Author Topic: HP 5340A Frequency Counter Resurrection  (Read 3500 times)

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Online TERRA Operative

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HP 5340A Frequency Counter Resurrection
« on: November 18, 2018, 05:20:19 am »
Time to start a new project, before the previous one is finished as is tradition...

I recently picked up a HP 5340A frequency counter from Yahoo Auctions. Sold as junk with no indication of what was (or wasn't..) inside.
It is a nixie tube version and specced for 10Hz to 18GHz.

When I got it, it looked in reasonable physical condition. It has the usual missing feet (Why does all HP hear seem to have missing feet in Japan? One day I'll find the guy sitting on a mountain of them like Smaug on his gold), and a few minor scratches and dents as to be expected of something from the early 70's.

Upon opening it up, a few things were immediately apparent.

- Someone has had the front and rear panels off, and snipped the cables to do so instead of removing the mounted parts...
- The voltage selector switch is broken beyond repair.
- The Resolution switch on the front is missing (probably salvaged)
- The can for the 'Dir. Count Amp' board is missing
- One SMB - SMC coax interconnect cable is missing (New one ordered to spec from ebay).
- A few screws loose and missing

Thankfully, there are no boards missing, whether they are all operational is another matter. And here's hoping the front end hasn't been blown out too.


Next step is to get the thing powering up to see what needs to be replaced and if it's even worth fixing (If the front end is blown, it might be terminal...)
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Offline bitseeker

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Re: HP 5340A Frequency Counter Resurrection
« Reply #1 on: November 18, 2018, 05:56:05 am »
When I got it, it looked in reasonable physical condition.

I see a lot of these being sold for parts. Makes you wonder if they're all meeting their demise from a common issue (something unobtanium?).

Quote
It has the usual missing feet (Why does all HP hear seem to have missing feet in Japan? One day I'll find the guy sitting on a mountain of them like Smaug on his gold), and a few minor scratches and dents as to be expected of something from the early 70's.

That happens in the US, too. Lots of feet going somewhere, that's for sure. It might be the same place as pen caps, left socks, and SMD passives.

Quote
Thankfully, there are no boards missing, whether they are all operational is another matter. And here's hoping the front end hasn't been blown out too.

Next step is to get the thing powering up to see what needs to be replaced and if it's even worth fixing (If the front end is blown, it might be terminal...)

I haven't worked on one of these, yet. What I recall is that they may have unobtanium hybrids or something to that effect. Anyway, I'm just as curious as you are.

Dropping a link in the TEA thread as some folks there have this model, too.
« Last Edit: November 18, 2018, 05:59:58 am by bitseeker »
I TEA.
 

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Re: HP 5340A Frequency Counter Resurrection
« Reply #2 on: November 18, 2018, 06:10:51 am »
Very nice counter - the Nixie's are glorious! I have two of them myself, one working and one is a parts unit.
Keep us updated as you work on it.
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Offline Cubdriver

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Re: HP 5340A Frequency Counter Resurrection
« Reply #3 on: November 18, 2018, 07:58:02 am »
When I got it, it looked in reasonable physical condition.

I see a lot of these being sold for parts. Makes you wonder if they're all meeting their demise from a common issue (something unobtanium?).

Quote
It has the usual missing feet (Why does all HP hear seem to have missing feet in Japan? One day I'll find the guy sitting on a mountain of them like Smaug on his gold), and a few minor scratches and dents as to be expected of something from the early 70's.

That happens in the US, too. Lots of feet going somewhere, that's for sure. It might be the same place as pen caps, left socks, and SMD passives.

Quote
Thankfully, there are no boards missing, whether they are all operational is another matter. And here's hoping the front end hasn't been blown out too.

Next step is to get the thing powering up to see what needs to be replaced and if it's even worth fixing (If the front end is blown, it might be terminal...)

I haven't worked on one of these, yet. What I recall is that they may have unobtanium hybrids or something to that effect. Anyway, I'm just as curious as you are.

Dropping a link in the TEA thread as some folks there have this model, too.

One part that I know is dead on mine is the custom Schmitt trigger IC on the A22 board - top right corner.  It's like a roach motel - signals check in, but they don't check out!  I've gotten another board from the 'bay, but the counter still hasn't found its way back onto the bench for me to install it and poke about further.



It sounds like yours /really/ got pillaged.  Good luck with your repair efforts, and please keep us posted on your progress.

-Pat
If it jams, force it.  If it breaks, you needed a new one anyway...
 

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Re: HP 5340A Frequency Counter Resurrection
« Reply #4 on: November 18, 2018, 09:16:54 am »
Yeah, I'll soon see how bad it is when I start digging...

If anyone has any parts they are willing to sell, let me know! I'll probably have to pick the bones of a few parts machines I expect. :D
Right now I need the voltage selector switch from the rear panel and the range selector switch from the front panel. At least then my unit should be mostly complete.


I'll have to make one of those riser cards too. I'll add a card edge connector to my next Digikey order.
« Last Edit: November 18, 2018, 09:50:10 am by TERRA Operative »
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Re: HP 5340A Frequency Counter Resurrection
« Reply #5 on: November 18, 2018, 04:43:43 pm »
Started poking around a bit. Looks like this may have been a bit of a parts mule...

Here's the input board for the BNC jack.
It has a missing 2N3906 transistor, two Shottky diodes (HP P/N 1901-0535) that I still need to cross reference, a burnt poly cap and a questionable IC.

The transistor and capacitor are easy to get. Hopefully the diodes cross reference to something common, anyone have any clues?
That IC will be interesting... It seems to unplug, and has been unplugged before. I'm not sure what's up wth that metal brace thingo. Is that supposed to be attached, or is it just a shield/heatsink?

According to the parts manual, it should be part number 1820-0754, but the part there is 1DD8-0502.


This hole just keeps getting deeper.... :D
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Re: HP 5340A Frequency Counter Resurrection
« Reply #6 on: November 19, 2018, 04:40:58 pm »
Had another poke around today.

I pulled the oscillator board out and tested it, seeing as it was relatively easy to do so. Just apply +5V and -5V and hook it to the scope.
The output waveform looks the same as what is shown in the manual if I squint hard enough at the grainy low res image, and as spot on to 10MHz as my scope can display (it bounced around a bit, but was hovering around the mark) so that's a win.

I also hooked up all the clipped wires on the back panel including the mains wiring, except for the voltage selector switch.
I'll need to replace it as it's been ripped open and the innards are long gone, but it'll be a bit of a search to track down. It's a Switchcraft brand 4PDT switch.
I found one on ebay (sent a request to see if they'll send to Japan) but if anyone has one like in the picture below, let me know! I'll buy it from you. :)

Once that's all together, I'll be able to switch it on and see what goes pop...  :-BROKE  :-/O
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Offline factory

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Re: HP 5340A Frequency Counter Resurrection
« Reply #7 on: November 19, 2018, 08:29:49 pm »
I'm fairly certain I have one of those double voltage selector switches somewhere, I had a quick look in the shed tonight but couldn't find it. I also had another really rusty one recently, but as the item it was salvaged from looked to have been underwater for sometime, I filed it in the bin.

David
 

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Re: HP 5340A Frequency Counter Resurrection
« Reply #8 on: November 20, 2018, 03:25:23 am »
Feel free to have another look! :D
Once I get the switch sorted, it'll be time to turn it on.

I should get some incandescent light bulbs to use for current limiting with my variac.
« Last Edit: November 20, 2018, 03:28:52 am by TERRA Operative »
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Re: HP 5340A Frequency Counter Resurrection
« Reply #9 on: November 20, 2018, 04:17:51 pm »
So I got a little bored and poked around where I shouldn't. :D
A good excuse to crack out the Amscope and see what's happening at the Ant Man level.

I had a look inside the Pre Amp Assembly #1 to check that nothing was obviously burnt out.
It all looks good for a visual inspection, and the transistors are still available too if needed, the larger metal can can be got NOS for a not completely unreasonable price, and the two smaller cans (2N5179) are available from Digikey, so that's good.

However, if the other two bits pictured in closeup are bad, it'll be up to what I can salvage from another unit. Fingers crossed they are ok...
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Re: HP 5340A Frequency Counter Resurrection
« Reply #10 on: November 24, 2018, 06:03:13 am »
Quick update.

I snagged a replacement front panel from ebay, including the missing 'resolution' switch and a n A3 Input Amplifier board for the BNC jack (The one with the missing diodes and transistor, and the wrong IC), so I'll install that as soon as it arrives.
I also ordered a replacement SMB - SMC coax interconnect cable to replace the one I found that was missing.

Next step is to sort out that missing voltage selector switch if I can find one somewhere.
Also, find a replacement for the missing can for the 'Dir. Count Amp' (Circled in red in the image below) and find a replacement PCB support as I noticed one is missing (Circled in blue in the image below).
(Photo taken from Google)

Oh, also, I should turn it on soon and see if the stupid thing even works too. :D
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Offline Ordinaryman1971

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Re: HP 5340A Frequency Counter Resurrection
« Reply #11 on: November 24, 2018, 09:51:34 am »
I've got one of those that's partially working, it actually counts up to 300MHz and after this just... stops. I does count  only when switched to the range from 10Hz to 18GHz, the other high frequency range 225MHz to 18GHz doesn't work at all.... didn't check the BNC input.
Mine has LED display, very nice condition, few stickers but nothing broken or missing.
No feet on mine too...
Somebody was inside before me.... I guess trying to fix it. The SMA connectors were loose... I've tightened them up thinking that it may be a problem but still the same.
I've made few adjustments to the potentiometers in the the.... direct amplifier, got a little higher count but that's it, nothing major.
Anybody experiencing the same problem or maybe knowing the solution?
 

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Re: HP 5340A Frequency Counter Resurrection
« Reply #12 on: November 24, 2018, 09:58:55 am »
I think there might be a fault checking flowchart or procedure in the service manual, you might be able to narrow it down to a particular board or module, then cross your fingers that there are no unobtanium parts needed. :D


Ooorrrrrrrrrr, you could just scrap it and sell me some parts!  ;D
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Offline factory

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Re: HP 5340A Frequency Counter Resurrection
« Reply #13 on: November 25, 2018, 05:42:03 pm »
Feel free to have another look! :D
Once I get the switch sorted, it'll be time to turn it on.

It took me a while but I located the switch, pictures attached, it looks slightly different, hopefully it is the correct one. Not sure how much it would cost or how long it would take to send to Japan.

David
« Last Edit: November 25, 2018, 05:44:35 pm by factory »
 

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Re: HP 5340A Frequency Counter Resurrection
« Reply #14 on: November 25, 2018, 11:12:11 pm »
Oh nice. PM sent.
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Re: HP 5340A Frequency Counter Resurrection
« Reply #15 on: December 19, 2018, 04:34:01 am »
Updates!

Special thanks to factory for getting a voltage selector switch to me. :)

I got the whole unit all together and ready to turn on to see if it doesn't work...

I purchased a replacement front panel from ebay, which included the BNC input board, resolution switch and the knob for the range switch, so they all went in last night.
I also ordered a custom cable from ebay to replace one of the missing RF interconnects inside.

Then, while disassembling the unit, I thought I'd test the two power transistors on the back, and found one had a Hfe that was waaayy out of spec, so I replaced them both with new (They only cost a few bucks each).



I still need to source some stainless steel pozi-drive imperial screws (not so easy to do here in Japan) to replace some missing screws.
I found a seller on ebay in the US who has exactly what I need, but the completely refuse to respond to my multiple requests as to the possibility of international shipping. Grrrrrr. |O

Anyone in the USA want to do me a freight forwarding favour? :D


Anyways, this unit is basically ready to switch on, so I'll get the video camera out to film it just in case something interesting happens (fingers crossed there's no fireworks......  :popcorn: )



As usual, here's the list of images:

1. Voltage selector switch
2. Voltage selector switch installed.
3. New power transistors.
4. Resolution Switch installed.
Any circuit design must contain at least one part which is obsolete, two parts which are unobtainable, and three parts which are still under development.

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Re: HP 5340A Frequency Counter Resurrection
« Reply #16 on: December 19, 2018, 04:36:21 am »
More pictures:

1. Replacement front panel (It's an LED version so I mixed and matched with mine to make one good panel)
2. Replacement RF cable (the copper coloured one at the bottom in amongst the grey ones), and the BNC input board (at the top)
3. Overview of the unit as it stands now.
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Re: HP 5340A Frequency Counter Resurrection
« Reply #17 on: December 19, 2018, 04:46:10 am »
I have also made a few test PCB's.
Two are my versions of HP official parts, and the other is inspired by Cubdriver.

From left to right we have:

- K05-5340A Feed-Forward Simulator - Used for adjusting boards A8 and A9 by replacing board A7 and providing a variable simulated feed forward signal to boards A10 and A12.
- HP 05340-60047 riser board - Used for elevating the boards out of the shielded box for testing and adjustment.
- My own riser board for elevating the other PCB's for testing and adjustment (the one inspired by Cubdriver).


If anyone needs the first two, let me know. I made a number of them (minimum PCB quantities and all) so I can sell you them for a reasonable price while stocks last. :)
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Offline coromonadalix

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Re: HP 5340A Frequency Counter Resurrection
« Reply #18 on: December 19, 2018, 10:53:14 am »
Nice to see all work done for restoring stuff and the passion put into this  :)  :-+
 

Offline Zucca

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Re: HP 5340A Frequency Counter Resurrection
« Reply #19 on: December 19, 2018, 01:07:49 pm »
Respect, do japanese people always work like this? Do not stop.
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Re: HP 5340A Frequency Counter Resurrection
« Reply #20 on: December 19, 2018, 01:27:48 pm »
I'm not entirely sure, I'm Australian. :D
Some are cowboys, but some are meticulous to a fault. I tend to lean towards the latter, despite my Australian heritage. :)

I see restoration like this as a puzzle, you can't put it down until it's fully solved!
Any circuit design must contain at least one part which is obsolete, two parts which are unobtainable, and three parts which are still under development.

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Offline xrunner

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Re: HP 5340A Frequency Counter Resurrection
« Reply #21 on: December 19, 2018, 01:33:36 pm »
Very nice restoration project. I'll be following along.  :-+
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Re: HP 5340A Frequency Counter Resurrection
« Reply #22 on: December 19, 2018, 06:22:35 pm »
Hardcore! I should have just sold you my parts unit. I bought it just for the nixie module. It booted and almost worked but some parts had been swapped in the front end.
VE7FM
 

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Re: HP 5340A Frequency Counter Resurrection
« Reply #23 on: December 20, 2018, 03:51:09 am »
Well, if you (or anyone) has the small box that covers the Dir. Count Amp or some PCB supports ( https://www.eevblog.com/forum/repair/hp-5340a-frequency-counter-resurrection/msg1987187/#msg1987187 ) I'm all ears! I know I need that to start with.

Also screws! I need all the spare screws! :D


If anyone has spare parts, let me know. I'm sure I'll need some once I figure this unit out...
I'll poke at it more in a few weeks after my holiday.
« Last Edit: December 20, 2018, 03:53:37 am by TERRA Operative »
Any circuit design must contain at least one part which is obsolete, two parts which are unobtainable, and three parts which are still under development.

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Re: HP 5340A Frequency Counter Resurrection
« Reply #24 on: January 27, 2019, 12:12:12 pm »
So time for an update.

I got it all reassembled enough to try turning it on, and found the 5V regs getting rather hot (but no smoke releasingly hot thankfully).
After a closer look, I found the main smoothing caps were a bit rattly, so I'm approximately 100% sure they need replacement...

Once I get new caps, I'll be able to give it another go and see what else is busted down the line, one bit at a time........ :D
Any circuit design must contain at least one part which is obsolete, two parts which are unobtainable, and three parts which are still under development.

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