Re: Boonton 250 RX Meter question
I saw your post to the Boonton group.
Do you have a manual? There is one for the 250-A at
and it has some information about
adjusting the bridge. The manual also states that mechanical shock
can mess up the bridge.
DaveD
On 2/17/2016 4:51 PM, `Richard Knoppow
dickburk@... [hp_agilent_equipment] wrote:
toggle quoted message
Show quoted text
?
??? I posted this to the Boonton group
but I am not sure anyone follows it any more.? I want to
check the tuning of the 100Khz IF. I can find nothing in
the handbooks or other literature about tuning it.? I
suspect its broadbanded by either stagger tuning or
perhaps overcoupling. No clues.?
??? My RX meter took a header. Fortunately it fell with
some cushioning and is not destroyed but the sensitivity
is way down.? I have not yet tested the tubes.? I
confirmed both oscillators are running but don't know
the expected voltage at the connectors.? However, both
voltages are the same as measured with an -hp- 410-B.? I
have to check the mixer tube and IF tubes.? I hope no
damage was done to anything really hard to obtain.
--
Richard Knoppow
dickburk@...
WB6KBL
|
Boonton 250 RX Meter question
??? I posted this to the Boonton group but I am not
sure anyone follows it any more.? I want to check the tuning of
the 100Khz IF. I can find nothing in the handbooks or other
literature about tuning it.? I suspect its broadbanded by either
stagger tuning or perhaps overcoupling. No clues.?
??? My RX meter took a header. Fortunately it fell with some
cushioning and is not destroyed but the sensitivity is way down.?
I have not yet tested the tubes.? I confirmed both oscillators are
running but don't know the expected voltage at the connectors.?
However, both voltages are the same as measured with an -hp-
410-B.? I have to check the mixer tube and IF tubes.? I hope no
damage was done to anything really hard to obtain.
--
Richard Knoppow
dickburk@...
WB6KBL
|
On Wed, 17 Feb 2016, Bob Macklin macklinbob@... [hp_agilent_equipment] wrote: Some programmers won't, some will. The rule is you can only BLOW a fuse, not "unblow" it. If programming does not call for "unblowing" any fuses programmer should work even if a device already lost its virginity. As of programming file -- you MUST have one. If there are "security fuses" in a device they will be almost certainly blown so it would be not posible to read a known good device programming info. It it relatively easy to circumvent if a device is pure combinatorial (just read it as if it's a memory then derive equations for each output based on input states) and next to impossible for a stateful device with feedbacks. If this is the case you would need a new PROGRAMMED chip. Don't know about all of them but e.g. Tek 2710/11/12 used PLS1{5,7)x Signetics chips extensively and those do _NOT_ have any security fuses so they are easy to read and clone. However "enhanced" PLS1{5,7)xAA chips added security fuses so no luck reading those. Tek 2710/11/12 used non-enhanced chips so I was able to read all of them and have a full set of .JED files from a known good fully working unit (had to pull them from the boards for reading then install 'em back that is not fun). The problem is some programmers will not blow them unless the chip is in the unblown state and there is no way to return these chips to the erased state.
How do you create a programming file for these chips? If they have a security fuse they cannot be read.
I avoid messing with this stuff anymore. I prefer to work with analog instruments wit no micros now.
Bob Macklin
K5MYJ
Seattle, Wa.
"Real Radios Glow In The Dark"
----- Original Message -----
From: Sergey Kubushyn ksi@... [hp_agilent_equipment]
To: Bob Macklin macklinbob@... [hp_agilent_equipment]
Sent: Wednesday, February 17, 2016 10:47 AM
Subject: Re: [hp_agilent_equipment] HP 8753B CPU issue
On Wed, 17 Feb 2016, Bob Macklin macklinbob@... [hp_agilent_equipment] wrote:
Luckily enough that failure usually caused by blown fuses self-healing so
they are no longer blown. It can be cured by re-programming them with the
same valid pattern so the ressurrected fuses would get blown again. It does
NOT guarantee the failure won't happen again but allows fixing those
instruments without programming new virgin chips. Programmed new chips will
have that exactly bit rot problem and they are rare as hens' teeth -- try to
find e.g. PLS155 in PLCC package...
> Bipolar/Fuseable Link PALs have the same Bit Rot problem of ROMs of that period.
>
> Bob Macklin
> K5MYJ
> Seattle, Wa.
> "Real Radios Glow In The Dark"
> ----- Original Message -----
> From: Nathan Johnson jdownj@... [hp_agilent_equipment]
> To: ChuckA chuck@... [hp_agilent_equipment]
> Sent: Wednesday, February 17, 2016 8:31 AM
> Subject: Re: [hp_agilent_equipment] HP 8753B CPU issue
>
>
>
>
> I'm sure you already considered, but the PAL was burned fresh, or swapped from a board of the same revision? As a programmable device, it is possible that the code in the PAL did change between board or prom revisions.
>
>
> Note that I have no knowledge of that unit specifically but I just got burned by different PAL code on a different repair.
>
>
> Nathan
> KK4REY
>
>
> Sent using CloudMagic Email
>
>
> On Wed, Feb 17, 2016 at 19:09, ChuckA chuck@... [hp_agilent_equipment] <hp_agilent_equipment@...> wrote:
>
>
> I've been working on this problem 8753B CPU card for a few months now
> with very limited results. The original problem was no video, which I
> tracked down to a bad PAL 16R1 chip, replacing that got me a screen with
> random lines and various flashing characters. I thought that problem was
> bad DRAM so I replaced them, still no change. Watching the status lights
> while changing the position of the A9CC jumper and pressing the "PRESET"
> button I was able to get it to occasionally start to work, but not all
> the time.
>
> The short story is I can now get it to run every time by following
> this procedure; turn the unit on with the A9CC jumper in the "NORMAL"
> position, then move the jumper to the center position and press
> "PRESET", then move the jumper to the next position to the right and
> press "PRESET". This will display "DRAM Passed" on the screen, then move
> the jumper back to the "NORMAL" position and press "PRESET", at which
> time the unit will start up and operate normally as long as power is
> applied.
>
> Any change in that sequence and it will not operate. I've swapped the
> PROM's into a working board and they work fine.
>
> Anyone have any idea what is going on with this?
>
> Chuck
>
> --
> See Early TV at:
>
> www.myvintagetv.com --- * * KSI@home KOI8 Net < > The impossible we do immediately. * * Las Vegas NV, USA < > Miracles require 24-hour notice. * *
|
The problem is some programmers will not blow them
unless the chip is in the unblown state and there is no way to return these
chips to the erased state.
?
How do you create a programming file for these
chips? If they have a security fuse they cannot be read.
?
I avoid messing with this stuff anymore. I prefer
to work with analog instruments wit no micros now.
?
Bob Macklin
K5MYJ
Seattle, Wa.
"Real
Radios Glow In The Dark"
?
?
toggle quoted message
Show quoted text
----- Original Message -----
Sent: Wednesday, February 17, 2016 10:47
AM
Subject: Re: [hp_agilent_equipment] HP
8753B CPU issue
?
On Wed, 17 Feb 2016, Bob Macklin macklinbob@... [hp_agilent_equipment]
wrote:
Luckily enough that failure usually caused by blown fuses
self-healing so
they are no longer blown. It can be cured by re-programming
them with the
same valid pattern so the ressurrected fuses would get blown
again. It does
NOT guarantee the failure won't happen again but allows
fixing those
instruments without programming new virgin chips. Programmed
new chips will
have that exactly bit rot problem and they are rare as hens'
teeth -- try to
find e.g. PLS155 in PLCC package...
>
Bipolar/Fuseable Link PALs have the same Bit Rot problem of ROMs of that
period.
>
> Bob Macklin
> K5MYJ
> Seattle, Wa.
>
"Real Radios Glow In The Dark"
> ----- Original Message -----
>
From: Nathan Johnson jdownj@... [hp_agilent_equipment]
> To:
ChuckA chuck@... [hp_agilent_equipment]
> Sent: Wednesday,
February 17, 2016 8:31 AM
> Subject: Re: [hp_agilent_equipment] HP 8753B
CPU issue
>
>
>
>
> I'm sure you already
considered, but the PAL was burned fresh, or swapped from a board of the same
revision? As a programmable device, it is possible that the code in the PAL
did change between board or prom revisions.
>
>
> Note that
I have no knowledge of that unit specifically but I just got burned by
different PAL code on a different repair.
>
>
>
Nathan
> KK4REY
>
>
> Sent using CloudMagic
Email
>
>
> On Wed, Feb 17, 2016 at 19:09, ChuckA
chuck@... [hp_agilent_equipment]
>
>
>
I've been working on this problem 8753B CPU card for a few months now
>
with very limited results. The original problem was no video, which I
>
tracked down to a bad PAL 16R1 chip, replacing that got me a screen
with
> random lines and various flashing characters. I thought that
problem was
> bad DRAM so I replaced them, still no change. Watching the
status lights
> while changing the position of the A9CC jumper and
pressing the "PRESET"
> button I was able to get it to occasionally
start to work, but not all
> the time.
>
> The short story
is I can now get it to run every time by following
> this procedure;
turn the unit on with the A9CC jumper in the "NORMAL"
> position, then
move the jumper to the center position and press
> "PRESET", then move
the jumper to the next position to the right and
> press "PRESET". This
will display "DRAM Passed" on the screen, then move
> the jumper back to
the "NORMAL" position and press "PRESET", at which
> time the unit will
start up and operate normally as long as power is
>
applied.
>
> Any change in that sequence and it will not operate.
I've swapped the
> PROM's into a working board and they work
fine.
>
> Anyone have any idea what is going on with
this?
>
> Chuck
>
> --
> See Early TV
at:
>
>
www.myvintagetv.com
>
>
>
>
>
>
---
*
*
KSI@home KOI8 Net < > The impossible we do immediately. *
* Las Vegas
NV, USA < > Miracles require 24-hour notice.
*
*
|
On Wed, 17 Feb 2016, Bob Macklin macklinbob@... [hp_agilent_equipment] wrote: Luckily enough that failure usually caused by blown fuses self-healing so they are no longer blown. It can be cured by re-programming them with the same valid pattern so the ressurrected fuses would get blown again. It does NOT guarantee the failure won't happen again but allows fixing those instruments without programming new virgin chips. Programmed new chips will have that exactly bit rot problem and they are rare as hens' teeth -- try to find e.g. PLS155 in PLCC package... Bipolar/Fuseable Link PALs have the same Bit Rot problem of ROMs of that period.
Bob Macklin
K5MYJ
Seattle, Wa.
"Real Radios Glow In The Dark"
----- Original Message -----
From: Nathan Johnson jdownj@... [hp_agilent_equipment]
To: ChuckA chuck@... [hp_agilent_equipment]
Sent: Wednesday, February 17, 2016 8:31 AM
Subject: Re: [hp_agilent_equipment] HP 8753B CPU issue
I'm sure you already considered, but the PAL was burned fresh, or swapped from a board of the same revision? As a programmable device, it is possible that the code in the PAL did change between board or prom revisions.
Note that I have no knowledge of that unit specifically but I just got burned by different PAL code on a different repair.
Nathan
KK4REY
Sent using CloudMagic Email
On Wed, Feb 17, 2016 at 19:09, ChuckA chuck@... [hp_agilent_equipment] <hp_agilent_equipment@...> wrote:
I've been working on this problem 8753B CPU card for a few months now
with very limited results. The original problem was no video, which I
tracked down to a bad PAL 16R1 chip, replacing that got me a screen with
random lines and various flashing characters. I thought that problem was
bad DRAM so I replaced them, still no change. Watching the status lights
while changing the position of the A9CC jumper and pressing the "PRESET"
button I was able to get it to occasionally start to work, but not all
the time.
The short story is I can now get it to run every time by following
this procedure; turn the unit on with the A9CC jumper in the "NORMAL"
position, then move the jumper to the center position and press
"PRESET", then move the jumper to the next position to the right and
press "PRESET". This will display "DRAM Passed" on the screen, then move
the jumper back to the "NORMAL" position and press "PRESET", at which
time the unit will start up and operate normally as long as power is
applied.
Any change in that sequence and it will not operate. I've swapped the
PROM's into a working board and they work fine.
Anyone have any idea what is going on with this?
Chuck
--
See Early TV at:
www.myvintagetv.com
--- * * KSI@home KOI8 Net < > The impossible we do immediately. * * Las Vegas NV, USA < > Miracles require 24-hour notice. * *
|
?
Bipolar/Fuseable Link PALs have the same Bit Rot problem of
ROMs of that period.
?
Bob Macklin
K5MYJ
Seattle, Wa.
"Real Radios Glow In
The Dark"
----- Original Message -----
Sent: Wednesday, February 17, 2016 8:31
AM
Subject: Re: [hp_agilent_equipment] HP
8753B CPU issue
?
I'm sure you already considered, but the PAL was burned fresh,
or swapped from a board of the same revision? ?As a programmable device,
it is possible that the code in the PAL did change between board or prom
revisions.
Note that I have no knowledge of that unit specifically but I just got
burned by different PAL code on a different repair.
Nathan
KK4REY
On Wed, Feb 17, 2016 at
19:09, ChuckA chuck@... [hp_agilent_equipment]
wrote:
?
I've been working on this problem 8753B CPU card for a few months now
with very limited results. The original problem was no video, which I
tracked down to a bad PAL 16R1 chip, replacing that got me a screen with
random lines and various flashing characters. I thought that problem was
bad DRAM so I replaced them, still no change. Watching the status lights
while changing the position of the A9CC jumper and pressing the "PRESET"
button I was able to get it to occasionally start to work, but not all
the time.
The short story is I can now get it to run every time
by following
this procedure; turn the unit on with the A9CC jumper in
the "NORMAL"
position, then move the jumper to the center position and
press
"PRESET", then move the jumper to the next position to the right
and
press "PRESET". This will display "DRAM Passed" on the screen, then
move
the jumper back to the "NORMAL" position and press "PRESET", at
which
time the unit will start up and operate normally as long as power
is
applied.
Any change in that sequence and it will not operate.
I've swapped the
PROM's into a working board and they work
fine.
Anyone have any idea what is going on with
this?
Chuck
--
See Early TV
at:
www.myvintagetv.com
|
Re: Test Equipment where battery failure causes SERIOUS problems
No battery in the 3456A. Calibration is by knob twiddling.
?
?
toggle quoted message
Show quoted text
----- Original Message -----
Sent: Wednesday, February 17, 2016 12:46
PM
Subject: RE: [hp_agilent_equipment] Re:
Test Equipment where battery failure causes SERIOUS problems
?
Does anyone know
about the HP 3456A DMM? I can’t remember if it requires a battery for cal
memory or not.
Thanks
Gary?
K4FMX
?
The 859X series
spectrum analyzers loose: band leveling offsets, attenuator corrections, and
clock corrections if the memory battery dies. There is at least a procedure to
copy these down from the operator interface so they can be reloaded in event
of failure.?
On
Wednesday, February 17, 2016 2:02 AM, "Peter Hansen oz1lpr@...
[hp_agilent_equipment]"
<hp_agilent_equipment@...>
wrote:
?
Hello
David?I think the HP 8756 Scalar analyzer?Looses all the Channel
calibration data if the battery is lost. This requires?programming
through a HP computer with obsolete software.
best regards Peter Hansen
?
To:
hp_agilent_equipment@...
From:
hp_agilent_equipment@...
Date: Tue, 16 Feb 2016
21:39:40 +0000
Subject: [hp_agilent_equipment] Re: Test Equipment where
battery failure causes SERIOUS problems
?
On 16 February
2016 at 21:27, Dr. David Kirkby (Kirkby Microwave Ltd) <drkirkby@...>
wrote:
2) HP 3457A 6.5
digit multimeter
whilst not so
catastrophic, a report I read recently on one of the newsgroups from someone,
said he sent a 3457A in for calibration, and the company was not happy as the
failure of the battery added an hour to the calibration time. They were going
to charge for this, but in the end they did
not.
Just to clarify,
the extra hour was not for replacing the battery - the owner had already done
that. The extra hour was for the fact every range needed zeroing and setting
to full scale.?
|
Well that should eliminate that issue. ?Hopefully someone here has an idea more specific to that model.
Nathan KK4REY On Wed, Feb 17, 2016 at 20:46, ChuckA chuck@... [hp_agilent_equipment] wrote:
?
Nathan
I swapped the new PAL into a working board with no problem, and tried
firmware version 2.01 and 3.0 PROMs and both worked.
Chuck
On 2/17/2016 11:31 AM, Nathan Johnson jdownj@...
[hp_agilent_equipment] wrote:
>
>
> I'm sure you already considered, but the PAL was burned fresh, or
> swapped from a board of the same revision? As a programmable device, it
> is possible that the code in the PAL did change between board or prom
> revisions.
>
> Note that I have no knowledge of that unit specifically but I just got
> burned by different PAL code on a different repair.
>
> Nathan
> KK4REY
>
> Sent using CloudMagic Email
>
>
> On Wed, Feb 17, 2016 at 19:09, ChuckA chuck@...
> [hp_agilent_equipment] wrote:
>
> I've been working on this problem 8753B CPU card for a few months now
> with very limited results. The original problem was no video, which I
> tracked down to a bad PAL 16R1 chip, replacing that got me a screen
> with
> random lines and various flashing characters. I thought that problem
> was
> bad DRAM so I replaced them, still no change. Watching the status
> lights
> while changing the position of the A9CC jumper and pressing the
> "PRESET"
> button I was able to get it to occasionally start to work, but not all
> the time.
>
> The short story is I can now get it to run every time by following
> this procedure; turn the unit on with the A9CC jumper in the "NORMAL"
> position, then move the jumper to the center position and press
> "PRESET", then move the jumper to the next position to the right and
> press "PRESET". This will display "DRAM Passed" on the screen, then
> move
> the jumper back to the "NORMAL" position and press "PRESET", at which
> time the unit will start up and operate normally as long as power is
> applied.
>
> Any change in that sequence and it will not operate. I've swapped the
> PROM's into a working board and they work fine.
>
> Anyone have any idea what is going on with this?
>
> Chuck
>
> --
> See Early TV at:
>
> www.myvintagetv.com
>
>
>
>
--
See Early TV at:
www.myvintagetv.com
|
On Sun, 14 Feb 2016, Orin Eman orin.eman@... [hp_agilent_equipment] wrote: A little more on the 545xx power supplies.
So the 0950-2369 supersedes the 0950-1879 - I doubt there is much
difference given the discussion so far. My HP54542A uses the 0950-2369 with P/N 700202-001. I did quite some research regarding schematics without success. The supply was from 1993 and has manufacturer part number XL130-3630E. I would not buy any of these supplies on eBay - the likely reason the
instrument was parted out was the supply died. However, the -1879 was used
in the 1650B logic analyzer and working instruments run around $50! That sounds a clever idea for Michael's 54542C, too! I bought one of the chinese supplies (for much less than the current ones run) as a spare and it works... Best regards, Erik.
|
Nathan
I swapped the new PAL into a working board with no problem, and tried firmware version 2.01 and 3.0 PROMs and both worked.
Chuck
toggle quoted message
Show quoted text
On 2/17/2016 11:31 AM, Nathan Johnson jdownj@... [hp_agilent_equipment] wrote:
I'm sure you already considered, but the PAL was burned fresh, or
swapped from a board of the same revision? As a programmable device, it
is possible that the code in the PAL did change between board or prom
revisions.
Note that I have no knowledge of that unit specifically but I just got
burned by different PAL code on a different repair.
Nathan
KK4REY
Sent using CloudMagic Email
<>
On Wed, Feb 17, 2016 at 19:09, ChuckA chuck@...
[hp_agilent_equipment] <hp_agilent_equipment@...> wrote:
I've been working on this problem 8753B CPU card for a few months now
with very limited results. The original problem was no video, which I
tracked down to a bad PAL 16R1 chip, replacing that got me a screen
with
random lines and various flashing characters. I thought that problem
was
bad DRAM so I replaced them, still no change. Watching the status
lights
while changing the position of the A9CC jumper and pressing the
"PRESET"
button I was able to get it to occasionally start to work, but not all
the time.
The short story is I can now get it to run every time by following
this procedure; turn the unit on with the A9CC jumper in the "NORMAL"
position, then move the jumper to the center position and press
"PRESET", then move the jumper to the next position to the right and
press "PRESET". This will display "DRAM Passed" on the screen, then
move
the jumper back to the "NORMAL" position and press "PRESET", at which
time the unit will start up and operate normally as long as power is
applied.
Any change in that sequence and it will not operate. I've swapped the
PROM's into a working board and they work fine.
Anyone have any idea what is going on with this?
Chuck
--
See Early TV at:
www.myvintagetv.com
--
See Early TV at:
www.myvintagetv.com
|
Re: Test Equipment where battery failure causes SERIOUS problems
Does anyone know about the HP 3456A DMM? I
can’t remember if it requires a battery for cal memory or not.
?
Thanks
Gary? K4FMX
?
toggle quoted message
Show quoted text
From: hp_agilent_equipment@... [mailto:hp_agilent_equipment@...]
Sent: Wednesday, February 17, 2016
8:10 AM
To: hp_agilent_equipment@...
Subject: Re:
[hp_agilent_equipment] Re: Test Equipment where battery failure causes SERIOUS
problems
?
?
The
859X series spectrum analyzers loose: band leveling offsets, attenuator
corrections, and clock corrections if the memory battery dies. There is at
least a procedure to copy these down from the operator interface so they can be
reloaded in event of failure.?
On
Wednesday, February 17, 2016 2:02 AM, "Peter Hansen oz1lpr@...
[hp_agilent_equipment]" <hp_agilent_equipment@...>
wrote:
?
?
Hello
David?I think the HP 8756 Scalar analyzer?Looses all the Channel
calibration data if the battery is lost. This requires?programming through
a HP computer with obsolete software.
best regards Peter Hansen
?
To:
hp_agilent_equipment@...
From: hp_agilent_equipment@...
Date: Tue, 16 Feb 2016 21:39:40 +0000
Subject: [hp_agilent_equipment] Re: Test Equipment where battery failure causes
SERIOUS problems
?
?
On
16 February 2016 at 21:27, Dr. David Kirkby (Kirkby Microwave Ltd) <drkirkby@...>
wrote:
?
2) HP 3457A 6.5 digit multimeter
whilst
not so catastrophic, a report I read recently on one of the newsgroups from
someone, said he sent a 3457A in for calibration, and the company was not happy
as the failure of the battery added an hour to the calibration time. They were
going to charge for this, but in the end they did not.
Just
to clarify, the extra hour was not for replacing the battery - the owner had
already done that. The extra hour was for the fact every range needed zeroing
and setting to full scale.?
?
|
On Sun, 14 Feb 2016, Jack Mcmullen forjack842@... [hp_agilent_equipment] wrote: Like I said, map and draw out the over heating 350's circuit. If its being supplied by the +5.2v supply is providing a voltage reference in the 3v range. If that's 0vdc at pin 2, fix that then proceed on to isolate what hangs on the voltage bus. This ain't rocket science guys just methodical troubleshooting without a schematic. See my thread from 2013 - I had probably a similar problem with my 54542a which has the identical power supply: In my case it was the -12V generation which was faulty and I already drew the schematic in 2013... And yes - this is no rocket science, but it is very cumbersome to do measurements on the opened supply as the cable to the oscilloscope is rather short ;-) Good luck to Michael and his 54542C... Erik.
|
Hi Orin, thanks for your hints to Michael and his 54542C. I had a similar Problem in 2013 with a 54542a which uses the same supply. See the thread in this forum's archive: than required to avoid dropout and may be dissipating excess power. The
report of 0.5V on the LM350 input sounds wrong - it's dropped out of
regulation. Yes, that is what I observed to be the USECASE in this weired design. In 2013 I drew out a schematic of the -12V generation, see here The output is tied to 0V and the regulator's ground pin can be adjusted. So the regulator actually sees a short on its output and thus the input MUST be as low as the drop out voltage. The purpose of this design is (IMHO), that the switch mode supply charges the capacitor C2 to 12.5V via T and D1. Normally the input of the regulator is close to 0.5V giving an output of unregulated -12V. If there is escessive current drawn from the supply, the current flowing into the regulator increases as well and if it is above the maximum permitted value of the LM350, it is going to "open". This means the voltage at the LM350's input increases towards e.g. 3V where the -12V are changing to -9.5V (remember, C2 is still charged by the switcher to 12.5V and the switcher can supply much more current). In this way a current protection is realized... One of the LM350s regulates the ground line of the -12V supply, so again,
voltages don't seem out of line with the adjustment pin at -1.2V. As far as I can remember, there is another LM350 in this supply, but this was not the problem in my case... a little high for the 15.5V unregulated line, but without observing a
working supply, we don't know). I had 16.12V with 200mV ripple on the 15.5V line. The ripple had the form of small v's going to lower voltage. I'd recommend Michael to supply the -12V from an external, current protected supply to see, how much current the mainboard draws. There are small switch moder regulators generating a whole bunch of other voltages from the -12V and maybe one of the many Tantalum Cs there is the evil part ;-) Erik. [hp_agilent_equipment] <hp_agilent_equipment@...> wrote:
Hi guys,
Your outpouring of help is amazing. Many comments are very relevant to
this PS, but some seem to be addressing a different version. The HP
numbers are 0950-2369, Mfg numbers XL130-3630E and the diagrams I've seen
reverse engineered are fairly accurate even though the one I saw was
created from a different version PS.
I've looked over the voltages and every rail appears to be right where it
should be. A bit noisy, but DC is very good throughout the unit. There
are some devices in the PS and on the mother board which are getting very
warm, a bit too hot to touch, but far from burning anything. One thing
I've noticed, the unit as a whole is drawing about 160 AC watts, seems a
bit high. I recall reading it should be somewhere around 145 watts? So...
I'm 'thinking' something is drawing too much current, as brought up in
thread, not enough enable shutdown but enough to create some switching
noise in the PS rails. Does that make sense?
Here what I would like to do, if this is appropriate, upload a few
seconds of capture so everyone can see what I'm seeing so I'm not confusing
anyone. I've tried several generators from 50kC to 500Mhz so I know it
isn't signal noise, I see the noise at all levels albeit much more
pronounced in the single digit milli-volt levels. One issue I personally
have is, I've this is my first 'digital' scope so I'm unfamiliar with how a
trace should appear.
~Michael - AF7U
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Hi Joe.
Can you provide some detail on the jumper settings for the 2 rom solution??
Thanks.
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Re: HP 3325A ROM Replacement
?
Either a 27C128 or a? 1/2 of a 27C256 would do it. A small PC board
with some pins to match one of the four 4k sockets as well as some chip select
jumper(s) to the other socket(s). Both of these chips are supported by most
programmers and the supply should persist.
?
This may be useful for many other equipment that used the same Roms.
?
I repaired a HP DMM that had Mostek Roms by installing a 24 pin socket in
one position and installing the 27C128 with the four pins bent out and wired to
the other sockets.
?
?
?
----- Original Message -----
Sent: Tuesday, February 16, 2016 8:00
PM
Subject: [hp_agilent_equipment] HP 3325A
ROM Replacement
?
I thought I would summarize a somewhat meandering thread.
I’ve
received the Artek manual and it is great!?
It appears I do have
a failing ROM IC.?
As time went by HP changed from 4 4k*8 chips
to 2 8k*8 chips and there is a way to jumper some boards to tell it which is
installed.? (Joe: is that just the A/B jumpers near U5, or is it more
than that?).? Apparently there are even some 3325a’s with 3 ROM
ics.
The HP nano-processor only has 11 address lines for a 12 bit space
and so they played games to extract the 12 bit.? In the 4-chip solution,
each chip has 2 select pins which are used in such a way as to provide the top
2 most significant bits.
Thus far, I have not found a 4k*8 EPROM or
EEPROM that is pin-compatible with the original Synertek Sy2332/Motorola
MCM88A332 masked ROM.? The TMS2532 are almost right, but lack the second
select pin. [I keep seeing this listed even in historical literature as
pin-compatible, but it is not according to the data sheets.? I’ve seen
this so many places that I wonder if the datasheets are wrong and pin 20 can
be used as a second select.]
The original 2-IC solution used the
Motorola MCM68764C EEPROM.? A later version of that chip? is the
Motorola MCM68766.? Joe has previously extracted the 2-IC ROM
program.? I would guess that the 4-IC data is the same, just split
between chips.? I also think the data is the same independent of options
as otherwise the signature analysis info would have to change between
machines, and it does not.
My repair options include:
4
IC’s.? This looks to require some extra glue logic to decode the second
select unless a pin-compatible EEPROM can be found.? It would also
require me to extract my data or split the existing 2-IC data.
2
IC’s.? This only requires some jumper changes and the ROM program is
already available.
1 IC solution.? Because the 3325a already
decodes the 2 select pins as if they’re address pins, this would only require
a simple pin-remapping board for the new IC.
Option B looks like the
obvious choice except that I have so far only been able to find used
replacement EEPROMs and I wonder about the longevity of those.
I’d also
like to help the next person that needs to fix the ROM in a 3325a, and that
argues for Option C.? Once option C is chosen almost any parallel ROM can
be used and I’m seeing some flash-ROM with a listed lifetime of 100+
years.
Does anyone have a favorite 16k*8 EEPROM ic that is common and
likely to be available for a few more years?
|
Hi Michael, thanks for the update and sorry for my delayed response: I have been on a trip in the Alps without access to the Internet... The parts came in this morning and I R&R'd the LM350 and it didn't seem to have any effect on the issue, maybe reduced but maybe not. OK, that is bad. Do you observe the noise on all channels? In my case in 2013 I had all channels showing the same noise, see here: I.e. turn on all channels and set them to different y-positions and see whether the noise is correlated! 0v, and pin 3 = 5.37 volts. From reading your prior post I'm assuming something is drawing too much current as you mentioned. Yes, I guess that this is the case. If the noise is synchronous on all channels I bet for the supply a the prolem! In 2013 I prooved this by supplying the -12V temporarily from an external supply and 0.5A -0.7A have been sufficient and the noise was gone with the external supply. HOT, interestingly, all the other rails are within specs, save the +15, which is +16.66 volts, (I'm really curious what's causing that). My supply has more than +15V here, too. but I see no other recourse. I can't help but think that the -12 should be loaded down a bit?!?! But it's solid at -12... That sounds strange - in my case (and using a second oscilloscope) I was able to see some temporal excursions on the -12V power line as the noise was visible on the screen. Let's see the other responses... Erik.
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I'm sure you already considered, but the PAL was burned fresh, or swapped from a board of the same revision? ?As a programmable device, it is possible that the code in the PAL did change between board or prom revisions.
Note that I have no knowledge of that unit specifically but I just got burned by different PAL code on a different repair.
Nathan KK4REY On Wed, Feb 17, 2016 at 19:09, ChuckA chuck@... [hp_agilent_equipment] wrote:
?
I've been working on this problem 8753B CPU card for a few months now
with very limited results. The original problem was no video, which I
tracked down to a bad PAL 16R1 chip, replacing that got me a screen with
random lines and various flashing characters. I thought that problem was
bad DRAM so I replaced them, still no change. Watching the status lights
while changing the position of the A9CC jumper and pressing the "PRESET"
button I was able to get it to occasionally start to work, but not all
the time.
The short story is I can now get it to run every time by following
this procedure; turn the unit on with the A9CC jumper in the "NORMAL"
position, then move the jumper to the center position and press
"PRESET", then move the jumper to the next position to the right and
press "PRESET". This will display "DRAM Passed" on the screen, then move
the jumper back to the "NORMAL" position and press "PRESET", at which
time the unit will start up and operate normally as long as power is
applied.
Any change in that sequence and it will not operate. I've swapped the
PROM's into a working board and they work fine.
Anyone have any idea what is going on with this?
Chuck
--
See Early TV at:
www.myvintagetv.com
|
I've been working on this problem 8753B CPU card for a few months now with very limited results. The original problem was no video, which I tracked down to a bad PAL 16R1 chip, replacing that got me a screen with random lines and various flashing characters. I thought that problem was bad DRAM so I replaced them, still no change. Watching the status lights while changing the position of the A9CC jumper and pressing the "PRESET" button I was able to get it to occasionally start to work, but not all the time.
The short story is I can now get it to run every time by following this procedure; turn the unit on with the A9CC jumper in the "NORMAL" position, then move the jumper to the center position and press "PRESET", then move the jumper to the next position to the right and press "PRESET". This will display "DRAM Passed" on the screen, then move the jumper back to the "NORMAL" position and press "PRESET", at which time the unit will start up and operate normally as long as power is applied.
Any change in that sequence and it will not operate. I've swapped the PROM's into a working board and they work fine.
Anyone have any idea what is going on with this?
Chuck
--
See Early TV at:
www.myvintagetv.com
|
John, ? I don’t know of any source of the Synertec EPROM data.? The person I helped with this problem in 2013 ultimately removed his chips and installed the two chips referred to in the link below.? IIRC, one of the problems with the ‘direct replacement’ approach was finding chips that were, in fact, direct pin for pin compatible. ? With the ‘two chip’ approach, you wind up with a board that is ‘original’, sort of, since it was one of the ‘original options’ for the unit.? And, it is relatively straight forward, not requiring building any additional circuitry, with issues of ‘timing’, etc. ?
? Let me know if you have any questions or if I can help. ? Good luck. ? Joe ?
toggle quoted message
Show quoted text
From: hp_agilent_equipment@... [mailto:hp_agilent_equipment@...]
Sent: Tuesday, February 16, 2016 11:34 PM
To: hp_agilent_equipment@...
Subject: [hp_agilent_equipment] Re: HP 3325A What ROMS?? ? Sorry to connect up to this thread. tried to make a new one but Yahoo no
longer recognizes my id and wont let me post
new thread
Been following the 3325A threads as I think I have a ROM issue with
mine, but have looked at all the referenced
threads and cant find mine there
My printed manuals including the Hp cross references are currently
under a 4 ft pile of manuals etc after a 6 shelved cheap bookshelf
collapsed and threw everything on the floor ... had been Ok for the last
3 years, but gave up under the weight last night, so apologies for
asking stuff I may have been able to find otherwise... its over 40Deg C
in there at the moment as were having a continual heatwave her in West
Australia
and I cant even breath properly in that room.right now
3325A S/N 1748A03039 OPTION 1 Bought at local auction 5 years ago
4 X ROMS soldered in Probably Synertec (Large square "S")
U1
7941E
C51030
Hp No 1818-0702
U2
7932E
C51031
Hp No 1818 -0703
U3
8007E
C51032
Hp No 1818 -0704
U4
7952E
C51243
Hp No 1818-9705
The "5" after the C is definitely a Five, not a Y
Q: can you point me to where I can find mod info for these chips
replacements please?
Have downloaded ( start Jun 3rd 2013) 3325A collection as directed ,
but don't see anything relevant to my chip set there
Symptoms are: crazy randomized LED display constantly randomly repeating.
Previous work done:
Replaced On/Off switch
Replaced all ribbon interconnects with made up ones as originals
separated (All connections checked out OK ....big job)
Replaced a (wire wound!!) output resistor from a previous "repair" with
original HF type.
All PSU voltages correct with ripple within specs
Had been working fine until a few months ago
Thanks for your time
John
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Re: Test Equipment where battery failure causes SERIOUS problems
The 859X series spectrum analyzers loose: band leveling offsets, attenuator corrections, and clock corrections if the memory battery dies. There is at least a procedure to copy these down from the operator interface so they can be reloaded in event of failure.?
-Kelly
On Wednesday, February 17, 2016 2:02 AM, "Peter Hansen oz1lpr@... [hp_agilent_equipment]" wrote:
?
Hello David?I think the HP 8756 Scalar analyzer?Looses all the Channel calibration data if the battery is lost. This requires?programming through a HP computer with obsolete software. best regards Peter Hansen ?
To: hp_agilent_equipment@... From: hp_agilent_equipment@... Date: Tue, 16 Feb 2016 21:39:40 +0000 Subject: [hp_agilent_equipment] Re: Test Equipment where battery failure causes SERIOUS problems
?
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Sergey Kubushyn