Teardown: Unbranded Digital LCD Satellite Finder

In a previous posting, I explored two different styles of satellite finders, as part of attempts to repair those units. I did mention that I had a third type of unit, based on a digital LCD display.

For completeness, I thought I might as well tear it apart as well, to see what’s inside.

The Unit

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As far as satellite finders go, this one is a slightly more deluxe unit. It features a monochrome backlit matrix LCD display for signal level as a percentage and as a bar graph, digital step attenuator, backlight toggle and buzzer toggle on the front panel. There is also a small compass, but it’s not very accurate or smooth – it’s not very useful at all. The satellite finder is powered from the LNB power from the receiver, just like the others.

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There doesn’t seem to be any model numbers on the label, however, the label appears very similar to the vast majority of the unbranded finders on the market. There is a hole in the rear for the beeper. The unit is held together by four Philips screws.

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The side also features a potentiometer wheel which adjusts the sensitivity within the attenuator step and controls the buzzer threshold.

Teardown

Removing the four rear screws allows the case to come apart.

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The unit itself is quite interesting. The buzzer is mounted at the rear of the casing and connected by insulated hook-up wire. The F-connectors seem to be very sturdy and are supported by a locking washer and nut to the casing to relieve the PCB of strain. It’s not a bad design.

The PCB features a fairly beefy unmarked IC, which is likely to be an ASIC. This satellite finder uses discrete inductors to filter the RF from the power lines, and the layout of the PCB is pretty neat. A 78M09 voltage regulator, 4558D opamp, and HCF4051 multiplexer is employed similar to the other digital satellite finder. The similarities are surprising.

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The other side of the PCB features four push-button switches and a small trimpot. The trimpot might be used to set contrast of the LCD display. The LCD assembly isn’t a stand-alone assembly, and instead, is a LCD glass panel with ribbon bonded to the PCB without connector to save cost. Taking this apart requires care to ensure the ribbon isn’t damaged or torn, as it’s not repairable.

That being said, the LCD panel is a general purpose graphical matrix display, which has a limited update rate, and might be found in other products as well. The backlight panel is a discrete unit and is “clipped in” behind the glass panel in the front casing.

Conclusion

The two digital satellite finders in the teardowns have surprising levels of similarities, although they are both built around unmarked ASICs. It makes the unit somewhat “black-box”. This unit does seem to be built somewhat better, although, functionally the slow LCD update and sensitive gain settings make it somewhat less easy to use. Nothing’s perfect …

About lui_gough

I'm a bit of a nut for electronics, computing, photography, radio, satellite and other technical hobbies. Click for more about me!
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3 Responses to Teardown: Unbranded Digital LCD Satellite Finder

  1. Steven Wolfe says:

    Hello Dr.Gouggh I read all your postings it’s so good to read about someone who is very noligable in the electronics field and who is so kind as to share your skills thank you so much .I have searched the internet for my cheap SF 95 dr satelite finder to help me understand why mine was working fine but the other day I went to use it and for some reason it powers up but stays on 00 and a present sign.I don’t know what’s wrong with it but I am sure it’s something you would know .If please I would like your insite on it .I am going to try to take it apart but will wait for your input.Thank you my friend for sharing your such smart knowledge.kindly Steven Wolfe.

    • lui_gough says:

      It may be because the F-connector to the cable has detached from the printed circuit board of the finder – a touch of solder may repair it, although be careful not to put any stress on the connectors. Otherwise, occasionally, they can get damaged by static electricity when plugging in/unplugging but that is very rare. They are relatively cheap, so buying another is always an option if you don’t fancy taking it apart yourself.

      – Gough

      • Steven Wolfe says:

        Thank you kindly I was waiting for your input before I took it apart.I it not shipped in a static electric bag.I am on my 11th cancer and I can not aford to buy a expensive one.Again thank you my friend it is so kind of you to give out free advice and to get back to me so quick ! Will be following all your postings.I will try what you said and get back to you my friend tks .

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