HP 46 repair

[Geoff Quickfall]

Hello!

Repairing and restoring an HP46. All functional now and cleaned however, the far right LED display block has a bad 7 segment display in the EEX TENS digit.

It is the display not a driver.

This is a five bubble LED block. Apparently similar to the classics 35, 45, 65, 70 and etc. Now, before I raid a board in the hoard will these work:

5 digit / 7 segment display with decimal point

Conversely, what is the part number I should be looking for or will my dead canabalized HP 80 be an appropriate donor.

Cheers, Geoff

[Geoff Quickfall]

Oops,asked and answered thanks to:

Led block descriptions by Kees VanderSenden

So yes, the classics LED will work with a centre decimal point display and no those listed above on eBay will not work as they are right hand decimal point displays. So it looks like the hp 80 board will be losing another LED block!

Cheers, Geoff

[Dieter]

(03-10-2019 04:20 AM)Geoff Quickfall Wrote:  Repairing and restoring an HP46. All functional now and cleaned however, the far right LED display block has a bad 7 segment display in the EEX TENS digit.
...

Geoff, could you please correct the subject line of you posts in this thread? At the moment it says "H 46" so this thread cannot be found by other users that may look for HP-46 related information.

Dieter

[Geoff Quickfall]

Shouldn’t type at 02:30 with spell check on. Computer hates HP and replaces it with Ho or just H.

Then I get lazy and think what I have typed made it past the iPad language police!

Cheers

[BobVA]

Hi Geoff:

Glad you found the answer, but just curious...

Is there enough elbow room in the 46 to perhaps allow an interstitial board to remap the pins of a different LED module?

Congratulations on another rescue!

Bob

[Maximilian Hohmann]

Hello!

(03-10-2019 05:30 PM)BobVA Wrote:  Is there enough elbow room in the 46 to perhaps allow an interstitial board to remap the pins of a different LED module?

There is plenty of room inside an HP-46. Here are some good pictures of what it looks like (not my website): https://www.keesvandersanden.nl/calculat...inside.php
The HP-46 would greatly benefit from a slightly larger LED display anyway. As it is, the size of the display (small pocket calculator) and the size and mass of the machine do not fit together at all. From the distance that one usually sits in front of a desktop calculator it is hardly readable.

The display is an optional item BTW. If have never seen one, but there must be displayless HP-46s out there somewhere.

And to Geoff: I have a broken (keys and parts of the printer missing) HP-46 that I keep for spares. If all else fails I can probably extract a working LED module from it. Shipping to Canada will probably be very expensive though.

Regards
Max

[Geoff Quickfall]

Well Max said it all!

Max, many thanks but not required in the light of a new day!

I have quite a few dead classics, and when I mean dead, the boards were stripped of every but the LEDs and drivers. So no problem on the LED but I did manage to find 2 NOS in my other hoard box.



Bob, thanks, now where to put it on display without the wife noticing!

Yes a whole new LED set up board would fit between the pea and the screen especially with the original LEDs harvested and the patch applied directly.

Geoff

[Geoff Quickfall]

So here it is, case and calculator:

My new old stock 5 section LED displays arrived and I have some time off between flights. Lots of flying as the 787 has taken up the slack of 25 parked boeing 737 max’s.

The top and keyboard removed:



Keyboard obverse:



Keyboard reverse:



Optional display board obverse:



Optional display board reverse:



5 digit LED display with separated decimal point. The decimal points take up a whole digit display:



The display board with bad LED display removed and solder removed:



Image of LED block orientation. Note the two end elements consist of rectangles on stalks. There are no notches as with ICs to show orientation. I placed a flashlight under the circuit board to see how the contacts were oriented:



New LED block soldered in place and fully functional:



Continued in part 2...

[Geoff Quickfall]

Of course the ribbon ink had totally dried up. So a shot of me rewinding the feed spool and soaking it in 90% isopropyl alcohol. Used to do this with dads 1960s office Remington at university. Couldn’t afford new ink ribbons. Of course I wonder if replacements can be found and wound on to the HP 46 spools. I will look into it!



Shot of the reenergized ribbon, negative numbers in red and positive in black:



Compare the above to the before shot of the printer contrast:



Those of you not familiar this is a desktop HP 45 with print capability but no ‘hidden timer’.

Completed and reassembled:



I was fortunate with this machine. The only failure was in the far right 5 LED block and the dried ink ribbon. The case and PCA were clean. I will be taking the machine completely apart as the printer probably could do with a lube job! Also checked the big electrolytic caps and they were within 5% so I put them back in. Will replace them later.

Cheers, Geoff

[BobVA]

What? You're not adding it to your flight bag?! :-)

Thanks for the detailed photographs. I never realized that the 46 has an impact printer.

Typewriters are in vogue, so perhaps you could find a ribbon of the correct width at a typewriter shop to rewind on the HP-46 spools?

[AndiGer]

Here in Germany you can find the ribbons.
Just search on TAS for "51s+u"
Also on Canadian site you find more than one but mostly delivery from Germany (I wonder --> OK I see - due to my German registration on TAS).
Shipping - if any - not cheap to Canada.
Still got some spares ... ;-)

[Geoff Quickfall]

Off to Honolulu today (someone has to go) and will check out the large office supply shop on my walkabout.

Thanks for the part number Andi

[AndiGer]

Got that one here on German amazon ...

https://www.amazon.de/Pelikan-Kassenfarb...B000L5KCW0

Maybe helps to find the appropriate part by pics

[AndiGer]

What is the best material for lubrication?
What do you use for those old machines?
Often hardened grease is told to be the problem of breaking the printer's hammers ...

I have an HP-81 and an HP-46 to care for ...

The HP-46 suffers from the printer not working at all. Does not run the printer motor even when PRT OFF pressed while powered (so being very silent when powered on but not the kind I hear when I turn the HP-81 on).

PRT OFF pressed down when powered runs the machine as desired. Calculates everything ok. PRT OFF released (i.e. print should be done) and powered just gives a hardly to hear "Cilck" and the machine does not turn on. PRT OFF released after successful power on and some print request gives error on Option 1 display and needs power off (another "Click" to be heard) to reset the machine.

[teenix]

(04-15-2019 08:27 PM)AndiGer Wrote:  What is the best material for lubrication?
What do you use for those old machines?
Often hardened grease is told to be the problem of breaking the printer's hammers ...

I have an HP-81 and an HP-46 to care for ...

The HP-46 suffers from the printer not working at all. Does not run the printer motor even when PRT OFF pressed while powered (so being very silent when powered on but not the kind I hear when I turn the HP-81 on).

PRT OFF pressed down when powered runs the machine as desired. Calculates everything ok. PRT OFF released (i.e. print should be done) and powered just gives a hardly to hear "Cilck" and the machine does not turn on. PRT OFF released after successful power on and some print request gives error on Option 1 display and needs power off (another "Click" to be heard) to reset the machine.

The "click" maybe the motor trying to turn. Maybe seized mechanics overloading the motor drive, a broken/bent part jamming the works, that hardened grease?? A stalled motor when powered usually presents a short circuit which might explain the faulty running. Could also be faulty electronics.

cheers

Tony

[AndiGer]

Today took the top cover off. You can not look inside the printer or how things work together.

On the left side of the printer the is a hole. Using needle nose pliers I could rotate the drum when I turned on that cam.
When I try to start the printer this cam just moves a little bit forth and back but not running in circles as I expect. Just a short swing and then stops.

Can't imagine how to remove and examine anything of the printer.

Are the service manual and printer service manual of some help here? Francisco (fxsuarezc) in 2016 mentioned not to be of much help ... https://www.hpmuseum.org/forum/thread-5847.html

Andi

[AndiGer]

Today found some pictures of the printer here:
http://www.schlepptops.de/wiki/index.php..._Model_102

I knew that site before but didn't remember there are great pictures.

So I now know that the "cam" I mentioned before is the motor of the printer. And it does not turn as it should.
Maybe the first thing I can do is to go to the +15V test point that is mentioned at Alex Knight's repair tip. Will see what I can do on the weekend ...

[AndiGer]

Went to the test points.
+6 V --> +5.72 V
-12 V --> -11.50 V
+15 V --> PRT OFF -0.5 V, PRT ON 14.80 V increasing to 15.00 V
Seem to be ok.

Measured at the (blue) printer connector at the board, red vs. black wire: PRT OFF 0.00 V, PRT ON 13.80 V. Motor does not spin.

Will remove the printer's screws so I can open the left side cover where the motor and the electronics of the printer are situated. But still no idea, what to observe there. I will see. Or maybe somebody can give some hints ... ?

[Geoff Quickfall]

Diagnostics look good. When running and attempting to print what is the current draw.

Haven’t looked at the printer as I was only fixing the LED display on mine. Now that I have that fixed I will be disassembling and restoring.

I will see what responses are to my testing of the printer which is functional.

Also I have a ribbon coming thanks to you Andi.

Best regards, Geoff

[AndiGer]

Took the printer's side covers off.
This way I can turn the motor manually while printer turned on.

In my HP-81 the motor spins counterclockwise so I assume it is the same in the HP-46 - thus turning the print drum upwards (0 first up to 9).

Turning the motor manually this way the 8 rightmost hammers always move. As I found out the appropriate 3 solenoid switches always work (tear and release) when I turn the motor. (The same when I turn clockwise but then the hammers don't move.)

As I saw the solenoid switches are connected to transistors on the main board. All transistors (4-087) have a common connection that leads to the negative terminal of the 3000µF capacitor and the motors cathode lead (black wire). Suspicious.

Maybe there is ripple comming from that capacitor? Shall I try to change it even +15 V test performed nearly perfectly?

Any advice welcome.
Andi