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HOWTO: Hengstler Counter Maintenance and Adjustment

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You finally had some extra scratch and bought that vintage Hengstler you've had your eye on?

Now you want to set your TK number or make your counter functional, but don't want to risk damaging it?

 

Follow along and gain confidence to perform some simple work on your counter.  I will disassemble, set numbers and perform modifications to a German Hengstler counter.  This particular counter is likely pre-WWII because it has a large eagle logo.  When WWII started, the Hengstler company replaced the 'eagle' logo with an 'H' logo to avoid association with Nazi politics.  "TK Bondservnt 2392" has covered some of this procedure in different postings over the years and he also provided some background history, so this thread wouldn't be complete without mentioning him as a resource.  If anyone KNOWS these counters, it's Vern.

 

By the way, I've seen several threads talk about brass sockets.  So far as I've seen, NO Hengstler counter has a brass socket.  The sockets are just cheap "pot metal" castings which are cadmium plated.  For comparison, the first common item that comes to mind when I think cadmium plating is automotive power brake boosters.  Cadmium plating offers excellent corrosion resistance and can be used as a final finish or a base coating for paint on many metals including aluminum.  The gold color is a result of the cadmium plating process.  With cadmium plating, you usually also see hints of reds and greens mixed in with the gold color.

 

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If you need help identifying the specifications of your counter, especially electrical, try referencing the chart below.  These counters were originally used in industrial automation - the most common use I've heard is counting post office letters.  In a 2012 post, Michael from Germany said the engraved writing "Patent applied for DBP angem." means this counter was probably used by Deutsche Bundes Post.  The Hengstler company still produces instrumentation, but today they've advanced into digital instrumentation.

 

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Start by using the correct tools.  Use jeweler's screwdrivers and a light touch.  Many parts are delicate plastic, and remember, back in it's day, this was a precision piece of measuring equipment.  Be careful and go slowly so as not to scratch or damage anything.  I'll refer to "front, rear, left and right" as seen when the counter is properly mounted on an E-11 balster.  For reference, imagine holding the blaster and looking at the numbers.

 

One last tip before we get started...the screws are TINY and if you drop one, good luck finding it.  I use a trick I learned while working on avionics in Air Force fighter jet cockpits - cover your work area with a contrasting color fabric.  On the flightline, we would get as many clean, white rags as we could find and lay them in the cockpit under and around the equipment we were working on.  If you drop a screw or a nut in a fighter jet cockpit, you MUST FIND IT, otherwise it could find its way into the wrong place during flight and cause a short-circuit.  The rags cover gaps and provide contrast so a dropped screw or nut is easily found.  The NEMISIS of flightline avionics specialists?  The F-16 throttle grip, with 6 switches, a tiny electrical connector and two WICKED springs to prevent unintended throttle movement past "mil thrust".  I guarantee more than one ejection seat has been removed because of parts lost during throttle quadrant maintenance!

 

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So, now that we have a good, clean work area over a contrasting color, let's get started.

 

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Remove two brass screws from the top and bottom of the rear plastic cover.  I like to set the screws on their heads so they don't roll off the table.

 

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After both screws are out, carefully pull the cover off.

 

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Remove the front socket by simply pulling it off.  There's a small metal tension clip on the right side that holds the socket in place.

 

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The electrical connector on the socket may or may not have external pins.  The connector attaches to the cover with a small screw.  The screw was missing on my counter, so I'll replace it during reassembly.  If you'd like to remove the connector, remove the screw and carefully pull the connector off.  The external pins just use a compression fit over the inner pins.  I've heard of some counters being bought with other electrical components attached - they were not sold this way, so if yours has "extras", it's likely because it was actually used.  You might have a small resistor soldered across the two lower pins - this is done to prevent "chattering" caused by "noisy power".  In an industrial environment with lots of equipment, small amounts of stray voltage induced by electromagnetic interference is common - the resistor is used to drop voltage and prevent counting the "noise" voltage in the wires.  Some people like to remove the pins.  These pins are retained by very tiny e-clips.  Remove the e-clips using the tip of your screwdriver and/or needle-nose pliers.  Be careful with these - they're known to shoot across the room as you release them.  Once the clips are off, you can push the pins from front to back through the plastic housing.

 

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Inside the counter, there's a metal plate used as a linkage which may or may not be loose.  If it's loose, it might fall out, so be aware and keep the counter over your work area.  If all you want to do is adjust the numbers, you DON'T need to remove this plate.

 

To adjust the numbers, the easiest way I've found to do it is by using the reset button.  You need to apply JUST ENOUGH pressure to the reset button to disengage the plastic gears, but NOT SO MUCH that the numbers reset.  It's a fine balance.  When you find just the right balance, you can use your finger to freely rotate each number wheel to your liking.  Patience is key.  DO NOT force anything.  The numbers should rotate easily.  If they don't, try applying a little more or a little less pressure to the reset button.  You should be able to easily accomplish this after a few tries.  I can't really show a picture of this because it takes both hands.  Use one hand to gently push the reset button and the other to rotate the wheels.  If a number is slighty off, you probably need to rotate that number wheel one more tooth.

 

In this picture, I'm holding the counter between my thumb and finger and applying pressure to the button with another finger.  It's easier than it sounds.

 

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In this picture, I'm showing how to use your finger to rotate the number wheels.

 

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You may want to temporarily install the rear cover with the number window to check the alignment of the numbers.

 

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As an alternative to manually adjusting the numbers, you could actually push the number incrementing lever hundreds or thousands of times, but I figure that's not likely.  It gets old real fast.  In the following photo, the toothpick is touching the incrementing lever.

 

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Once you've set your number, you will want to ensure a simple push of the reset button won't eliminate all of your work.  This can be done by 'disabling' the reset button.  There's a small slot in the bottom of the button.  You can place something in the slot to prevent the button from being pushed.  I've seen a scrap of plastic placed in the slot.  I used a small, brass, flathead rivet.  Whatever you use, make sure the cover fits over it.  Just remove the item if you want to reset the numbers.

 

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If you just wanted to change the numbers, then you can skip the coil section and begin reassembly.

 

If you want to remove or replace the solenoid coil, the metal linkage plate must be removed.  The plate in my counter was tight, so I used the tip of a screwdriver to work one edge loose.  Because of the retaining tabs, the plate has to come out at a slight angle.  Work one side out, then carefully pull the plate out at an angle.

 

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Remember the orientation of the linkage plate.  The small, raised arm actuates the number incrementing lever.

 

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Under the linkage plate is a thin plastic insulator.  Carefully remove the insulator by lifting each side over the retaining tabs.  Remember the orientation.  There's a cut out area for the number incrementing lever.  Don't tear the insulator.

 

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Remove the coil bracket retaining screws.  Again, these are small, so stay over your work area.

 

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After both coil screws are removed, you can help remove the coil assembly by applying light pressure to the top of the linkage plate retaining tabs.

 

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The coil assembly slides out of the metal housing just like a drawer.

 

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Carefully pull until the coil assembly is removed.

 

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Coil assembly removed.

 

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I need to make some internal electrical modifications to my coil, so I'll also be removing the internal pins to expose the ends of the wires.  This probably isn't necessary for most people, but I'll cover it anyway.  I also didn't like the "sticker" on my coil, but didn't want to destroy something "original", so I VERY carefully peeled the sticker back using a screwdriver tip to work at the adhesive.

 

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MUCH better and I think more "vintage" looking without the sticker.

 

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To preserve the sticker and prevent it from getting lost, I just flipped over the assembly and stuck it on the back side.

 

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Internal pin removal.  These pins are retained by a V-shaped plastic clip.  Use the tip of your screwdriver to carefully pop each side of the clip out of the pin grooves.

 

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With the V-shaped plastic clip removed, the pins are free, but they still have wires attached.  These pins pull out of the front of the plastic assembly.  Use a soldering iron to melt the solder and remove the wires.  These are tiny wires and it only took about a second to melt the solder.  Keep in mind that you are working very close to plastic parts and the wire insulation is thin.  Any more than a second or two and unintended things will start melting.  This is also precisely WHY I removed the V-shaped clip FIRST.

 

Wires de-soldered and internal pins removed.

 

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I put the clip back onto the pins so these loose parts don't get lost.

 

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Now my wires are prepared to be extended and wired into an internal switch and batteries.  The 12V coil will activate with a single 9V battery.  24V coils will activate with two 9V batteries wired in series.  Don't be surprised if the steel core in your coil is stuck...these counters likely haven't been used for a long time.  Sometimes, you can loosen them up with a short burst of more power or by working the core manually. 

 

Reassemble the coil by positioning it correctly and sliding it back into the housing.  You'll notice there are metal "guide" rails cast into the housing, similar to drawer rails.  When the coil is fully seated in the housing, install the coil assembly screws.  Next, install the plastic insulator.  Make sure it's in the correct orientation, so the cutout area provides clearance for the incrementing lever.  Next, install the linkage plate, making sure the arm is engaged with the lever.

 

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Slide the front socket on and install the rear cover and screws.  Install the electrical connector and screw and you're done!  Easy.

 

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Hopefully, this guide has helped you maintain, adjust or just get to know your Hengstler counter a little better.

Don't hesitate to post or PM if you have questions. :)

Edited by usaeatt2

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Nice thread Aaron. Haven't seen this before, and it's a good thing to get familiar with.

 

Very cool so far!

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wow..thank you for the post Aaron

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Nice thread Aaron. Haven't seen this before, and it's a good thing to get familiar with.  Very cool so far!

 

wow..thank you for the post Aaron

 

Thanks guys!  Much of this was spread out in various FISD threads and I had to go digging on the internet for the specifications chart.  Now it's all assembled in one place.

Edited by usaeatt2

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Fantastic topic!  :duim:  Especially for people who want to adjust their Hengstler counters.

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Very detailed information about the Hengstler :D

 

My Big eagle counter logo isn't golden colored, more like metal look...

 

I think i can polish it...(clean) before some painting ...

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Very detailed information about the Hengstler :D

 

My Big eagle counter logo isn't golden colored, more like metal look...

 

I think i can polish it...(clean) before some painting ...

It's possible someone before you already did some polishing/cleaning and removed the original cadmium plating in the process. Without the plating, I think the unprotected pot metal would oxidize to a dull finish. Just be careful not to polish the sharp edges off the logo...

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Sorry, I don't know if you covered it and I just missed it or something, but I read this pretty closely and I'm still confused as to why you would remove the coil assembly and the solder. What interior electrical modifications did you make (or are you planning to make)? I did see the stuff about wiring it up to batteries, but I'm very confused.

Although that may just be because I have almost no experience with electrical wiring like this.

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On most of the screen used blasters, the counter pins are removed (I'm sure someone can find an exception to this, but I surely wouldn't want to be running around with those gold pins sticking out the front of my blaster).  In other words, in most cases, you only see the plastic connector on the front of the counter, but no pins sticking out.

 

The other reason for desoldering was so I could reroute the coil wires to the hidden batteries on my E-11.  Hengstler made coils with several different impedance values to accomodate different real world industrial installations.  In this thread, my coil has an impedance of 154 ohms - it is likely one of the 24 VDC versions of the counter (see chart above).  A coil with a smaller impedance would allow more current to flow from a 9V battery.  As it is, a single 9V can't supply enough current through a 154 ohm resistance to pull in the coil, so I have to use TWO 9V batteries to make the coil activate.  If I could find a 12V version of the counter, that coil would have a lower impedance and then I would only need a single 9V to activate the coil.  Hope this makes sense.

 

For almost everyone, NONE of this electrical stuff matters because their counters are for display ONLY.

On my E-11, I made the Hengstler counter increment every time I pull the trigger, so I needed the coil to actually function.

 

Aaron

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Ah, okay. That was the only real application I could think of for the counter- counting trigger pulls. I didn't realize that you'd left the pins off (though now it's incredibly obvious). I also didn't know if the screen-used blasters kept their pins in, so I think you just inadvertently answered a different question about counters that I'd been knocking around in my head!

Thanks for your help!

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Hi guys!<br>

Sorry to bump this old thread but I recently discovered something amazing!<br>

At my work, we use very old machines to compress medical rubber to shapes used in the medical business( sorry if this sounds weird, English is not my native language ) but....<br>

We have like over 20 of these machines and they all have...you guessed it hengstler counters! <br>

I talked to the technicians to eventually replace them with modern counters, ours just keep track on how many hours the machine is running.<br>

I'll keep you updated!

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Fortunately, you're there to save those archaic Hengstler's from the trash bin.

Makes me wonder how many have been pitched over the years to make way for advanced technology...

An average worker would probably have little idea what these are worth on the prop market. 

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Ok I checked how many there are, there are 52 machines in total, 5 of them were replaced by new ones a few years back, those are gone but they kept some pieces and are checking if they kept the counter, they doubt it but it could be someone threw them in a box.<br>

Wait and see I guess...

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