Date   

Re: 577D1 Phantom base current

DW
 

Michael,

Thanks for the reply. From what you observed I am not getting the same results. The phenomenon I am experiencing seems to be an issue with improper biasing on the base terminal.

When you set the set the step generator to the single setting, do you notice when raising the collector voltage there appears to be current increase initially then levels off horizontally across the display. And when setting the step amplitude higher or lower this will affect how how much vertical deflection until the line goes horizontal again. Or does it just stay flat at 0. I hope this makes sense.


Re: 067-0912-00 needed

Dave Daniel
 

A schematic for the -00 version of the board is in the datasheet link on the TekWiki page to which Dennis pointed.

DaveD

On Oct 21, 2020, at 13:45, Dennis Tillman W7pF <dennis@ridesoft.com> wrote:

Hi Eric,
I can't help with a schematic, but there is some information on this card on TekWiki at
http://w140.com/tekwiki/wiki/067-0912-00
Dennis Tillman W7pF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Eric
Sent: Wednesday, October 21, 2020 8:55 AM
To: TekScopes@groups.io
Subject: [TekScopes] 067-0912-00 needed

I am thinking about trying to tackle a calibration on my 7854. I have confirmed that the digital and analog sections are out of adjustment. The digital section is about .8 division left of center. In looking through the calibration document It seems I have everything I need to do the calibration except the 067-0912-00 the analog test board. How likely is this something that I am going to be able to acquire it does not look too complex from the schematic just a few IC’s and a data bus.







--
Dennis Tillman W7pF
TekScopes Moderator





Re: 067-0912-00 needed

 

Hi Eric,
I can't help with a schematic, but there is some information on this card on TekWiki at
http://w140.com/tekwiki/wiki/067-0912-00
Dennis Tillman W7pF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Eric
Sent: Wednesday, October 21, 2020 8:55 AM
To: TekScopes@groups.io
Subject: [TekScopes] 067-0912-00 needed

I am thinking about trying to tackle a calibration on my 7854. I have confirmed that the digital and analog sections are out of adjustment. The digital section is about .8 division left of center. In looking through the calibration document It seems I have everything I need to do the calibration except the 067-0912-00 the analog test board. How likely is this something that I am going to be able to acquire it does not look too complex from the schematic just a few IC’s and a data bus.







--
Dennis Tillman W7pF
TekScopes Moderator


067-0912-00 needed

Eric
 

I am thinking about trying to tackle a calibration on my 7854. I have confirmed that the digital and analog sections are out of adjustment. The digital section is about .8 division left of center. In looking through the calibration document It seems I have everything I need to do the calibration except the 067-0912-00 the analog test board. How likely is this something that I am going to be able to acquire it does not look too complex from the schematic just a few IC’s and a data bus.


Re: Tek 4654M; No Trace, No +5V, No +95V; Help

Michael W. Lynch
 

On Tue, Oct 20, 2020 at 11:20 PM, <adesilva_1999@yahoo.com> wrote:


I wonder what made them use the same part number for two entirely different
things - one with the tripler and the rest of the HV circuitry and one that
has just the tripler!
They did not use the same part number for two different parts. The 455 and 465M both use the U550 designation in their schematics, both use the identical TEK part # 152-0635-00. 152-0635-00 is the "all in one" HV Multiplier along with other circuitry.

The 465(not "M)/465B/475 , on the other hand, use the 152-0552-01, which is the stand alone "6 stage" Multiplier, not usable in the 455/465M. This series of scopes has the other circuitry externally, on the main board. Much easier to fix, but less manufacturing friendly.

--
Michael Lynch
Dardanelle, AR


Re: smd precision resistor "paint layer" peeled off while soldering *** advice needed ***

Richard in Edenton NC
 

Thanks Chuck

73 Richard W4MCD


Re: 7A26 edge distortion

 

On Wed, Oct 21, 2020 at 04:20 AM, Raymond Domp Frank wrote:


One of my 7A26's distorts a 1 ns falling edge (PG506, followed by 50 Ohm
attenuator) as shown in this photo:

https://groups.io/g/TekScopes/album?id=255438

Both channels show the same. I've looked for what I considered obvious
problems like the Display Switching area (7A26 SM dwg 4) but haven't found the
cause yet. Other 7A26's show the edge fine.
This is my newest 7A26 (main PCB code 670-2549-21)!
S/N 709928, so Heerenveen. It's the only one in my collection with a green PCB and 155-0078's with date code "429", I guess that's 8429.

Raymond


Re: 7A26 edge distortion

 

On Wed, Oct 21, 2020 at 07:52 AM, Roger Evans wrote:


The picture suggests that the signal might be switching from the full
bandwidth to the 20MHz version at around the 40% level. Have you looked at the
biassing of Q860, Q880 and also for leakage in Q860, Q880, CR860 CR880? It
seems to me that the problem must be related to the semiconductors since a
purely linear circuit should affect positive and negative edges equally.
Hi Roger,
Since these components constitute most of the common parts, I had done some testing in that area. I checked Vbe across Q820 / Q840, Q860 / Q880 and they were correct. I pulled Q860 and Q880 and lifted one end of CR860. No difference.
Next, I bridged some of the trimmer caps with small fixed caps each at a time and found a significant influence. I'm going to check and replace trimmer caps!

Raymond


Re: 7A26 edge distortion

 

On Wed, Oct 21, 2020 at 06:55 AM, John Gord wrote:


The 7A26 has a number of small ceramic trim caps of a design that has proved
to be prone to going open circuit. You may have failures at the same point of
both channels, unlikely as that seems. I would suspect C1432 and C2432 in
particular, since they seem likely to affect the highest frequency signals.
Try turning them: if they have gone open circuit turning them will have little
to no effect. If those are not the problem, try others!
Hi John,
I know the problem with the trimmer caps. I found several that had no effect, initially blaming that on the lack of HF content in the signal as it appears and not expecting a multi-device failure.
I temporarily put some small caps (3 - 10 pF) in parallel with one trimmer-cap at a time and so far, I've found 5 (yes, five) that immediately made the pulse steeper, without overdoing it, in both channels!
I'm afraid this is going to exhaust my donor supply...

Raymond


Re: 7A26 edge distortion

 

On Wed, Oct 21, 2020 at 06:27 AM, John Gord wrote:


Is the rising edge OK?
Hi John,
Both edges show the same behavior.

Raymond


Re: Nice 556 still available for free but pickup only

Chris J
 

Omit, previous message as I see your title, plainly states, "available for free".... Still waking up, here. Good price for a hobbyist with little to spare. Best email is Cjuried@yahoo.com and phone is 954-478-4355 


Sincerely,    
 
Chris
https://juriedengineering.com/

FCC Licensed RF Coordinator
Audio Engineering Society (AES) Member  


This e-mail, and any attachments thereto, is intended only for use by the addressee(s) named herein and may contain legally privileged and/or confidential information. If you are not the intended recipient of this e-mail, you are hereby notified that any distribution or copying of this email, and any attachments thereto, is strictly prohibited. If you have received this email in error, please immediately notify me at (954) 478-4355 and permanently delete the original and any copy of any e-mail and any printout thereof.

On Tuesday, October 20, 2020, 10:53:14 PM EDT, Grayson Evans <wa4gvm@gmail.com> wrote:





Hi Chris,
You are welcome to come pick it up.  Ft. Lauderdale to here is about an hour and 15 maybe 30 I think.
If you are interested, send me an email and I will send you an address.

Grayson


Re: Nice 556 still available for free but pickup only

Chris J
 

Sure. Cjuried@yahoo.com how much are you a asking? 


Chris Juried, WRCB719

FCC Licensed RF Coordinator
Audio Engineering Society (AES) Member  
InfoComm-Recognized AV Technologist
http://www.JuriedEngineering.com
http://www.HistoryOfRecording.com
http://www.linkedin.com/in/chrisjuried

Email: CJuried@yahoo.com  
Voice: (954) 478-4355 


This e-mail, and any attachments thereto, is intended only for use by the addressee(s) named herein and may contain legally privileged and/or confidential information. If you are not the intended recipient of this e-mail, you are hereby notified that any distribution or copying of this email, and any attachments thereto, is strictly prohibited. If you have received this email in error, please immediately notify me at (954) 478-4355 and permanently delete the original and any copy of any e-mail and any printout thereof.

   

On Tue, Oct 20, 2020 at 10:53 PM, Grayson Evans<wa4gvm@gmail.com> wrote: Hi Chris,
You are welcome to come pick it up.  Ft. Lauderdale to here is about an hour and 15 maybe 30 I think.
If you are interested, send me an email and I will send you an address.

Grayson


Re: Tek 2430A collapsed screen image

Tom Lee
 

Hi Szabolcs,

By any chance, are you related at all to the violinist Joseph Szigeti?

--Cheers,
Tom

--
Prof. Thomas H. Lee
Allen Ctr., Rm. 205
350 Jane Stanford Way
Stanford University
Stanford, CA 94305-4070
http://www-smirc.stanford.edu

On 10/21/2020 02:01, Szabolcs Szigeti wrote:
Hi,

This could be a lot of things. But the first thing is to check the power
supplies. If you don't have the service manual, first get it from for
example TekWiki: http://w140.com/tekwiki/wiki/2430
Check all the power rails for proper voltage and ripple. If they are not
good, chances are that you have bad caps in the PSU, common for this model
r have a shorted cap on one of the boards.
Also check the interconnecting cables between the boards.
These are the checks I would do first.

Szabolcs


<jwdtek@charter.net> ezt írta (időpont: 2020. okt. 21., Sze, 6:39):

Does anyone know what can cause the screen image to collapse and only show
a large dot in the middle of the screen on a TEK 2430? I'm new to this
group. I post a photo in "Tek 2430A collapse Screen image"

Thanks!







Re: Tek 2430A collapsed screen image

Szabolcs Szigeti
 

Hi,

This could be a lot of things. But the first thing is to check the power
supplies. If you don't have the service manual, first get it from for
example TekWiki: http://w140.com/tekwiki/wiki/2430
Check all the power rails for proper voltage and ripple. If they are not
good, chances are that you have bad caps in the PSU, common for this model
r have a shorted cap on one of the boards.
Also check the interconnecting cables between the boards.
These are the checks I would do first.

Szabolcs


<jwdtek@charter.net> ezt írta (időpont: 2020. okt. 21., Sze, 6:39):

Does anyone know what can cause the screen image to collapse and only show
a large dot in the middle of the screen on a TEK 2430? I'm new to this
group. I post a photo in "Tek 2430A collapse Screen image"

Thanks!






Re: High-Risk Ceramic Strip Locations in Types 535/545

tek_547
 

Thanx for the info David. I had the same experience with trace intensity variations on a 547.
After several hours searching and measuring it was a voltage variation on the grid of V800, and so increasing the HT. Inspecting of the ceramic strips around I saw a kind of black sooting at the solder joints so time to clean them all with IPA.
After that the voltage around V800 was stable and also the intensity, so happy at all that it was not the HV transformer.
I think it must be that after warming up the scope the sooting gets conductive wich give voltage variations at the grid of V800.
grtz and stay safe, René


Re: Signal occasionally disappears on 492, needs to be power-cycled by unplugging

ulf_r_k
 

John Miles KE5FX has an excellent "Service Notes" on his web-site that detailsa lot of information about what needs to be done with an old 492/494 Tek Analyzer.
Apart from this information, I also had to replace U1040B (74LS74) in the Phase lock synthesizerhaving encountered the same problem described by KO4BB and the transistor in the CRT high voltagesupply module.

Cheers

Ulf KylenfallSM6GXV


Re: 7A26 edge distortion

Roger Evans
 

Raymond,

A simple test - lift one end of each of CR860, CR880 and see if the signal behaves as it should.

Roger


Re: 7A26 edge distortion

Roger Evans
 

Raymond,

The picture suggests that the signal might be switching from the full bandwidth to the 20MHz version at around the 40% level. Have you looked at the biassing of Q860, Q880 and also for leakage in Q860, Q880, CR860 CR880? It seems to me that the problem must be related to the semiconductors since a purely linear circuit should affect positive and negative edges equally.

Regards,

Roger


Re: 7A26 edge distortion

John Gord
 

Raymond,
The 7A26 has a number of small ceramic trim caps of a design that has proved to be prone to going open circuit. You may have failures at the same point of both channels, unlikely as that seems. I would suspect C1432 and C2432 in particular, since they seem likely to affect the highest frequency signals. Try turning them: if they have gone open circuit turning them will have little to no effect. If those are not the problem, try others!
--John Gord

On Tue, Oct 20, 2020 at 07:20 PM, Raymond Domp Frank wrote:


Dear experts,
One of my 7A26's distorts a 1 ns falling edge (PG506, followed by 50 Ohm
attenuator) as shown in this photo:

https://groups.io/g/TekScopes/album?id=255438

Both channels show the same. I've looked for what I considered obvious
problems like the Display Switching area (7A26 SM dwg 4) but haven't found the
cause yet. Other 7A26's show the edge fine.
Any ideas?

Thanks,
Raymond


Tek 2430A collapse screen image

jwdtek@...
 

Does anyone know what can cause the screen image to collapse and only show a large dot in the middle of the screen on a TEK 2430?

9881 - 9900 of 182191