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From Tim P (UK)
further to the discussion on removing components
from boards, I remember Weller produced a device
for de-soldering ICs which was like a metal IC socket
on a soldering iron, which went over all 16 pins.
I think it's main problem was that the molten solder
would then short out adjacent pads, needing careful
clean-up.
Tim

So I'm not the only one makes weird soldering tips. I had to make a .5" wide one a while back that worked great. I also made one with a 2.5" wide blade for a DC/DC converter that was really stubborn- it worked, but not very well.

-Dave

--- In TekScopes@..., "gehp01" <rodd@...> wrote:

Folks,
I bought two Tektronix THM565 portable scopes at a local surplus
dealer for a very cheap price.
However, the units came without batteries.
I could download the operating manual and found that there is an ac
adapter for this model, the THM5AC, but the only source I could find
for them was charging a modest value of $365.00 for one.
Since I do not even know if the units are operational, it makes no
sense trying to buy one.
Does anybody knows the pin assignment for the THM565 rear connector in
order to allow me to build a DIY power supply and test the units.
Thanks in advance for any help.
Roger
-------

Why not get six standard alkaline AA cells and run it as it was
intended ?
/H?kan

Hi,

I am very close to replacing my 475 scope with another 465. Having a little trouble deciding between replacing my 475 with another 475 or a 475A or 485. Just doing a little more checking.

What are the sources for a good working 485 scope?

Has any 485 owner ever used the 'fast rise time' of the built in 'probe calibrator' to check coax cables for defects like a TDR? I think the 485 'probe calibrator' has a fairly fast rise or fall time. Is it wise to buffer the probe calibrator output when using the calibrator to test coax cable?

Regards, 73, W6MIK, Dave

I have 1 CG551AP which is having issues with its Low SAC that I
can't seem to understand. The output of the Low SAC is being driven
to -12.5V, after some stuffing around I have found that the output
of U1311 which provides offset adjustment for the Low SAC has is
output at about -13V despite the inverting input (roughly -13V)
sitting well below the non-inverting input (roughly -4.5V). I have
tried removing U1311 which allows the Low SAC to function normally
apart from there being an offset which is unable to be corrected
for. I have also tried replacing both U1311 (LM725) and U1211
(LF356) which did not help at all.

The big mystery for me is why the output of U1311 is not at positive
saturation rather than what appears to be negative saturation given
that the voltage of the inverting input is below that of the non
inverting input. The input voltages appear to be in the specified
range for the supply voltage being used i.e. +/-13.5V (worst case)
for a supply of +/-15V. I am even considering the possibility that
the circuit may be going unstable due to the frequency compensation
components going out of spec.

Has anyone experienced this problem before with the Low SAC in the
CG551AP or had similar issues with OP-Amps?

Re: [TekScopes2] Re:Replacing caps


Hi everybody
Hurrah, I just got my TDS 544A working, usual acq fault, replaced all the
electrolytics on the acquisition PCB - still same fault, so I replaced all the
double and quad SOIC op.amps (TL 02/04 )--fault finding by attrition

I removed the caps by making a 2 pronged fork out of wire for the tip of the
soldering iron, to unsolder both sides of the cap simultaneously.
You can alternate the iron from one side of the cap to the other whilst lifting
the cap, but there a serious risk of pulling a pad off.
For the ICs I made a U shaped tip for the end of the iron out of brass sheet,
which with a bit of adjustment gripped the IC and unsoldered both sides at the
same time, very quick.

I then cleaned up all the pads with desoldering (the spellcheck tried to
change this to 'disordering' braid) and cleaned the board with isopropyl
alchohol.

For replacement i used solder paste and a very fine iron tip, all helped
enormously by a great purchase on XXXX,
a nearly new Leica StereoZoom 4 binocular microscope for under $180, it's one
of those things you don't know how you managed without
Finally a wash in the dishwasher.

Jonathan



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Hi everybody
Hurrah, I just got my TDS 544A working, usual acq fault, replaced all the electrolytics on the acquisition PCB - still same fault, so I replaced all the double and quad SOIC op.amps (TL 02/04 )--fault finding by attrition

I removed the caps by making a 2 pronged fork out of wire for the tip of the soldering iron, to unsolder both sides of the cap simultaneously.
You can alternate the iron from one side of the cap to the other whilst lifting the cap, but there a serious risk of pulling a pad off.
For the ICs I made a U shaped tip for the end of the iron out of brass sheet, which with a bit of adjustment gripped the IC and unsoldered both sides at the same time, very quick.

I then cleaned up all the pads with desoldering (the spellcheck tried to change this to 'disordering' braid) and cleaned the board with isopropyl alchohol.

For replacement i used solder paste and a very fine iron tip, all helped enormously by a great purchase on XXXX,
a nearly new Leica StereoZoom 4 binocular microscope for under $180, it's one of those things you don't know how you managed without
Finally a wash in the dishwasher.

Jonathan

--
I am using the free version of SPAMfighter for home users.
SPAMfighter has removed 12850 spam emails to date.
Paying users do not have this message in their emails.
Get the free SPAMfighter here:

Just acquired a TDS460A.
Display intensity seems low (I have is set to 100)?and the contrast adjustment does nothing (on both internal and external monitor). Is this a common problem?
?
Is there an hours counter on it somewhere? wondering if the CRT is going out or some other problem. Seems to work perfectly otherwise.
?
Thanks,
?
David.
?




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

Folks,
I bought two Tektronix THM565 portable scopes at a local surplus
dealer for a very cheap price.
However, the units came without batteries.
I could download the operating manual and found that there is an ac
adapter for this model, the THM5AC, but the only source I could find
for them was charging a modest value of $365.00 for one.
Since I do not even know if the units are operational, it makes no
sense trying to buy one.
Does anybody knows the pin assignment for the THM565 rear connector in
order to allow me to build a DIY power supply and test the units.
Thanks in advance for any help.
Roger

All of the items are now taken.
--John Gord

--- In TekScopes@..., "johncharlesgord" <johngord@...> wrote:

All,
I posted this on the HP/Agilent group and haven't had anyone jump
at the chance to pick this stuff up:
I have upgraded my spectrum analyzers and I no longer have room for
the old units. The following items are available free to anyone who
can use them and is willing pick them up. (I live in Venice,

California.)

140T/8552B/8553B system with a 8443A (late model, LED) tracking
generator.
2 each 8556A
8250A storage normalizer
Tek 604 monitor (use with 8250A)
HP 1331A variable persistence display

Let me know if you are interested.
-- John Gord ( johngord(at)verizon.net )

I have heard that
the frequency response of the recent digital scopes is not
guassian - that the rise time is
somewhat faster than bandwidth alone would indicate. That
makes me think that my
estimate of 111 risetime is actually erring on the high side.

That is one of the reasons that I prefer scopes from the steam age. What
you see is generally what is happening, rather than something that has been
digitised and processed using a process I have no control over.

Mostly I'm just glad it works at all, actually, I shouldn't
complain too hard. I suppose the
3S gear and the 111 can bootstrap themselves up to speed, one
step at a time.

Yeah - that sounds a good move. The 111 is actually a really nice pulser,
and should do nicely.

I also have a very odd avalanche pulser of more recent vintage that fits in
a TM5xx series power unit. The part number is not marked on the front, and
by all accounts there are several variants of this rather rare, and somewhat
prototypic beast - I've only heard of another two, and all three are
different. Over 4 years ago I put some pics on the tekscopes gallery,
including some sampler traces of the rise time, which measures an
aberration-free 250ps on an S6 sampling head (<30ps rise) - it is a fast
beastie. Gallery is called "Wierd TM500 plug in".

Craig

If I have a whole bunch to replace, I use solder paste, hot air, and a
quartz under board preheater. If I have only one or two to replace, I
use a fine tipped soldering iron and some #28AWG solder.

-=-=-=-

No hot air SMT apparatus or oven. Will be using fine tip iron.

Can you actually touch the tip to the caps' leads while the cap is resting in place? Or do you heat the pad while pressing down on the cap? (Flux paste is probably a good idea, too, I'd think...)

Thanks,
Dave

Chuck,
What about the small SM electro caps? Seems to me that these might be difficult to solder (being originally wave soldered) -- getting an iron in there might be difficult. I read that some folks use radial caps with very short, bent leads soldered to the pads.

Your experience?

Thanks,
Dave

-=-=-=-

--- In TekScopes@..., "Craig Sawyers" <c.sawyers@...> wrote:

Subject: [TekScopes] Type 111 Pretrigger Pulse Generator not
up to speed


I finally got around to replacing the caps in my Type 111 (s/n 490)
and find that it is not as fast as advertised; it's around 790pS,
where i had expected <=500pS.

Trying to deconvolve a fast rise time from a longer one is fraught with
problems. 500ps on a 1ns instrument response is a nominal 1.12ns - which is
only 14% different from your measured 1.275ns. Are you sure your timebase
is that accurate on the fastest sweep ranges (they often aren't).

I've got a chicken-and-egg problem here. I have a pile of 560-type sampling plugins that
I want to fix up, and need to get the 111 going to help do that :) Right now I'm borrowing
time on a modern Tek TDS4000 series. 350MHz digital phosphor unit. I have heard that
the frequency response of the recent digital scopes is not guassian - that the rise time is
somewhat faster than bandwidth alone would indicate. That makes me think that my
estimate of 111 risetime is actually erring on the high side.

Mostly I'm just glad it works at all, actually, I shouldn't complain too hard. I suppose the
3S gear and the 111 can bootstrap themselves up to speed, one step at a time.

From Tim P (UK)
I have a 281 TDR pulser on a 3S1.
After about 10 minutes the pulser
feels very hot. Should it?
I get a nice 1 volt pulse OK.
Tim.

--- On Fri, 9/19/08, Pierre F1BLF <pierrot8254@...> wrote:

From: Pierre F1BLF <pierrot8254@...>
Subject: [TekScopes] Tek 315D Oscilloscope Instruction Manual
To: TekScopes@...
Date: Friday, September 19, 2008, 9:29 PM






Hi Tekscopers,

I'm looking for a Tek 315D Instruction Manual,
preferably in a scanned form of PDF.

Many thanks in advance.

Pierre F1BLF


I could use one of those manuals too as I have one of those fine old relics in my collection. It is the only scope I have that I seriously thought of washing as it's the filthiest. Has broken fan mounts thanks to UPS but otherwise it is in very good physical condition. Complete with stacks of selenium rectifiers with a sticker that fell off stating that those had been replaced ages ago. Also contains plenty of "bumblebee" caps. Think I might be missing a cover plate over the HV section though. Occasionally I'll look at the scope but not planning on restoration any time soon, mainly due to the washing issue keeping me from even getting started. I?have?the scoped?wrapped in plastic so it doesn't get any dirtier!
?

?
Sorry to hijack the message. A few good pics in?there of the little beast if you care to look.
?
?
Dave

All,
I posted this on the HP/Agilent group and haven't had anyone jump
at the chance to pick this stuff up:
I have upgraded my spectrum analyzers and I no longer have room for
the old units. The following items are available free to anyone who
can use them and is willing pick them up. (I live in Venice, California.)

140T/8552B/8553B system with a 8443A (late model, LED) tracking
generator.
2 each 8556A
8250A storage normalizer
Tek 604 monitor (use with 8250A)
HP 1331A variable persistence display

Let me know if you are interested.
-- John Gord ( johngord(at)verizon.net )

Hi Tekscopers,

I'm looking for a Tek 315D Instruction Manual,
preferably in a scanned form of PDF.

Many thanks in advance.

Pierre F1BLF

Greetings,

Does someone have a list of the tektronix parts numbers for 1/8w 1%
metal film resistors? The prefix is 321. For example the part number
for a 1.47k resistor is 321-0209-00. I am trying to organize my part
bins.

jerry

Subject: [TekScopes] Type 111 Pretrigger Pulse Generator not
up to speed


I finally got around to replacing the caps in my Type 111 (s/n 490)
and find that it is not as fast as advertised; it's around 790pS,
where i had expected <=500pS.

Trying to deconvolve a fast rise time from a longer one is fraught with
problems. 500ps on a 1ns instrument response is a nominal 1.12ns - which is
only 14% different from your measured 1.275ns. Are you sure your timebase
is that accurate on the fastest sweep ranges (they often aren't).

The only sure way to measure it more accurately is to use something with a
response much faster than what you are trying to measure - ie a sampling set
up (which is precisely what the pretrigger of the 111 is for - getting the
sampling timebase up and running before the measurement event). To get a
good grip on the rise time and potential aberrations, you need a rise time
at least three times faster than what you are trying to measure (for a 10%
error). So at most at 170ps rise time. An S2, S4 or S6 sampling head will
do this, or a 1S2 from the earlier generation.

My main scope is set up with a spectrum analyser at the moment, or I would
get sampling up and running and measure my own type 111. It would just be
confirmation though - I've measured it before, and know for certain that it
gives less than 500ps rise.

Craig