(Re-)Print labels on back side of classics

[Sadsilence]

Hello all,

as it is my aim to bring back (broken) HP calculators of classics series (HP-35, HP-45, HP-55, HP-67) in best possible state I am looking for a method to restore lost or damaged back labels by printing it on my own.

Maybe some of you tried same before. So I do not have to start from scratch. Any help, idea or even a contact address is highly appreciated.

Thanks in advance!

Werner

[isanchez]

Hi,

if the label is in good condition and you want to open the calculator, you can carefully remove the sticker using a hairdryer and a lot of patience. Use a exacto knife just to start lifting the sticker corner, while you project the hot air (medium level, not extremely hot)...lift the sticker corners just the minimum to unscrew the two screws under. My recommendation is not to screw them back after the reparation...they are not necessary to keep the calculator closed, and maybe it will be necessary to open it again in the future. The sticker is always affected...more or less depending of your skills and patience.

If the sticker is very damaged or does not exist, may I recommend you to buy a copy from a guy located in Singapour or Indonesia (can't remember now). He prints quality stickers very close to original of all classic models...the cost is 10USD, including the shipping cost...I believe it is the best option to replace the damaged. He is often offering this stickers in ebay. If not, I can provide you his email address.

I don't think this labels can be restored.

Good luck!
Ignacio

Added: the guy is Ben Ong; ebay seller id.: obh8899

[Sadsilence]

Hi Ignacio,

thanks for your answer. Ben Ong is the one I am looking for ;-).

I use hairdryer method (or to be more exactly regulated heat gun normally used for heat shrink tubes) by my own. But as you mentioned. Sometimes there is nothing left for heating.

Let away two screws is a good advise. Before I removed sticker completely with a lot of patience and relabeled calculator when finished surely.

Werner

[Dave Frederickson]

(09-01-2015 03:49 PM)Sadsilence Wrote:  I use hairdryer method (or to be more exactly regulated heat gun normally used for heat shrink tubes) by my own. But as you mentioned. Sometimes there is nothing left for heating.

That's the technique I used.

Donor calc on left and the end result.

Click to zoom


Dave

[isanchez]

Good work Dave!
the contact for Ben is: ben"dot"ong"at"outlook"dot"com or gmail"dot"com

good luck.

Ignacio

[Sadsilence]

Dave, Ignacio,

thanks for your assistance again. Using Kapton tape is really an improvement.

Mailed to Ben. Now I am waiting.

Best regards,

Werner

[Dave Frederickson]

I'm aware of the knock-off labels on eBay. When I decided to refurb my 35 that I mangled as a kid I choose to locate an original label. You may have noticed that the eBay labels are not exact duplicates as they can't say Made in U.S.A. Fortunately one of the forum-friendly eBay sellers generously offered to send me a 35 from which to salvage the label. So, donor calc on the left, mine on the right (see above). The donor along with the label I mangled was returned.

I've also seen a refurbed Classic sold on eBay by another forum member with both the original and replacement labels.

Dave

[Sadsilence]

Dave,

hope I got it right. Of course there are two labels on rear side. "Made in USA, 500 mW" sticker normally is in good shape. Only large one with short operating explanations is damaged more often than not, cause you have to remove it somehow for opening case.

It is hard to explain (even more as English is my personal enemy since school days), but a classic without a well shaped operation label is not complete in my eyes. Even more when spending hours bringing it back to life and clean it. It is only for personal reason, not for enhancing market values So, if knock-off labels are really knock-off, I will do printing tests by my own.

By the way. Ben replied and I ordered some labels. Will give a feedback after delivery.

Werner

[isanchez]

Hi Werner,

The thing is to choose between a lightly damaged ORIGINAL label (a couple of bendings in the corners) and a copy. This is a dilema...how much damage can you support? ;-D.

Personally I suppose that impementing this two screws under the label was a way to know if it was manipulated by the owner in the case it was sent to the HP repair service.

Normally you have to open ALL models with card readers to repair the gummy wheel: this is for 65 and 67. Normally the labels are 100% OK and it is a pity to bend them a little bit. For the rest of the models it is only necessary to do it when there is a problem in the led display or the board. As a rule, I do normally prefer to keep the original labels. Only when it is missing or very damaged I do replace them.
As exceptions, I have a 45 with the back label corners in bad state...but I don't change it because instructions are in Spanish...the same case for the label in Spanish in a rare 35, model 2 (not red dot, but right after).

Good luck with Ben...for me is a good option to consider.

Kind regards

Ignacio

[Sadsilence]

Hi Ignacio,

I see, you understand my dilemma :-). Original labels in good shape are best, absolutely no point to discuss about.

Normally I repair units that are in seemingly bad shape with corroded contact springs due to leaking batteries. No way to do that right without completely disassemble calculators, cleaning case and internal electronics seperately, insert new brass contact springs etc. As classics series is built for eternity you can normally bring even really bad looking units back to life for the sake of completely removing labels or remaining parts of them.

HP-45 with it's "hidden" timer feature is my personal favorite. Inserting a tiny PCB with an adjustable oscillator as replacement for installed inaccurate LC curcuit or unavailable 784 kHz quartz you can get timer to an accuracy of about 0,01% or better instead of 10%...

When ready and everything is running a correctly labeled unit would be dot of an "i" as we say here.

So let's see how reprinted labels look like.

Best regards,

Werner

[Didier Lachieze]

(09-03-2015 04:09 PM)Sadsilence Wrote:  HP-45 with it's "hidden" timer feature is my personal favorite. Inserting a tiny PCB with an adjustable oscillator as replacement for installed inaccurate LC curcuit or unavailable 784 kHz quartz you can get timer to an accuracy of about 0,01% or better instead of 10%...

That's interesting ! Can you share more details about this tiny PCB ?

[Sadsilence]

(09-03-2015 04:36 PM)Didier Lachieze Wrote:  

(09-03-2015 04:09 PM)Sadsilence Wrote:  HP-45 with it's "hidden" timer feature is my personal favorite. Inserting a tiny PCB with an adjustable oscillator as replacement for installed inaccurate LC curcuit or unavailable 784 kHz quartz you can get timer to an accuracy of about 0,01% or better instead of 10%...

That's interesting ! Can you share more details about this tiny PCB ?

It was a spontaneous idea after reading this forum arcticle as I realized, that there are simply no 784 kHz crystal units available any more.

Idea is based on LTC6900 (LTC1799 is same with different resistor values). Frequency of those oscillators is set by a simple resistor value. Indeed I use a series or parallel curcuit of two resistors to be able setting frequency correctly. Together with a voltage filter capacitor and an output resistor for voltage level adjustment to HP 45's LED curcuit I put all components on a SOT to DIP PCB, using DIP pads as pads for 0603 smd resisitors and 0603 smd capacitor. What makes those chips so appealing are their little current consumption compared to normal VCOs and the easy setup. No programming, no highly precise voltage etc.

Linear states, that precision is only 2%, which would not pay off the effort. But that is only half the truth. Exactly it means, when using same resistor value for 100x LTC6900 output frequency of all would vary between +/- 2%. One LTC6900 in itself is very stable, you just have to get right resistor value for your unit.

You do not need to have great measurement equipment or high precision resistors. Later one is even bad as you cannot compensate LTC6900 variation. Just use your standard DMM, select resistors (24k9 + 560R from 1% default line in series works great for me) and let HP-45 do the measurement, comparing timer mode after 10000 seconds (2h:46m:40s) with your radio controlled watch. When HP 45 timer is to slow, reduce resistor value, using one out of your selected pool, that shows a little less value on your DMM and repeat test. 10 Ohm change normally affects oscillator frequency at around 0.003%. When timer is too fast increase resistor value. One or two iterations are normally enough to get a difference less than 1s for 10000s run time. To do more is not senseful as LTC6900 frequency is voltage supply depending (battery voltage decreases during runtime = NiCD/NiMH characteristic) and temperature depending. It is not really bad but in 0.01% variation range themselves.

During optimization phase I use long wires and let HP-45 open, supply it with an external 3.75V power suppy. 2 supply wires are soldered to battery supply line of HP-45 (please use a HP-45 pad after on switch for + line. Otherwise battery has to deliver around 1 mA, even when calculator is switch off. Frequency output pin of LTC6900 has to be connected to 330 uH inductor pin like mentioned in crystal article. Do not remove inductor! It is important not directly use output pin, as voltage levels are different. A decoupling resistor with any value between 1k and 10k does a good job.

When being happy with the result, PCB is glued with doublesided tape to inside of GOWANDA chip and wires are truncated and resoldered. As wires I use wirewrap ones' or small insulated copper wires.

Of course there is plenty of room for improvement, e. g. a stabilized Vcc for LTC6900 (easiest way: Z-diode) or a better output curcuit, allowing to remove inductor on HP-45. Nevertheless it is a 1000 times improvement for less than 10 Euro material value with an additional load of only about 1mA.

If there is interest I can produce some already optimized "ready to solder" units together with an "installation guide".

Best regards,

Werner

[Didier Lachieze]

Many thanks for all these details. I'm interested by one of these units to upgrade my HP-45.

[Sadsilence]

Thanks for your interest and your time to read.

I'll check material for 10 pcs monster series ;-) and try to create it during next two weeks. Keep you informed.

Best regards,

Werner

[Didier Lachieze]

Thanks. Btw, about the original topic, did you see this article: Removing the back labels to HP classic series calculators, describing the usage of a spoon to smooth the label before reapplying it ?

[Sadsilence]

(09-04-2015 10:59 AM)Didier Lachieze Wrote:  Thanks. Btw, about the original topic, did you see this article: Removing the back labels to HP classic series calculators, describing the usage of a spoon to smooth the label before reapplying it ?

Thanks for the link. Indeed it was new to me. Another enhancement of heat gun/hairdryer method. Will give it a try next time :-).

Best regards,

Werner

[Dave Frederickson]

(09-04-2015 10:59 AM)Didier Lachieze Wrote:  Thanks. Btw, about the original topic, did you see this article: Removing the back labels to HP classic series calculators, describing the usage of a spoon to smooth the label before reapplying it ?

I used a burnishing tool, a piece of glass, and a piece of release paper.

The pic isn't displaying properly, but here's the link:

https://drive.google.com/file/d/0B-GPxmp...sp=sharing

Dave