Re: HELP!! - 141T / 8555A
Hi Pete having disassembled the block and cleaned mine some time ago I am
pretty sure there is no electronics inside it . It is just a interface from
wire to the flat transparent ribbon cable. I cleaned it on the understanding
that I have had trouble with "zebra strips" in the past where cleaning was
the solution. It is of course possible that one of the traces in the ribbon
cable has broken on Chris's tube....they are very thin copper. However if I
remember he tried another tube which would mean a different ribbon cable ( I
think they are attached to the tube) so that negates that idea.
Alan G3NYK
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----- Original Message ----- From: Pete <peterawson@...> To: <hp_agilent_equipment@...> Sent: 18 January 2007 16:04 Subject: Re: [hp_agilent_equipment] HELP!! - 141T / 8555A This problem is tough to get a handle on w/o schematics & I have none. But, from your shcematics & parts list, what is the P/N
on that "junction" box (I suspect it has some functionality hidden under the potting compound). I may be able to get some
"inside" help to learn what the gizmo is.
Pete Rawson
Yahoo! Groups Links
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WG: Mysterious box: K-79-59992A Mixer/IF Amplifier
Hello,
I have written the following email about 3 month ago, no reply and I also
couldn't find any information on this thing. There must be some experts out
there who know this beast. If not here, where else? ...
I have found another mysterious (at least for me) HP box in my cellar: It's
labeled K-79-59992A Mixer/IF Amplifier. It has 3 BNC connectors on the
front panel labeled IF output / LO /RF and a IF bandwidth switch with range
from 25 Hz to 100KHz. I think it's a accessory for a spectrum analyzer??
Any ideas where it belongs to, what kind of IF is used (frequency), ect. ?
As always, ANY information greatly appreciated.
Regards from Austria
Gregor Lasser
OE1GLC
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Re: HELP!! - 141T / 8555A
This problem is tough to get a handle on w/o schematics & I have none. But, from your shcematics & parts list, what is the P/N
on that "junction" box (I suspect it has some functionality hidden under the potting compound). I may be able to get some
"inside" help to learn what the gizmo is.
Pete Rawson
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Re: HP8568B on screen text intensity
thats the way i would do it too and i think the kit is worth $1495
im not familiar with the 8568b but if it dosent have a vga output
then it is a fairly complex project to design a product like that.
"im sure their sales volume is small "100s of units"
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----- Original Message -----
From: Greg Werstiuk
To: hp_agilent_equipment@...
Sent: Wednesday, January 17, 2007 3:19 AM
Subject: RE: [hp_agilent_equipment] HP8568B on screen text intensity
That would be Test Equipment Plus which I pointed out to the group some
months back when we were having a discussion on weak/failing CRTs in 856x
units.
Web site:
<BLOCKED::>
Not inexpensive however.
- Greg
_____
From: hp_agilent_equipment@...
[mailto:hp_agilent_equipment@...] On Behalf Of Didier Juges
Sent: Saturday, January 13, 2007 7:44 AM
To: hp_agilent_equipment@...
Subject: Re: [hp_agilent_equipment] HP8568B on screen text intensity
Chuck Harris wrote:
> Hi David,
>
> You have a low emission CRT. Most HP CRT's are on RF instruments
> where the operator feels inclined to leave the instrument on 24/7 to
> keep it warmed up and stable for use at a moment's notice. This wears
> out the cathode in the CRT's gun assembly, and makes it become
increasingly
> dim, and blurry.
>
> There are only two fixes for this problem: 1) replace the CRT, something
> that is becoming more and more difficult, and 2) restore/rejuvenate the
> CRT, a process that sometimes extends the useful life of the CRT for a
> good while.
>
There is a third fix: a company (I forgot whom, but they should not be
too hard to google, or John Miles can post it here) makes a color LCD
replacement for the entire display. Pretty neat, and great use of color.
It's not cheap, but worth it, considering what these instruments are
worth in good condition. This replacement makes it better than new!
Didier KO4BB
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Re: HELP!! - 141T / 8555A
At 03:33 PM 18/01/07, you wrote: These two leads go to a small black "junction box", where they meet up with
the 6.6KV accelerator voltage and are channelled to the front of the CRT by
means of a three conductor ribbon cable. As these wires are moulded into
the box and I obviously cannot check the other end of where the ribbon cable
joins the CRT, I have no way of checking whether the little pressure pads
inside the junction box are not doing their job, or whether the problem is
due to some other reason. Suggest compare your junction box continuity with the other unit, might find a part inside like hi voltage diode or resistor etc, I'm not familiar with the devices but seems this step might help pin down a bit more difference etc Regards from Mike Massen Network Power Systems Lab +61 (0) 8 9444 8961 Mb +61 (0) 438 048961 Perth, Western Australia * USA GMC, Opel and Australian VL/VK Commodore Fuse Rail that wont warp or melt ! * RB30 Skyline/Nissan/VL Upgraded ignition driver now in long term economy trials * Twin tyres for most sedans, trikes and motorcycle sidecars * Industrial grade PolyVinyliDeneChloride (PVDC Copolymer) in bulk, the best oxygen and water protective barrier you can find for circuit boards. * Special Equipment for sale: 60KVA 3-phase UPS with large battery cabinet - $12,000 Web site under construction, Ebay and Oztion Auctions
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I posted this question on the HP list about a week ago and received only one reply, which unfortunately did not fix the problem, so I am trying again, this time with a little more information / test results.
I have a problem with my 141T/8555A spectrum analyzer. The gear works perfect in the conventional mode, but it will not operate in variable persistence mode. When I push the "STD" button, the screen does not change (no flooding, blooming etc)and the trace on the screen is the same as compared to the "CONVENTIONAL" mode. The same happens when I push " FAST". Don Collie has very generously swapped my pulse circuit board in his analyzer and has confirmed that the pulse board is OK. Indeed I have checked all voltages and waveforms / amplitudes on the pulse board and confirmed that they operate as expected. I have also checked all supply voltages and adjusted them to be spot on. The voltages at the various pins on the CRT socket and neck have been checked, including the -12.6V heater voltage for the flood gun and are all within limits. I have not checked the 6.6KV supply, as the unit is fine in the conventional mode. In sheer desperation I replaced the CRT with a brand new one (NOS) I was keeping for a rainy day, (which of course includes a brand new infamous 3 conductor ribbon cable), but it has not solved the problem. In other words everything is fine as a conventional analyzer, but when the "STD or FAST" button is pushed, nothing changes.
I have borrowed a functioning 141T and compared voltages waveforms etc and can find no difference between my unit and the "good" one, even after adjusting the various flood gun related trimpots to produce similar voltages. HOWEVER, I have noticed just a little while ago that disconnecting the CRT storage mesh backing electrode (6) and or the collector mesh (902), results in no change in the trace in any setting regardless of whether it is conventional or variable persistence. This leads me to suspect that perhaps these signals are not reaching the CRT. These two leads go to a small black "junction box", where they meet up with the 6.6KV accelerator voltage and are channelled to the front of the CRT by means of a three conductor ribbon cable. As these wires are moulded into the box and I obviously cannot check the other end of where the ribbon cable joins the CRT, I have no way of checking whether the little pressure pads inside the junction box are not doing their job, or whether the problem is due to some other reason.
I am hoping that someone can suggest what my next moves should be, or whether there is some way of checking the integrity of the junction box. Is there some signal/voltage I can apply to the CRT storage mesh backing electrode (6) and /or collector mesh (902), to check for continuity in the "junction" box?
Any other suggestions would be most welcome,as I am COMPLETELY STUMPED at this stage.
Cheers,
Chris
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HP 54601 vertical deviation trouble fixed
The screen size was reduced by 2 in vertical.(more compressed in the top)
Failure: C608 on the TV video board.(1O?F) By security change also the
1000uF and use good quality 105¡ãc (origin 85¡ãc)
Manufacturing date around 1990...
The IC who drives the vertical coil is ?PC1379c and the datasheet is
easy to find on the web.
AM
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Re: HP8568B CRT replacement question LCD?
(I should've been clearer on that... it's actually shift-g and shift-h
(lowercase). Those are the CLEAR-WRITE and MAX HOLD buttons for the B
trace. Or, use the KSg and KSh commands if you're talking to it remotely.)
-- john, KE5FX
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-----Original Message----- From: hp_agilent_equipment@... [mailto:hp_agilent_equipment@...]On Behalf Of Didier Juges Sent: Wednesday, January 17, 2007 7:49 PM To: hp_agilent_equipment@... Subject: Re: [hp_agilent_equipment] Re: HP8568B CRT replacement question LCD? Forget the previous question :-) Thanks Didier KO4BB John Miles wrote: Letting the tube run constantly at minimum intensity (low/no grid current)
does prevent burn-in, but it contributes to cathode poisoning. HP warns
against doing that in their manuals, and gives you a way to turn the whole
CRT supply including the filament on and off via those shift-G/H keys.
Aluminized phosphors may or may not have anything to do with burn-in
resistance; I don't know. I've seen plenty of HP and Tek CRTs with severe
burn-in, though.
-- john, KE5FX
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Re: HP8568B CRT replacement question LCD?
Forget the previous question :-)
Thanks
Didier KO4BB
John Miles wrote:
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Letting the tube run constantly at minimum intensity (low/no grid current)
does prevent burn-in, but it contributes to cathode poisoning. HP warns
against doing that in their manuals, and gives you a way to turn the whole
CRT supply including the filament on and off via those shift-G/H keys.
Aluminized phosphors may or may not have anything to do with burn-in
resistance; I don't know. I've seen plenty of HP and Tek CRTs with severe
burn-in, though.
-- john, KE5FX
-----Original Message-----
From: hp_agilent_equipment@...
[mailto:hp_agilent_equipment@...]On Behalf Of arthurok
Sent: Wednesday, January 17, 2007 5:54 PM
To: hp_agilent_equipment@...
Subject: Re: [hp_agilent_equipment] Re: HP8568B CRT replacement question
LCD?
you think that the crt beam is wearing out the phosphor? "ion
burns???
i thought aluminized tubes were immune to ion burns?
i have found that tek crts last allot longer then hp ones
----- Original Message -----
From: John Miles
To: hp_agilent_equipment@...
Sent: Wednesday, January 17, 2007 7:41 PM
Subject: RE: [hp_agilent_equipment] Re: HP8568B CRT replacement question
LCD?
>Alternately, consider what it costs to have these instruments repaired
>for business use. We have several (4 at last count) 8566B where I work,
>and the minimum repair cost is a flat $3,500. The CRTs are still OK on
>those because we have consistently been able to enforce the rule of
>turning brightness down when not in use
Don't do that -- make 'em hit shift-G/shift-H!
-- john, KE5FX
|
Re: HP8568B CRT replacement question LCD?
I can try that, what does it do?
Didier KO4BB
John Miles wrote:
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Alternately, consider what it costs to have these instruments repaired
for business use. We have several (4 at last count) 8566B where I work,
and the minimum repair cost is a flat $3,500. The CRTs are still OK on
those because we have consistently been able to enforce the rule of
turning brightness down when not in use
Don't do that -- make 'em hit shift-G/shift-H!
-- john, KE5FX
|
Re: HP8568B CRT replacement question LCD?
Letting the tube run constantly at minimum intensity (low/no grid current)
does prevent burn-in, but it contributes to cathode poisoning. HP warns
against doing that in their manuals, and gives you a way to turn the whole
CRT supply including the filament on and off via those shift-G/H keys.
Aluminized phosphors may or may not have anything to do with burn-in
resistance; I don't know. I've seen plenty of HP and Tek CRTs with severe
burn-in, though.
-- john, KE5FX
toggle quoted message
Show quoted text
-----Original Message-----
From: hp_agilent_equipment@...
[mailto:hp_agilent_equipment@...]On Behalf Of arthurok
Sent: Wednesday, January 17, 2007 5:54 PM
To: hp_agilent_equipment@...
Subject: Re: [hp_agilent_equipment] Re: HP8568B CRT replacement question
LCD?
you think that the crt beam is wearing out the phosphor? "ion
burns???
i thought aluminized tubes were immune to ion burns?
i have found that tek crts last allot longer then hp ones
----- Original Message -----
From: John Miles
To: hp_agilent_equipment@...
Sent: Wednesday, January 17, 2007 7:41 PM
Subject: RE: [hp_agilent_equipment] Re: HP8568B CRT replacement question
LCD?
>Alternately, consider what it costs to have these instruments repaired
>for business use. We have several (4 at last count) 8566B where I work,
>and the minimum repair cost is a flat $3,500. The CRTs are still OK on
>those because we have consistently been able to enforce the rule of
>turning brightness down when not in use
Don't do that -- make 'em hit shift-G/shift-H!
-- john, KE5FX
|
Re: HP8568B CRT replacement question LCD?
you think that the crt beam is wearing out the phosphor? "ion burns???
i thought aluminized tubes were immune to ion burns?
i have found that tek crts last allot longer then hp ones
toggle quoted message
Show quoted text
----- Original Message -----
From: John Miles
To: hp_agilent_equipment@...
Sent: Wednesday, January 17, 2007 7:41 PM
Subject: RE: [hp_agilent_equipment] Re: HP8568B CRT replacement question LCD?
>Alternately, consider what it costs to have these instruments repaired
>for business use. We have several (4 at last count) 8566B where I work,
>and the minimum repair cost is a flat $3,500. The CRTs are still OK on
>those because we have consistently been able to enforce the rule of
>turning brightness down when not in use
Don't do that -- make 'em hit shift-G/shift-H!
-- john, KE5FX
|
Re: HP8568B CRT replacement question LCD?
Alternately, consider what it costs to have these instruments repaired
for business use. We have several (4 at last count) 8566B where I work,
and the minimum repair cost is a flat $3,500. The CRTs are still OK on
those because we have consistently been able to enforce the rule of
turning brightness down when not in use Don't do that -- make 'em hit shift-G/shift-H! -- john, KE5FX
|
Re: HP8568B CRT replacement question LCD?
I agree that the cost of the CRT replacement LCD is fair, considering
the work that went into its design.
Alternately, consider what it costs to have these instruments repaired
for business use. We have several (4 at last count) 8566B where I work,
and the minimum repair cost is a flat $3,500. The CRTs are still OK on
those because we have consistently been able to enforce the rule of
turning brightness down when not in use, but I am not sure how much
longer that will last. I can promise you the first one with a weak CRT
will get the LCD treatment.
We do have those repaired not even so much to save on the cost of new
ones (we have a number of newer SA's too, such as 8565E and others)
because for a lot of things we do, they work better than the new stuff.
The FFT driven instruments are great to look at signals, they suck when
you want to look at (and measure) noise.
Didier
Kuba Ober wrote:
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On Sunday 14 January 2007 14:50, Sotiris wrote:
Hi
for the LCD CRT replacement kit take a look at the link below. Good
but WAY TOO EXPENSIVE!!!
I don't think so. They had to develop custom electronics to read the display
memory and feed it to the LCD, with colors applied. I'd say that's a *very*
fair price. Considering that a dead CRT makes those devices less useful (not
totally dead, but still), I wouldn't object to such a price, if I used the
unit for business.
I have a feel for how much work it'd take to develop such a unit, and given
their volume and a need for at least *some* profit, they sell it for a fair
price, IMHO.
To figure if it's worth it, think about whether you could afford a similar,
brand new instrument, for the price of the old one, the kit, and your time
(or someone else's service) to bring it up to spec.
Cheers, Kuba
|
Re: HP8568B CRT replacement question LCD?
On Wednesday 17 January 2007 15:15, John Miles wrote: The problem is, I think you have to compare it to what it costs to buy
another complete 8566/8568 display. Often, less than $1000 will get you
one of those with a usable (if not perfect) CRT.
I think it's a great modification, but I also think they'd do better if
they targeted the 8560 portables, too. Those don't go for less than $4K in
any condition. I'm thinking of something universal, i.e. a board which can then interface to any reasonably sized TFT LCD with standard flat panel digital inputs. Cheers, Kuba
|
Re: HP8568B CRT replacement question LCD?
Hi Exactly that was the base of my comments on the price of te LCD replacement... When I saw it at first, I was almost ready to buy it... and then I asked about the price of it. :(( ~1800U$ plus shipping to Greece... make it go up to 2K's that is almost 1650 Euros... then I've done the maths... Got two Display units 85662A, one with an almost brand new CRT and one that had run a lot, but it is still at a real good working condition, without any signs of failing CRT. Not expected soon at least! So lets say the second one has at least 2000 hours before I 'll start worrie about repairing it... Now I take measures with that analyzer almost every 2nd day. It is powered for 2-4 hours its time, for production testing... Say 3 hours average... or better, 2 hours EVERY day! These figure shows that I got 1000 days left. If you exclude the weekends on a year basis, then these is aproximatelly 3 working years! The 8568B I have it on, cost me 1250 Euros complete, with the shipping to GREECE! If i need 1650 Euros to replace the CRT only, plus the repairing time needed, then anyone can understand that it would be better (and more economical of course) to buy another complete set! Not even considering to use John Miles guide to restore tube for at least 800 hours (meaning 1.5 years more?) after complete failure of it! Second opton is to buy two 85662A Display units and keep them for replacement units. That option also is costless than buying 1 LCD unit. And Kuba, I also understand very well what this cost and what work have been put on it. And yes the market isn't so large for it (?), and that will keep that way, at that price! However, considering that those displays was used on some of the best selling analyzers (when you add all the 67,68 A/B, 66 A/B of the 856x series, sold all these 23 years of production run) you can estimate that there is a huge number for marketing a device like it! But in IMHO it's not a *fair* price considering all the above... It might be fair on some eyes, but not to mine! Best regards Sotiris --- In hp_agilent_equipment@..., "Mark" <marks@...> wrote:
It is a pity theydon't make a cheaper monochrome replacement screen.
As John said you can pick up a good display on the big auction for
~$500
Marks.
VK2HMC.
--- In hp_agilent_equipment@..., "John Miles"
<jmiles@> wrote:
The problem is, I think you have to compare it to what it costs
to buy another complete 8566/8568 display. Often, less than $1000 will get you one of those with a usable (if not perfect) CRT.
I think it's a great modification, but I also think they'd do
better if they targeted the 8560 portables, too. Those don't go for less than $4K in any condition.
-- john, KE5FX
-----Original Message-----
From: hp_agilent_equipment@...
[mailto:hp_agilent_equipment@...]On Behalf Of Kuba
Ober Sent: Wednesday, January 17, 2007 5:31 AM
To: hp_agilent_equipment@...
Subject: Re: [hp_agilent_equipment] Re: HP8568B CRT replacement question
LCD?
On Sunday 14 January 2007 14:50, Sotiris wrote:
Hi
for the LCD CRT replacement kit take a look at the link below. Good
but WAY TOO EXPENSIVE!!! I don't think so. They had to develop custom electronics to read
the display
memory and feed it to the LCD, with colors applied. I'd say
that's a *very*
fair price. Considering that a dead CRT makes those devices less useful (not
totally dead, but still), I wouldn't object to such a price, if I used the
unit for business.
I have a feel for how much work it'd take to develop such a unit, and given
their volume and a need for at least *some* profit, they sell it for a fair
price, IMHO.
To figure if it's worth it, think about whether you could afford a similar,
brand new instrument, for the price of the old one, the kit, and your time
(or someone else's service) to bring it up to spec.
Cheers, Kuba
|
Re: HP8568B CRT replacement question LCD?
It is a pity theydon't make a cheaper monochrome replacement screen. As John said you can pick up a good display on the big auction for ~$500 Marks. VK2HMC. --- In hp_agilent_equipment@..., "John Miles" <jmiles@...> wrote:
The problem is, I think you have to compare it to what it costs to
buy another complete 8566/8568 display. Often, less than $1000 will get you one of those with a usable (if not perfect) CRT.
I think it's a great modification, but I also think they'd do
better if they targeted the 8560 portables, too. Those don't go for less than $4K in any condition.
-- john, KE5FX
-----Original Message-----
From: hp_agilent_equipment@...
[mailto:hp_agilent_equipment@...]On Behalf Of Kuba Ober
Sent: Wednesday, January 17, 2007 5:31 AM
To: hp_agilent_equipment@...
Subject: Re: [hp_agilent_equipment] Re: HP8568B CRT replacement
question LCD?
On Sunday 14 January 2007 14:50, Sotiris wrote:
Hi
for the LCD CRT replacement kit take a look at the link below. Good but WAY TOO EXPENSIVE!!! I don't think so. They had to develop custom electronics to read
the display memory and feed it to the LCD, with colors applied. I'd say that's a *very* fair price. Considering that a dead CRT makes those devices less useful (not totally dead, but still), I wouldn't object to such a price, if I used the unit for business.
I have a feel for how much work it'd take to develop such a unit, and given their volume and a need for at least *some* profit, they sell it for a fair price, IMHO.
To figure if it's worth it, think about whether you could afford a similar, brand new instrument, for the price of the old one, the kit, and your time (or someone else's service) to bring it up to spec.
Cheers, Kuba
|
Re: HP8568B CRT replacement question LCD?
The problem is, I think you have to compare it to what it costs to buy another complete 8566/8568 display. Often, less than $1000 will get you one of those with a usable (if not perfect) CRT.
I think it's a great modification, but I also think they'd do better if they targeted the 8560 portables, too. Those don't go for less than $4K in any condition.
-- john, KE5FX
toggle quoted message
Show quoted text
-----Original Message----- From: hp_agilent_equipment@... [mailto:hp_agilent_equipment@...]On Behalf Of Kuba Ober Sent: Wednesday, January 17, 2007 5:31 AM To: hp_agilent_equipment@... Subject: Re: [hp_agilent_equipment] Re: HP8568B CRT replacement question LCD? On Sunday 14 January 2007 14:50, Sotiris wrote: Hi
for the LCD CRT replacement kit take a look at the link below. Good
but WAY TOO EXPENSIVE!!! I don't think so. They had to develop custom electronics to read the display memory and feed it to the LCD, with colors applied. I'd say that's a *very* fair price. Considering that a dead CRT makes those devices less useful (not totally dead, but still), I wouldn't object to such a price, if I used the unit for business. I have a feel for how much work it'd take to develop such a unit, and given their volume and a need for at least *some* profit, they sell it for a fair price, IMHO. To figure if it's worth it, think about whether you could afford a similar, brand new instrument, for the price of the old one, the kit, and your time (or someone else's service) to bring it up to spec. Cheers, Kuba
|
Hello, all aficionados:) I would like to use an HP 8503A Test set with
an HP 8754A , is it possible do I have to use special cable ? or is it
impossible ?
best regards to all
ON1EV
|
Re: HP8568B CRT replacement question LCD?
On Sunday 14 January 2007 14:50, Sotiris wrote: Hi
for the LCD CRT replacement kit take a look at the link below. Good
but WAY TOO EXPENSIVE!!! I don't think so. They had to develop custom electronics to read the display memory and feed it to the LCD, with colors applied. I'd say that's a *very* fair price. Considering that a dead CRT makes those devices less useful (not totally dead, but still), I wouldn't object to such a price, if I used the unit for business. I have a feel for how much work it'd take to develop such a unit, and given their volume and a need for at least *some* profit, they sell it for a fair price, IMHO. To figure if it's worth it, think about whether you could afford a similar, brand new instrument, for the price of the old one, the kit, and your time (or someone else's service) to bring it up to spec. Cheers, Kuba
|
