HP8924-Family-Spectrum-Analyzers@groups.io

If anyone is digging into their test sets to replace weak or failing memory cells, please think of taking pictures of what you find and uploading them to the pictures section.? There's a scarcity of photos of that kind from the members and not much from HP either, even for just line drawings.

Hank

Re: 8924c memory loss

#393

Important correction to an incorrect statement I made:

In replying to Ralph's initial question about an 8924C, I brought up the notion of two AA cells used to retain data (and run the system clock).? It seems pretty certain now that none of the 8920 and 8924 test sets have these.? My? assuming that the 24C had these was incorrect.? Sorry for getting any 892x owners concerned about a memory battery that doesn't exist in their instruments.

They are on some, maybe all, the 8935 series (both crt and electroluminescent display types) test sets.? One of these 8935s is pictured on the right side of our website and that's the one I have.? The AA battery is hidden behind the back plastic cover held on by six T15 Torx screws.

This battery (one of two) is described in the big repair manual that was just uploaded November 7 in the HP 8935 directory.??Here's part of that section:

? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?----------------------

Memory Backup AA Battery?

Two battery sources are used to maintain the contents of the Test Set’s memory when power is disrupted. One source is a set of two AA batteries mounted behind the rear frame of the Test Set. You must periodically change these batteries. The second battery source acts as a backup to the AA batteries. It is internally mounted and is not user serviceable.?

CAUTION: Replace these batteries every 2-3 years. Failure to take prompt action may result in loss of RAM data including IBASIC programs and SAVE/RECALL states stored in the RAM.

? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ??----------------------

? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ??

I think it would be a good thing for us to put together a FAQ that would provide specific details about the memory retention battery(ies) for as many of the 892X and 8935 series test sets as possible.

Hank

Re: 8924c memory loss

#392

The battery is only for the SRAM which holds? the power on settings for example? ?No calibration is impacted.

Calibration data is in the EEPROM on the processor board.? Usually a good idea to make a copy of that data.? That device is socketed since it needs to move over if the processor board is replaced.

The biggest concern about corrupting? the alignment data in that EEPROM is for the RF Input assembly.? ?Some of the other assemblies have the calibration data on the assemblies themselves ( 8920B and 8924 ) using a small serial EEPROM

Usually verify the RF Input? alignment data by jumpering the tracking gen out to the antenna in using the SA mode and the full 1Ghz span.? Should be pretty flat if the alignment data is intact and the RF input is working correctly.? +-4db flatness across the span should be good enough.? The level should match the tracking gen? output setting but if the average level is off that may be an SA? level adjustment.? ?Usually affects from 380-1000 Mhz with the varactor tuning used in that range if the EEPROM data is wrong.

That step is done on top of the normal diagnostics before anything else is looked at.

Re: 8924c memory loss

#391

Questions...

I have an 8920B. There is a lithium ion battery soldered to the controller board. Is this battery replaceable without losing calibration settings?

Is there another battery that must be replaced as described above?

Re: 8924c memory loss

#390

that screw holds the bracket securing the PCMCIA socket.

On the 8920a/b there are two screws directly holding the memory card connector to the side of the chassis.

Also the? 8920A early /mid versions use two of those batteries.

Later versions of the 8920A and 8920B only use a single battery like the 8924

Re: 8924c memory loss

#389

?

I ordered 3 of them as I have 3 of the 8924c units.? Shipping and all was only $23 for the 3 of them.? Shipping and tax was more than one battery.

?

There was a battery place that popped up but they are about $ 9 each there.

?

Wish you had mentioned that lone screw on the side.? Found it after 3 or 4 tries.? First try I had left the PCMCIA? card in, then 2 or 3 more tries and found that screw...

Battery shows about .7 volts.??

?

73 and thanks again.

?

Ralph

Re: 8924c memory loss

#388

THANKS very much.? I had pulled several of the other cards out that I though might have a battery? and did not think of that one having a battery.? Almost got an IC to replace on on a processor board,but looked it up and it did not seem to have a battery in it similar to the Dallas Clock type memory chips.

I will look into ordering a couple as I have 3 of the 8924c that are about the same age for me.??

Only about a 'million ' screws in that thing .? I use a? battery powered drill to remove the ones I needed.

Ralph ku4pt

On Sunday, December 12, 2021, 06:14:11 PM EST, jyelmgren <jyelmgren@...> wrote:

The SRAM battery has died on the PCMCIA /ROM/ memory card.? Far right hand side from the front ....lot's of screws though.

The batteries are commonly available? ...the 8924 on used one of the 3v lithium solder in type ...DIgikey?P270-ND or?BATTERY LITHIUM 3V 2/3 A

_._,_._,_

Re: 8924c memory loss

#387

The SRAM battery has died on the PCMCIA /ROM/ memory card.? Far right hand side from the front ....lot's of screws though.

The batteries are commonly available? ...the 8924 on used one of the 3v lithium solder in type ...DIgikey?P270-ND or?BATTERY LITHIUM 3V 2/3 A

Re: 8924c memory loss

#386
Edited

Better to say:

?And you almost can't send too many pictures, either contained in your post or uploaded to the files section.

Show quoted text

? ? And you almost can't send too many pictures, either inline or to the files section.

Re: 8924c memory loss

#385

Gang,

When replying to a post, please try to avoid automatically quoting (including) a lot, or all of the prior message.? ?Often you can just leave the old stuff out completely.

With the AA battery issue, I just quoted two lines out of Ralph's fairly lengthy reply.

This is not about saving bandwidth.? It's about keeping the replies shipshape and free of needless repetition.

It's also not about keeping your posts short.? I am a big proponent of long messages if they're needed.? You never need to do here on this Group.io what is seen too often -- the techie who apologizes for his long email.? ? And you almost can't send too many pictures, either inline or to the files section.

Hank

Re: 8924c memory loss

#384
Edited

?

I'll look into the battery changing.? I hate things with batteries in them for long term usage.? About as bad as some things that use that Dallas clock chip that has to be changed about every 10 or so years.? It would not be so bad if there was an easy way to change them like the water filter on my refrigerator.? Just screw the cover off and put in another without having to remove the 'million' screws.

?

Ralph

?

On Saturday, December 11, 2021, 04:13:07 PM EST, Hank wrote:

?

Put it on your to-do list to CHANGE those AA batteries pronto!? ?Whether that's your immediate problem or not.? ?On all three sets, too.

?

When you do I pray you'll find not a spot of evil battery juice has oozed out.

?

Re: 8924c memory loss

#383

Put it on your to-do list to CHANGE those AA batteries pronto!? ?Whether that's your immediate problem or not.? ?On all three sets, too.

When you do I pray you'll find not a spot of evil battery juice has oozed out.

____________________________________________________

On Saturday, December 11, 2021, 03:54:17 PM EST, Ralph? wrote:

Hank,?

I did not know about changing batteries.? I have never changed any batteries in the sets. I actually have 3 of the sets.? The oldest I bought over 10 years ago.?

Re: 8924c memory loss

#382
Edited

Hank,?

?

I did not know about changing batteries.? I have never changed any batteries in the sets. I actually have 3 of the sets.? The oldest I bought over 10 years ago.? It was only opened by me 2 times.? That was to change the input attenuator from 3 watts to a 60 watt unit and the? power supply quit so it was repaired.? It still works and the clock keeps time but it is left plugged in most of the time but turned off and may be a month before it is turned on.??

?

I bought 2 off ebay for about $ 600 .? One was suppose to work and the other was for parts.? The working one was fine and the parts unit had a broken knob that I repaired but no power supply.? When I opened the working one up to change the input attenuator I took the power supply out and put it in to the parts unit.? That unit powered up and seemed to work .? Later I found an inexpensive power supply for it.??

?

Both? of the other 2 units have been unplugged for? a few months.? One comes up fine.? The other comes up in the cell phone mode and the clock resets back to about 1980 and the time is way off.?

?

I used a battery drill to remove the 'million' screws in it and put them back in with the tork setting at the lowest.

?

I may have to install an over head crane to move them around.. Grin.? ?I have one on a Craftsman tool box and the other 2 on a table with rollers on it so I can move them around my basement.

?

Ralph ku4pt

?

On Saturday, December 11, 2021, 03:10:51 PM EST, Hank wrote:

?

Have you ever changed the two AA cells since you've owned the instrument?? They should be changed I think every two years at most; the HP book may say even a little more frequently.?

Re: 8924c memory loss

#381

Ralph,

I'm going to take a shot at this even though you have way more operating experience than I have.

Have you ever changed the two AA cells since you've owned the instrument?? They should be changed I think every two years at most; the HP book may say even a little more frequently.? They are towards the back of my test set (not a 24C) and torx 15 screws must be removed to do this; they're in their own little battery holder case.? I think there are less than 500 to remove you'll be glad to know.? ?This is all illustrated and explained in your 24C book.

This is one of two batteries (I think) that are inside, not counting cells that might be in the regular plug-in memory card.? Of course there are other things that could cause this symptom.? You might report to us if the clock is running, and if it looks to be running at full speed.

This is kind of psychic because I was just reading a few hours ago about the necessity to do this in a recent upload to our files section.? I need to get a T15 screwdriver ASAP because I don't want to get into trouble with these complex test sets just by my own inattention to simple maintenance tasks analogous to changing the oil.? ?The local big box does have them and for sale one by one without having to buy a whole set (there is a God).

Hank

8924c memory loss

#380

What would cause a 8924c to loose the memory.  That is I had it setup to come up in a FM service type mode by the command  POWERON.   Now it reverts back to the cell phone test screen.  It has worked well for around 5 or so years before this.  I did not use it for about 6 months and it lost the memory.  I let it run for 24 hours and it still lost the power on setting after I had reinstalled it.

There must be a battery somewhere as it does seem to have a clock function in the setup screen. If so what module is the battery in ?

Ralph ku4pt

Re: Spectrum Analyzer Trace Too High

#379

There are several things that will cause that if the settings are wrong.

1.? You have the tracking generator turned on

2.? ?The tracking generator is set too high

3 The RF in is selected instead of the ANT

Ralph ku4pt

On Monday, December 6, 2021, 10:19:14 PM EST, lobos305 via groups.io <lobos305@...> wrote:

Not sure if I hit a setting but my trace is not settling at the bottom of the scope - it is about three-quarters of the way to the top.? The reference level is at -10db.? Is there something else I should be lookig at?

Pat

Spectrum Analyzer Trace Too High

#378

Not sure if I hit a setting but my trace is not settling at the bottom of the scope - it is about three-quarters of the way to the top.? The reference level is at -10db.? Is there something else I should be lookig at?

Pat

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