HP 54111D dim display

[murrayatup...@gmail.com]

Anyone know if there is a solution to low display brightness on a HP 54111D oscilloscope, like maybe power supply capacitor replacement?

The CRT power supply voltage described in the service manual is puzzlingly-low...only 120 VDC (?!?) The 300V switching supply is described as used for generating the 5V logic supply.

I haven't dug further, but wonder how a color CRT can get by with such a low voltage...or if the CRT module has an integral flyback supply for anode voltage, and repair being module-focused, isn't discussed.

The CRT thought led me to wondering if CRT rejuvenation was an option.

Thanks

Murray

[tom]

<murrayatup...@gmail.com> wrote in message
news:a75540be-6105-45b5...@googlegroups.com...

Hi Murray,

Do you have the CLIP for the 54111D available? Can you get hold of an ESR
tester? And where abouts are you located - 120 or 240 volt land?

You might go on the HP Yahoo group with the same request.

https://groups.yahoo.com/neo/groups/hp_agilent_equipment/info

It does sound like one of the bulk capacitors has failed if the 300 volts is
that low.

You must get the power supply working first before any other diagnostics are
done.

[tabb...@gmail.com]

Never do that. I've seen so many CRTs ruined by rejuving. Increasing heater voltage works better and stays good.

But if your PSU rail is way out of spec, surely it's obvious that CRT emission failure is not likely to be the cause of a dim screen.


NT

[Murray atuptown]

Thanks for the replies.

120 v ac

OK on thumbs down to rejuvenation...


I overly simplified the comments on the power supply which was evidently more confusing than accomplishing a summary.

Based on the service manual’s description of how the voltages are produced, I offered two distractions. The overview described the +300 V supply as being used for producing the +5 VDC logic supply and the CRT supply as they name it is only +120 VDC. I didn’t mean to sound like only measures 120 instead of 300.

There was an implied question-how the heck do they run a CRT on 120 VDC? I didn’t (yet) see further explanation of internal functions on the CRT ass’y. I hope it’s an assembly with the ability to produce all support voltages for a CRT.

The diagnosis for CRT problems, as well as other modules, often ends with ‘replace the module’...I get ‘why?’, during the product’s heyday, but that leads to a ‘problem’ period (for wannabe users/restorers) in the future...which is now.

I haven’t measured anything yet...it’s usable, but I’m just snooping around for answers for that day when all the room lights have to be off to see anything. If I’m going to commit space to such a large (and loud!) I’m trying to be proactive.

I’ll read up on what I can measure without service accessories like extender board etc.

Thank you

[tom]

"Murray atuptown" <murrayatup...@gmail.com> wrote in message
news:46113352-8c9e-482c...@googlegroups.com...
> Tom - not sure CLIP is.
> ESR measurements- yes, if I remove parts & take them to someone else (have
> access).

CLIP is Component Level Information Package. Has all the schematics.

You can buy a copy - pdf - from artekmedia.com

Good quality scans and will not break the bank.

Regards

[Murray atuptown]

Tom-
Not sure what CLIP is but I see it discussed on a 54111D thread on Yahoo group-thanks,

I’ll have to lurk...9 years of blocked Yahoo password change access by AT&T and 9 years of grief led me to kill all Yahoo-owned accounts and now AT&T.

Nobody needs to hear that story.

That scope is heavy and obnoxiously loud. Sounds like it’s awaiting clearance for takeoff, but my basement isn’t long enough for a twin-propeller scope to

[Murray atuptown]

I think I better restrict my posting to a computer. I’m on my phone now and have no idea where my previous drafts are (I hope not posted...apologies if they are!)

[tabb...@gmail.com]

There's all manner of reasons why it might be dim, including muck on the screen. Let us know when you've got some facts we can work with.


NT

[pf...@aol.com]

On Monday, January 1, 2018 at 10:24:14 PM UTC-5, tabb...@gmail.com wrote:

> Never do that. I've seen so many CRTs ruined by rejuving. Increasing heater voltage works better and stays good.

Exactly what do you think rejuvenation entails?

Peter Wieck
Melrose Park, PA

[Terry Schwartz]

Rejuvenation entails *temporarily* running the heater of a tube at a high voltage, the theory being it boils up the thorium from the cathode and exposes fresh surface. It does not entail leaving the filament at a higher voltage in operation.

That was done with so-called CRT "brighteners" which were merely step-up auto-transformers. We've all seen those. They worked, for a while. But they did cause other picture problems, like saturation that made the contrast look eerie. Sometimes you could adjust some of that out.

Any tube tester could be used to "rejuv" a tube or CRT. The process was well known in the shops. The key was always to leave the tube in the tester for some period of time after applying the 2X or 3X heater voltage for a minute or so (hopefully you didn't burn out the heater) and then seeing if the emissions dropped off unacceptably over the next hour. If emissions stayed up, the rejuv "took" and you were good. If not, maybe you sold a new tube.

The problem with CRT rejuvenation was that the excess electron flow eroded the tiny aperture hole in the gun, causing blurry focus, smear, etc, on the face of the CRT. In lots of cases the customer didn't care, he did not want to spring for a new picture tube or new TV.

I often got the job of replacing CRTs after the sets came back in when the rejuvenation didn't hold up, or the customer didn't like the result. I had a knack for doing convergence, which can be one of the most frustrating things to attempt.

[tabb...@gmail.com]

The rejuve process used in repair shops that I'm familiar with involves a zapping discharge at the same time as applying heater power. Although it fairly often restores emission, it's only a short term result, and as the emission falls again the tube becomes unusable due to severe smearing.

You could say it was a way to ruin customer TVs prompting another purchase while appearing to be helpful.


NT

[Terry Schwartz]

The only zapping process I knew of was used when there were shorted elements in the tube. It can't be done with a tube tester -- rather a charged cap. It can restore emissions, depending on what was shorted in the tube. Heater voltage was not required. If it works, the picture is not typically affected. But too often the short cannot be removed. In fact sometimes it welds an intermittent short permanent.

NT: I'm curious as to your understanding of the process you described -- what is the mechanism that would be in play that would increase emissions by zapping it while powered? Emissions are largely a function of the cathode quality (useful remaining life) and unless a zap removes a cathode short, I don't see how it works. Also don't understand how it would contribute to smear, or how the emissions would fall again, unless the cathode was already bad, in which case the emissions would not have recovered at all.

Terry

[pf...@aol.com]

On Friday, January 5, 2018 at 10:01:46 AM UTC-5, Terry Schwartz wrote:
> The only zapping process I knew of was used when there were shorted elements in the tube. It can't be done with a tube tester -- rather a charged cap. It can restore emissions, depending on what was shorted in the tube. Heater voltage was not required. If it works, the picture is not typically affected. But too often the short cannot be removed. In fact sometimes it welds an intermittent short permanent.
>
> NT: I'm curious as to your understanding of the process you described -- what is the mechanism that would be in play that would increase emissions by zapping it while powered? Emissions are largely a function of the cathode quality (useful remaining life) and unless a zap removes a cathode short, I don't see how it works. Also don't understand how it would contribute to smear, or how the emissions would fall again, unless the cathode was already bad, in which case the emissions would not have recovered at all.
>
> Terry

Agreed.

I have used charged caps on three occasions (two successful) to restore bad coils in field-coil speakers. I have tried it several times without any success to 'save' open transformer windings.

But, otherwise, 'rejuvenation' for tubes has consisted of over-voltage on the filament for varying periods of time and at varying percentages over what is rated - and not much more. And CRT "Brighteners" increase voltage to the filament in my experience as well. Some by a variable (adjustable) amount as well. Perhaps NT is conflating different processes?

[Fox's Mercantile]

On 1/5/18 9:01 AM, Terry Schwartz wrote:
> The only zapping process I knew of was used when there were
> shorted elements in the tube.

I have a B&K CRT rejuvinator.
I pulled the CRT out of my 1948 Andrea.
It tested just below the Green range.
Hit the zap-o-matic rejuvinator button. It crept up into the
Green range.
The third time it fell all the way down to the bottom of the
Red range.

Well that settles that. Now it's dead instead of very dim.




--
"I am a river to my people."
Jeff-1.0
WA6FWi
http:foxsmercantile.com

[Terry Schwartz]

The B&K units and their ilk work exactly that way -- increasing the filament voltage temporarily. They may also change the grid bias during the process - not sure.

Jeff, I suspect your filament is open now.... unfortunate.

[Terry Schwartz]

Ok, a quick google search reveals that the CRT specific rejuvenators apply a high potential between the cathode and G1. The resulting arcing exposes some "fresh" cathode surface. I'd have to believe the area would be tiny and therefore the fix very temporary. Seems like it would also be prone to throwing cathode debris at the phosphor surface, aperture mask, or gun aperture. Ugh. But now I understand the ZAP reference.

I was familiar with the older method that used general purpose tube testers with CRT adapters. There was no such capability with those that I was aware of -- only raising the filament voltage to overheat the cathode and boil up the emitting surface. Seems like a better chance of lasting results, if the filament survives the process.

Funny because I owned a B&K 467 for a while, but I don't think I ever tried to use it for rejuvenation.

[tabb...@gmail.com]

The zapping method was standard in the TV repair industry here while CRTs were in use. It only takes a couple of minutes to do.

http://www.thegleam.com/ke5fx/crt.html
talks about a pulse of grid current much improving emission. How it works is I gather disagreed on, but it does. The problem is the tube declines after not long, giving a smeared picture.


NT

[tabb...@gmail.com]

On Friday, 5 January 2018 16:31:22 UTC, Terry Schwartz wrote:
> Ok, a quick google search reveals that the CRT specific rejuvenators apply a high potential between the cathode and G1. The resulting arcing exposes some "fresh" cathode surface. I'd have to believe the area would be tiny and therefore the fix very temporary. Seems like it would also be prone to throwing cathode debris at the phosphor surface, aperture mask, or gun aperture. Ugh. But now I understand the ZAP reference.

Temporary, yes. Typically the customer would get a few more months service then it became unusable due to smearing as the emission declined.

Throwing crud about didn't matter unless it created a short, which it could.

Some folk think it cleaned a bit of cathode, some thing it created electrode hotspots that scavenged gas.

I didn't like zapping at all, preferring an extra turn on the loptf heater wind. That gave a much better lasting result and didn't kill tubes.

> I was familiar with the older method that used general purpose tube testers with CRT adapters. There was no such capability with those that I was aware of -- only raising the filament voltage to overheat the cathode and boil up the emitting surface. Seems like a better chance of lasting results, if the filament survives the process.
>
> Funny because I owned a B&K 467 for a while, but I don't think I ever tried to use it for rejuvenation.

The worst CRT I ever did had no visible emission at all, and the tube type, sony trinitron, was known for not responding to attempts to improve emission. I gave it a large permanent heater boost after which it had plenty of emission all round. But colour tracking was lousy, although it gave a nice white the intermediate colours didn't match a healthy set at all well. That thing stayed in service many years and kept going. Occasionally it would arc over for a moment, causing green output to go way up for a few minutes then calm down. It was very much an experiment in trying to fix unfixable tubes.


NT

[Terry Schwartz]

The Trinitrons were among the hardest CRTs to converge. Those square corners were hell to get right. Some of the Sony chassis had better convergence controls than others. I will say the last CRT Sony I owned, a 35" 220 lb behemoth, had a beautiful picture and spot-on convergence.

[tabb...@gmail.com]

On Friday, 5 January 2018 21:39:47 UTC, Terry Schwartz wrote:
> The Trinitrons were among the hardest CRTs to converge. Those square corners were hell to get right. Some of the Sony chassis had better convergence controls than others. I will say the last CRT Sony I owned, a 35" 220 lb behemoth, had a beautiful picture and spot-on convergence.

I have vague memories of moving little disc magnets around.
But anything's better than the old delta sets with an entire panel of controls.


NT

[jurb...@gmail.com]

Forget all about rejuvinating. That CRT is not likely to respond like a TV CRT.

I couldn't get a real print on it but most of these things have a DC filament supply which is rectified off the flyback. Note that they are turned and the fast sweep is vertical and the slow sweep is horizontal. Just imagine the two deflection circuits swapped.

As such, off the flyback (VERTICAL OUTPUT) there should be a winding for the filament supply. There may be a filter going dry.

If the supply is alright, there is the place you put a tertiary coil in series with the winding to boost the voltage.

As far as what the voltages actually are, if the geometry is correct, the voltages are probably correct.

Rejuvination is a last resort on something like this. Even if you can get a CRT for it, the alignment is hairy and scary.

[tom]

<jurb...@gmail.com> wrote in message
news:e2fa9391-f0a7-47f4...@googlegroups.com...

++++++++++++++++++++++++++++++++++++++++++++

It is a color raster scanned display. OP should read up on the color display
adjustments and go through the procedure. If that does not work, a new tube
would be the next thing. There might even be a LCD upgrade available for
less than a new tube.

We still do not know what the power supply is doing.

I bet a simple adjustment of the screens on the CRT would get some more
years out of it.

[jurb...@gmail.com]

>"It is a color raster scanned display. "

How could you read my post and not realize that I know that ?

>"OP should read up on the color display
adjustments and go through the procedure."

Why ? To fuck it up ? When you have a fault the LAST thing you do is adjust. He should CHECK the geometry. In a raster scanned display the geometry is dependent on proper voltage supplies. If the geometry is right, the voltages are right, no matter what the print says.

>"If that does not work, a new tube
would be the next thing."

Sure, Keysight has them on the shelf right between the hen's teeth and the philosopher's stones.

>"There might even be a LCD upgrade available for
less than a new tube. "

What planet are you from ? Are you saying that they would engineer a Tcon board and backlight assembly for an old obsolete piece of equipment they no longer support ? You'll get that right after world peace.

>"We still do not know what the power supply is doing. "

If the geometry is right, it is doing what it has to do.

>"I bet a simple adjustment of the screens on the CRT would get some more
years out of it. "

Know much about CRTs ? Sure turning up the G2, which will be common to all three guns is likely to get a more usable brightness level. However, this type of video drive might start (or accelerate) the cathode stripping process.

The best bet is to increase the filament supply. Usually 10 - 20 % will do it, and it usually will last. Rejuvination might cause a G1-K short.

It can be run that way but with the likely bandwidth the circuit will have to be modified to overpeak the video output. I have done this a few times. First the G1 is tied to the K through a resistor, high enough not to cause damage due to the filament voltage but low enough that it is coupled to the cathode which stabilizes the frequency response. Then a proper location in the circuit for a peaking cap must be chosen, and of course its value. For this I would need a real print, not one of those enhanced block diagrams which seems to be the only thing I can get.

With a real print I can give more details on what to do. I am very experienced at extending the life of color CRTs, did it for decades. But this overpeaking stuff only applies if there is a short in the CRT. Most of the time it just works.

HAHA, an LCD refit for a color CRT. Thanks for the laugh.

The emgineering cost would exceed the value of the whole unit. That is before one such modification is produced. What's more, if it is a Trinitron it is a bit easier because it has a cylindrical curvature on the screen. A curved LCD screen is expensive, even if it is only curved on one axis.

Yup, be sure to let us know when you got that space/time continuum thing beat. I think ole' Bert Einstein was holding out on us.

[tom]

Top posting just so you don't need to read through all the BS again.


There is so much wrong with what you posted that it would take forever just
to tell you.

Here, check out this supplier of LCD displays that replace CRT tubes in
raster scanned displays used in HP and Tek instruments.

http://www.simmconnlabs.com/2001/2073.html

I just replaced the CRT in a HP70004A MMU unit - cost $400 .

Stop being such an asshole.





<jurb...@gmail.com> wrote in message
news:c32a6a71-c22d-45c3...@googlegroups.com...

[Fox's Mercantile]

On 1/6/18 12:32 PM, tom wrote:
> Stop being such an asshole.

Jurb6006

Like the fable about the fox and the scorpion.
"It is my nature."

>
>
>
>
>
> <jurb...@gmail.com> wrote in message
> news:c32a6a71-c22d-45c3...@googlegroups.com...
>> "It is a color raster scanned display."
> How could you read my post and not realize that I know that ?
>

[Fox's Mercantile]

On 1/5/18 10:31 AM, Terry Schwartz wrote:
> I was familiar with the older method that used general purpose
> tube testers with CRT adapters.

I killed my dim 12" CRT with a B&K Model 440
<https://ssli.ebayimg.com/images/g/8S0AAOSw-W5UrXOP/s-l1600.jpg>

[tabb...@gmail.com]

On Saturday, 6 January 2018 21:41:07 UTC, Fox's Mercantile wrote:
> On 1/5/18 10:31 AM, Terry Schwartz wrote:
> > I was familiar with the older method that used general purpose
> > tube testers with CRT adapters.
>
> I killed my dim 12" CRT with a B&K Model 440
> <https://ssli.ebayimg.com/images/g/8S0AAOSw-W5UrXOP/s-l1600.jpg>

I hear so many people killed their tubes. I wonder why, boosting heater voltage never caused me to lose one. And I pushed it all the way to 66% on occasion, and 33% routinely. I mean permanent boost.


NT

[Fox's Mercantile]

Failure to RTFM.
Rather that boost the filament voltage I hit the G1-K button.
It boosted it a bit so I hit a couple more times. The third time
killed it.

[jurb...@gmail.com]

>"Here, check out this supplier of LCD displays that replace CRT tubes in
raster scanned displays used in HP and Tek instruments. "

I'll stand corrected on that. I never thought anyone would put the money into such a unit. However what I said about the CRTs stands.

>"I just replaced the CRT in a HP70004A MMU unit - cost $400 . "

I am surprised the cost is so low. And congrats on getting that job done. Sounds like loads of fun.

>"There is so much wrong with what you posted that it would take forever just
to tell you. "

I did everything I said I did.

>"Stop being such an asshole. "

Born that way but sometimes it comes out that way. Though your knowledge of CRTs might not be top echelon, I did not mean to demean your skills. And CRTs are obsolete.

So, this asshole has useless knowledge.

[tabb...@gmail.com]

On Sunday, 7 January 2018 02:31:27 UTC, Fox's Mercantile wrote:

> On 1/6/18 6:28 PM, tabbypurr wrote:
> > On Saturday, 6 January 2018 21:41:07 UTC, Fox's Mercantile wrote:
> >> On 1/5/18 10:31 AM, Terry Schwartz wrote:

> >>> I was familiar with the older method that used general purpose
> >>> tube testers with CRT adapters.
> >>
> >> I killed my dim 12" CRT with a B&K Model 440
> >> <https://ssli.ebayimg.com/images/g/8S0AAOSw-W5UrXOP/s-l1600.jpg>
> >
> > I hear so many people killed their tubes. I wonder why, boosting heater voltage never caused me to lose one. And I pushed it all the way to 66% on occasion, and 33% routinely. I mean permanent boost.
> >
> >
> > NT
> >
>
> Failure to RTFM.
> Rather that boost the filament voltage I hit the G1-K button.
> It boosted it a bit so I hit a couple more times. The third time
> killed it.

My point is why are you doing that in the first place? Why use a method that either kills or damages the tube and only has short term benefit anyway?


NT

[Fox's Mercantile]

Did you not read what I said?

I didn't know any better. Never done one before.