HP 5340A Frequency Counter Resurrection - Page 1
Forum section: electronics / repair

author: TERRA Operative
author_rank: Super Contributor
timestamp: November 18, 2018, 05:20:19 am
content: 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 missingThankfully, 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...)

author: bitseeker
author_rank: Super Contributor
timestamp: November 18, 2018, 05:56:05 am
content: Quote from: TERRA Operative on November 18, 2018, 05:20:19 amI 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?).QuoteThat 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.QuoteI 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.

author: TheSteve
author_rank: Unknown
timestamp: November 18, 2018, 06:10:51 am
content: 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.

author: Cubdriver
author_rank: Unknown
timestamp: November 18, 2018, 07:58:02 am
content: Quote from: bitseeker on November 18, 2018, 05:56:05 amOne 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

author: TERRA Operative
author_rank: Super Contributor
timestamp: November 18, 2018, 09:16:54 am
content: 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.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.

author: TERRA Operative
author_rank: Super Contributor
timestamp: November 18, 2018, 04:43:43 pm
content: 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....

author: TERRA Operative
author_rank: Super Contributor
timestamp: November 19, 2018, 04:40:58 pm
content: 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...

author: factory
author_rank: Super Contributor
timestamp: November 19, 2018, 08:29:49 pm
content: 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

author: TERRA Operative
author_rank: Super Contributor
timestamp: November 20, 2018, 03:25:23 am
content: Feel free to have another look!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.

author: TERRA Operative
author_rank: Super Contributor
timestamp: November 20, 2018, 04:17:51 pm
content: So I got a little bored and poked around where I shouldn't.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...

author: TERRA Operative
author_rank: Super Contributor
timestamp: November 24, 2018, 06:03:13 am
content: 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.

author: Ordinaryman1971
author_rank: Frequent Contributor
timestamp: November 24, 2018, 09:51:34 am
content: 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?

author: TERRA Operative
author_rank: Super Contributor
timestamp: November 24, 2018, 09:58:55 am
content: 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.Ooorrrrrrrrrr, you could just scrap it and sell me some parts!

author: factory
author_rank: Super Contributor
timestamp: November 25, 2018, 05:42:03 pm
content: Quote from: TERRA Operative on November 20, 2018, 03:25:23 amIt 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

author: TERRA Operative
author_rank: Super Contributor
timestamp: November 25, 2018, 11:12:11 pm
content: Oh nice. PM sent.

author: TERRA Operative
author_rank: Super Contributor
timestamp: December 19, 2018, 04:34:01 am
content: 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.Anyone in the USA want to do me a freight forwarding favour?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......)As usual, here's the list of images:1. Voltage selector switch2. Voltage selector switch installed.3. New power transistors.4. Resolution Switch installed.

author: TERRA Operative
author_rank: Super Contributor
timestamp: December 19, 2018, 04:36:21 am
content: 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.

author: TERRA Operative
author_rank: Super Contributor
timestamp: December 19, 2018, 04:46:10 am
content: 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.

author: coromonadalix
author_rank: Super Contributor
timestamp: December 19, 2018, 10:53:14 am
content: Nice to see all work done for restoring stuff and the passion put into this

author: Zucca
author_rank: Unknown
timestamp: December 19, 2018, 01:07:49 pm
content: Respect, do japanese people always work like this? Do not stop.

author: TERRA Operative
author_rank: Super Contributor
timestamp: December 19, 2018, 01:27:48 pm
content: I'm not entirely sure, I'm Australian.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!

author: xrunner
author_rank: Super Contributor
timestamp: December 19, 2018, 01:33:36 pm
content: Very nice restoration project. I'll be following along.

author: TheSteve
author_rank: Unknown
timestamp: December 19, 2018, 06:22:35 pm
content: 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.

author: TERRA Operative
author_rank: Super Contributor
timestamp: December 20, 2018, 03:51:09 am
content: 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 needallthe spare screws!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.

author: TERRA Operative
author_rank: Super Contributor
timestamp: January 27, 2019, 12:12:12 pm
content: 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........

author: TERRA Operative
author_rank: Super Contributor
timestamp: March 27, 2019, 02:10:05 am
content: So I installed the new caps and promptly smoked a wire to the 5V power transistor.Seems I have a problem somewhere on the 5v rail... I disconnected everything on the 5V rail so far and it now is not releasing any more smoke, so at least the power supply is fine...It seems this unit was originally an LED display version it seems (it's a bit of a mix of parts in this unit) so I need the older style transformer and a bridge rectifier for the 175V for the nixies, plus that damned box for the 'Dir. Count Amp' plus a few other bits and pieces.Good thing is I found a parts unit for cheap(-ish) that has all the bits I need so far, it has the old style transformer with the nixie supply winding and that dir. count amp box, and also the transformer for option 001 too!I went ahead and designed the power supply board with the help of psykok who sent me pictures and measurements of his board and ordered the PCB's, so all I'll need to complete the Option 001 upgrade is to get the OCXO, but they are pretty common on ebay.Once the parts unit arrives I'll be able to at least get the nixies lit up, then I'll start tracing what is wrong on the 5v rail.Then the next thing, and the next thing........

author: tkamiya
author_rank: Super Contributor
timestamp: March 27, 2019, 03:25:23 am
content: Missing feet is due to the fact most equipment of the kind was racked. HP stuff does not have the side support. So take off the feet, install slide type stuff on both side of the rack, put the ears on, slide it in and bolt the front.It's the same in US, too.

author: psykok
author_rank: Frequent Contributor
timestamp: March 27, 2019, 08:17:34 am
content: hi,just one point, do you have the transformer for the regulator board for the option 1?Alex

author: TERRA Operative
author_rank: Super Contributor
timestamp: March 27, 2019, 08:23:38 am
content: Quote from: psykok on March 27, 2019, 08:17:34 amQuote from: TERRA Operative on March 27, 2019, 02:10:05 amYep.

author: psykok
author_rank: Frequent Contributor
timestamp: March 27, 2019, 08:34:46 am
content: ok I food so you will be able to install the option in your deviceNow I'm hunting for a logic analyser to continue the debugging of my non counting device

author: beanflying
author_rank: Super Contributor
timestamp: March 27, 2019, 08:35:05 am
content: Bookmarking for when I start playing with my 'for parts unit' I got earlier last year (winter time job). At least the Nixie's all glow properly, slide switch moves the DP, Oscillator works but alas I think someone has blown both inputs as they are deader than dead740B is in the que for a Recap and some other bits but the lure of the Nixie made me get it too

author: TERRA Operative
author_rank: Super Contributor
timestamp: March 27, 2019, 08:43:07 am
content: ooh, I'd love a good nixie volt meter or the like... They don't pop up so often in Japan, it's all frequency counters all the time...

author: beanflying
author_rank: Super Contributor
timestamp: March 27, 2019, 09:08:38 am
content: OT but well NIXIE. I do have a fully functioning 5326B with Nixies and a Voltmeter option if you come across one. I have never done a Cal on it but very accurate too.

author: TERRA Operative
author_rank: Super Contributor
timestamp: March 27, 2019, 09:11:52 am
content: OMG, so jelly.I got the 5340, and two small frequency counters so far. The two counters work (I repaired and restored them previously), one I use and one I'll sell to fund new purchases.

author: beanflying
author_rank: Super Contributor
timestamp: March 27, 2019, 09:17:23 am
content: I have trawled up the parts from France and the USA to add the 8th Nixie Digit to it as well. Fairly easy to do as it is all plug in parts but I haven't got around to it

author: TERRA Operative
author_rank: Super Contributor
timestamp: December 29, 2019, 08:49:19 am
content: Alrighty, new update!I managed to score myself another two of these units in parts-mule and semi-working condition.I've installed the Option 001 transformer, and replaced the main transformer with an older style and added the missing bridge rectifier for the +170v nixie supply.Also, I used various other bits to replace missing parts in my unit, including that small box I was missing for the Dir. Count Amp board.The semi-working one was showing random numbers on the display, so I began swapping the logic cards from my existing unit and found that the first one I swapped (board A23, Count Register Assembly) which I suspected, is bad, but the unit sprang to life with the replacement board from my original unit.So this 'new' unit looks like it works on the BNC input at least which is awesome as I can use it for testing boards from my non-working unit, and I might even end up with two units working at the end (Assuming the front ends in both units aren't blown out.....)Next step is to fix this A23 board just because it's known faulty, but I'll swap parts in and out of my original unit to get the display working right and also do repairs there as needed.Interestingly, this A23 board is 4 layer, and gold played. Not a cheap board to make I'm sure from the mid 80's, the date codes on the IC's are around 1986...Photos as follows:- 'New' unit- Original unit with stuff added.- Faulty A23 board.

author: TERRA Operative
author_rank: Super Contributor
timestamp: December 29, 2019, 04:36:47 pm
content: Ok, so I have narrowed down the faulty on that A23 board to 2 or 3 chips. I'll replace all 3 just to be sure I think.Trick is finding some.... They are HP part number 1820-0986, which are a DM86L75N or DM76L75 which cross references to SN74160, all of which seem hard to come by...Mouser do have a SMD SOIC16 version of the SN74160, but then I'd need to use a SMD to DIP adapter board for each chip, which isn't too hard (I can get them on ebay), just a little messy.Anyone got any of these chips laying around in your spare parts you want to sell?Also, I found a dry solder joint on the +15V PSU PCB, so that's been fixed too.I think I'll be using this new chassis as my main chassis for now as it powers up and works so far. All I really need to do is transfer the Option 001 transformer and the main power filter caps across, but the caps are screw mount so easy enough to do.Once I have this one all working, I'll continue to fix up my existing unit so I can use the good unit as a reference seeing as the first one was a bit of a junkbox assembled unit.

author: TERRA Operative
author_rank: Super Contributor
timestamp: December 30, 2019, 03:04:23 pm
content: Well, Akihabara saves the day yet again!I went to a little semiconductor store on my way to work and asked the old guy if he had any 74160, and after a bit of a think, he pulled out an old box from the shelf, blew off the dust and opened it to reveal a bunch of brand new TI parts for about a dollar each.I bought 5 (so I have some spare) and replaced the faulty chips tonight, and now I have a fully working card.Next step, swap some parts from the original unit to the new unit then start running performance tests to find what the next broken thing is.

author: Cubdriver
author_rank: Unknown
timestamp: December 30, 2019, 03:08:41 pm
content: Sounds like you're making good progress! Nice to hear.-Pat

author: psykok
author_rank: Frequent Contributor
timestamp: March 12, 2020, 03:15:12 pm
content: I still have to fixe mine and I suspecting the same board.Unfortunately without spare part or logic analyser it's almost impossible to track the problem

author: TERRA Operative
author_rank: Super Contributor
timestamp: March 12, 2020, 03:21:02 pm
content: I took the shotgun approach and swapped chips until it worked and replaced the last chips I swapped.Helps having parts from 3 units though.I'll get back into it sometime soon, once the Wheel OfFortuneRepair lands in the right spot for this thing to get some bench time again.I'm currently designing a new motherboard for my 16 digit nixie tube Casio 161K desktop calculator.

author: psykok
author_rank: Frequent Contributor
timestamp: March 12, 2020, 03:33:05 pm
content: did you found exactly which chip was faulty?

author: TERRA Operative
author_rank: Super Contributor
timestamp: March 12, 2020, 03:34:56 pm
content: I'll take a look when I get home and let you know. Looks like it was 5, 6, and 7 on A23 that I replaced with SN74LS160AN parts from TI.