From: Chuck Harris
Subject: Re: [TekScopes] Re: Sony/Tektronix 318 - UPDATE
To: "Gala Dragos"
Date: Sunday, March 17, 2013, 6:24 PM

Run the EPROM through a Z-80 disassembler?

-Chuck

Gala Dragos wrote:
> I've found out that A03W101 really go to nowhere. Following the circuits it goes
> to A04 board into some resistor which is not mounted. So I'm at a dead end. Any
> ideas ? --- On Fri, 3/15/13, Chuck Harris <cfharris@...> wrote:
>
> From: Chuck Harris <cfharris@...> Subject: Re: [TekScopes] Re:
> Sony/Tektronix 318 - UPDATE To: "Gala Dragos" <gala_dragos@...> Cc:
> "ArtekMedia" <manuals@...> Date: Friday, March 15, 2013, 10:30 PM
>
> Hi Gala,
>
> I would give you a copy if I had one, but I only have the military manual that you
> already have.? I would suggest that you send an email to Dave Henderson at :
> ArtekMedia <manuals@...>
>
> He has been known to send schematics to people in need.
>
> -Chuck Harris
>
> Gala Dragos wrote:
>> Not having the full schematics makes this a very difficult repair process !
>> After a very lengthy probing session, in which I've managed to find a connection
>> from A03W102 to A02 and back, I decided to try and remove the last jumper wires
>> that differ between 318 and 338 instruments. Apart from A04W118 which is marked
>> as TYPE ID and sets the corresponding number of probes and possible the memory
>> size that is required to test at startup, there are two more jumper wires
>> A03W102 and A03W101. A03W102 is tied on A03 pin 23B and from what I could tell
>> is responsible for checking the presence of the A02 and possibly A01 boards (and
>> their types ?). W101 seems not to be connected anywhere, I could not find any
>> connection, but I could be mistaking as I don't have the full schematics. Now I
>> have unsoldered the jumpers one at a time and started the instrument with them
>> removed, below is what I've found. When W102 removed gives an error in
>> diagnostics on the PRL section which states: "TIME BASE, WR, ACQ,NDL SEQ". When
>> W101 is removed nothing happens (as long as W102 is in its place). I somehow
>> find it hard too believe that Tektronix made a PCB with a ghost jumper that is
>> not used for anything. There must be something on the missing pages of the
>> schematic that can shade some light, there must be a loop somewhere ! Can anyone
>> provide the full schematics? Please. PS: both A03W101 and A03W102 are coming out
>> of A04U104 (pins 1 and 2) and are marked EDB6 and EDB7 respectively. --- On Fri,
>> 3/15/13, Gala Dragos <gala_dragos@...> wrote:
>>
>> From: Gala Dragos <gala_dragos@...> Subject: Re: [TekScopes] Re:
>> Sony/Tektronix 318 manual with full schematic To: TekScopes@...
>> Date: Friday, March 15, 2013, 10:12 AM
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>> At least page 4 of the tektronix 318 schematics, if not full ?
>>
>> --- On Thu, 3/14/13, Gala Dragos <gala_dragos@...> wrote:
>>
>> From: Gala Dragos <gala_dragos@...> Subject: Re: [TekScopes] Re:
>> Sony/Tektronix 318 manual with full schematic To: "TekScopes"
>> <TekScopes@...> Date: Thursday, March 14, 2013, 9:09 PM
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>> I'm missing part of A02 board form the schematics, it is necessary to follow two
>> signals that differ between 318 and 338. Can anybody provide the full schematic
>> of the 318 logic analyzer?
>>
>> --- On Wed, 3/13/13, Chuck Harris <cfharris@...> wrote:
>>
>> From: Chuck Harris <cfharris@...> Subject: Re: [TekScopes] Re:
>> Sony/Tektronix 318 manual with full schematic To: "Gala Dragos"
>> <gala_dragos@...> Date: Wednesday, March 13, 2013, 10:25 PM
>>
>> Hi Gala,
>>
>> Sounds like you static zapped something.? ECL, LSTTL, and TTL are pretty
>> resistant to static, but not so any of the NMOS.? NMOS and CMOS chips from that
>> era were extremely sensitive to static electricity.
>>
>> Given that little tidbit of information, I would spend some time looking closer
>> to the CPU... particularly anything that could prevent you from setting the 20ns
>> setting.? I don't remember how the 318 did that, but I recall it required a few
>> steps.
>>
>>
>> Gala Dragos wrote:
>>>>> Do you suppose that your 318 is doing something like that?
>>> Don't know, I don't own this for that long. The story starts in January, when
>>> I've realized I need a logic analyzer, so I managed to find one close by, well
>>> in the same continent and fiscal area that is (Europe). Got the instrument,
>>> but it came without the probes, which I have acquired from Jerry here on the
>>> forum. When the instrument arrived I have checked that the menu displays what
>>> it should, including the 20ns, and that it actually trigger on to something,
>>> which it did. During these tests I noticed that the
>> fan blows a lot of dust, it looked like a diesel exhaust. So, naturally, I took
>> it apart and cleaned the thing. Put it back together and, to my surprise, no
>> 20ns clock was available.
>>> I need that 20ns clock up and running as I have some apps that run at 40+ Mhz
>>>
>>>>> That actually is a very good sign!Good, but what to do next? It is still
>>>>> unexplained.
>>> --- On Wed, 3/13/13, Chuck Harris <cfharris@...> wrote:
>>>
>>> From: Chuck Harris <cfharris@...> Subject: Re: [TekScopes] Re:
>>> Sony/Tektronix 318 manual with full schematic To: TekScopes@...
>>> Date: Wednesday, March 13, 2013, 9:26
>> PM
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>> Hi Gala,
>>>
>>>
>>>
>>> That actually is a very good sign!
>>>
>>>
>>>
>>> I have used some logic analyzers where the glitch memory reduced
>>>
>>> the storage speed by a bit... and others where the synchronous
>>>
>>> storage mode was somewhat slower than the asynchronous storage
>>>
>>> mode.
>>>
>>>
>>>
>>> ... And, I have seen other units where there were lower priced
>>>
>>> siblings that were made specifically to use up the slow memory
>>>
>>> boards (that otherwise would have to be discarded).? It used to
>>>
>>> be a very common practice with minicomputers.
>>>
>>>
>>>
>>> Do you suppose
>> that your 318 is doing something like that?
>>>
>>>
>>>
>>> It's always better when it turns out to be operator error.
>>>
>>>
>>>
>>> -Chuck
>>>
>>>
>>>
>>> Gala Dragos wrote:
>>>
>>>> So situation is now like this:- instrument type detection works, by adding
>>>> or
>>>
>>>> removing w118 from A04 board (acquisition)- the 20ns clock is still not
>>>> available
>>>
>>>> from the menu What the heck is going on? --- On Wed, 3/13/13, Gala Dragos
>>>
>>>> <gala_dragos@...> wrote:
>>>
>>>>
>>>
>>>> From: Gala Dragos <gala_dragos@...> Subject: Re: [TekScopes] Re:
>>>
>>>> Sony/Tektronix 318 manual with full schematic To: TekScopes@...
>>>> Date:
>>>
>>>> Wednesday, March 13, 2013, 11:28
>> AM
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>> >> Well that 20ns clock is missing in the diagnostics menu as well. TYPE ID is
>>>> only
>>>
>>>> tested at startup, I've just checked that by soldering a wire across W118
>>>> and
>>>
>>>> removing it (with a switch) when I entered
>> the trigger menu. When W118 is jumpered
>>>
>>>> at startup the instrument is a 338 until next startup (or MPU reset). The
>>>> 20ns
>>>
>>>> clock is no where to be seen no matter the if W118 is soldered or not.
>>>
>>>>
>>>
>>>> --- On Wed, 3/13/13, sbirdasn <sbirdasn@...> wrote:
>>>
>>>>
>>>
>>>> From: sbirdasn <sbirdasn@...> Subject: [TekScopes] Re: Sony/Tektronix
>>>> 318
>>>
>>>> manual with full schematic To: TekScopes@... Date: Wednesday,
>>>> March
>>>
>>>> 13, 2013, 6:32
>> AM
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>> >>
>>>
>>>> Comments inline...
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>> --- In TekScopes@..., Gala Dragos wrote:
>>>
>>>>
>>>
>>>>>
>>>
>>>>
>>>
>>>>> I have that manual, I cannot find half of
>> A02 board.
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>> You're right! page <4> is missing! The doc looked pretty good to me when I
>>>> first
>>>
>>>> looked at it. ;)
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>> That being said, my dead-tree version that is truly complete has the
>>>> following
>>>
>>>> circuits:
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>> 1) External clock input buffer with its threshold comparator/delay circuit.
>>>
>>>>
>>>
>>>> 2) Internal/external clock select logic.
>>>
>>>>
>>>
>>>> 3) Some buffers for qualifiers.
>>>
>>>>
>>>
>>>> 4) Threshold buffer amplifiers for the pods.
>>>
>>>>
>>>
>>>> 5) The signal routing to get one pod connector's differential signals to
>>>> the
>>>
>>>> interconnect header for the
>> A01's differential to ECL signal w/ glitch detection
>>>
>>>> circuits. (one pod is handled on A01, one pod on A02)
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>> For the problems you're experiencing, it probably won't help much, if any.
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>> The full symptoms are these:- 20ns clock? disappeared;- there are 4
>>>>> selectable
>>>
>>>>> groups in the setup screen;- each group has 16 bits available for
>>>>> display;- only
>>>
>>>>> 2 pods can be selected for input (pod A and pod B), the rest are
>>>>> unavailable;
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>> By that, I think you mean that groups 3 & 4 are disabled by default, and you
>>>> can
>>>
>>>> only enter signals A0-7 or B0-7 into groups.
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>
>> Correct?
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>> - all tests pass, including acq and sram;- the pods are capturing
>>>>> external
>>>
>>>>> signals properly (checked them with the available calibration output);
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>> This would imply that upon power-up, it *does* ID itself as a 318.
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>> I have noticed that the instrument can be "used" without the?
>>>>> acquisition?
>>>
>>>>> board, albeit you can only browse the menus.
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>> Not surprising, since much of the hardware is write only or limited in how
>>>> the CPU
>>>
>>>> can interact with it.
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>> Excerpt from the manual:? "The chip
>> select latch (A04U114) is used to enable
>>>
>>>>> each 8-bit pair of the acquisition memory and for identifying instrument
>>>>> type.
>>>
>>>>> It is written by the MPU with the WRITE BS signal from the A03 ACQ
>>>>> Control
>>>
>>>>> board."
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>> I have checked that circuit for continuity of traces and they are all ok.
>>>>> On the
>>>
>>>>> schematic there is a jumper wire called W118 which in the 338 is mounted
>>>>> and in
>>>
>>>>> the 318 is not mounted, checked that as well and it is not mounted.
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>> Since you've checked the signal connections, it sounds like a hardware
>>>> failure in
>>>
>>>> one or more chips.
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>> Consider the following (I have no idea how they
>> wrote the firmware, so I have to
>>>
>>>> make some educated guesses):
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>> The Bank Select pin used for Type ID is "wire-OR'ed" with the ACQ/Glitch
>>>> Memory
>>>
>>>> output data bus, which has pull-up/termination resistors to bring the bus to
>>>> a
>>>
>>>> known inactive state.
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>> Since the 318 has the jumper removed, then when the ID bank bit is driven
>>>> active,
>>>
>>>> the signal to be read *should* be in the "inactive" state.
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>> If one of the ACQ/Glitch SRAM's were to drive this pin to a "active" state,
>>>> then
>>>
>>>> the bit will be incorrectly read (there is also some status bits that are
>>>> selected
>>>
>>>> by the 2-1 muxes, so something could be wrong there
>> too).
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>> When would this happen?
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>> Apparently, not on power-up, as it knows to be a 318 for pod count and
>>>> memory to
>>>
>>>> test.
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>> But perhaps when you enter the Trigger menu and start moving the clock rate,
>>>> then
>>>
>>>> the firmware *might* check the hardware jumper state again, read the wrong
>>>
>>>> information, and prevent selecting the highest clock rate.
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>> This is just a guess, but it would be easy to check-
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>> Solder a jumper wire onto the W118 pad on the latch side for probing with a
>>>> scope,
>>>
>>>> and check for
>> activity by the CPU to drive it active (to read the ID TYPE). The
>>>
>>>> signal will be fairly slow, as it is driven active across several
>>>> instructions,
>>>
>>>> and thus will be in the micro-second range, unlike the sampling circuitry.
>>>> Not an
>>>
>>>> ideal situation for signal integrity, but then I doubt you have a pair of
>>>> extender
>>>
>>>> cards handy (made of unobtanium).
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>> I think the signals in this area are ECL, so the logic transition delta is
>>>> about
>>>
>>>> 0.8V between 1's and 0's, and does not go to either "ground" or V- (ECL is
>>>
>>>> technically a -5.2V logic family).
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>> Explore the operation of the analyzer, and note when the signal goes active.
>>>> Try
>>>
>>>> various menus, field changes, etc. to see when the
>> CPU fiddles with this signal.
>>>
>>>> You might also look at when the Bank Select Latch is clocked too.
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>> You could check some other signals from the bank latch and the read side as
>>>> sanity
>>>
>>>> checks if necessary.
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>> I can't think of any other explanation as to why you can't select 20 nS
>>>> clock.
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>> Good luck.
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>
>> Sbirdasn.
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
& gt;>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>> br>>
>>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>

?

In getting started troubleshooting a 2213 with low gain on one channel, I figured I should probably check the supplies just to make sure they were okay -- they aren't.

They are all significantly high and won't adjust (-8.6 is -9.5, 100 is about 110, etc.) The preregulator is good at about 42.7. I checked the primary on the transformer, figuring there is nothing on the secondary side that could cause such a problem, and it is being driven at about 175VAC whereas in comparison to one that is not running at overvoltage I got around 154VAC. This makes sense -- if the primary voltage is too high, the secondary voltages will all be too high too and that is exactly the situation. The transformer windings ohm out okay (low resistance, no shorts and exactly like one that I compared it too)

So, in troubleshooting the inverter with power off I can find nothing wrong with it either. With power on, measuring the voltages on the smaller transformer connected to the switching transistors Q40 and Q42 I see no difference compared to one that is working normally and I see little difference in comparatively measuring the voltages on the collector, emitter or base of those transistors either.

I even followed the troubleshooting chart in the manual as well and it says to check the error circuit in the inverter (which I already did because I was sure I would find an obvious problem there) but no dice. But, I don't have an isolation transformer and Variac so I can't do it quite the way it recommends.

I'm stumped (for now).

Phil...

P.S.

I could still use some advice on whether to build an HV multiplier or I should just bite the bullet and scrap one defective scope (maybe this one!) and cannibalize it for that and other parts.

I advice AGAINST the prologix adapters. Their I/O model is garbage..
effectively negating the intent of asynchronous use and making it
polling. DNU

I would recommend a used NI GPIB-PCI board off eBay to use it the right
way, IMO.

In getting started troubleshooting a 2213 with low gain on one channel, I figured I should probably check the supplies just to make sure they were okay -- they aren't.

They are all significantly high and won't adjust (-8.6 is -9.5, 100 is about 110, etc.) The preregulator is good at about 42.7. I checked the primary on the transformer, figuring there is nothing on the secondary side that could cause such a problem, and it is being driven at about 175VAC whereas in comparison to one that is not running at overvoltage I got around 154VAC. This makes sense -- if the primary voltage is too high, the secondary voltages will all be too high too and that is exactly the situation. The transformer windings ohm out okay (low resistance, no shorts and exactly like one that I compared it too)

So, in troubleshooting the inverter with power off I can find nothing wrong with it either. With power on, measuring the voltages on the smaller transformer connected to the switching transistors Q40 and Q42 I see no difference compared to one that is working normally and I see little difference in comparatively measuring the voltages on the collector, emitter or base of those transistors either.

I even followed the troubleshooting chart in the manual as well and it says to check the error circuit in the inverter (which I already did because I was sure I would find an obvious problem there) but no dice. But, I don't have an isolation transformer and Variac so I can't do it quite the way it recommends.

I'm stumped (for now).

Phil...

P.S.

I could still use some advice on whether to build an HV multiplier or I should just bite the bullet and scrap one defective scope (maybe this one!) and cannibalize it for that and other parts.

?€?I cannot understand guys, WHY BOTHER??€?<<<<

The key to this one is to understand that?€??€?by claiming to save a couple of bucks we can easily justify the repair taking 3 to 5 times as long to implement than is should?€?.. thus turning a 1 (maybe 2) beer repair (time wise) into a full six pack minimum. With the added possibility of another 6pack in consultation with an ?€?expert?€?



Hopefully helpful

Rob
(now hopefully I don?€?t lose my man club card do to letting out some insight)



From: TekScopes@... [mailto:TekScopes@...] On Behalf Of Sergey Kubushyn
Sent: Sunday, March 17, 2013 5:56 PM
To: TekScopes@...
Subject: Re: [TekScopes] Re: Replacement to DS1230AB Lithium backed NVRAM





On Sun, 17 Mar 2013, Gala Dragos wrote:

I can not understand guys, WHY BOTHER?

You can get DS1230 from Mouser for something like $15 (I purchased one a
week ago to replace DS1225Y in my 2467B scope.) You will get a real thing
that you can just swap in and forget for the next 10 years. And you can
transfer the original chip content to the new one easily so you won't have
to recalibrate.

What are you trying to save here? A buck? Whopping two bucks? Is it worth a
trouble and all that work involved?

You could add extra logic and a counter to switch between fram chips and increase the mtbf time, or even better make your own NVRAM.
Oh, and if you keep the fram at 25 degrees Celsius you will probably get 10 times more write cycles.

--- On Sun, 3/17/13, bravovb <vbingei@... <mailto:vbingei%40yahoo.com> > wrote:

From: bravovb <vbingei@... <mailto:vbingei%40yahoo.com> >
Subject: [TekScopes] Re: Replacement to DS1230AB Lithium backed NVRAM
To: TekScopes@... <mailto:TekScopes%40yahoogroups.com>
Date: Sunday, March 17, 2013, 8:54 AM

Mr. Silva,

Its been a while. How is the 2465B going with FRAM ?

--- In TekScopes@... <mailto:TekScopes%40yahoogroups.com> , "Victor Silva" <daejon1@> wrote:

I have found that the FRAM devices are not a viable option in the
243X/40. Sadly I must report that what looked like a very promising
alternative to the DALLAS RAM/Lithium cell combo has turned out to be
a dead end.

I have been testing for over one month now on a 2430A, 2440 and 2465B
and everything seemed fine. My last test was to actually determine
the read/write frequency to the device.

It turn out a 2430A writes to the battery-backed devices as often as
once every microsecond. Since the FRAM device as a maximum of 10^10
read/write cycles (before it loses its NV capability) a quick
calculation reveals that the 2430A scope will render the FRAM device
a volatile device in one to three months.

For now I can only recommend the DALLAS (or other vendors)
RAM/Lithium cell combo pack device for use in Tek scopes.

Sorry for getting everyone's hopes up for a more inexpensive
replacement for NVRAM.

--Victor Silva

---
*
* KSI@home KOI8 Net < > The impossible we do immediately. *
* Las Vegas NV, USA < > Miracles require 24-hour notice. *
*

----- Original Message -----

From: Ed Breya

To: TekScopes@...

Sent: Monday, March 18, 2013 9:54 PM

Subject: [TekScopes] Re: Could please any one give a clue about this nice pulsed line generator??

?

The simplest and most likely to work way to extend the line is just using more .141 semi-rigid line. If you have any RG-8 cables - the big stuff - and an adapter for N to SMA, it should definitely work better than RG-58 since it will have much lower loss, and maybe comparable to .141.

There is a slightly more compact possible alternative, but I don't know yet. For one of my pulser designs, I had planned to try a section of scope vertical delay line in differential mode, with the avalanche operation between the oppositely charged lines, then transformer-coupled into a nonlinear transmission line edge compressor. I have the line mounted mechanically in a plug-in only, but not yet rigged for any experiments.

The 7000 series appear to all (I don't know about the 7104) use the same stuff, which looks like it's made with bare copper conductors and outer foil, with HDPE dielectric. It's supposedly about 100 ohms differential, but may act as about 50 ohms common-mode with the conductors tied, or maybe with one conductor grounded to the foil. I found that the outer foil has a longitudinal gap so that it doesn't totally enclose the conductors, so it may behave strangely as a single line - it's really optimized for differential use.

If you happen to have any pieces of delay line or 7000 carcasses available, you may want to experiment with it. I'm curious about how it would act with different wiring arrangements, what the true impedance is, and whether it's low enough in loss for pulser applications. It's heavier than the .141 cable, but on the other hand, it doesn't have silver plated conductors, and the HDPE isn't as good as PTFE. Maybe it's comparable then - the larger size offsetting the lossier materials. Or maybe not.

It's also possible to extend the pulse width arbitrarily by terminating and feeding the charge line at the distal end with a 50 ohm source (at the charge voltage!), but it is much more complicated than the normal method. The power dissipation can quickly get out of hand, and the commutation must be provided by additional circuitry, since there's no reflection from the line.

For the immediate purpose, I'd recommend just using more cable.

For the actual scope measurements, you should have some good coaxial attenuators, or a step attenuator, to knock the level down some. The average pulser power is no problem, but the peak voltage may cause all sorts of strange effects by turning on protection devices and ringing the front-end parasitics.

Ed

--- In TekScopes@..., "iglesia_cristiana_arpas_eternas" wrote:
>
> Today the Pulse Gen come to live, after replace the weak Q100 transistor by selected from what ever transistor I have in my shop..the winner was a npn switching "MPSH10".
> The rise time seems to be right on my unfinished to cal high frequency response 2465B scope..paradoxical..I brought this Gen in order to Cal my scopes ..now I haven`t a calibrated scope in this high impulse picosecond domain..to test this Gen..a dog chasing his tail!!!
> The only I can do is an act of "believe" in avalanche physic & Tek circuit implementation.
>
> As you people warning early, make an extension transmission line from common RG58...work but the pulse is not flat, the decay near linearly along his width..about 80ns.
> Any suggestion about how to make/obtain 15 feet of very good coax cable??? .
> Also please could any one post a pic on what is expected to see on a 2465B once connected to this Gen, about rise time and flatness?.
>
> --- In TekScopes@..., "iglesia_cristiana_arpas_eternas" wrote:
> >
> > The Generator arrive today from USA to my Argentine door!!! .
> >
> > Unfortunately not work fine.
> > Rt=1,67nS (instead 300pS)
> > Width pulse= 5,84nS (wave exponential decay instead rectangular pulse)
> > Max out= 3,5V (instead 25V)
> > Rep Rate=15Mhz (instead 50 or 100Khz)
> >
> > The ratio of different att step, seems to be good.
> > Probability arise that my previous intuition about bipolar avalanche transistor burned out come truth.
> >
> > Perhaps the out pulse I see is not else than the trigger pulse passing trough a short avalanche transistor.
> > Any way, this nice generator will be fixed (tomorow)....all kind of help & advice will be welcome.
> > Gabriel...from the Holly land of Francisco Pope!!..God bless all of Us.
> >
> >
> > --- In TekScopes@..., "iglesia_cristiana_arpas_eternas" wrote:
> > >
> > > Here the link to this almost new pulsed generator, at first glance is a
> > > transmission line pulser with 300ps ..but no model or number at all.
> > > I just brought it with the hope work right...but a good service manual
> > > will be very appreciated and gratefully.
> > > Link to Pulse Gen.
> > > <> > > 2112187?autorefresh=true&pt=LH_DefaultDomain_0&hash=item3a7e99ce3b&nma=t\
> > > rue&si=w4%252BkkAkTYIq9sTkPYLC8H98HEpU%253D&orig_cvip=true&rt=nc&_trksid\
> > > =p2047675.l2557>
> > >
> > > Regards Gabriel.
> > >
> >
>

Today the Pulse Gen come to live, after replace the weak Q100 transistor by selected from what ever transistor I have in my shop..the winner was a npn switching "MPSH10".
The rise time seems to be right on my unfinished to cal high frequency response 2465B scope..paradoxical..I brought this Gen in order to Cal my scopes ..now I haven`t a calibrated scope in this high impulse picosecond domain..to test this Gen..a dog chasing his tail!!!
The only I can do is an act of "believe" in avalanche physic & Tek circuit implementation.

As you people warning early, make an extension transmission line from common RG58...work but the pulse is not flat, the decay near linearly along his width..about 80ns.
Any suggestion about how to make/obtain 15 feet of very good coax cable??? .
Also please could any one post a pic on what is expected to see on a 2465B once connected to this Gen, about rise time and flatness?.

--- In TekScopes@..., "iglesia_cristiana_arpas_eternas" <iglesia_cristiana_arpas_eternas@> wrote:

The Generator arrive today from USA to my Argentine door!!! .

Unfortunately not work fine.
Rt=1,67nS (instead 300pS)
Width pulse= 5,84nS (wave exponential decay instead rectangular pulse)
Max out= 3,5V (instead 25V)
Rep Rate=15Mhz (instead 50 or 100Khz)

The ratio of different att step, seems to be good.
Probability arise that my previous intuition about bipolar avalanche transistor burned out come truth.

Perhaps the out pulse I see is not else than the trigger pulse passing trough a short avalanche transistor.
Any way, this nice generator will be fixed (tomorow)....all kind of help & advice will be welcome.
Gabriel...from the Holly land of Francisco Pope!!..God bless all of Us.


--- In TekScopes@..., "iglesia_cristiana_arpas_eternas" <iglesia_cristiana_arpas_eternas@> wrote:

Here the link to this almost new pulsed generator, at first glance is a
transmission line pulser with 300ps ..but no model or number at all.
I just brought it with the hope work right...but a good service manual
will be very appreciated and gratefully.
Link to Pulse Gen.
<;
2112187?autorefresh=true&pt=LH_DefaultDomain_0&hash=item3a7e99ce3b&nma=t&#92;
rue&si=w4%252BkkAkTYIq9sTkPYLC8H98HEpU%253D&orig_cvip=true&rt=nc&_trksid&#92;
=p2047675.l2557>

Regards Gabriel.

Okay, here's my report on the loss of center frequency on a 7L13 plugin (digest #7424), albeit a bit late. I had to put together a parts order (Thanks to the tip from 'crippo2', Vernonia Northern, right next door here in Oregon has many Tek parts in stock.) and they just got here today, very quickly I might add. 'David' Hess's advice on control line 'E', it should have been appx. 4 volts, and was at nearly 7 volts. Thanks David for your tips, they were very welcome. U2145 was indeed out to lunch, it's plus and minus supplies were fine. Due to internal issues it allowed pin 6 to swing above the expected 4 volts. R & R the LM311 and viola, the DVM circuit was once again functional. This was the second issue this module had since its arrival from a seller on Ebay. I just love the 'phrase' "We don't know how it works, so it's being sold As-Is", translated: "It's broke, and it don't work". HiHi The first was a shorted tantalytic in the +15 volt rail. Once that was replaced,
the machine worked but no center frequency display, LED or on screen. So... a sincere Thanks to David for your help, you were spot on. I kept thinking something downstream was causing the issue, compounded by my non-familiarity with the DVM to begin with. I was thinking 'Frequency counter', when I was dealing with a Digital Voltage Meter, ya live and learn.

73,
~Michael - AF7U

--- In TekScopes@..., David <davidwhess@...> wrote:

On Mon, 11 Mar 2013 06:35:34 -0000, "Michael" <af7u@...> wrote:

This post is a follow up from post #7360, and my 7L13 with center frequency LED readout all zeros. I am a bit further along with my investigation. I now understand the operation 'somewhat' more. I have looked over the diagrams and taken some voltage readings, I also understand the basic DVM logic and readout operation which sends data to the LCD and the CRT. I have an article from a Jan, 1975 '73' magazine which talks about the Fairchild 3814 digital voltmeter. I must admit I am not too clear on the 'Analog' section of the meter. On board 'A2100', diagram 12, the input to pin 2 of U2110 comes from plug P2540 pin 4. Looking over the A2500 board shows that pin 4 goes to chassis ground. Why would pin 2 from U2110 go all the way back to A2500 to reach chassis ground.

U2110 (LM308 style low bias current bipolar operational amplifier) is
configured as a differential amplifier. The signal ground that the
tuning voltage uses may not be at quite the same potential as the
signal ground that the readout uses so the differential amplifier
subtracts the difference. The differential amplifier will also
subtract low frequency noise between the grounds.

Anyway, the A2000 board seems to be working, albeit the frequency of the clock oscillator is not 200kHz as the diagram shows, it is running at 153.7kHz, though amplitude is good at 5 volts, I would think that would affect calibration but not operation. Back on A2100, the tuning control voltage at R2104 is good, it swings from + - 9.6 volts. The output of U2110 swings + - 10.7 volts. The DCPL Supply rails 15, -15, and 5 volts are all good. The reference voltage at the cathode of VR2115 (Zener) is 3.1, not the 3.3 volts is shows. Voltage at TP 2100, (output of U2130) is 11.65, a bit higher than the listed 11.3 volts. The voltages around the N-channel FET (Q2120) is Drain = 3.37 volts, Source = -3.1 volts, and Gate = -3.5 volts, are those in the ball park?

Those voltages all sound good to me and they are mostly the ones I
would have asked you to measure. In the worst case they add up to a
calibration problem and not a complete failure.

Needless to say there is NO signals present, waveform, 1, 2, 3, and 4 are all missing. Lines 'E' and 'F' are both quiet, the voltages on 'E' are 7.08 volts, on 'F' the voltage is 5.12 volts which swings a bit higher when I adjust center frequency, up to 5.44 volts. Of course 'E' has no signal as would be expected without drive from U2145 there is nothing to trigger the multivibrator U2030 on board A2000 sending a signal back up line 'F'. I keep thinking of this in terms of a frequency counter, I keep thinking there should be a driving input signal. I try to keep in mind it's a voltmeter, and keep in mind the circuit description given in the manual. It describes a ramp signal coming from the output of U2110, I don't understand that statement. The 'Tune' voltage is just a DC voltage, plus to minus. The minus input of U2120 goes to chassis ground??? What 'RAMP' are they speaking about?

E is 7 volts? That is quite a trick since the pull-up resistor
(R2149) is connected to +5V and the output of U2145 (LM311 style
comparator) is wired open collector (pin 1 is the emitter of the
output transistor and wired to ground) so it can only pull down and
not pull up. On the receiver side, U2010D is part of a 74L04 and also
has a 5 volt supply voltage so even if it failed, it can not pull up
to 7 volts

U2145 (LM311) is probably bad but you might want to look for a bad
socket or open trace. Nothing should be able to make its output go to
7 volts except an open on pin 4 or failed part.

The operational amplifiers and comparator are all TO-99 8 pin metal
cans which are difficult to find these days. If you can not find
metal cans, I would try replacing them with 8 pin DIP parts which
conveniently have the same pinout. I have done this before by cutting
the DIP leads short and soldering little wires to them. Cutoff 1/4
watt resistor leads work well.

Texas Instruments still sells TO-99 LM311 comparators but they are $10
each.

U2010 may be damaged as well. I think it can be replaced without
problems with a 74LS04 or even a 74HCT04 which are both more common.

If you have to order the LM311, pick up an LM308 and 74L04 replacement
as well just in case. The LM308 operational amplifiers can be
directly replaced with the Linear Technology LT1008. An LT1012 or
lots of other devices can be used if you pull the compensation
capacitor. JFET or MOSFET input devices should work as well.

Lastly the manual's circuit description on page 5-10 talks about a positive going ramp from U2110, aren't these just DC levels, what 'Ramp' are they talking about?

I think the ramp they talk about is the output of U2140 (another
LM308) which is configured as an integrator. The frequency (and
slope) of the ramp is proportional to the measured voltage.

Okay, I see there are a lot of questions here. I had better post this and hope for the best. It's a great 7L13, it works well, but without a 'Center' frequency display, it's pretty much just a toy. Also, I do appreciate the feedback~!~ I am not accustom to working on test equipment, my experience has been mostly all in Hi-Fi, but this has been very interesting.

I had to add a few pages of the 7L13 manual to my book of stuff I do
not have so it took a bit longer to respond to your post. The 7000
series spectrum analyzers look like fun. I will have to keep an eye
out for one.

On Mon, 11 Mar 2013 06:35:34 -0000, "Michael" <af7u@...> wrote:

This post is a follow up from post #7360, and my 7L13 with center frequency LED readout all zeros. I am a bit further along with my investigation. I now understand the operation 'somewhat' more. I have looked over the diagrams and taken some voltage readings, I also understand the basic DVM logic and readout operation which sends data to the LCD and the CRT. I have an article from a Jan, 1975 '73' magazine which talks about the Fairchild 3814 digital voltmeter. I must admit I am not too clear on the 'Analog' section of the meter. On board 'A2100', diagram 12, the input to pin 2 of U2110 comes from plug P2540 pin 4. Looking over the A2500 board shows that pin 4 goes to chassis ground. Why would pin 2 from U2110 go all the way back to A2500 to reach chassis ground.

U2110 (LM308 style low bias current bipolar operational amplifier) is
configured as a differential amplifier. The signal ground that the
tuning voltage uses may not be at quite the same potential as the
signal ground that the readout uses so the differential amplifier
subtracts the difference. The differential amplifier will also
subtract low frequency noise between the grounds.

Anyway, the A2000 board seems to be working, albeit the frequency of the clock oscillator is not 200kHz as the diagram shows, it is running at 153.7kHz, though amplitude is good at 5 volts, I would think that would affect calibration but not operation. Back on A2100, the tuning control voltage at R2104 is good, it swings from + - 9.6 volts. The output of U2110 swings + - 10.7 volts. The DCPL Supply rails 15, -15, and 5 volts are all good. The reference voltage at the cathode of VR2115 (Zener) is 3.1, not the 3.3 volts is shows. Voltage at TP 2100, (output of U2130) is 11.65, a bit higher than the listed 11.3 volts. The voltages around the N-channel FET (Q2120) is Drain = 3.37 volts, Source = -3.1 volts, and Gate = -3.5 volts, are those in the ball park?

Those voltages all sound good to me and they are mostly the ones I
would have asked you to measure. In the worst case they add up to a
calibration problem and not a complete failure.

Needless to say there is NO signals present, waveform, 1, 2, 3, and 4 are all missing. Lines 'E' and 'F' are both quiet, the voltages on 'E' are 7.08 volts, on 'F' the voltage is 5.12 volts which swings a bit higher when I adjust center frequency, up to 5.44 volts. Of course 'E' has no signal as would be expected without drive from U2145 there is nothing to trigger the multivibrator U2030 on board A2000 sending a signal back up line 'F'. I keep thinking of this in terms of a frequency counter, I keep thinking there should be a driving input signal. I try to keep in mind it's a voltmeter, and keep in mind the circuit description given in the manual. It describes a ramp signal coming from the output of U2110, I don't understand that statement. The 'Tune' voltage is just a DC voltage, plus to minus. The minus input of U2120 goes to chassis ground??? What 'RAMP' are they speaking about?

E is 7 volts? That is quite a trick since the pull-up resistor
(R2149) is connected to +5V and the output of U2145 (LM311 style
comparator) is wired open collector (pin 1 is the emitter of the
output transistor and wired to ground) so it can only pull down and
not pull up. On the receiver side, U2010D is part of a 74L04 and also
has a 5 volt supply voltage so even if it failed, it can not pull up
to 7 volts

U2145 (LM311) is probably bad but you might want to look for a bad
socket or open trace. Nothing should be able to make its output go to
7 volts except an open on pin 4 or failed part.

The operational amplifiers and comparator are all TO-99 8 pin metal
cans which are difficult to find these days. If you can not find
metal cans, I would try replacing them with 8 pin DIP parts which
conveniently have the same pinout. I have done this before by cutting
the DIP leads short and soldering little wires to them. Cutoff 1/4
watt resistor leads work well.

Texas Instruments still sells TO-99 LM311 comparators but they are $10
each.

U2010 may be damaged as well. I think it can be replaced without
problems with a 74LS04 or even a 74HCT04 which are both more common.

If you have to order the LM311, pick up an LM308 and 74L04 replacement
as well just in case. The LM308 operational amplifiers can be
directly replaced with the Linear Technology LT1008. An LT1012 or
lots of other devices can be used if you pull the compensation
capacitor. JFET or MOSFET input devices should work as well.

Lastly the manual's circuit description on page 5-10 talks about a positive going ramp from U2110, aren't these just DC levels, what 'Ramp' are they talking about?

I think the ramp they talk about is the output of U2140 (another
LM308) which is configured as an integrator. The frequency (and
slope) of the ramp is proportional to the measured voltage.

Okay, I see there are a lot of questions here. I had better post this and hope for the best. It's a great 7L13, it works well, but without a 'Center' frequency display, it's pretty much just a toy. Also, I do appreciate the feedback~!~ I am not accustom to working on test equipment, my experience has been mostly all in Hi-Fi, but this has been very interesting.

I had to add a few pages of the 7L13 manual to my book of stuff I do
not have so it took a bit longer to respond to your post. The 7000
series spectrum analyzers look like fun. I will have to keep an eye
out for one.

The Generator arrive today from USA to my Argentine door!!! .

Unfortunately not work fine.
Rt=1,67nS (instead 300pS)
Width pulse= 5,84nS (wave exponential decay instead rectangular pulse)
Max out= 3,5V (instead 25V)
Rep Rate=15Mhz (instead 50 or 100Khz)

The ratio of different att step, seems to be good.
Probability arise that my previous intuition about bipolar avalanche transistor burned out come truth.

Perhaps the out pulse I see is not else than the trigger pulse passing trough a short avalanche transistor.
Any way, this nice generator will be fixed (tomorow)....all kind of help & advice will be welcome.
Gabriel...from the Holly land of Francisco Pope!!..God bless all of Us.


--- In TekScopes@..., "iglesia_cristiana_arpas_eternas" <iglesia_cristiana_arpas_eternas@> wrote:

Here the link to this almost new pulsed generator, at first glance is a
transmission line pulser with 300ps ..but no model or number at all.
I just brought it with the hope work right...but a good service manual
will be very appreciated and gratefully.
Link to Pulse Gen.
<;
2112187?autorefresh=true&pt=LH_DefaultDomain_0&hash=item3a7e99ce3b&nma=t&#92;
rue&si=w4%252BkkAkTYIq9sTkPYLC8H98HEpU%253D&orig_cvip=true&rt=nc&_trksid&#92;
=p2047675.l2557>

Regards Gabriel.