Date   

Re: looking for a 7A22 V/div knob (366-1057-00)

 

On Mon, Aug 24, 2020 at 10:15 AM, Egge Siert wrote:


The same Knob (outer) is used on a 7S11 and 7A29.
Thanks for that, Egge Siert.
I've verified that the same outer knob fits my 7S11's, 7A22's, 7A26's and 7A29's (tried one sample of each...).
In their (my) respective SM's the knobs are specified as 366-1057-00 for the 7A22 and 366-1059-00 for the 7A26 and 7A29.
The inner knobs are different because the 7A26's and the like have a slot for gain adjustment, which the 7A22 and 7A29 don't.

Raymond


Re: Tek 465: CH1 No signal, CH2 signal reads a fraction of input, V Pos distorts signal

Greenpitu@...
 

Hello Roger,

It was the C443 I mistakenly adjusted, that went around and around. Service manual states:

C443, 5.5-18 pf, Var, Air

I think you are right, Roger. According to the service manual this var cap does indeed serve to "Adjust Ch2 and vertical output high frequency compensation" calling for 42" bnc cable, two X10 attenuators, 50 ohm terminator and a high frequency pulse generator - I understand on +/- 50V.

The pulse generator I will be able to source (alongside the additional scope) is a 200Mhz DDS, but unsure of the amplitude/peak-to-peak spec at this stage. Hoping it will reach those 50V...

I was thinking of building the 10X attenuators myself to run this test.

Regards
Luis


Re: Tek 465: CH1 No signal, CH2 signal reads a fraction of input, V Pos distorts signal

Roger Evans
 

Luis,

In the previous mail you said you had been adjusting a pot, which you mistakenly identified as R429, and it went around and around, which sounds like something is broken. It is worth checking it again when you know what it should be affecting. If it is one of the high frequency adjustments then you need a fast, square edge from a suitable pulse generator which is not a cheap item to purchase. It is possible to make a fast, reasonably square pulse from fast logic gates if you fancy building something yourself. You always then have the problem of knowing if the pulse quality is good enough without having another, faster scope to measure it!

Regards,

Roger


Re: Tek 465: CH1 No signal, CH2 signal reads a fraction of input, V Pos distorts signal

Greenpitu@...
 

Hello Roger,

Thanks for your email. I think I have good news!

I opened up the scope once again to proceed as indicated and measured 174.8 ohm on one side of R429 (i.e. R427) and about 1 ohm on the other (R428). Confused as I was I went back to the service manual pictures and I realized my mistake: when I then tried to adjust R429 the other day to move the trace line at the center of the graticule I was operating and adjacent pot instead... no wonder the trace wasn't moving! :-)

It took a few rounds of calibration on the Vertical output amplifier bias, the vertical output centering, Ch1/Ch2 step attenuator balances and Ch1/Ch2 position centering adjustments to get a stable, centered trace that wouldn't compress/expand when operating Ch1/Ch2 vertical position. I will repeat the operation and further checks once I get hold of second scope and trustworthy generator.

At this stage I'd say the issues originally posted on this topic are fixed on both Ch1 and Ch2. I have the occasional arcing (almost absent now after thorough cleaning in the area and with scope cover on) and just sourced the neutral silicon as per instructions above.

I am immensely grateful to Roger, Raymond, Simon, Chuck, David and scm for all your guidance and patience to help fix this great scope!

Best regards


Re: looking for a 7A22 V/div knob (366-1057-00)

Egge Siert
 

Hi again,

See for some other Knob PN's:

http://www.barrytech.com/tektronix/knobs/tekknobs.html

Greetings,

Egge Siert


Re: looking for a 7A22 V/div knob (366-1057-00)

Egge Siert
 

Hi Leo and Raymond,

The same Knob (outer) is used on a 7S11 and 7A29.

Greetings,

Egge Siert


SC504 INT SYNC queries

EJP
 

1. What is the internal switch behind the SC504 indicator lamp for? Is this the switch referred to at the bottom of p.2-5 of the Specifcation and Performance Check section of the manual? and if so can someone expand on the rather cryptic description?

2. I'm looking into this area because the INT SYNC signal I am providing at 15B/14B of the backplane isn't triggering. It seems to be getting through correctly, because if I rotate the Triggering Level control rapidly through its top dead centre it momentarily syncs, lights the SYNC light, and freezes the display, but there is no position of this control I can find, however slowly, that will keep it that way. The plugins I'm using to provide the SNC vary from two SG505s to an SG502 and an AF501. The main SG505 I use has been adjusted by me to provide 200mV at the front SYNC output with this backplane connection in place, which sucks the level down a bit due to the 50-ohm termination, but even setting it as high as 350mV doesn't fix it, and this is about as high as it can go.

I've checked both 24R loading resistors at this input, they are OK, and all these oscillators can trigger everything in the place via their front panel SYNC outputs.

Any clues?

EJP


Re: PS503A Mod FF Photos?

J Mcvein
 

So 4.5 to 5.5 Vdc
In ye olde days, enough to test TTL logic circuit at min/max supply voltage.
7805 regs are usually on the low side. -J-
-----Original Message-----
From: "Eric" <ericsp@gmail.com>
Sent: Sunday, August 23, 2020 9:26pm
To: TekScopes@groups.io
Subject: Re: [TekScopes] PS503A Mod FF Photos?



I hate to be the barrier of bad news but the mod FF only gives a +0.5 -0.5
adjustment not a fully adjustable output.

So 4.5 to 5.5 Vdc

Eric

On Thu, Aug 20, 2020, 9:12 PM Jared Cabot via groups.io <jaredcabot=
protonmail.com@groups.io> wrote:

Hi,
Does anyone have a PS503A Dual Power Supply module with the Mod FF
(adjustable 5v output) installed?
I'm just looking for some photos to determine the difficulty of
retrofitting this mod to my unit.


Thanks!
Jared




Re: TDS 68x Fan replacement

Tom Bowers
 

Rogerio,

I had the same issue on a TDS684B. I removed the fan, peeled off the label
and popped off the rubber cap. Then the bearing was exposed and I added 2
or 3 drops of oil. Slide the impeller in and out to get the oil all the way
along the bearing and then reassemble. I use either 3 in 1 oil or a good
synthetic motor oil, whatever is handy. This solved my problem. Good Luck,

Tom Bowers
PVH Engineering

"I have a TDS 684A with a very noisy fan. ------ Any suggestions?"

On Sun, Aug 23, 2020 at 8:06 AM Rogerio O <rodd414@gmail.com> wrote:

Dear all,
I have a TDS 684A with a very noisy fan.
I searched this forum ( Google it) for a replacement and or mod but I
could not find any information at all.
Any suggestions?




Re: PS503A Mod FF Photos?

Eric
 

I hate to be the barrier of bad news but the mod FF only gives a +0.5 -0.5
adjustment not a fully adjustable output.

So 4.5 to 5.5 Vdc

Eric

On Thu, Aug 20, 2020, 9:12 PM Jared Cabot via groups.io <jaredcabot=
protonmail.com@groups.io> wrote:

Hi,
Does anyone have a PS503A Dual Power Supply module with the Mod FF
(adjustable 5v output) installed?
I'm just looking for some photos to determine the difficulty of
retrofitting this mod to my unit.


Thanks!
Jared




Re: looking for a 7A22 V/div knob (366-1057-00)

 

Leo,
Isn't that the same as on a 7A18, 7A26 etc.? (ATM, I'm not where my collection is).
Are you talking about both the inner and outer knob?
If so, I have one for you free, to be picked up in Amsterdam.

Raymond


Re: TDS684A freezing during boot (erratic behaviour)

Stephen Hanselman
 

I would look in the HVPS. This PS is fed 24V only and makes all of its internal use voltages it self. Usual suspects caps and such. Shoot me on you have and I’ll see if I have a spare.

If you get it working otherwise and don’t’ try mind spending some money look at SimmCon Labs for the lcd replacement. I have one in my TDS-540C and also my 8593 both work fantastic, lower the heat output and are sharper imaged. Downside they do range in cost from 399 to 899(8566’s). Our customers love them also.

Regards,

Stephen Hanselman
Datagate Systems, LLC

On Aug 23, 2020, at 14:44, Rogerio O <rodd414@gmail.com> wrote:

That you all for the replies.
I tried to turn it on just to make sure I would provide a correct answer to reply to amirb and I had two different issues now.
First I had SPC fail ( which not happened when I rebboted).
The second is a "shaky display".
What is the "usual cause" for a shaky display? PSU?
Thanks,
Roger



Re: TDS684A freezing during boot (erratic behaviour)

amirb
 

Now, this very much looks like a power supply problem or (less likely for the time being) the CRT driver board.

the PSU (and also acquisition board) on these units run very very hot generally and need a lot of air flow
and the caps are more likely to give up under these conditions

psu can be run without connecting to the other parts, so it is easy to work on it


Re: TDS684A freezing during boot (erratic behaviour)

Rogerio O
 

That you all for the replies.
I tried to turn it on just to make sure I would provide a correct answer to reply to amirb and I had two different issues now.
First I had SPC fail ( which not happened when I rebboted).
The second is a "shaky display".
What is the "usual cause" for a shaky display? PSU?
Thanks,
Roger


Re: looking for a 7A22 V/div knob (366-1057-00)

Ray
 

You be suprized postage for small stuff like a knob is not that high if it fits into a padded envelope.Normal mail is $1.15 so with a knob in it the extra weight might up to $ 2 or 3. RaySent from my T-Mobile 4G LTE device------ Original message------From: Leo PotjewijdDate: Sun, Aug 23, 2020 13:29To: TekScopes@groups.io;Cc: Subject:[TekScopes] looking for a 7A22 V/div knob (366-1057-00)Title says it practically all, I want to improve the usability of my 7A22 which has that knob broken.
Living in the Netherlands: European offers are preferred for the (probably) lower postage.
Please reply off list.


looking for a 7A22 V/div knob (366-1057-00)

Leo Potjewijd
 

Title says it practically all, I want to improve the usability of my 7A22 which has that knob broken.
Living in the Netherlands: European offers are preferred for the (probably) lower postage.
Please reply off list.


Re: 184 Schematics

Brian
 

That's a great idea.  I might have to work on that for mine. Thanks for the ideas and offering them to share!
On Sat, Aug 22, 2020 at 4:24 PM, david via groups.io<davide_us=yahoo.com@groups.io> wrote: I have taken all the schematics for a 184 that were in two pieces and assembled each schematic into a single document. All PDF files. If anyone is interested I can put the in a ZIP file and Email them to you. Much easier to understand circuits when looking at complete schematic.
David


Re: FG 504 problems

Colin Herbert
 

Has anyone ever tried cleaning the contacts on the "Frequency Multiplier" switch? They are (I'm sure) cam-type switches and are probably rather similar to the "Attenuator" switch contacts. The problem is access. While the "Attenuator" contacts are easy to get at and use the "paper soaked in isopropanol trapped between the contacts" technique, the "Frequency Multiplier" contacts can barely be seen. While I can't detect any higher-resistance situations, I'm wondering if (since these contacts are on a pcb, not like the attenuators in the 400-series scopes which are on a sensitive substrate) a few gentle and sparing squirts of Servisol would be a good or a bad idea?
Any opinions welcome.
Colin.

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Colin Herbert via groups.io
Sent: 22 August 2020 10:32
To: TekScopes@groups.io
Subject: Re: [TekScopes] FG 504 problems

I am still puzzling over this. I have read the manual relating to the capacitance multiplier and have checked that C210, the resistors associated with it and switches 5, 6, 7 and 8 all look OK as far as I can tell. Also, R216 measures 10K and the slider is operating correctly (when U215 is out-of-circuit). I am left with the possibility that U215 is faulty, but I can't find a replacement. Does anyone have any better ideas, or maybe a replacement for U215 (Tektronix-made 156-0484-00)?
TIA, Colin.

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Colin Herbert via groups.io
Sent: 17 August 2020 13:53
To: TekScopes@groups.io
Subject: Re: [TekScopes] FG 504 problems


I still have some problems with the Function Generator (though I have fixed one) which relate to the symmetry adjustments.
All of the power-supply voltages and ripple levels are within spec. I have got through and ensured that items #6 and #7 in the adjustment procedures are correct. These relate to the "Top Dial Waveform Symmetry (R52)" and "Minimum Dial Waveform Symmetry (R155)". The problem comes in with the next procedure "Adjust Low Dial Waveform Symmetry (R215)". This requires a 10Hz square-wave to be generated and output, but my FG 504 stops oscillating at something like 90 Hz and just gives positive pulses of approximately 3.25 ms width. This cannot be corrected with R215, which has -15 VDC on its slider, but doesn't change the voltages on pins #1 and #5 of U215. At the other end of the "Frequency Start" dial, the square-wave is more symmetrical (but not completely so) and the positive pulses are about 1.75 ms wide. This is all with the "Frequency Multiplier" switch at 10. Could this be a failure of the timing capacitor at this setting, or is R215 or U215 at fault? I have tried reseating U215 with no improvement.
The +1V/-1V triangle waveform at the junction of R225 and R228 under the conditions stated in the manual is fine.

Any suggestions as to what is going on?

TIA, Colin.


Re: TDS684A freezing during boot (erratic behaviour)

Stephen Hanselman
 

If you have not done it already open it up and blow all the dust out of the unit. The fan sucks air through the PS andHV card. We have found virtually all of the units we’ve worked on had a serious reduction in air flow through the PS area

Regards,

Stephen Hanselman
Datagate Systems, LLC

On Aug 23, 2020, at 07:18, Rogerio O <rodd414@gmail.com> wrote:

Dear all,
I bought this scope from Ebay some time ago and it has been working very well.
However, since one month ago, it started to "freeze" during boot.
It does not happens all the time, but once every two or three power on attempts.
When it happens, I manage to make it run by powering on/off a couple of times, but that made me think I will run into trouble soon.
I suspected that I could have a capacitor leakage problem but I inspected the boards for corrosion but I could not find it.
Maybe the caps are just starting to fail so here comes the one million dollar question: Should I recap this scope?
Is this a common failure in this model?
Any other suggestions?
Thank you very much in advance for the help.



Re: TDS684A freezing during boot (erratic behaviour)

amirb
 

psu is a good starting point but it could be your NVRAM about to give up
at what stage during boot does it freeze?
I would suggest you build the debug port and see the debug console first. That will give you a better clue as to what the problem is

11341 - 11360 of 182077