10Gtek Ethernet to Fibre Converter Teardown

Introduction
This post provides a teardown of the 10Gtek G0101-SFP Ethernet to Fibre Media Converter.

10Gtek Ethernet to Fibre Media Converter

Background
To electrically isolate Ethernet test equipment on the bench, a pair of media converters were being utilised. I wanted to know what was inside the media converters since standalone boards performing the same Ethernet to Fibre conversion were available on AliExpress for less than USD 9.

10Gtek Media Converter Nameplate

Teardown
The case of the 10Gtek converter is of two-part metal construction. Both of the case parts are held together with four screws. At one end of the metal case are two media connections (Ethernet and SFP). Status LEDs are also visible on this side. On the opposite end of the case is the DC power jack.

10Gtek SFP  Module

After removing the SFP (Small Form-factor Pluggable) Transceiver and the metal screws for the case, the metal parts slide apart then the printed circuit assembly (PCA) is visible.

10Gtek Ethernet to Fibre Media Converter PCA

The PCA sold by AliExpress look very similar to the PCA used in the 10Gtek unit. On the circuit operation, Ethernet to SFP hardware conversion is performed using a Realtek device part RTL82138.

Elsewhere on the PCA is the metal-cased SFP Transceiver connector, low dropout regulator (ASM 1117 from Monolithic Power Systems), Ethernet magnetics and 25 MHz crystal for the Realtek driver.

It shall be noted that during the disassembly of two 10Gtek units, one of the 10Gtek units contained solder balls on the PCA. Post-manufacturing QA processes commonly identify and remove solder balling.

Solder Balling on PCA

The unit draws approximately 300 mA at DC 5 V when powered. Heatsinking for the regulator was provided using the circuit board. Low Dropout Regulator (LDO) heat generation is a result of regulating the input supply voltage down to 3.3 V.

The M3 screws used for retaining the circuit board to the case appear to have oversized heads, or the circuit board footprints are undersized. The screw head's outer dimension measures 6.8 mm however, the circuit board footprint is 5.2 mm.

Mismatch of Sizes for Screws or Board Land Pattern

Additionally, a capacitor is connected between the converters DC 0 V and the case of the unit. If the case is considered Earth, then there is no dedicated external Earth connection provided on the case. The shell of the Ethernet connector is connected to the converter case

Summary
For those seeking just an Ethernet to Fibre converter, many online suppliers have PCAs available. The 10Gtek is useable as manufactured, although a PCA inspection is highly recommended. Also, by applying minor updates to the unit's power supply input, the electrical robustness of the 10Gtek unit could be strengthened.