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Re: HP 5245L counting/gate problems

jerzy przezdziecki
 

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You can use the old vintage cans and put a newer, low ESR capacitors inside to keep the vintage look.

Just make a simple pcb to solder the new cap inside and keep the old pins outside.

?

Jurek

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From: <[email protected]> on behalf of "Tom Smith via groups.io" <n5ama@...>
Reply to: <[email protected]>
Date: Saturday, 22 February 2025 at 16:00
To: <[email protected]>
Subject: Re: [HP-Agilent-Keysight-equipment] HP 5245L counting/gate problems

?

OK Scott, it has never been recapped as far as I know. I’ll look into how/where the supply voltages are tested and will probably just go ahead and recap to avoid any future supply problems.

Thanks,

Tom N5AMA
Re: HP 5245L counting/gate problems

 

OK Scott, it has never been recapped as far as I know. I’ll look into how/where the supply voltages are tested and will probably just go ahead and recap to avoid any future supply problems.
Thanks,
Tom N5AMA
Re: HP 5245L counting/gate problems

 

Hi Pete,
Thanks for the reply. The neon bulb is working on the start and stop test function. When placed on the start position, the bulb comes on but the counter doesn’t display any counting. All the Nixie tubes are working because when the counter is first turned on there is a number displayed that goes away when the counter is reset.
?
There appears to be two problems on that counter. One is it’s not counting and the other is the gate isn’t working.
?
The second counter appears to have only one problem. It counts when placed on manual test start and stops counting when placed on stop. When this 5245L is placed in the frequency position, it doesn’t show any gate or frequency response on the display. I’m assuming there is only a gate failure here.
?
Thanks,
Tom n5ama
Re: HP 5245L counting/gate problems

 

I just resurrected one.

If the power supply hasn't been re-capped, check the supply voltages first.? In my case every d*** capacitor was bad.? Check back then.
Re: HP 5245L counting/gate problems

 

Just an idea: In the case of the gate indicator (a neon bulb): try shining a bright light on it to see if that "fixes" it.
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As for "not counting", I don't know an alternative other than to probe signals to find out where things are failing. Is there a gate signal?
I don't remember if the lowest digit display module is unique, or if it's the same as the 2nd digit. If they're the same, try swapping them with each other.
?
Pete
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Re: HP 3403C True RMS Voltmeter display fault

 

There are days when Murphy's Law just seems to run in overdrive mode, but the fun will resume in a few day and I hope to have more news soon !
Joel
Re: HP 3403C True RMS Voltmeter display fault

 

Well, It did not go well lol.
This is actually not that badly packed. It is somewhat dense but this is really well designed. The boards can be freed from their metal case easily, and A22 (AD board) is socketed from the rest, and the LDs themselves are socketed too. Really easy to work on actually. Nothing to complain about, great job from the good fellas at HP.
Expect I wanted to reseat the chips in case of moisture but my hand slipped when doing LD110 and it badly bent a pin which broke on straightening. Meh. I guess the replacement is mandatory now. I have ordered the pair. I'll still take some measurements later but there it goes. At least the chips are easy to find on Ebay, and wasn't even crazy expensive nor far away.
HP 5245L counting/gate problems

 

I have several of the HP 5245L counters and until recently, had at least one working. Now it seems that the last “working” counter I own has gone belly up.
Two of them have the same problem, (the gate indicator isn’t flashing and one of the two isn't counting). I have the manual and it gives some trouble shooting points to check but in some cases, it only states there is a problem with a board instead of providing a list of components that could be faulty.
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This appears to be a common problem, at least with two of mine. It may be common enough for one of you experts to have fixed it and remembers what component failed. If so, I would greatly appreciate some help.
?
Tom. N5AMA
Re: 54003A success

 

Thank you for that detail!?

Jeremy?


On Fri, Feb 21, 2025 at 7:32?PM Peter Gottlieb via <hpnpilot=[email protected]> wrote:

Indeed, but with a 1000:1 probe that becomes a +/- 2000 volt input range which is sufficient.

That was a work requirement and their solution covers more, although this would be sufficient for them too.

Peter


On 2/21/2025 10:25 PM, Jeremy Nichols via wrote:
Peter, didn’t you have some high-voltage requirements for your application? Looks like the 54003A is limited to +/- 2 Volts, after whatever reduction the probe provides. (Just curious. I missed the last couple of days of discussion.)?

Jeremy?


On Fri, Feb 21, 2025 at 7:07?PM Peter Gottlieb via <hpnpilot=[email protected]> wrote:
Thank to those who provided information I was able to successfully use
54003A input modules as 1 meg probe converter/extenders.

For my company the current COTS device was used to allow remotely using
scope probes (like the Tek HP probes) at a distance from the test
equipment, which also happened to have 50 ohm inputs. However I also
wanted this capability in my home lab and didn't want to spend a lot of
money.

The 54003A modules are available very inexpensively.? With a small +/-
10 volt supply and soldering on a 50 ohm coax cable these modules will
very nicely allow high impedance measurements with 50 ohm instruments
like spectrum analyzers, up to 300 MHz or so.

These can be had for under $30 shipped from the auction site.

IMHO a very useful device to have hanging around the lab. Especially for
the money.

Peter
Re: 54003A success

 

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Indeed, but with a 1000:1 probe that becomes a +/- 2000 volt input range which is sufficient.

That was a work requirement and their solution covers more, although this would be sufficient for them too.

Peter


On 2/21/2025 10:25 PM, Jeremy Nichols via groups.io wrote:

Peter, didn’t you have some high-voltage requirements for your application? Looks like the 54003A is limited to +/- 2 Volts, after whatever reduction the probe provides. (Just curious. I missed the last couple of days of discussion.)?

Jeremy?


On Fri, Feb 21, 2025 at 7:07?PM Peter Gottlieb via <hpnpilot=[email protected]> wrote:
Thank to those who provided information I was able to successfully use
54003A input modules as 1 meg probe converter/extenders.

For my company the current COTS device was used to allow remotely using
scope probes (like the Tek HP probes) at a distance from the test
equipment, which also happened to have 50 ohm inputs. However I also
wanted this capability in my home lab and didn't want to spend a lot of
money.

The 54003A modules are available very inexpensively.? With a small +/-
10 volt supply and soldering on a 50 ohm coax cable these modules will
very nicely allow high impedance measurements with 50 ohm instruments
like spectrum analyzers, up to 300 MHz or so.

These can be had for under $30 shipped from the auction site.

IMHO a very useful device to have hanging around the lab. Especially for
the money.

Peter
Re: 54003A success

 

Peter, didn’t you have some high-voltage requirements for your application? Looks like the 54003A is limited to +/- 2 Volts, after whatever reduction the probe provides. (Just curious. I missed the last couple of days of discussion.)?

Jeremy?


On Fri, Feb 21, 2025 at 7:07?PM Peter Gottlieb via <hpnpilot=[email protected]> wrote:
Thank to those who provided information I was able to successfully use
54003A input modules as 1 meg probe converter/extenders.

For my company the current COTS device was used to allow remotely using
scope probes (like the Tek HP probes) at a distance from the test
equipment, which also happened to have 50 ohm inputs. However I also
wanted this capability in my home lab and didn't want to spend a lot of
money.

The 54003A modules are available very inexpensively.? With a small +/-
10 volt supply and soldering on a 50 ohm coax cable these modules will
very nicely allow high impedance measurements with 50 ohm instruments
like spectrum analyzers, up to 300 MHz or so.

These can be had for under $30 shipped from the auction site.

IMHO a very useful device to have hanging around the lab. Especially for
the money.

Peter
54003A success

 

Thank to those who provided information I was able to successfully use 54003A input modules as 1 meg probe converter/extenders.

For my company the current COTS device was used to allow remotely using scope probes (like the Tek HP probes) at a distance from the test equipment, which also happened to have 50 ohm inputs. However I also wanted this capability in my home lab and didn't want to spend a lot of money.

The 54003A modules are available very inexpensively.? With a small +/- 10 volt supply and soldering on a 50 ohm coax cable these modules will very nicely allow high impedance measurements with 50 ohm instruments like spectrum analyzers, up to 300 MHz or so.

These can be had for under $30 shipped from the auction site.

IMHO a very useful device to have hanging around the lab. Especially for the money.

Peter
Re: Test Set Program Development Tool DEV_PL on 3.5" floppy

 

Not quite.? A USB solution was addressed earlier which is the defacto standard nowadays for communicating with old floppy deives under a modern OS.?
Re: Stuck APC-7 connector

 

Thanks, guys.
Yes, what I really need to do above all is avoid over-torquing/over-stressing the connector at the point where it goes into the bulkhead. If I can get them apart without doing that, I don't see how I could cause any damage.
Re: Keysight U1242B Schematic

 

Hi Ozan. Thank you for that tip. Unfortunately the jack tests open. But the resistance on the jack contacts on the board reads 6.02 Mohm. So the fault is somewhere on the board.
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I have found other posts where the individual just removed the jack to clear the issue of high resistance in the jack.
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Mark
Re: Service manual scan post processing

 

Which Minolta do you have?
?
I am in the process of trying to get a 2400DSV-E to talk to a PC myself
Re: Stuck APC-7 connector

 

Can you determine which end has the threads out - the N adapter or the port?
Then using a padded jaw pliers and the hex wrench, turn the nut that doesn’t have the threads exposed. I would guess the port has the exposed threads and the N adapter is threaded on. In this case turn the hex nut CCW.
If this is not the case then turn the port collar collar to release the connection.
Someone put it on too tight or really tightened an N cable onto the adapter, spinning both adapter and cable, over tightening the adapter to the port. Do use the padded jaw pliers with the hex wrench so that you don’t twist the port connector.

Don Bitters
Re: HP 3403C True RMS Voltmeter display fault

 

My guess is that the clock source must be OK, otherwise the blinking function would not work or the display would blink at a "wrong" rate.
I think I would probe all pins around both the LD110 and LD111 with a voltmeter and an oscilloscope, and check for correct supply voltages, reference voltage, "illegal" logic levels, proper multiplex signals etc ... I know the 3403 insides are "densely packed" and the probing may be difficult, but it may give very useful clues.
... And of course please keep us posted !
Jo?l
Re: Stuck APC-7 connector

 

Put a few layers of masking tape around the knurled nut closest the panel and apply clockwise torque gently with channel-lock pliers. If it doesn't come loose easily, put a wrench on the flats of the hex section at the N-connector end and torque it slightly CCW while turning the ring CW.
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Ed
Re: VNA Reference Impedance Renormalization

 

Good point. I use a DC block permanently installed at the RF input of any DC-sensitive piece of test equipment. It only takes a couple of hundred millivolts of DC to trash the front end of an expensive - for example - spectrum analyzer and that's something you don't want to do once, let alone twice!
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