Author Archives: Mikko

Repairing the Marconi 2955A (part 2)

After removing the CRT and associated drive electronics, I am now focusing on recovering the video signal using a modern microcontroller. Therefore I have taken some waveforms captures from the three associated signal lines; field sync, line sync and video.

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Repairing the Marconi 2955A (part 1)

As I mentioned in my previous blog post, I purchased a malfunctioning Marconi Instruments 2955A Radio Communications Test Set in the spring. During the summer I tried to start it, but nothing much happened. Random LEDs flashed, relays clicked and … Continue reading

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NMT-450 project, part 4: new test gear

Another year has passed and not much has happened in the development side of things. I have purchased some test gear though. For very small price (100 euros) I bought a (malfunctioning) Marconi 2955A along with the NMT add-on device.

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NMT-450 project, part 3: Some silicon and practically no progress

Nothing much has happened in the past half a year. I am having a hard time finding contiguous stretches of time to devote to this project. I have had some international interest. Mainly from countries where NMT has been relevant. … Continue reading

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NMT-450 project, part 2: FM and LO design work

I have started the project from the ground-up; learning the basics behind all the key systems. The control signalling is pretty straight-forward. You have commands that are prefixed with sync bytes and suffixed by checksums. Nothing special.

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NMT-450 BS/MTX project, part 1

Introduction A few months ago I developed an interest in radio frequency communications. Before that, it has mostly been a complete mystery to me. I read about the subject and figured out basic concepts such as super heterodyning, frequency modulation … Continue reading

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Samsung CLX-3175 DEVE HOME SENSOR ERROR Fix

If you have this type of Samsung color laser MFD, you might have run into this issue. You try to print or copy a page and after a while, the printing stops and you see “DEVE HOME SENSOR ERROR” on … Continue reading

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I²C troubleshooting

Sometimes you might run into a situation when one or more of your I2C devices don’t work. I deal with barometric pressure sensors in my work and these work on the I2C bus. I’ve been banging my head against the … Continue reading

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What happens when a V-groove hits your copper pour

When you design PCBs for work, cost-effectiveness is a big factor. To help you out in the that department, you usually design your board to be a big panel. This panel is then CNC routed to contain a V-groove. This … Continue reading

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I²C Address Probe for PICs (CCS compiler)

As a part of my work, I wrote this simple I2C address probe. It’s for PIC microcontrollers, using CCS compiler. (It’s here mostly as a note for myself, but you might find it useful as well.)

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