Date   
Re: Service manual spine font

stefan_trethan
 

I think you should ask Tek, sorry, Tk, for the font used in the new logo.

ST

Re: Replacing probe-sensing BNC inputs.

Clive Redfern
 

I forgot to mention that you may drill the edge of the nut from outside the case. The hole would be later covered by the new plug and its washer.One side should be sufficient to subsequently split it with a bit of screw driver prying.If its severely stuck then drill both sides....then it falls in half.Clive F5VHS

Re: Tektronix (7854 e.a.) Fan Controller revisited

 

On 07 Feb 2016 01:16:34 -0800, you wrote:

Hi Raymaond, good possibility that you are right with the relative quit fan but mine maybe is a bit tired so I choosed for another option.
I wonder if there was another change then. I have a 7854 which is
later than yours (B105xxx with the uprated RAM and ROM and lithium
battery backup which I believe is the same version as Raymond's) and
while its fan is audible, I would not consider it objectionable.


...

Another question about my 7854;

it´s from spring 1984 (SN B063508) with the A31 ROM board 670-5847-03. Thus the last version of this ROM board.

Are these also suspected for the ROM rot problems or is this only a problem with the very first versions of this board with the Mosteks ( I have Motorola´s)?
I think that was a problem only with the Mostek mask ROMs.

Re: Service manual spine font

snapdiode
 

Draw is too basic and finicky. Gonna try Draftsight, but I still need the typeface for the model...

Re: Tek 555 part needed.

ChuckA
 

They don't have the same part number.

I parted a 555 out awhile ago (had 3 and it didn't have PS), not sure if I kept the transformers. I'll look through my parts pile and see.

Chuck

On 2/7/2016 9:41 AM, W8ZV kim.herron@... [TekScopes] wrote:
Morning!

I have a 549 that is a parts unit. I may have your transformer, but
I've got to check to see if they are the same part number.
Thanks,

Kim
--
See Early TV at:

www.myvintagetv.com

Re: Replacing probe-sensing BNC inputs.

stefan_trethan
 

Hi Colin,

I just got a 3D printer, so....

Now seriously, I have had good luck in the past with making custom
thin wall tube spanners (light duty) out of copper pipe. It can be
formed easily, and the shape doesn't have to be perfect to work.

ST

On Sun, Feb 7, 2016 at 2:16 PM, 'Colin Herbert'
colingherbert@... [TekScopes] <TekScopes@...>
wrote:

Hi,

I have now made some attempts to replace the BNC socket, but I’m at a bit of an impasse. I have de-soldered most of the attached components, but it looks as though the nut fastening the socket is a bit difficult to get at. On top of this, the Service Manual shows it to be duodecagonal (12-sided) rather than hexagonal. I can’t get any kind of conventional spanner, or pair of pliers into the space to try to loosen the nut. I thought of trying to make some kind of short box-spanner to do this, but my engineering facilities are a bit limited.

Does anyone have a solution to this that I can’t see myself? Any help appreciated; I don’t really want to put all the components back onto the faulty BNC socket having got this far, but in the end I might just have to give in and do that.

Colin.





[Non-text portions of this message have been removed]



------------------------------------
Posted by: "Colin Herbert" <colingherbert@...>
------------------------------------


------------------------------------

Yahoo Groups Links


Re: Tek 555 part needed.

kim.herron@sbcglobal.net
 

Morning!

I have a 549 that is a parts unit. I may have your transformer, but I've got to check to see if they are the same part number. I'm going to be gone in a bit, and won't be back to late this afternoon, but I'll check the two manuals and see if they are the same. You can reply directly to me off list at kim.herron@....

Thanks,

Kim

On 2/6/2016 4:56 PM, lbfulton@... [TekScopes] wrote:
Was wondering if anyone here had, or knew where to get, a Tek part no.
120-124 high voltage transformer. This is T901, lower beam high voltage
transformer, on the CRT schem. for a Tek 555. I need this to get the
lower beam right and have had no luck with an internet search. Thanks
for your time and any help.


--
Kim Herron W8ZV
1-616-677-3706

Re: 1241 logic analyzer power supply debug

Bert Haskins
 

On 2/6/2016 6:54 PM, Murray murrayatuptowngallery@... [TekScopes]
wrote:

Hello:

New here.

I'm helping someone with three Tektronix 1241 logic analyzers trying
to get 2 of 3 working. 3 of 3 if really lucky.

One (call it #3) has not been looked at yet but has the same symptom
as #2.

#1 had a display that went dark after 5 minutes. Found a seized
cooling fan. Replaced it and it works.

#2 and 3 both have trigger self test failure 6111 sequence control.

#2 to my surprise experiences this selftest failure due to the 3V
power supply (service manual calls it '-2V' derived from +5VDC.

The -2 supply (referenced to +5) which is +3 referenced to ground is
actually -0.74 (4.23).

Service manual has some info on the -2 supply, which is a bit
strange...fed from a 5V 3-terminal regulator, it's apparently a
discrete part pwm current sink with shutdown that tracks 5V shutdown.

I've already talked too much but know 100% it is a supply problem
(complete module swap in both directions between units #1 & #2).

What I would like to ask before defending the troubleshooting done so
far, is whether anyone knows what is necessary to get the power supply
to run without the rest of the analyzer connected.

I found two 'requirements' (front panel DC 'kickstart' power switch
(may be an anti-shutdown), and the thermal fuse on the interface card
that goes to ground.

The outputs pulse when operated alone. +3 (-2) and 5 have sense
resistors on the PS board. I added 100 ohm loads to 4 of the outputs
and both the good and bad supplies have the same strange startup so I
think I need to satisfy one other issue.

Thanks!

Murray
Holland MI
That "Holland MI" made me notice.
I'm in Grand Haven and have about a dozen Tek scopes.

Thanks,
Bert




Re: Replacing probe-sensing BNC inputs.

Clive Redfern
 

Perhaps drill one side ad split the nut.
Clive

From: "'Colin Herbert' colingherbert@... [TekScopes]" <TekScopes@...>
To: TekScopes@...
Sent: Sunday, February 7, 2016 2:16 PM
Subject: [TekScopes] RE: Replacing probe-sensing BNC inputs.

  Hi,

I have now made some attempts to replace the BNC socket, but I’m at a bit of an impasse. I have de-soldered most of the attached components, but it looks as though the nut fastening the socket is a bit difficult to get at. On top of this, the Service Manual shows it to be duodecagonal (12-sided) rather than hexagonal. I can’t get any kind of conventional spanner, or pair of pliers into the space to try to loosen the nut. I thought of trying to make some kind of short box-spanner to do this, but my engineering facilities are a bit limited.

Does anyone have a solution to this that I can’t see myself? Any help appreciated; I don’t really want to put all the components back onto the faulty BNC socket having got this far, but in the end I might just have to give in and do that.

Colin.



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[Non-text portions of this message have been removed]

Re: Replacing probe-sensing BNC inputs.

Dale H. Cook
 

At 08:16 AM 2/7/2016, Colin Herbert wrote:

... the Service Manual shows it to be duodecagonal (12-sided) rather than hexagonal.
Have you tried a 12-point box wrench or socket?

You may have to remove the panel from the chassis, as the socket was likely installed on the panel before it was installed on the chassis.

Dale H. Cook, GR / HP Collector, Roanoke/Lynchburg, VA
http://plymouthcolony.net/starcity/radios/index.html

Re: TDS 380 calibration and vertical scale problem

Siggi
 

On Sat, 6 Feb 2016 at 22:28 david.wilson92@... [TekScopes] <
TekScopes@...> wrote:

I uploaded a video so you can see what I mean when I did this test as I
just recently posted. It looks like before everything was made worse as I
was running lower frequency square waves. Why didn't this occur to me
sooner? Then again as mentioned I probably have bad hybrids and about that.
Would a failed hybrid be able to pass signals like this? Would I even get
get a signal to go through where it is intelligible on the screen? Maybe
hybrids can get burned or popped in many different ways, maybe in my case I
have a partially blown decade. Or maybe we're missing something... ???
Enjoy the video
Hey David,

great video, though it's probably better to e.g. upload to YouTube and
share from there as I couldn't view this on my iPad. It looks to me that
this is consistent with the loss of a resistive divider element. High-Z
attenuator input impedance is always specified as 1 MOhm parallel with some
capacitance, in your case "TDS 380: 1 MOhm ±1% in parallel with 12 pF ±2.0
pF". A 10X probe is a resistor/capacitor combo that makes an exact 1/10
voltage divider across all frequencies (see e.g. <
https://www.youtube.com/watch?v=OiAmER1OJh4>).
Note the phase shift between the channels, another hint that you've lost a
resistor.

IMHO it's likely that one of the thick film resistors on the hybrid (note
the hybrid is the whole attenuator module, the preamp IC is on the hybrid
for our discussion) has gone open, and that you'd be able to see the damage
if you remove the attenuators from the scope. Possibly this is fixable by
soldering in a suitable SMD resistor, though this won't give you all the
properties the hybrid construction has. The SMD resistor is sure to have a
different tempco than the thick-film elements, as a case in point.
The preamp IC is likely still good, though that's not for certain, it's
possible that what's gone open is some sort of switching element in the IC.

As to how this would happen the same way for both channels, a likely
scenario is that someone's looking at a terminal signal with CH1, and the
signal all of a sudden vanishes. The operator goes "huh" and hooks the
signal up to CH2, thus burning out that channel too.
This is apparently a common occurrence in student labs :/.

Siggi


[Non-text portions of this message have been removed]

Re: TDS 380 calibration and vertical scale problem

Siggi
 

On Sat, 6 Feb 2016 at 19:06 edbreya@... [TekScopes] <
TekScopes@...> wrote:

Sorry guys, didn't mean to send it off on a tangent.
No worries, it's great to get another viewpoint on David's trouble, and it
appears we don't have a whole lot of collective wisdom on the TDSen in this
group yet. It seems to me these scopes are becoming more and more numerous
on ePray, so I'd expect we'll see more and more questions on those.

What's the maximum V/div of the scope?
I believe it's 10V/div.

I just looked at the TDS544A - it looks like 10V/div tops. It says it can
take 400V peak, but that's survival range, not necessarily working range.
Let's say we allow for +/-10 divs of dynamic range up front, so +/-100V
input for a valid signal. A switchable 20x attenuator would get it down to
+/-5V, which may be in the ballpark. A 100x would give +/-1V, allowing a
400V input to fit into less than 5V.
The TDS380 schematic labels the relay input "25/100" EN for what it's worth.

The max voltage is specified as: ±300 V (DC or AC) CAT II; derate at 20
dB/decade above 100 kHz to 13 V peak AC at 3 MHz and above.
I could easily see this exceeded by an order of magnitude when e.g.
troubleshooting a switching power supply or some such.

This could change the front-end topology quite a bit from traditional
scopes. There are a lot of advantages, especially in direct up-front
DC-offsetting, to preserve dynamic range. I built a front-end this way
once, that operated directly at up to 500V/div with 10 megs input R, up to
2500V, and could be offset that amount. One attenuator step provides pretty
wide dynamic range, but the feedback is quite complicated.
My TDS784D does have a settable offset with a range that goes something
like 10V/1V/100mV depending on the attenuator settings.

Just in case, input R should always be viewed with power on, and tested at
both polarities to make sure bias current isn't upsetting the measurement.
David - I mentioned this on the EEVBlog thread. I suspect the outcome will
be the same, but please see whether there's significant difference in the
input resistance when measured with the test leads reversed.


[Non-text portions of this message have been removed]

Re: Replacing probe-sensing BNC inputs.

Colin Herbert
 

Hi,

I have now made some attempts to replace the BNC socket, but I’m at a bit of an impasse. I have de-soldered most of the attached components, but it looks as though the nut fastening the socket is a bit difficult to get at. On top of this, the Service Manual shows it to be duodecagonal (12-sided) rather than hexagonal. I can’t get any kind of conventional spanner, or pair of pliers into the space to try to loosen the nut. I thought of trying to make some kind of short box-spanner to do this, but my engineering facilities are a bit limited.

Does anyone have a solution to this that I can’t see myself? Any help appreciated; I don’t really want to put all the components back onto the faulty BNC socket having got this far, but in the end I might just have to give in and do that.

Colin.

Re: Ebay Rip-off ? - "Global Shipping Program"

tek_547
 

Interesting info Menahem, thanx for that and good to know...
and btw, I saw a while ago a very informative explanation about recapping a Tek 2465b,
compliments for that !
grtz, René

[Non-text portions of this message have been removed]

Re: OT: Wanted: Specific Mallory cap...

Michael A. Terrell
 

Were the actually made by Mallory, or did Mallory buy them from someone else? A lot of what I bought from Mallory was made by someone else. Like their old FP twistlock sockets.

-----Original Message-----
From: "edbreya@... [TekScopes]" <TekScopes@...>
Sent: Feb 3, 2016 8:24 PM
To: TekScopes@...
Subject: [TekScopes] Re: OT: Wanted: Specific Mallory cap...

If you know what they should look like, maybe you can fake them by printing your own labels on transparency sheets, cut and wrap around similar blank cans as needed, and dirty and stain them up a little to look old.

Ed
Michael A. Terrell

Re: Tektronix (7854 e.a.) Fan Controller revisited

tek_547
 

Hi Raymaond, good possibility that you are right with the relative quit fan but mine maybe is a bit tired so I choosed for another option.

But in my madness (like most other people here I think ;-) I bought also a few other 7000´s and in one of my (fanless) 7904 I made a very thin computer fan under the powersupply. Thus between the perforated housing of the SMPS and the perforated bottom plate of the scope.

There is not much space but is was possible to place a very thin Scythe Slipstream fan between it, including some filtermaterial to protect it against dust. It is type SY1212SL12L (120mm x 120mm x 12mm by 1200rpm) and the total space is I thought 18mm so enough room for it.
Scythe sell three types of these thin fans from 800rpm till 2500rpm but with the 1200rpm version I have a bit headroom to "adjust" the amount of airflow with a series resistor.

With that resistor between the 15V suppy on the regulator board you can lower the rpm´s till the fan gets about 9V and then it´s almost noiseless and protects the electronics from overheating. Give me better feeling for better lifetime for the switcher because I don´t want troubles with it; lower temp is less trouble.

btw I tried also such a construction with a 7704a (fanless) but the space between is less, IIRC 10mm so not enough and I mounted a fan above the regulator board and workes also perfect :-)

Another question about my 7854;
it´s from spring 1984 (SN B063508) with the A31 ROM board 670-5847-03. Thus the last version of this ROM board.
Are these also suspected for the ROM rot problems or is this only a problem with the very first versions of this board with the Mosteks ( I have Motorola´s)?

grtz and glad to hear, René

[Non-text portions of this message have been removed]

Re: Vote on plain text posting

sergio_lopez3@...
 

agree

Re: Service manual spine font

Merchison Burke
 

It is possible that the font in question is proprietary to or copyrighted by Tektronix and as such is not commercially available. You may have to try duplicating it.

On 2016-Feb-06 3:54 PM, snapdiode@... [TekScopes] wrote:
Windows and Libre Office Draw. I looked through all the fonts I have, some are close. It's the K that's hard to match.

I think I'll just use lines and shapes, I only need 9 glyphs.

I'll measure with a caliper and see what I can come up with.

Re: Ebay Rip-off ? - "Global Shipping Program"

 

I always email the seller, and advise him that I am willing to bid, only on condition that the item is sent by Regular Post, and NOT via the Ebay GSP.

Of course, there always follows a "Why?", and then the explanations.


About 50% of the time, the seller agrees, and the deal is done. The other 50%, I just pass - there will always be other opportunities.


The fact is that Pitney Bowes charges a premium of 15% over the regular Postal charge for the privilege of touching the item.
Many times, the item is repackaged to get rid of the "excessive" protective packaging, to save weight, therefore negating the seller's efforts to ensure safe arrival, and the package is more likely to arrive damaged.


I don't know about price-fixing, but USPS's outrageous charges are due entirely to their enormous Pension Fund deficits which must be covered (piss-poor management). This was covered extensively on the web about a year ago. The other carriers (who don't have that overhead) just follow in line.


Menahem Yachad
CondorAudio
Israel

Re: Tek 555 part needed.

zerousair
 

Morris,
The lower beam HV is stuck at -860 volts. The HV adj. pot., R952, has no effect on the lower beam HV voltage. The HV for both beams is supposed to be adjusted to -1350 and the upper beam adjusts correctly. Lower beam is weak and the focus has little effect. I assumed V900 and the HV oscillator was working normally or I wouldn't have the -860 at the test point. Tube V900 checks good in my tester. The insulation wafer over the windings on T901 has a ~3/4 in. burnt spot and the adjacent components are covered dark with soot/smoke. No, I'm through with it for the night and haven't desoldered T901 and checked the windings. Thanks for your input.