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Vintage Test Gear and Workshop Equipment For discussions about vintage test gear and workshop equipment such as coil winders. |
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19th Nov 2023, 3:10 pm | #1 |
Octode
Join Date: Jul 2009
Location: Cheshire, UK.
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Resurrecting HP 5245L frequency counter E515 prefix
The remains of this HP 5245L were given to me with some TE I bought, it's one that was made at the HP Bedford site, prior to the Scotland move, there seems to be very little remaining from the first few years of HP UK.
As I got it, it was missing all the removable PCBs & the case covers, I thought of using it for parts, as the cable loom could have been used to update my 5243L for the later plug-ins. The side frame got used on something else, I can't remember what, the crystal oven control board got disconnected when I was having problems with the 5243L and it had been sitting in this state for a few years, I just couldn't bring myself to scrap it. A few weeks back I found someone offering a pile of boards/parts from these counters, I bought most of the missing boards needed (except the decade divider boards), I also had a couple of display boards from Sphere in Canada too (minus the numerical readout devices), finally I could attempt to resurrect this counter. David |
19th Nov 2023, 3:17 pm | #2 |
Octode
Join Date: Jul 2009
Location: Cheshire, UK.
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Re: Resurrecting HP 5245L frequency counter E515 prefix
First job was to give it a good cleaning, then I reconnected the oven controller board & added an extra wire for adding a fuse to the heater output, to prevent transformer failure if the crystal oven heater winding shorts.
At the same time I installed two sockets, for the optional extra decade divider boards (100 & 1000 second gate time). Next was to install all of the boards, I checked the rectifier board & found several bad diodes, good job I did this before installing it, I've borrowed one from another counter for testing. It was then brought up slowly using various lamps in the lamp limiter, the power supplies were checked, two were OK, but the +20V had a large ripple on it, I wasn't surprized to find the 1500uF 15V capacitor C10 was open circuit (the exact same one, that was open in two different 412A voltmeters), the others all tested fine. A temporary replacement 1500uF 25V has been fitted to the card edge connectors underneath, will re-stuff the original in the future. David |
19th Nov 2023, 4:11 pm | #3 |
Octode
Join Date: Jul 2009
Location: Cheshire, UK.
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Re: Resurrecting HP 5245L frequency counter E515 prefix
As can be seen in the previous post, only one of the seven numerical readout bulbs I got in the parts lot is working, hardly surprizing given they were from a coastal area, these end view types seem to have quite a high failure rate IMO, all with cracked glass from pin corrosion (oxide jacking).
I'm ignoring this at the moment, as there were other faults to fix first, firstly the gate light is on all the time, secondly the timebase output on the front was only giving outputs at 10Mc & 1Mc (this older counter uses the cycle 'c' symbol not 'Hz'). The timebase problem was looked at first, after a few false leads due to using a paper manual for the 1964 version, apparently the A26 5243A-65F oscillator board is quite different to the A26 05245-6013 in the 1965 version, they are completely incompatible due to wiring differences. This counter uses the newer of the two. Next was to investigate the decade divider chain, this takes one of the three 1Mc outputs from the A26 oscillator board & divides it down via a higher speed board A28, then six to eight lower speed boards (A29-A34 & A50-A51), each board divides by ten. The 1Mc was getting to the A28 board, but no output, checking each pair of flip-flop transistors it was only getting past the first pair, borrowing another board confirmed this fault. The leads of the two transistors (Q3 & Q4) were quite rusty, they were removed, a lead fell off one, the other had half of the junction open internally, two replacement 1583-0034 were taken from one of the Sphere spare boards, this fixed the board and I finally had output on all the timebase settings. David Last edited by factory; 19th Nov 2023 at 4:16 pm. |
19th Nov 2023, 4:41 pm | #4 |
Octode
Join Date: Jul 2009
Location: Cheshire, UK.
Posts: 1,687
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Re: Resurrecting HP 5245L frequency counter E515 prefix
And the gate light fault, this was lit continuously, turning the sample rate/ hold control made no difference, the manual states to check the A22 gate control board.
The signal was getting past Q1, but everything else seemed to give no signal, just DC levels, the frequency, start & stop on the function switch were giving strange levels, it seemed to switch high & low turning between the three functions, but stuck in one state with just start & stop. Something was very wrong with this board, I was measuring a lot of short circuits on the 2N708/2N709 transistors with a DMM on diode check, pulling them one by one, until only one of the seven small NPN silicon transistors remained, the removed ones all checked either shorted or as Zener junctions on the tester. Searching through my spares I managed to find enough good used ones, to replace the six failed transistors, after this I now had a fully working gate board and usable one digit (ATM) HP 5245L electronic counter. Next will be to try & find some more numerical readout bulbs and replace a few failed symbol & decimal point indicator lamps. David |
20th Nov 2023, 10:24 am | #5 |
Pentode
Join Date: Oct 2013
Location: Southport, Merseyside, UK.
Posts: 119
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Re: Resurrecting HP 5245L frequency counter E515 prefix
Hi David,
You're a brave man! I don't know if you are aware of this but there's a chap called Marc Verdiell that runs YouTube channel curiousmarc (and also his related web site). He has a great interest in all (vintage) things Hewlett Packard. Recently he did a lot of work restoring a 5425L counter, and its associated plug in modules, which may be of interest to you. Either way, he has an excellent channel and is well worth a look (one of my favourites!) curiousmarc YouTube channel is here:- https://www.youtube.com/c/CuriousMarc/videos Playlist specific to the HP 5425L restoration is here:- https://www.youtube.com/watch?v=B-4c...gdKCaUPY1zaPh_ Jerry |
20th Nov 2023, 10:21 pm | #6 |
Octode
Join Date: Jul 2009
Location: Cheshire, UK.
Posts: 1,687
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Re: Resurrecting HP 5245L frequency counter E515 prefix
Thanks Jerry, either I'm brave or it's insanity but these early UK made ones aren't very easy to find these days, too many have been parted out by people not interested in our historic test gear. Oddly there seems to be more UK made HP TE appearing for sale in Germany than here.
I've watched the videos on the 5245L, it's plug-ins & the 5327B that Curiousmarc has repaired, they are excellent videos. David |
20th Nov 2023, 11:30 pm | #7 |
Nonode
Join Date: Oct 2008
Location: Warsaw, Poland and Cambridge, UK
Posts: 2,666
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Re: Resurrecting HP 5245L frequency counter E515 prefix
This thread has reminded me of my own 5245L which is in storage because there's sadly no room for it in my lab. I got it from the Pye TVT factory in Cambridge in 1987 and it's great, though the crystal oven has been troublesome. It's burned out at least two oven mains transformers in my ownership, due to damaged wiring in the oven latterly caused by the Germanium power transistor that feeds the oven going leaky and thus cooking everything. I had to hack the insulation out to repair it. I replaced it with fibreglass loft insulation so the heater has to work harder than it used to!
I added a confidence check feature: switching to the sensitivity range formerly known as 10V now displays the oven temperature in tenths of a degree C. I don't have a good photo of the back panel so can't remember the full serial number right now, but it's UK made and ends 02543. A few years ago I scratched the itch to acquire a few plugins useful to me: the time interval counter and video amplifier (Nuvistor!) are neat, the voltmeter is surprisingly good with a full 6 digits of resolution, and the 5257A transfer oscillator is just so cool in spite of being fairly hard to use. Chris
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21st Nov 2023, 12:55 am | #8 |
Heptode
Join Date: Oct 2009
Location: Melbourne Australia
Posts: 892
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Re: Resurrecting HP 5245L frequency counter E515 prefix
I repaired a Systron Donner 6250A of what looks like similar vintage and with 1Hz resolution for 10MHz, but a much better storage history than those photos show since the 1970's. That was the first step that then led to how to calibrate such a counter. Luckily I came across a cheap diy GPSDO that easily provided 0.1Hz resolution, so I was in calibration heaven (not a typical outcome for some metrology pursuits).
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25th Nov 2023, 6:27 pm | #9 |
Hexode
Join Date: Nov 2006
Location: Biedenkopf, [Hessen], Germany.
Posts: 423
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Re: Resurrecting HP 5245L frequency counter E515 prefix
good luck with the counter.
And let us know what°s going on in the restoration. You are not allone greetings Martin
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26th Nov 2023, 12:16 am | #10 | ||
Octode
Join Date: Jul 2009
Location: Cheshire, UK.
Posts: 1,687
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Re: Resurrecting HP 5245L frequency counter E515 prefix
Quote:
Also found an early UK one E328 sn 00112, sold in Germany, hope it's survived. I need to look up your repair thread, want to find out the transformer rating and figure out the most appropriate fuse value, to add in series with the heater. You have a few of the useful most plug-ins, there is also a later FET version of the 5261A video amplifier plug-in, I have one here with a few of others shown below, also pictured is my later 5245L prefix 1840A, it uses the newer 10544 oven. Still haven't found a 5253A, 5254C, 5263A & 5268A. There is one that got recalled, the 5259A frequency converter, no idea if any survived, also don't know if 5266A got allocated to a plug-in. Something a bit rarer, a H16 5243L counter, it's 20Mc maximum with the 100 second gate time option, had to import this one from the US, haven't seen one sold here for many years. It's pictured with a 512B frequency converter, the Systron DMM was monitoring the HT rail during capacitor reforming. Quote:
Haven't got a timer/counter from Systron, but do have a couple of frequency counters of similar age from them, plus the DMM above and an LC meter. David |
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26th Nov 2023, 12:54 am | #11 | |
Octode
Join Date: Jul 2009
Location: Cheshire, UK.
Posts: 1,687
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Re: Resurrecting HP 5245L frequency counter E515 prefix
Quote:
Decimal point & symbol lamps are a little tricky to access, replacement is currently on hold while I figure out how to make some ordinary lamps into frosted versions, only the decimal points were frosted originally, probably will replace all of them, as the leads of three are broken due to rust, the others would probably break moving the assembly back into place. Frosted glass paint is available, but it needs baking and I would need to buy one of those cheap toaster ovens & modify it, as people do to make cheap reflow ovens. David |
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26th Nov 2023, 2:07 pm | #12 |
Hexode
Join Date: Nov 2006
Location: Biedenkopf, [Hessen], Germany.
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Re: Resurrecting HP 5245L frequency counter E515 prefix
about plugins:
the video amplifier is a must have, with a simply scope probe the counter is always at work. on my picture you see the Digital Voltmeter plugin. The accuracy is amazing. But it use only 6 of the digits bec. it`s not a 3458A
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18th Jan 2024, 10:10 pm | #13 |
Octode
Join Date: Jul 2009
Location: Cheshire, UK.
Posts: 1,687
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Re: Resurrecting HP 5245L frequency counter E515 prefix
A quick update on the 5245L, when I started this thread, I was using a set of decade divider boards borrowed from the 5248M, for testing & repairing the bought parts.
Last year I had created a close copy of the 5212A-65C (Rev B version) board using KiCAD, 10 of these new boards arrived from JLC and I've built a set of 8 boards for this 5245L, mostly using salvaged parts to keep costs down (thank you to a forum member, for a couple of old boards that provided some of the parts), the completed boards were tested in the restored H16 5243L, all are working fine. David |
19th Jan 2024, 2:48 pm | #14 |
Hexode
Join Date: Nov 2006
Location: Biedenkopf, [Hessen], Germany.
Posts: 423
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Re: Resurrecting HP 5245L frequency counter E515 prefix
the repair extender
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19th Jan 2024, 11:57 pm | #15 |
Pentode
Join Date: Jan 2012
Location: Heswall, Merseyside, UK
Posts: 160
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Re: Resurrecting HP 5245L frequency counter E515 prefix
Did you source the dp frosted neons? I've got a few of them - maybe 3 or 4 not a full complement. You'd be welcome to them, but they are old and there's a lot of dismantling to get them out if they fail!
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20th Feb 2024, 10:31 pm | #16 |
Octode
Join Date: Jul 2009
Location: Cheshire, UK.
Posts: 1,687
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Re: Resurrecting HP 5245L frequency counter E515 prefix
Been busy painting & baking neon lamps over a few days, they have turned out pretty close to the originals, it took a couple of coats of the frosting paint to get the desired finished. Will repeat this with a few more, as the 5248M needs a full set too.
When you put them under the display window, it becomes obvious why they specified frosted neons for the decimal points, it gets rid of unwanted reflections of light on the electrodes. P.S. there will be a few spare extender boards to be listed on the forum in the future. David |
26th Feb 2024, 6:43 pm | #17 |
Octode
Join Date: Jul 2009
Location: Cheshire, UK.
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Re: Resurrecting HP 5245L frequency counter E515 prefix
An update on the 5245L, all the decimal point neons have been replaced with the new frosted A9A (NE-2E) lamps, only a couple were broken, but once they were disturbed the corroded leads broke off the rest. The two dead symbol neons were replaced with salvaged ones from the spares, I do have new NE-2H if needed.
And I finally got round to cleaning up the two side frames for this counter, these have been fitted, unfortunately the top & bottom covers are a problem, the spare covers I have turned out to be too short, once again I find out the counters use different covers to any other HP TE. Today I serviced the noisy fan, some worn parts were replaced with some spares I bought recently, it's much quieter now. Still to do, I have a replacement rectifier board on it's way from JLC, the one installed at the moment belongs to the 5248M. Also I need to find & wire up a switch, for the optional 100 & 1000 second gate time divider boards I've made & fitted. And there is a problem with one of the display boards, in non-storage mode with the timebase set to 1ms, it displays a 2 instead of 0, in storage mode it works fine. David |
26th Feb 2024, 6:55 pm | #18 |
Heptode
Join Date: Jun 2010
Location: Zurich, Switzerland
Posts: 538
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Re: Resurrecting HP 5245L frequency counter E515 prefix
David,
your success and endurance is excellent, very nice to see the old HP in work-congratulations! K. |
28th Feb 2024, 9:26 pm | #19 |
Octode
Join Date: Jul 2009
Location: Cheshire, UK.
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Re: Resurrecting HP 5245L frequency counter E515 prefix
I've been working on the H18 option the last two days, the pdf has all the information on this option, it adds gate times of 100 & 1000 seconds, to use this multiplier option, the timebase is set for 10 seconds, the "Mult" switch selects the X10 & X100 for 100 & 1000 seconds and the reading is divided by 10 or 100 in these positions.
HP H18-5245L.pdf First I had to find a selection of parts & a 3-way switch mechanism, the rod & plate for the reset switch had to be modified to fit behind the new switch. I had to rotate the reset switch, due to the inductor underneath, to allow everything to fit in place and the timebase switch had to be loosened, to allow the fitting of the new switch. After the new switch was assembled & fitted, I moved diode CR22 from A35 to the switch. David Last edited by factory; 28th Feb 2024 at 9:34 pm. |
28th Feb 2024, 9:31 pm | #20 |
Octode
Join Date: Jul 2009
Location: Cheshire, UK.
Posts: 1,687
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Re: Resurrecting HP 5245L frequency counter E515 prefix
Next was wiring up the two extra decade divider PCBs and the wiring in place of the removed diode on A35.
The front panel will need labelling, the button for the reset needs the arrow removing, I might see if I can find one fitted to something else that is worn off first. Testing went well, both the 100 & 1000 second gate times are working fine. David |