How to do interpolation on calculators

Satellite 600 professional

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Grundig: 600 professional; Satellite, LCD displayHans-Dieter Haase † February 5, 2018
06.Dec.06  1

I got a Grundig satellite 600 as a present, on which the LC display does not show anything. Reception in all areas is possible and the stored frequencies can be stored and retrieved. So the most important part of digital technology should be fine. The lights for the display lighting are defective. The segments of the display are visually recognizable (like burned-in on a picture tube).
I suspect contact problems with the display or total failure. Someone already seems to have tried on the digital part, or on the expansion of it. Before I take everything apart, I would be grateful for testimonials. The device is too good to dispose of.

Greetings Hans-Dieter Haase

Detlef Boeder
07.Dec.06  2

Hello Mr. Haase,

with mine (but 650) it was similar. Remove the RW and look for the foil ribbon cable to the display. The conductor tracks are silver-plated at the contact points and turned black on mine. It is the area with the terminal connectors. After careful cleaning with a glass hair brush and washing with tuner spray, everything was ok again.

Greetings DeBo


Hans-Dieter Haase † February 5, 2018
08.Dec.06  3

Hello Mr. Boeder,

thanks for the hint, but the construction of the 600 seems to be different. The display is pressed with the plastic frame directly onto the circuit board and thus contacted. How to get the frame is not quite clear to me yet, although there is a reference to it in the description from the radio show. I may have to remove the rear shielding tray.

Here is the corresponding excerpt from the radio show article:

The LC display is connected to the circuit board using silicone rubber interconnectors. A plastic frame holds the display, diffuser, light guide (with reflector) and interconnectors. The frame is hooked in at the bottom and secured with locking hooks at the top. This creates the contact pressure required by the interconnectors between the printed circuit board and the display. The light guide is also snapped into the plastic frame. If the plastic frame has to be removed in the event of service, the LCD and accessories remain in the frame. This means that the LCD or its contact surfaces can neither be damaged nor contaminated.

Greetings Hans-Dieter Haase

Wolfgang Bauer
08.Dec.06  4

Sg.Mr Haase,

I have downloaded the removal instructions for the device for you.

Kind regards. W.B..

Hans-Dieter Haase † February 5, 2018
08.Dec.06  5

Thank you Mr. Bauer.

I will report on success or failure.

Greetings Hans-Dieter Haase


Hans-Dieter Haase † February 5, 2018
08.Dec.06  6

As already suspected, the plastic frame of the display is not only locked in place, but also fastened from behind with two screws that also hold a small additional circuit board. In order to be able to loosen these screws, the rear shielding hood of the digital module has to be removed. This is soldered to the board on three sides, a bit difficult to handle because the lower soldered connection is quite large.

At this point someone must have tried because the screw heads were totally screwed up. The connection between the display and the circuit board is established above and below with so-called silicone-rubber interconnectors. There is nothing conspicuous about these connections from a purely visual point of view. Whether and how this contact can be checked electrically is beyond my knowledge.

There are actually only two sources of error left: the display itself or the controlling component (IC804). The way the display looks (segments appear blurred, as if "burned in"), I actually type on it. I did not take any measurements, however, because the plug connections to the digital module cannot be connected when dismantled. It would also be too risky to put the device into operation without a shielding hood. You may be able to measure something on the front accessible side of the circuit board (hidden by the keyboard).

I will put the project on hold for now.

Greetings Hans-Dieter Haase

Henning Oelkers
08.Dec.06  7

Hello, Mr. Haase,

With displays of pocket calculators (and this one should be constructed in exactly the same way), it is sufficient to place a multimeter in a (medium) ohm range and to scan the contact surfaces (directly on the glass) piece by piece. At some point, individual segments will be displayed.

This is certainly not a perfect test method, but I think it is relatively unlikely that the display itself is defective.

Maybe you still have a (giveaway ...) calculator lying around somewhere. There you can (without having to remove the display) try out how the individual segments react.

The silicone contact strips consist, as it were, of a sequence of conductive and non-conductive "rubber blocks", so that each contact surface on the circuit board is opposed to a "conductive" rubber block, on the other side of which (if correctly installed) the respective contact surface of the display comes to lie. The contact strips can also be tested with a multimeter; the continuity is usually relatively high-resistance. Since the display itself requires (almost) no power, that doesn't matter.

It is important that the contact strips and the glass surfaces are clean.

During assembly it could be important that the conductive sides come to rest on the circuit board contacts and on the glass.

Maybe this will help you.

With best regards from Berlin,

Henning Oelkers


Wolfgang Bauer
09.Dec.06  8

Sg.Mr Haase,

You write at the beginning:

The segments of the display are visually recognizable (like burned-in on a picture tube).

Is it like this when the power is off or when the power is on? A photo would also be very helpful.

Kind regards. W.B..

Hans-Dieter Haase † February 5, 2018
09.Dec.06  9

Hello Mr. Oelkers, hello Mr. Bauer,

thanks for the helpfulness.

First of all, the photo of the display in the dismantled state without voltage. (Built-in when the device is switched on, no change can be seen).

The ohmmeter test method was good advice. I scanned the two silicone contact strips and was able to control the individual segments. They became noticeably darker. In my opinion, the individual segments should not be so clearly recognizable without voltage, so my guess is that the display is defective. But it doesn't seem to be completely defective.

From a purely visual point of view, the contact strips are also pressed firmly onto the circuit board. So there may be an electrical fault after all. I will search further.

Warm greetings from Nienburg

Hans-Dieter Haase




Henning Oelkers
09.Dec.06  10

Hello, Mr. Haase,

when I look at the photo, I see a diagonal dark line in the upper left corner. Is the front or rear glass broken there?

Unfortunately, this cannot be seen exactly in the photo. Using a flashlight could help you judge this accurately.

If the glass is broken, the display is defective. Because the functional principle is based essentially on the liquid enclosed between the glasses. If air comes in or liquid comes out, this means the end of the display.

With best regards to Nienburg,

Henning Oelkers

Hans-Dieter Haase † February 5, 2018
Dec 10, 2006  11

Hello Mr. Oelkers,

I have now also completed the last step and removed the display from the frame. No mechanical damage can be seen at the front or rear. The irregularly dark background seems to indicate to me that the display must have drawn air.
The only thing left now is the search for a replacement, because the device is pretty worthless without a display. I can enter the frequencies blindly and hear them with the device, but of course that is not satisfactory.

At this point, many thanks again to everyone who tried to help me (also by email).

Best regards
Hans-Dieter Haase

Hans-Dieter Haase † February 5, 2018
06.Mar.07  12

First a note: according to Schiffhauer, Weltempfänger-Testbuch 1986/87, Siebel Verlag, the interior of the satellite 600 is identical to that of the satellite 650. I can at least confirm that for the digital part. I received a digital part from the 650 satellite from Mr. Janßen. It has the same assembly number as the digital part from my satellite 600. Both assemblies look completely identical from the outside.

I installed this assembly in my defective satellite 600. Result: LCD display works, reception only on FM and MW, no keyboard entries possible.

So I built the working LCD display into the old digital part and tried it with it. Result: Reception possible in all areas, keystrokes are not accepted, attempting a keystroke freezes the time display.

The troubleshooting that followed was extremely tedious. I didn't count the number of times I removed and reinstalled the digital part. In the end I measured a "1" signal of approx. +1.2 V at input K4 of the SAA 6006. If a button is not pressed, there must be a "0" signal there as well as at inputs K2 and K3. Even after removing the keyboard, the signal was retained and thus blocked the SAA 6006. The oscilloscope showed that the signal was a square wave with additional "blanking gaps".

Here is an excerpt from the Funkschau description of the satellite 600:

The keypad is decoded via a 3 x 8 matrix, the 8 input powers of which also work as driver lines for the LCD display (square-wave signals on the Oij lines - see LCD control). The matrix output lines go to the inputs K2, K 3, K 4 of the SAA 6006, which carry the H level when the key is pressed and thus activate the key routine.
And below:
While the key is being decoded, the LCD cannot be controlled because the Oij lines are used twice. However, in order to obtain a display, the LCD and the key decoding are controlled in time division multiplex, which can be recognized by the> flickering


The square-wave signal present at K4 was therefore possibly an LCD control signal. The keyboard input had worked with the defective LCD display (even if only with blind input). So the bug could be related to the new working LCD display.

The conductor track routing in the corresponding area was examined again. The conductor tracks for inputs K2, K3 and K4 run between the contacts for the LCD display. A short circuit at this point, caused by the display's silicone contact strips, can cause such an error.

As an experiment, the conductor track in question was insulated with a narrow strip of scotch tape. The bug was fixed. It turned out, however, that the scotch tape was still too thick and the adjacent LCD control track was no longer properly contacted by the silicone contact strip. I then applied a sufficiently thin insulating layer made of plastic insulating spray with a fine brush (2x to be on the safe side). You could also have tried to move the silicone contact strip a little sideways. But since you don't know whether to the right or left and the contact strip is also clamped between the cover frame and the light guide, I decided on this solution. With the postponement solution, conclusions might have been drawn elsewhere.

I apologize for the poor quality of the pictures, but with a maximum of 40k, despite a few attempts, it was no longer possible. If desired, I can upload them in better quality as an attachment.

Thanks again to everyone who helped me here in the forum or by email. My special thanks go to Mr. Janßen for the digital module, Mr. Langfeld for the shielding plate and Mr. Bauer for arranging the source of supply.

Hans-Dieter Haase