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Re: Defective YTO 5086-7906 HP-8561E

 

Thanks for your replies, I will look for a repair service.
Does anyone have a schematic for the small control board on top of the YTO assy ?
Re: HP8753C Source Pretune after YIG replacement

 

On Wed, Feb 2, 2022 at 07:40 AM, Peter Hansen wrote:
yig is dead. The Yig in the 8753 part of the dreaded HP yigs that tend to fail. Find a new 5086-7934. Repair is only possible with a part that is not easy to source and you need a wirebonder
best regards Peter
Yes, my conclusion also (unfortuantely). I did find a replacement YIG (not cheap) but I still have the original question regarding the pretune constants setup when I replace it.
Re: Convert monochrome 5454x scope to color

 

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Depending on the display, you may be able to find a commercial LED replacement.

Harvey


On 2/2/2022 10:34 AM, Glen Hoag wrote:

That makes sense. I would assume that at least early LCD panels used a CCFL lamp as a backlight. It may be possible to retrofit LEDs on such a unit.?


On Feb 2, 2022, at 09:14, Bill E <solartron@...> wrote:

?The display controller logic is completely different, no pads for replacing the CRT stuff with the components for the LCD. You could probably do a daughter board to add the logic, but you're going to end up spending more than you could get a C for. While we're on the subject, I've been trying to figure out a replacement for the panel. The model number of the panel shows up for sale by various vendors, but the specs seem to differ between the vendors for the same number. Not sure if that's just poor description, or if there are variants with the same model number. Just want to have a source for a replacement if my panel dies.

HP 140A and 141A power supplies

 

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Hi folks,

I'm in the process of attempting to repair two older oscilloscopes - one is an HP 140A and the other is an HP 141A (its storage tube "brother" version). My 140A frame has serial prefix 546 and my 141A frame's serial prefix is 844. Both are experiencing power supply problems and it would appear that HP went through MANY power supply design changes (both in the HV and LV sections) with this product line over the course of time. One result is that the service manuals that I've been able to find do not correspond well at all with my scopes in the power supply areas. I think the manuals are at least close enough in most other areas.

Is there someone kind soul here who might be able to help?

Thanks,
Neil
Re: HP8753C Source Pretune after YIG replacement

 

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yig is dead. The Yig in the 8753 part of the dreaded HP yigs that tend to fail. Find a new 5086-7934. Repair is only possible with a part that is not easy to source and you need a wirebonder
best regards Peter
Fra: [email protected] <[email protected]> p? vegne af vk2bea via groups.io <vk2bea@...>
Sendt: 2. februar 2022 15:15
Til: [email protected] <[email protected]>
Emne: Re: [HP-Agilent-Keysight-equipment] HP8753C Source Pretune after YIG replacement
?
On Tue, Feb 1, 2022 at 05:40 PM, peter bunge wrote:
Are you sure the YIG is dead? How do you know? I suggest you don't adjust anything until you know what the problem is.
My method of troubleshooting is to go through the adjustments procedure but WITHOUT ADJUSTING ANYTHING. Anything way off indicates the?problem area. Often a failure in a closed loop.
?
The voltages are OK but there is NO outut from the YIG. I see the 3.8 GHz signal (+10dbm) from the cavity oscillator but absolutely nothing from the YTO.? If it's no the YTO what else could it be?

Re: Convert monochrome 5454x scope to color

 

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That makes sense. I would assume that at least early LCD panels used a CCFL lamp as a backlight. It may be possible to retrofit LEDs on such a unit.?


On Feb 2, 2022, at 09:14, Bill E <solartron@...> wrote:

?The display controller logic is completely different, no pads for replacing the CRT stuff with the components for the LCD. You could probably do a daughter board to add the logic, but you're going to end up spending more than you could get a C for. While we're on the subject, I've been trying to figure out a replacement for the panel. The model number of the panel shows up for sale by various vendors, but the specs seem to differ between the vendors for the same number. Not sure if that's just poor description, or if there are variants with the same model number. Just want to have a source for a replacement if my panel dies.
_._,_._,_
Re: Convert monochrome 5454x scope to color

 

The display controller logic is completely different, no pads for replacing the CRT stuff with the components for the LCD. You could probably do a daughter board to add the logic, but you're going to end up spending more than you could get a C for. While we're on the subject, I've been trying to figure out a replacement for the panel. The model number of the panel shows up for sale by various vendors, but the specs seem to differ between the vendors for the same number. Not sure if that's just poor description, or if there are variants with the same model number. Just want to have a source for a replacement if my panel dies.
Re: HP8753C Source Pretune after YIG replacement

 

On Tue, Feb 1, 2022 at 05:40 PM, peter bunge wrote:
Are you sure the YIG is dead? How do you know? I suggest you don't adjust anything until you know what the problem is.
My method of troubleshooting is to go through the adjustments procedure but WITHOUT ADJUSTING ANYTHING. Anything way off indicates the?problem area. Often a failure in a closed loop.
?
The voltages are OK but there is NO outut from the YIG. I see the 3.8 GHz signal (+10dbm) from the cavity oscillator but absolutely nothing from the YTO.? If it's no the YTO what else could it be?
Re: Convert monochrome 5454x scope to color

 

Hello Glen,

??? Thanks for your suggestions. I google around since a while to try fixing this scope, and checked every element known to interfere with initialization. I replaced the battery by two AA alkaline as you did, and check carefully all the voltages and currents of the supply, which was in any case faulty. I even replaced it by another working one, but no issue.?
??? I am now convinced that it's a matter of an actuator some where, which is checked at boot, and does not return the right value, since the program is looping around a sequence which tests the input relays. The screen is not black, but scrambled, except if I press the blue key at start, then entering the sequence to activate the floppy for PROM update.
??? To fix this scope might be possible with the firmware source program (68020), but reverse engeneering of such a 8k piece of firm is out of my skill, even with a sophisticated logic analyzer (which I don't possess anayway). That's the reason for which I was asking Bill E if he was selling a motherboard.

???? Jean-claude
Re: Convert monochrome 5454x scope to color

 

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Jean-claude,
Did you check the voltage on the Lithium battery at the rear of the main board?

A common problem with these oscilloscopes is that they will boot to a black screen when the battery is dead.?

I recently purchased a 54540A ¡°for parts¡± and it¡¯s main problem was the battery. I replaced it for testing with a pair of AA alkaline batteries and ordered a Lithium battery to replace it.?

It also had a number of leaky electrolytic capacitors in the power supply unit. I replaced all of the aluminum electrolytics for fresh units. It has helped; I don¡¯t have screen distortion before warmup anymore.?

¡ªGlen Hoag
? hoag@...


On Feb 2, 2022, at 06:50, JCB_SFR <jean-claude.bernengo@...> wrote:

?Hello Bill E,
?? I have a 54522 which has booting problems. It does not get out from initialisation, and i struggled a lot to to try fixing it, but without success. It's a CRT version, and the motherboards are the same for 522 or 542. Therefore one of your 542 would have been of great help, if shipping costs to France (and extra custom fees either) would not have been so expensive. May be a motherboard alone might be a solution to my problem, if you agreed to sell your scopes by parts.
??????? Jean-claude
_._,_._,_
Re: Convert monochrome 5454x scope to color

 

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I haven¡¯t looked at the two boards side-by-side, but I don¡¯t believe the differences are ¡°significant¡±. They use the same ribbon cable to interface both the CRT in the A models as the LCD panel in the C models.?

I have an A model on which I just recapped the power supply. A significant number of the aluminum electrolytics were leaking.?

If I luck out and get hold of a C model, I¡¯ll compare the boards.?


On Feb 2, 2022, at 05:35, Bill E <solartron@...> wrote:

?

I looked into this a while back. There are significant differences between the CRT and LCD versions, including different main pcbs. It seems the only practical path would be a hack that would convert the CRT scan signals to LCD usable, but you wouldn't have the color info.

I solved the problem by getting lucky, found a color 54542 on EPray for $199. "Not working". Apparently it wasn't working because the seller never plugged it in or some such, worked perfectly, all in spec. Now I need something to do with my 2 CRT 542s.
Re: Convert monochrome 5454x scope to color

 

Hello Bill E,
?? I have a 54522 which has booting problems. It does not get out from initialisation, and i struggled a lot to to try fixing it, but without success. It's a CRT version, and the motherboards are the same for 522 or 542. Therefore one of your 542 would have been of great help, if shipping costs to France (and extra custom fees either) would not have been so expensive. May be a motherboard alone might be a solution to my problem, if you agreed to sell your scopes by parts.
??????? Jean-claude
Re: Convert monochrome 5454x scope to color

 

Hmm don't see how that would be possible.? I suppose it could be done it you had an exact circuit diagram,?and the right colour CRT.?
Re: Convert monochrome 5454x scope to color

 

Hello, can you fund around one LCD with XY imput? I got one dead HP182T mainframe for my S.A some help please.
Thank you all for some imput.
Francesco.

?
?
Sent:?Wednesday, February 02, 2022 at 11:35 AM
From:?"Bill E" <solartron@...>
To:[email protected]
Subject:?Re: [HP-Agilent-Keysight-equipment] Convert monochrome 5454x scope to color

I looked into this a while back. There are significant differences between the CRT and LCD versions, including different main pcbs. It seems the only practical path would be a hack that would convert the CRT scan signals to LCD usable, but you wouldn't have the color info.

I solved the problem by getting lucky, found a color 54542 on EPray for $199. "Not working". Apparently it wasn't working because the seller never plugged it in or some such, worked perfectly, all in spec. Now I need something to do with my 2 CRT 542s.
Re: Convert monochrome 5454x scope to color

 

I looked into this a while back. There are significant differences between the CRT and LCD versions, including different main pcbs. It seems the only practical path would be a hack that would convert the CRT scan signals to LCD usable, but you wouldn't have the color info.

I solved the problem by getting lucky, found a color 54542 on EPray for $199. "Not working". Apparently it wasn't working because the seller never plugged it in or some such, worked perfectly, all in spec. Now I need something to do with my 2 CRT 542s.
Re: HP 5090B Droitwich receiver documentation wanted

 

I have never seen a 5090B manual but did upload a scan of my 5090A manual to Mediafire some time ago and have just confirmed the link is still good.....

https://www.mediafire.com/file/u0bf1eips89uo3h/HP_5090A_Ops_and_Service.pdf/file

You could also ask on the on the Time-Nuts mailing list, or check their archives, but discussions there when I bought my 5090B in 2010 confirmed one thing I'd already decided from the 5090A manual, that attempted conversion of the unit itself would probably not be a very good idea:-)

At one time I thought perhaps the only difference between the A and B versions might just be the chart recorder on the B but I have seen it suggested there could be other differences, I have not checked that.

Since Droitwich changed frequency in 1988 there have been quite a few articles published offering 198KHz to 200 KHz converters but one I particularly liked used the existing 200KHz frequency locked standard as part of the conversion loop and didn't require any additional tuned circuits.
That was published in RadCom in 1989 and a copy is attached.

If that copy doesn't get through I'd be happy to send it direct but again it's not something I've tried, and probably not likely to now, so can't confirm how effective it might be.

Nigel, GM8PZR


HP 5090B Droitwich receiver documentation wanted
From: Donald Prins
Date: Tue, 01 Feb 2022 19:01:54 GMT
Dear Fellow HP fans,
Would anybody have documentation of the receiver available? This receiver and the antenna 15500A provided the standard frequency in the quartz crystal Philips plant at Doetinchem in the Netherlands till Droitwich changed to 198kHz. The plan is to build in a converter for 198 to 200kHz and do the necessary maintenance.
A manual for the B model and information on a converter would be very welkome.
Yours Donald Prins PE1AHJ

G7EAH_198to200KHzConverter.pdf
G7EAH_198to200KHzConverter.pdf

Re: HP8753C Source Pretune after YIG replacement

 

I generally try not to kibitz, but your comment about going through the adjustment procedure WITHOUT touching ANYTHING is ABSOLUTELY SPOT ON !!
Quoting peter bunge <bunge.pjp@...>:

Are you sure the YIG is dead? How do you know? I suggest you don't adjust
anything until you know what the problem is.
My method of troubleshooting is to go through the adjustments procedure but
WITHOUT ADJUSTING ANYTHING. Anything way off indicates the problem area.
Often a failure in a closed loop.
Finding a failure in a closed loop can be tricky and requires a
knowledge of the circuit function.
When you have repaired the problem then you can do the adjustments.
Making adjustments without repairing the problem just makes new problems
and it will be much more difficult to identify the fault.
Many HP problems are due to power supply failure.


On Tue, Feb 1, 2022 at 11:24 AM vk2bea via groups.io <vk2bea=
[email protected]> wrote:

I have a dead YIG (5086-7473) in the source of an HP8753C that I am
replacing.
The manual says to do the procedure for setting the 'source pretune
constants correction'.
The section on setting the 'source default correction constants' says that
this must be done before the source pretune; however, this will require me
to set the 'RF Output Power Correction Constants' and I do not have the
equipment for this step (HPIB power meter).

Since I'm just changing the YIG and not the whole source block, do I
really need to reset all the souce default CCs? Can I just do the 'source
pretune constants correction'?
Convert monochrome 5454x scope to color

 

Has anyone converted a monochrome 54540 or 54542 oscilloscope to color. If so what is actually required to do the conversion?
Re: HP8753C Source Pretune after YIG replacement

 

Does replacing the YIG without adjusting anything bring the VNA back to life? If not it possibly isn't a bad YIG.


On Tue, Feb 1, 2022 at 8:40 PM peter bunge via <bunge.pjp=[email protected]> wrote:
Are you sure the YIG is dead? How do you know? I suggest you don't adjust anything until you know what the problem is.
My method of troubleshooting is to go through the adjustments procedure but WITHOUT ADJUSTING ANYTHING. Anything way off indicates the?problem area. Often a failure in a closed loop.
Finding a failure in a closed loop can be tricky and requires a knowledge?of the?circuit function.?
When you have repaired the problem then you can do the adjustments.
Making adjustments without repairing the problem just makes new problems and it will be much more difficult to identify the fault.
Many HP problems are due to power supply failure.


On Tue, Feb 1, 2022 at 11:24 AM vk2bea via <vk2bea=[email protected]> wrote:
I have a dead YIG (5086-7473) in the source of an HP8753C that I am replacing.
The manual says to do the procedure for setting the 'source pretune constants correction'.?
The section on setting the 'source default correction constants' says that this must be done before the source pretune; however, this will require me to set the 'RF Output Power Correction Constants' and I do not have the equipment for this step (HPIB power meter).

Since I'm just changing the YIG and not the whole source block, do I really need to reset all the souce default CCs? Can I just do the?'source pretune constants correction'?

Re: HP8753C Source Pretune after YIG replacement

 

Are you sure the YIG is dead? How do you know? I suggest you don't adjust anything until you know what the problem is.
My method of troubleshooting is to go through the adjustments procedure but WITHOUT ADJUSTING ANYTHING. Anything way off indicates the?problem area. Often a failure in a closed loop.
Finding a failure in a closed loop can be tricky and requires a knowledge?of the?circuit function.?
When you have repaired the problem then you can do the adjustments.
Making adjustments without repairing the problem just makes new problems and it will be much more difficult to identify the fault.
Many HP problems are due to power supply failure.


On Tue, Feb 1, 2022 at 11:24 AM vk2bea via <vk2bea=[email protected]> wrote:
I have a dead YIG (5086-7473) in the source of an HP8753C that I am replacing.
The manual says to do the procedure for setting the 'source pretune constants correction'.?
The section on setting the 'source default correction constants' says that this must be done before the source pretune; however, this will require me to set the 'RF Output Power Correction Constants' and I do not have the equipment for this step (HPIB power meter).

Since I'm just changing the YIG and not the whole source block, do I really need to reset all the souce default CCs? Can I just do the?'source pretune constants correction'?

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