Railway GPS module made by a Polish company - construction and interior

I got a bit of 'railway' equipment after liquidation, the whole thing rather qualifies as scrap, but you can still take a look inside and satisfy your curiosity. The case is all the more interesting as the item presented here appears to be our domestic product.

The module shown here is unlikely to count as retro electronics, dating from 2011, but it is still worth examining. On the side of the case it has an RS422 port (i.e. a variant of RS232), an NMEA (GPS message standard) and an antenna connector. I don't see a power port - my bet is that it's in the plug from RS422.

Let's take a look inside.


The board is a two-layer board, mainly surface-mounted, although a few through-hole components can also be found on it. Immediately striking is the section with the GPS module, where you can see a lot of vias, probably to reduce interference.
However, let's start with the power supply section. The first capacitor is at 50 V, the second at 16 V. I also see an inductor - could it be an inverter?

Yes, you can see it on the other side of the PCB:

This is the MC34063, a fairly popular and versatile chip. Here it works in a voltage-decreasing role and I think it controls the BCP53 transistor, which means we have it in a version with an external keying transistor.

We look further down the line. The main MCU is probably the H8/36057F - a 16-bit microcontroller made by Renesas with 56 KB of Flash and 3 KB of RAM.

Right next to it you can see a 1.8432 MHz quartz resonator, two 24C04WP EEPROM bones and the chips responsible for communications, SP3491EN (RS-485/RS-422 transceiver) and TJA1040 (CAN transceiver).

The GPS module itself is a TIM-4H-0-000 made by uBlox, although I can also see the logo of the then Atmel (later acquired by Microchip) there - probably from the chip? Right next to it I see a 74HC14D (HEX type inverter with Schmitt flipper inputs), perhaps for matching logic levels of signals.

There is also an RS232 connector in the area, which is not brought out to the chassis. Could it be for service?

There is still the bottom of the PCB left. Next to the MCU we have a 3.3 V LDO there, power supply is known:

And also at the service connector section we have ST232C, which is a TTL to RS232 level converter. It would probably be possible to communicate with a simple USB to UART converter, if soldered into its corresponding legs.

For the test, I powered the device from a laboratory power supply:

The 7-segment display counts down the digits and then displays the letter P. The 5 V LED is on and the GPS LED is flashing. There is the correct voltage after the step-down converter:


In summary , the module looks to be in working order, I don't know what happened to the casing on this scrap that it got so crushed. The PCB is not damaged at all. The module responds to voltage, counts down (?) and lights up the diodes. One could go one step further and try to communicate with it via RS232, but I don't have a converter at the moment, and I also don't know if it sends data itself. With this NMEA you could try, although this is not likely to be TTL level either, a brief voltage measurement on one of the pins shows negative values.
The module itself has subtitles in Polish, m. in. SIMS 03/2009 SGPSD4 LUTTING PAGE, which suggests that it was designed in our country, looking at the company it would also agree.
That's it for now, if anyone has any documentation for it or specifics on where to receive at least this NMEA stream then I can plug it in and give it a try, if not then the board will wait for some free long weekend.
It would be useful to connect an antenna and see if it catches a signal.

PS: How do I know it's "railway" equipment? This is information from a parts source - unverified.