Date   

Re: OT: HP70843B 12 GHz BERT info needed

Ed Breya
 

I'll try to post some pictures in the hpagilent group later. There are quite a few pieces in this complicated system, but I've gotten it somewhat figured out, structurally.

The 70843B is normally hooked to a 70004A or equivalent display MF via two local control cables (I forget the name - something HP specific control interface), and the 70004A needs a synthesizer (I forget the model) module installed, which supplies the clock (100 MHz - 12 GHz). The source unit in the 70843B amplifies and squares up its clock input with a GaAs amplifier, and sends it to the front panel in true and inverted forms via two of the output amplifier modules.

The clock internally also goes to a band-switched variable phase shifter system for skewing over a wide range. Since the system knows and controls the clock rate, the bands and amount of phase shift can probably be worked out precisely to desired time delay or whatever else is needed. The clock from the input amplifier goes through an HP8768K coaxial relay which routes it to a selected phase shifter module - a 6-12 GHz variable (with three varicap sections), a 3-6 GHz (similar), or a <3 GHz block with apparently PIN-switched delay lines of 250 pSec, 500 pSec, and 1 nSec, plus one varicap variable section. There is also a straight through mode that bypasses all the shifters. A second HP8768K selects the appropriate output and sends it to another GaAs amplifier, then that becomes the internal clock for data pattern generation.

The RX unit has the exact same kind of phase shifter assembly, but hooked up a little differently. The input amplifier clock outs are not used, just terminated, and its version of its delayed clock is used for decoding the data stream.

The TX and RX units each have a block full of small board sub-modules (about a dozen) that do the sub-rate multiplexing (TX) or de-multiplexing (RX). I have been able to ID some of the parts, which are mostly GaAs IC source-coupled logic drivers or switches, made by NTT, circa 1990s. I'll list them all here for reference, once I figure out all the types and quantities. These run at the top speeds involved, and apparently the rest of the stuff runs at one-quarter or one-eighth the clock rate.

I'll have more info later, and maybe some pictures too.

Ed


Re: 7B92 problems

Tomas Alori
 

Hi, have you ever managed to fix the missing portions in the alt/intensified modes? My 7B92A never shows the alternate (delayed) sweep. It just shows the intensified portion of the delaying sweep. Any ideas? Thanks!!


Re: Tektronix DM5010 NiCa 2.4V battery replacement

Harvey White
 

On Sat, 21 Jul 2018 11:40:14 -0700, you wrote:

Hi everyone,

I need to replace the backup battery of a DM5010. It has leaked but I cleaned up the mess.
The service manual specifies a Nickel Cadnium 2.4V 150mAH at 14mA.

So far, I was able to find (on Mouser) a 2.4V 110mAH (https://www.mouser.fr/datasheet/2/331/PCBM-2.4_R_complete_11_Jan_25-21018.pdf).
Does it meet specification? In particular, we have 0.11AH vs 0.15AH.

I've absolutely no experience with rechargeable batteries. So I welcome your help.
I'd suggest a different approach. The backup battery will leak again,
sooner or later. In addition, even with 150 mah, if it's in storage,
it will go below the point where the cal constants are valid. You
will have to provide various (highly accurate) voltages, including 250
or so and 700 VAC to calibrate this.

Calibration, unless you have the equipment, is a pain. (there are
ways of working around the accuracy requirement, but you still need
the 700 volts AC and 1000 volts DC).

I'd put in a lithium battery, I'd suggest a Tadiran TL-2155, which
will fit in the slot. You MUST put a diode in series to prevent the
battery from being charged, however.

Before you go to the trouble, I'd suggest temporarily wiring in two
small NiCd batteries, capacity not super important. Let them charge
up. Then go through and attempt to calibrate the unit as best you
can. What you're looking for is bad calibration constants, indicating
that the battery corrosion has damaged part of the backup circuitry.

At that point, if you can fix it, good, if not, then you'll have to
figure out a workaround.

One workaround is to rebuild/remake the CPU board with a more modern
processor, an AVR mega (a big one) would work. However, you'll want
to know how the insides interact with the processor, and I do not have
anywhere near complete information on that.

Given that information, a more modern board can be made, the functions
may be expanded, and you can restore the DMM to full service.

I put the battery in, and the memory storage was still not working, so
rebuilding is going to be what I do, for now, unless I find one that
is still working.

Harvey



Best regards



Re: Tektronix DM5010 NiCa 2.4V battery replacement

Tom Gardner
 

On 21/07/18 19:40, anotherlin@... wrote:
Hi everyone,

I need to replace the backup battery of a DM5010. It has leaked but I cleaned up the mess.
The service manual specifies a Nickel Cadnium 2.4V 150mAH at 14mA.

So far, I was able to find (on Mouser) a 2.4V 110mAH (https://www.mouser.fr/datasheet/2/331/PCBM-2.4_R_complete_11_Jan_25-21018.pdf).
Does it meet specification? In particular, we have 0.11AH vs 0.15AH.

I've absolutely no experience with rechargeable batteries. So I welcome your help.
One point to be aware of is how it is charged. If a cell is charged too fast or for too long, it will be damaged.

An "intelligent" charger will determine when a cell is fully charged, and stop charging. Frequently a backup battery does not have an intelligent charger, but simply "trickle charges" the cells all the time it is connected to the mains.

So you probably need to determine the trickle charging current in the circuit, and compare that with the datasheet's spec. In the absence of more specific information, it is usual to assume than trickle charging at "C/10" is OK, which would be 11mA for a 110mAh cell.


Re: OT: HP70843B 12 GHz BERT info needed

alberto.vaudagna
 

Can you post some photo of the board somewhere on the internet? It is
always interesting see what is inside mysterious instruments

Il giorno sab 21 lug 2018 alle ore 20:20 Jim Ford <james.ford@...> ha
scritto:

Hi, Ed.

I'm forwarding your message to another Ed I know who may know something
about this beast. I envy you for finding it!

Jim

------ Original Message ------
From: "Ed Breya via Groups.Io" <edbreya=yahoo.com@groups.io>
To: TekScopes@groups.io
Sent: 7/21/2018 10:53:01 AM
Subject: [TekScopes] OT: HP70843B 12 GHz BERT info needed

I posted this in the hpagilent group a while back, but no one seems to
have info. That group seems pretty quiet lately, and I don't see
indications that it's moved to groups.io yet. Since it's mostly the
same folks in both groups, I thought I'd put it here for a bit where
there's more traffic, and hope for some more visibility. Sorry that
it's not Tek stuff, but it is highly related to fast pulse generators,
which are near and dear to our hearts.

Anyway, here goes - it may be fun and useful to talk (some more) about
fast pulsing technology, and GaAs devices, etc. I'd appreciate any info
on this unit or its guts.

"I just picked up this beast for cheap, figuring there would be some
fun microwave goodies inside. It seems to be a fairly obscure unit,
with no info on the guts, and barely any about the unit itself. I found
an operating and programming manual, and that's it. I've already parted
it out and found lots of interesting stuff, including the four main
source output modules, rated for tr and tf of about 30 pSec. These
should be good for fast pulse generator work, but not unless I can
figure out how to power them up and activate the control lines. The
outputs apparently can run up to 12 GHz (or Gb/sec) data rate, up to a
couple volts swing on 50 ohms. They appear to be some type of GaAs
amplifier, so could be complicated making the biasing all work out
right without any info or some reverse engineering of the support
circuitry.

Does anyone know of any technical info on the innards? This is from the
era of "No User Serviceable Parts Inside," and no manuals about the
insides.

My plan is to put some of the sections back together enough to trace
out the supply connections, and power up the pieces and see if I can
get some of the items operational. I realize it would have been cool to
use it in its complete form with lots of capability, but it would have
taken lots of effort and more stuff to cable it up to a 70004 display,
and maybe some SW, just to see if it worked. I'll be satisfied if I can
get the output modules figured out and working. There's also a bunch of
other microwave parts, and lots of EL-series "modern" high-speed ECL
parts all over the place.

The SMPS is big - over 400W out I'd say, and I plan to use the whole
carcass as a big multi-output supply after I figure out the modules and
such. It has heavy -5.2V and -2 V, handy for ECL work, besides the
usual +5V and +/-15V. There's room to add other supplies where the high
speed pulse guts were, and plenty of cooling - six 3" fans pull air
from one side, through the guts, and out the other side. Two are for
the PS, and the others for the working guts up front."

That's what I wrote before. I've been studying it more and have some
interesting observations that I'll report on later.

Ed







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Tektronix DM5010 NiCa 2.4V battery replacement

Ke-Fong Lin
 

Hi everyone,

I need to replace the backup battery of a DM5010. It has leaked but I cleaned up the mess.
The service manual specifies a Nickel Cadnium 2.4V 150mAH at 14mA.

So far, I was able to find (on Mouser) a 2.4V 110mAH (https://www.mouser.fr/datasheet/2/331/PCBM-2.4_R_complete_11_Jan_25-21018.pdf).
Does it meet specification? In particular, we have 0.11AH vs 0.15AH.

I've absolutely no experience with rechargeable batteries. So I welcome your help.

Best regards


Re: OT: HP70843B 12 GHz BERT info needed

Jim Ford
 

Hi, Ed.

I'm forwarding your message to another Ed I know who may know something
about this beast. I envy you for finding it!

Jim

------ Original Message ------
From: "Ed Breya via Groups.Io" <edbreya=yahoo.com@groups.io>
To: TekScopes@groups.io
Sent: 7/21/2018 10:53:01 AM
Subject: [TekScopes] OT: HP70843B 12 GHz BERT info needed

I posted this in the hpagilent group a while back, but no one seems to
have info. That group seems pretty quiet lately, and I don't see
indications that it's moved to groups.io yet. Since it's mostly the
same folks in both groups, I thought I'd put it here for a bit where
there's more traffic, and hope for some more visibility. Sorry that
it's not Tek stuff, but it is highly related to fast pulse generators,
which are near and dear to our hearts.

Anyway, here goes - it may be fun and useful to talk (some more) about
fast pulsing technology, and GaAs devices, etc. I'd appreciate any info
on this unit or its guts.

"I just picked up this beast for cheap, figuring there would be some
fun microwave goodies inside. It seems to be a fairly obscure unit,
with no info on the guts, and barely any about the unit itself. I found
an operating and programming manual, and that's it. I've already parted
it out and found lots of interesting stuff, including the four main
source output modules, rated for tr and tf of about 30 pSec. These
should be good for fast pulse generator work, but not unless I can
figure out how to power them up and activate the control lines. The
outputs apparently can run up to 12 GHz (or Gb/sec) data rate, up to a
couple volts swing on 50 ohms. They appear to be some type of GaAs
amplifier, so could be complicated making the biasing all work out
right without any info or some reverse engineering of the support
circuitry.

Does anyone know of any technical info on the innards? This is from the
era of "No User Serviceable Parts Inside," and no manuals about the
insides.

My plan is to put some of the sections back together enough to trace
out the supply connections, and power up the pieces and see if I can
get some of the items operational. I realize it would have been cool to
use it in its complete form with lots of capability, but it would have
taken lots of effort and more stuff to cable it up to a 70004 display,
and maybe some SW, just to see if it worked. I'll be satisfied if I can
get the output modules figured out and working. There's also a bunch of
other microwave parts, and lots of EL-series "modern" high-speed ECL
parts all over the place.

The SMPS is big - over 400W out I'd say, and I plan to use the whole
carcass as a big multi-output supply after I figure out the modules and
such. It has heavy -5.2V and -2 V, handy for ECL work, besides the
usual +5V and +/-15V. There's room to add other supplies where the high
speed pulse guts were, and plenty of cooling - six 3" fans pull air
from one side, through the guts, and out the other side. Two are for
the PS, and the others for the working guts up front."

That's what I wrote before. I've been studying it more and have some
interesting observations that I'll report on later.

Ed







---
This email has been checked for viruses by AVG.
https://www.avg.com


Re: Dead 7603

Jim Ford
 

Thanks, Dave!

I will try the largest value cap I have in parallel with C821 this
evening. The rest of the day is dedicated to my other addiction (I
meant strikethrough) hobby, playing musical instruments.

Jim

------ Original Message ------
From: "Dave Hills" <dadhills@...>
To: TekScopes@groups.io
Sent: 7/21/2018 9:44:06 AM
Subject: Re: [TekScopes] Dead 7603


So I checked out the 8 V supply feeding the 5 V supply - it looks
really
bad! Similar waveform to the 5 V rail but dips from a high of maybe
14
V down to about 2 V. That's at the junction of the cathodes of
rectifiers CR820 and C821, C821, R821, and the collectors of Q829 and
Q835 on the Rectifier Board.
If either of the rectifiers were shorted, you would see the waveform go
negative across C821. The minimum value of 2v indicates they are OK.


Then I checked at the anodes of CR820 and CR821; more convenient to
look
across C820. I saw about a 30 Vp-p near-sinewave there, with the
anode
of CR820 180 degrees out of phase with the anode of CR821.
This is OK.


I tried to measure C821 (18,000 uF) in-circuit with my cheapo Chinese
transistor/resistor/diode/capacitor checker, but it couldn't get a
reading. Ditto for C820 (0.1 uF, 100 V). I assume the transformer
effectively presents a short and throws off the checker.
This is what I would expect. Don't expect in-circuit measurements to
be meaningful with respect to a single component in a network. The
measuring instrument can't sort out a single component, as it see's
everything connected to it and makes a futile attempt to make sense of
the measurement.


Also, R821, from the cap/diode cathodes/transistor collectors point to
GND, reads 5.5k ohms, when it's supposed to be 4.7k +/-10%. I was
surprised to see it read high; most times the sneak paths make
resistors
read low in-circuit. Not that 5.5k probably makes a difference.
Either due to residual charge on C821, or R821 has drifted high, which
is not unusual if it is an aged carbon composition resistor.


Anyway, should I suspect the cap C821 or one of the diodes CR820 or
CR821? Or something else altogether?
All the info you have provided points to an open C821. Easy to confirm
by tacking an additional electrolytic cap across it and looking at the
waveform again. Even a small value, say, 100uF should make a
measurable difference. If the lowest level, 2v, increases, then you
have confirmed it is likely bad.

Dave


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OT: HP70843B 12 GHz BERT info needed

Ed Breya
 

I posted this in the hpagilent group a while back, but no one seems to have info. That group seems pretty quiet lately, and I don't see indications that it's moved to groups.io yet. Since it's mostly the same folks in both groups, I thought I'd put it here for a bit where there's more traffic, and hope for some more visibility. Sorry that it's not Tek stuff, but it is highly related to fast pulse generators, which are near and dear to our hearts.

Anyway, here goes - it may be fun and useful to talk (some more) about fast pulsing technology, and GaAs devices, etc. I'd appreciate any info on this unit or its guts.

"I just picked up this beast for cheap, figuring there would be some fun microwave goodies inside. It seems to be a fairly obscure unit, with no info on the guts, and barely any about the unit itself. I found an operating and programming manual, and that's it. I've already parted it out and found lots of interesting stuff, including the four main source output modules, rated for tr and tf of about 30 pSec. These should be good for fast pulse generator work, but not unless I can figure out how to power them up and activate the control lines. The outputs apparently can run up to 12 GHz (or Gb/sec) data rate, up to a couple volts swing on 50 ohms. They appear to be some type of GaAs amplifier, so could be complicated making the biasing all work out right without any info or some reverse engineering of the support circuitry.

Does anyone know of any technical info on the innards? This is from the era of "No User Serviceable Parts Inside," and no manuals about the insides.

My plan is to put some of the sections back together enough to trace out the supply connections, and power up the pieces and see if I can get some of the items operational. I realize it would have been cool to use it in its complete form with lots of capability, but it would have taken lots of effort and more stuff to cable it up to a 70004 display, and maybe some SW, just to see if it worked. I'll be satisfied if I can get the output modules figured out and working. There's also a bunch of other microwave parts, and lots of EL-series "modern" high-speed ECL parts all over the place.

The SMPS is big - over 400W out I'd say, and I plan to use the whole carcass as a big multi-output supply after I figure out the modules and such. It has heavy -5.2V and -2 V, handy for ECL work, besides the usual +5V and +/-15V. There's room to add other supplies where the high speed pulse guts were, and plenty of cooling - six 3" fans pull air from one side, through the guts, and out the other side. Two are for the PS, and the others for the working guts up front."

That's what I wrote before. I've been studying it more and have some interesting observations that I'll report on later.

Ed


Re: Dead 7603

Dave Hills
 

So I checked out the 8 V supply feeding the 5 V supply - it looks really
bad! Similar waveform to the 5 V rail but dips from a high of maybe 14
V down to about 2 V. That's at the junction of the cathodes of
rectifiers CR820 and C821, C821, R821, and the collectors of Q829 and
Q835 on the Rectifier Board.
If either of the rectifiers were shorted, you would see the waveform go negative across C821. The minimum value of 2v indicates they are OK.


Then I checked at the anodes of CR820 and CR821; more convenient to look
across C820. I saw about a 30 Vp-p near-sinewave there, with the anode
of CR820 180 degrees out of phase with the anode of CR821.
This is OK.


I tried to measure C821 (18,000 uF) in-circuit with my cheapo Chinese
transistor/resistor/diode/capacitor checker, but it couldn't get a
reading. Ditto for C820 (0.1 uF, 100 V). I assume the transformer
effectively presents a short and throws off the checker.
This is what I would expect. Don't expect in-circuit measurements to be meaningful with respect to a single component in a network. The measuring instrument can't sort out a single component, as it see's everything connected to it and makes a futile attempt to make sense of the measurement.


Also, R821, from the cap/diode cathodes/transistor collectors point to
GND, reads 5.5k ohms, when it's supposed to be 4.7k +/-10%. I was
surprised to see it read high; most times the sneak paths make resistors
read low in-circuit. Not that 5.5k probably makes a difference.
Either due to residual charge on C821, or R821 has drifted high, which is not unusual if it is an aged carbon composition resistor.


Anyway, should I suspect the cap C821 or one of the diodes CR820 or
CR821? Or something else altogether?
All the info you have provided points to an open C821. Easy to confirm by tacking an additional electrolytic cap across it and looking at the waveform again. Even a small value, say, 100uF should make a measurable difference. If the lowest level, 2v, increases, then you have confirmed it is likely bad.

Dave


Re: Dead 7603

Jim Ford
 

Thanks, Harvey.

So I checked out the 8 V supply feeding the 5 V supply - it looks really bad! Similar waveform to the 5 V rail but dips from a high of maybe 14 V down to about 2 V. That's at the junction of the cathodes of rectifiers CR820 and C821, C821, R821, and the collectors of Q829 and Q835 on the Rectifier Board.

Then I checked at the anodes of CR820 and CR821; more convenient to look across C820. I saw about a 30 Vp-p near-sinewave there, with the anode of CR820 180 degrees out of phase with the anode of CR821. That seemed OK, but the output is just wrong!

I tried to measure C821 (18,000 uF) in-circuit with my cheapo Chinese transistor/resistor/diode/capacitor checker, but it couldn't get a reading. Ditto for C820 (0.1 uF, 100 V). I assume the transformer effectively presents a short and throws off the checker.

Also, R821, from the cap/diode cathodes/transistor collectors point to GND, reads 5.5k ohms, when it's supposed to be 4.7k +/-10%. I was surprised to see it read high; most times the sneak paths make resistors read low in-circuit. Not that 5.5k probably makes a difference.

Anyway, should I suspect the cap C821 or one of the diodes CR820 or CR821? Or something else altogether?

Thanks, everybody.

Jim

------ Original Message ------
From: "Harvey White" <madyn@...>
To: TekScopes@groups.io
Sent: 7/15/2018 6:16:20 PM
Subject: Re: [TekScopes] Dead 7603

On Sun, 15 Jul 2018 23:32:06 +0000, you wrote:

OK, here's where I am now: Power light comes on, and all LV DC voltages
are within tolerance except +5 V, which reads ~+4.4 V.
suspicious

Ripple is out of
spec on all except for +130 V. +5 V rail looks like a high duty ratio
dipping from 5 V down to about 2 V periodically, synchronous with the AC
mains.
DING DING DING!

Problem here. Possible that one of two things is at fault (maybe
both, but not likely). FIRST: suspect the bulk capacitor. SECOND:
suspect the bridge rectifier. (On a 5440, had the same thing, as well
as a toasted resistor in the 15 volt supply. filter capacitor (10000
uf, 12 vols) read extremely high esr (couldn't measure), and did not
tell me what the capacitance was.)

Replacing main capacitor, will mention what the result was, bridge
tested OK.

I figured a tantalum capacitor on the 5 V rail was a nominal
short, but I don't see any tantalums anywhere in this scope, a late
model 7603, Serial Number B345179. Just ceramic discs and aluminum
electrolytics.
Could be an aluminum electrolytic, but high ripple on a supply points
you at either the main filter capacitor *or* the rectifier. I'm
betting on the capacitor.



Any ideas on where to look? I figure the crap on the 5 V rail may be
messing up the others - make sense?
The ripple may be causing all sorts of problems. Regulators do expect
voltages at their inputs that never drop below the output voltage.
(most of the ones in TEK equipment being series regulators,
effectively).


Harvey


Thanks.

Jim

------ Original Message ------
From: "Al Holt" <@wd4ah>
To: TekScopes@groups.io
Sent: 6/25/2018 4:21:40 AM
Subject: Re: [TekScopes] Dead 7603

You've got a dead 7603 with no lights. Definitely look at the low
voltages first. Check the 0.15A (150mA) fuse, F855, just because its
'filament' is so delicate it can easily become disconnected from its
end caps from heat and age. In my case this wasn't the 'magic bullet'
to fixing my 7603, but losing the 130V line kills the HV system.

Getting the front panel power indicator to light would be the next
challenge. The LV regulators are interconnected in a way that will
prevent this lamp from lighting if one of them is bad. I can't remember
how it all hangs together now, but there are a number of posts here
that spell it out.

Sorry, about being too vague, but I'm writing this from memory. I think
the LV rectifier board is going to be the key to this, and it's worth
the time to pull it, give it a visual and check the condition of the
electrolytic caps. And be sure to mark the ribbon cables as you
disassemble things!

Good luck!

--Al



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Re: 7A29 attenuator fault corrosion issue

Adrian
 

Hi George,

Glad it worked for you too! I guess you may have figured this out as well but when it comes to re-engaging the slots in the SMA connector with the stripline I found the springy stripline position seemed to be offset from centre a bit. I assume this is to ensure good contact with the slot in the pin.

I found that by leaving the screws holding the top plate slightly loose and angling the SMA plate a small amount away from the bottom plate it was possible to use the SMA plate to push down on the top plate a tiny amount and still just see (with a good light!) the end of the stripline and the slot to align them and then 'hinge' the SMA plate into position before tightening the top plate fully.

As to what caused the problem my guess is that the corrosion is galvanic in nature as it was very local to the contact area of the resistor ground connection. I couldn't figure out what that contact 'lip' was made from though - I thought it looked like some sort of elastomer in color but on mine at least it seemed pretty hard for that?

I notice there's I guy selling a dozen or so 7A29s on the 'bay tonight - 60 bucks each or offers, would be a good deal if I wasn't on the wrong side of the Atlantic these days! he has them all listed as 'TA29' for some (typographical?) reason.

Adrian

On 7/20/2018 12:53 PM, glkinst@... wrote:
As you mentioned, it is really important to remove the SMA connectors first before removing of the bottom plastic plate that has the gold-plated fingers and tabs. The tabs fit in the slot on the SMA connector. Re-assembly requires patience, don't force for it or you will damage the connection.


Re: 7A29 attenuator fault corrosion issue

cmjones01
 

On Fri, Jul 20, 2018 at 04:53 AM, <glkinst@...> wrote:
Also, I found cracks on the plastic cams on the shaft. The cams are still
secure, but I wonder if the cracks will cause problems at some point.
Yes, both of my 7A29s are like that. On one of them a couple of cams had rotated so the attenuator settings no longer made sense. I added a fillet of epoxy at each side of each cam (I used Loctite 3430 because it's what I have in the lab, but other would probably do fine) to support the cams on the shaft. Time will tell whether it works long-term, but they've been OK for a couple of years now.

Chris


Re: 7A29 attenuator fault corrosion issue

glkinst@...
 

Adrian,
I was able to restore one and now two of my 7A29 units following your procedure! It is definitely a ground contact issue between the resistors and aluminum block. One more to go. It is indeed a tedious and a delicate operation. As you mentioned, it is really important to remove the SMA connectors first before removing of the bottom plastic plate that has the gold-plated fingers and tabs. The tabs fit in the slot on the SMA connector. Re-assembly requires patience, don't force for it or you will damage the connection.

Also, I found cracks on the plastic cams on the shaft. The cams are still secure, but I wonder if the cracks will cause problems at some point.

George


Re: My "new" Tek 485 with opt 4

Reginald Beardsley
 

Not sure it will work, but I'm attaching a scan of the 465 manual pages describing the option. It's basic SMPS EMI filtering plus a mesh screen on the face of the CRT. I'm guessing the mesh screen was removed from mine at some point.


Re: My "new" Tek 485 with opt 4

Kevin Oconnor
 

My 585 manual says “with 485 EMI mod option 4 meets mil 1-618D req: power line conducted, 150khz -25mhz; radiated , 150khz-GHz [sic].
Don’t know what the mod is though. If someone knows, please post.

Sent from kjo iPhone


Re: Looking at a broken 2440

Jim Ford
 

Ah, the HP 54503A must be similar to the 400 MHz 54504A DSO that we have
unused in the storage area at work. Came from a power supply vendor who
went out of business, but we have more modern Tek TDS3034's and 3054's
to do the job it used to do, and theyr'e easily portable to boot. The
hardware lead said he wants the 54504A thrown in the trash. I said,
don't do that, give it to me for my garage lab! Would be nice to have a
digital sampling scope to "stop time". Analog scopes like my 7904, 7603
(still working on nursing that one back to health), and 5103N/D10 are
great, but since I don't want to fool with analog storage scopes, I
don't have a way to get screen persistence. Until the lab manager fills
out the paperwork - the bane of those who work for big companies like me
(Raytheon).

Jim

------ Original Message ------
From: "Kevin Oconnor" <@KO3Y>
To: TekScopes@groups.io
Sent: 7/19/2018 8:25:16 PM
Subject: Re: [TekScopes] Looking at a broken 2440

The 2440 can be a real craps shoot. I had one on the shelf for many
years that was failing self tests so bad that it would never boot to
even crippled functionality. One of the failures, as I recall, was one
of the custom ADC chips. Since I already had a 500mhz HP 54503A & a
Tek485, I sold the 2440 off as a parts mule.
I remember opening it several times trying to muster the energy to fix
it. I remain to this day amazed at the quantity of thru hole ICs on all
4 sides ! Hats off to those who are willing to work on these scopes!

Sent from kjo iPhone



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Re: Looking at a broken 2440

Kevin Oconnor
 

The 2440 can be a real craps shoot. I had one on the shelf for many years that was failing self tests so bad that it would never boot to even crippled functionality. One of the failures, as I recall, was one of the custom ADC chips. Since I already had a 500mhz HP 54503A & a Tek485, I sold the 2440 off as a parts mule.
I remember opening it several times trying to muster the energy to fix it. I remain to this day amazed at the quantity of thru hole ICs on all 4 sides ! Hats off to those who are willing to work on these scopes!

Sent from kjo iPhone


Re: OT: +19.5 V connector on laptop computers

Leon Robinson
 

I just got a 19.5 volt 45 watt HP supply today.
The connector is a large 3 contact coaxial, Positive Center pin, Negative Outside Sleve
and Voltage control on the Inside Sleeve.
Voltage measured 13.4 from Outside to Center Pin with the Inside Sleeve open.

Voltage measured 22.2 from Outside to Center Pin with the Inside Sleeve shorted to the Center Pin.
I will probably cut the connector off for my use, because the Supply will be mounted
inside the case along with the other circuitry. Leon Robinson    K5JLR

Political Correctness is a Political Disease.

From: Jeff Urban <@JURB>
To: TekScopes@groups.io
Sent: Thursday, July 19, 2018 9:12 PM
Subject: Re: [TekScopes] OT: +19.5 V connector on laptop computers

On Mon, Jul 16, 2018 at 05:08 PM, Harvey White wrote:


I've seen a standardization to several end destinations. One is that
the voltage rating seems to determine the size of the barrel
connector. That's now, from what I can see.
You mean the outer diameter ? It seems the pin is more based on the current. this laptop, I can plug its adapter into a smaller and older laptop, but the for it will not plug into this one because of the pin diameter.

I'm going to conclude that there's an evolving standard out there, and
I have no idea of what it is.

Now, that is completely screwed up by the "DELL" standard, which
apparently includes some HP laptops.

Dell has a 3 wire cable to the power supply brick. The inner pin is
apparently an I2C connector. The inner and outer shells are power and
ground (suggest that the outer is ground). In a DELL computer, if the
power block does not identify itself as a "genuine" power adaptor,
then the battery will not charge.
Typical corporate behavior.  Captive market is king. If they continue this and sell enough of them like that then a market will be created for aftermarket chargers. It is not all that difficult. Just a matter of a custom tailored current output and their batteries are not of any brand new technology that doesn't exist yet.

Those adaptors (and don't ask me what I think of them) work with a
different standard. Not sure what the effective voltage and current
limits are in this case.
That's why we have test equipment. Take all OEM parts and let them work together a couple of times, Measure everything. Would I do a one off for myself ? No, I would get rid of the thing. I almost didn't buy these Gateways but the price was right. Large screen, full keyboard and 2 HD bays. But though there are multiple connection on the batteries (I have 3 I think) but the adapter only has 2, so there is none of that captive market shit.

I  used to build all my own PCs, and some for others, but you really can't do that with a laptop.

Actually for Jim's needs, there are probably surplus VCR power supplies that would do the job. For a one off it might be free on Craigslist or whatever. They fry out but with a new chopper, sometimes another transistor and changing the caps they can definitely do the job. Inmost the 3 major caps they need are those in the pi filter for the 5 volts because it feeds the feedback loop, and there is one in the snubber without which the chopper will short. Very rarely any other parts except do change a bunch more caps.

It's a thought.


Re: OT: +19.5 V connector on laptop computers

Harvey White
 

On Thu, 19 Jul 2018 19:11:56 -0700, you wrote:

On Mon, Jul 16, 2018 at 05:08 PM, Harvey White wrote:


I've seen a standardization to several end destinations. One is that
the voltage rating seems to determine the size of the barrel
connector. That's now, from what I can see.
You mean the outer diameter ? It seems the pin is more based on the current. this laptop, I can plug its adapter into a smaller and older laptop, but the for it will not plug into this one because of the pin diameter.
The outer diameter. I've seen 6, 9 and 12 volt adaptors where the
plugs will not go into something with the "wrong" voltage requirement.
The older ones seem to standardize on one thing and it's up to you to
hit the right voltage.

I design all my stuff with polarity protection, and the voltage
limiting/protection is starting to be a design feature, too.


I'm going to conclude that there's an evolving standard out there, and
I have no idea of what it is.

Now, that is completely screwed up by the "DELL" standard, which
apparently includes some HP laptops.

Dell has a 3 wire cable to the power supply brick. The inner pin is
apparently an I2C connector. The inner and outer shells are power and
ground (suggest that the outer is ground). In a DELL computer, if the
power block does not identify itself as a "genuine" power adaptor,
then the battery will not charge.
Typical corporate behavior. Captive market is king. If they continue this and sell enough of them like that then a market will be created for aftermarket chargers. It is not all that difficult. Just a matter of a custom tailored current output and their batteries are not of any brand new technology that doesn't exist yet.
Now ask what happens if the MOTHERBOARD won't recognize a valid power
adaptor.

Now ask if I buy any more DELL computers.


Those adaptors (and don't ask me what I think of them) work with a
different standard. Not sure what the effective voltage and current
limits are in this case.
That's why we have test equipment. Take all OEM parts and let them work together a couple of times, Measure everything. Would I do a one off for myself ? No, I would get rid of the thing. I almost didn't buy these Gateways but the price was right. Large screen, full keyboard and 2 HD bays. But though there are multiple connection on the batteries (I have 3 I think) but the adapter only has 2, so there is none of that captive market shit.
Not a connection on the battery. Didn't look and didn't at that time
care. Power brick and laptop.

Harvey



I used to build all my own PCs, and some for others, but you really can't do that with a laptop.

Actually for Jim's needs, there are probably surplus VCR power supplies that would do the job. For a one off it might be free on Craigslist or whatever. They fry out but with a new chopper, sometimes another transistor and changing the caps they can definitely do the job. Inmost the 3 major caps they need are those in the pi filter for the 5 volts because it feeds the feedback loop, and there is one in the snubber without which the chopper will short. Very rarely any other parts except do change a bunch more caps.

It's a thought.