Quick Teardown: Mini VGA2HDMI Converter

With my recent upgrade to 4K monitors, I’ve come to realise that VGA has (at long last) become obsolete. There are no analog interfaces at all on my new monitors – so how am I going to connect my vintage PCs?

The solution was obvious – I’d have to get it into HDMI digital form. There is an upside to this – it would mean that it would be easy to record the video as well, using an HDMI capture card as used by streamers and gamers.

Looking for a converter was a bit challenging – the searches often yielded the wrong sort of converter (e.g. dongles going the other way). Eventually, I came across a $7 converter that was seemingly what I needed – the Mini VGA2HDMI.

But would it work? I had previously bought a converter which had such “noisy” video, I threw it out. I initially didn’t have much hope for this one …

The Item

The item came inside a folded zip-lock bag. No expense spared on packaging, as we can see.

Inside, there are three items – a very very thin USB A to mini-B cable for power, a user manual and the palm-size converter unit itself.

The manual is basic – as expected, the unit is very much “plug and play” with nothing to configure. The display modes supported are listed, including 640×480 up through to 1920×1080/1600×1200. Unfortunately, it seems to lack support for the lower resolutions (e.g. 640×400) or interlaced resolutions (720x480i/720x576i/1024×[email protected]).

The unit is encased in a white plastic shell. Inputs and outputs are clearly marked.

Power comes in on one side.

VGA input and a 3.5mm stereo socket are supplied to input video and audio to be converted to HDMI. No audio cable is included – a 3.5mm stereo male-to-male cable is required to use it.

The other side has the HDMI output. Nothing complicated about it.

Teardown

The case is of a screwless construction, which can be opened by running around the seams to unclip the internal clips.

It seems the casing is shared with other converters – the QC label covers a hole which appears to be used by a slide-switch (e.g. PAL/NTSC selector on another type of converter).

The PCB is relatively sparsely populated with all of the work being done by a Macro Silicon MS9288A with a few linear voltage regulators used to provide the necessary voltages. The IC is clocked by a 24.576Mhz crystal.

U2 is unpopulated, and I suspect, it may be a position for the EDID EEPROM. Note that there are no ferrite beads on any of the HDMI differential pairs – so I suspect they have been omitted in the name of cost saving.

The underside is free of components with mostly a solid ground plane and a few traces. It seems they were also too lazy to clip off the crystal’s legs – by leaving them in the air, they may act as antennas and “radiate” – not a good idea. The PCB also has some flux-like deposits as if it wasn’t cleaned properly.

In Use

On the whole, the unit operated as expected – plug and play. Unfortunately, the lack of support for resolutions below 640×480 results in problems with vintage computers as it becomes impossible to access the BIOS, MS-DOS or anything that uses 80×25 character mode as it outputs 720×400. Other odd resolutions used by older cards (e.g. interlaced SuperVGA, reduced resolution modes for games) are also unsupported, so it’s probably best for semi-modern vintage computers running standard 640×480 or above 4:3 or 16:9 resolutions.

At times, the image does come up a little soft as it seems it hasn’t quite synched to the VGA signal properly in terms of phase. Cycling the power causes it to re-adjust its timing which often produces a sharp picture. On the whole, the quality of the image was very acceptable with no noticeable noise bars or fuzziness when properly synchronised.

I wasn’t able to get the audio input working – possibly due to a HDMI detection issue. Capturing this directly using a separate input on an HDMI capture card or sound card may be a better option.

I also found that connecting the output from the converter into an HDMI splitter resulted in a purple bar appearing on the left side of the image. The cause is not known but may be related to signal timing. But using it with my Avermedia LiveGamer Portable was no problem provided the converter had synced.

The thin cable was a little concerning, so I swapped it out for a better one. That being said, the converter did perform just fine with the thin cable – it’s just a bit short and thin for my liking.

Conclusion

The Mini VGA2HDMI converter is an inexpensive way to bring an old VGA output into the modern “digital” HDMI world. This is useful for using modern LCD monitors lacking VGA inputs with older computers and for making higher-quality recordings of the video from vintage computers by leveraging the commonly-available HDMI capture cards intended for game recording and streaming.

The converter itself is small and conveniently powered by USB, although using the older mini-USB connector and a low-quality cable. It omits a number of RF-suppression components and has mixed build quality but seems to work as advertised.

The downsides seem to be that the video can be a little soft occasionally if the phase is not aligned, which can be remedied by cycling power to the converter. It doesn’t support resolutions below 640×480, so access to BIOS menus (720×400) and some lower resolutions used by games are not supported. It doesn’t appear that interlaced modes are supported either. I’ve also found that piping the video through an HDMI splitter can result in some purple stripes appearing on the left side.

These are, however, small downsides considering the price and the possibilities that it opens. As a result, it’s a good idea to have one of these around just in case.

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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2 Responses to Quick Teardown: Mini VGA2HDMI Converter

  1. Krzyś says:

    I’ve used something like that for interfacing some older laptop with HDMI-only TV.

    (my unit looks externally the same, but in case of such Chinese cheap stuff this means absolutely nothing. I haven’t opened it yet so I can’t say if it is similar or not.)

    Together with audio.

    You could consider yourself lucky that you hadn’t managed to use audio with this. It is terribly noisy, even on normal listening levels.

  2. Dan Gauthier says:

    I have a similar no-sound issue with a DVR and 47″ Vizio TV. I found that changing the TV away to another input, then back to HDMI brings in the sound. Also try pulling and plugging in the HDMI cable (or connect it last).

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