Date   
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" [@jgriessen]
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@... 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

Re: Help restoring a 547 scope

Albert Otten
 

On Fri, Jan 26, 2018 at 02:15 pm, <felix_cantor@...> wrote:


Alrighty.... sorry for the delay, I´ve been super busy.

I just uploaded two new pictures from scope images taken at the anode of the
tunnel diode d45 from both time base A and B with the trigger mode set at Norm
and the trigger source at Ext.

The image files are called: "Test point TD anode ch ..."

https://groups.io/g/TekScopes/album?id=16016

Let me know if you suspect anything or if you have any suggestion where to
continue testing.

I need to test some voltages and waves according to schematic <5> still, and
see if I find something

Thank you very much.

F.
It looks as if the test scope (at which you show the waveforms) itself is causing the "double" waveform in B. It's easier for comparisons to trigger that test scope from the signal generator and not from the observed waveforms. I think you won't find much difference between A and B then.

Albert

Re: Any experience with ELECTRONIC LOADS would be appreciated

sittners
 

Nigel-

I'm also interested so please include me with the mailing of a schematic copy.

regards,

Phil

On 1/27/2018 9:29 AM, Leon Robinson wrote:
Nigel,
Please send me the schematic.I bought a heatsink full of 2N3055's to build a load but haven't
started on it yet. Leon Robinson    K5JLR

Political Correctness is a Political Disease.

From: NigelP <nigel-pritchard@...>
To: TekScopes@groups.io
Sent: Saturday, January 27, 2018 7:29 AM
Subject: Re: [TekScopes] Any experience with ELECTRONIC LOADS would be appreciated
Why not build one? You are welcome to the schematic of the one I built decades ago. Uses 4x 2N3055H (hometaxial version for good SOAR) driven as a current sink and can sink 20A up to 50V (or more..... 50V meter fitted). Mine is fitted with a 5" fan just in case it gets a bit warm.

It has a knob to control the current from a DC point of view, or you can externally ramp it linearly, or you can pulse it with TTL, "any frequency", to really exercise the dynamics of the PSU!

Regards

Nigel G8AYM








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Re: 485 after the recap.

Brendan
 

Yes I have tweaked the grid bias. I think im also having an issue with the focus circuit. Later today i will see if I can start making some progress there.