. Also the beam finder does the same. I assume this is normal or maybe I didn’t let it warm up enough. I will check the voltages and probe it later but for now I’ll just see how it works.
Sent from my iPhone

On Jan 27, 2018, at 4:48 AM, Roger Evans via Groups.Io <very_fuzzy_logic=yahoo.com@groups.io> wrote:

I found some more useful information in the previous thread which I assume is still valid.

You said that Ch2 would flash on when you pulled the Ch2 Invert switch and also that with the invert switch half way out the trace would stay on screen but not showing any signal.

With display set to Ch2 and Invert pushed in (normal) press the beam finder switch. Is there a line showing that the trace was originally off screen? Now pull the invert switch and press beam finder. Is the trace off centre in the same direction or the opposite direction? If the direction changes the Ch 2 imbalance is probably before SW181, if not then the fault is probably after SW181 (Q184, Q194 or the switching diodes, note that Q184, Q194 are PNP Germanium).

The manual gives the DC levels to be expected in the Ch2 preamp with no signal applied. Start at the collector of Q124 and then the emiiter of Q134. You should be able to get Q134 emitter close to zero with the Ch2 vertical position control.

Q164 and Q174 should have almost identical voltages on their emitters (-0.78V) and collectors (+2.0V) and their bases should be close to 0V, but since the observation implies that the balance is way off at SW181 you may have found something wrong by now. Since the preamp is DC coupled it may not be obvious whether the fault is where you first observe a 'wrong' voltage or due to the DC operating point being wrong because of a fault later on. The observation using the invert switch should help to narrow things down. Another test is to swap Q164 with Q174 and see if the off-screen direction changes and similarly with Q184 and Q194. You can also use the good Channel 1 on the 454 to probe Channel 2 preamp. Display Ch1, put your probe on Ch1 and connect Ch2 to the calibrator, Ch2 set to 1V/div. Then look for where the signal disappears.

Regards,

Roger





Re: Tektronix 454

erik erickson
 

Thanks for all the help. For some reason channel two is working perfectly right know. Trace shows with invert switch on or not but it moves down from the center, one horizontal line. Also the beam finder does the same. I assume this is normal or maybe I didn’t let it warm up enough. I will check the voltages and probe it later but for now I’ll just see how it works.
Sent from my iPhone

On Jan 27, 2018, at 4:48 AM, Roger Evans via Groups.Io <very_fuzzy_logic=yahoo.com@groups.io> wrote:

I found some more useful information in the previous thread which I assume is still valid.

You said that Ch2 would flash on when you pulled the Ch2 Invert switch and also that with the invert switch half way out the trace would stay on screen but not showing any signal.

With display set to Ch2 and Invert pushed in (normal) press the beam finder switch. Is there a line showing that the trace was originally off screen? Now pull the invert switch and press beam finder. Is the trace off centre in the same direction or the opposite direction? If the direction changes the Ch 2 imbalance is probably before SW181, if not then the fault is probably after SW181 (Q184, Q194 or the switching diodes, note that Q184, Q194 are PNP Germanium).

The manual gives the DC levels to be expected in the Ch2 preamp with no signal applied. Start at the collector of Q124 and then the emiiter of Q134. You should be able to get Q134 emitter close to zero with the Ch2 vertical position control.

Q164 and Q174 should have almost identical voltages on their emitters (-0.78V) and collectors (+2.0V) and their bases should be close to 0V, but since the observation implies that the balance is way off at SW181 you may have found something wrong by now. Since the preamp is DC coupled it may not be obvious whether the fault is where you first observe a 'wrong' voltage or due to the DC operating point being wrong because of a fault later on. The observation using the invert switch should help to narrow things down. Another test is to swap Q164 with Q174 and see if the off-screen direction changes and similarly with Q184 and Q194. You can also use the good Channel 1 on the 454 to probe Channel 2 preamp. Display Ch1, put your probe on Ch1 and connect Ch2 to the calibrator, Ch2 set to 1V/div. Then look for where the signal disappears.

Regards,

Roger



Re: Any experience with ELECTRONIC LOADS would be appreciated

ed beers
 

The KL283 (marked with several brand names) seems to 1/2 half the price of the other Chinese 300W options.

Lots of sellers but few user reports.

I take it that you would buy another one?


Re: Help restoring a 547 scope

felix_cantor@...
 

Hi Albert, thanks for the response. The test scope has a pretty good trigger, and I tried different trigger levels but it didn´t change a bit.

I will still try what you suggest though.

Cheers.


almost free (postage) TM500 plugin extender pcbs

John Griessen
 

These are much simpler than Dan Meeks's extenders, and parts are running out and they will be no more.

There are 12 pcbs for making one of of these: http://ecosensory.com/tek/tek_tm_flex_soldered-sm.jpg

12 left: http://ecosensory.com/tek/TEK_TM_FLEX-production-board.jpg

I'll mail two for $1.60 first class paid via paypal. More for a little more. Not less than 2 though.

--
John Griessen -- building lab gear for biologists
Ecosensory Austin TX blog.kitmatic.com

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