Thread: M4 sounds REALLY hit or miss....

I have been using the M4 for some time now; the major problem was interference to DAB+ and more importantly GPS reception. This is not uncommon in other supplies, it’s more common in supply’s that can run a PC with the input voltage as low as 6 or 7 volts.

I overcame the noise by designing and fitting the M4 in a special RF enclosure. In some installations there can be a slight glitch on the IGN input (on/off input) with the system in Sleep mode. I overcame that with a simple diode and cap on that line.

The M4 has operated faultlessly after that. With this PSU you need 8G cable minimum for low noise even in low power systems, preferably 4G for systems drawing over 10A (130W).

I have not had a single failure to resume from Sleep or Hibernate for months at a time. No unexpected shutdowns or glitches of any kind.

If you don’t have a problem with interference then it should work fine without any mods.

I'm running the M4 with a very similar setup to yours. I have a quad core AMD Phenom II (90w) on a micro-atx board with 8gb of ram and it's been doing just fine on it.

ahh thats what i needed to hear, thanks for the reassurance both of you. I'm gonna use you two for references later if i run into those problems. Last q, so mp3's store seems to offer the best prices on these so i'll go with them but they have two slightly different models one that has an HV at the end of it. which one would be ideal for mysetup?

HV is for vehicles with 24V - this is more towards big duty trucks, if i'm not mistaken. Ordinary vehicles will be 12V (or non HV).

fwiw my M4 is powering Zotac mini-itx + Intel E7500, 4 GB, several USB devices and 2 HDD's and it hasn't given me any issues yet.

I'm running the m4 with a intel core 2 duo, ga-ep35-ds3, 4GB RAM, 80GB HDD, Optical Drive, gforce 94xx, 10 port USB HUB (powered from molex) with GPS, Phoenix mt107a, touch screen (powered from splicing into cigarette).

I am currently getting drop outs with the HUB but I am not sure if it's an interference issue or the fact it's a cheap hub. Otherwise I have no issues with the M4 but I have purchased the M4 enclosure anyway to deal with any possible interference.

My M4 is in the SFF enclosure.

Originally Posted by elpres

I'm running the m4 with a intel core 2 duo, ga-ep35-ds3, 4GB RAM, 80GB HDD, Optical Drive, gforce 94xx, 10 port USB HUB (powered from molex) with GPS, Phoenix mt107a, touch screen (powered from splicing into cigarette).

I am currently getting drop outs with the HUB but I am not sure if it's an interference issue or the fact it's a cheap hub. Otherwise I have no issues with the M4 but I have purchased the M4 enclosure anyway to deal with any possible interference.

Hi, any problems with the HUBS will likely not be from the M4-PSU. I have around 20 USB ports at the front of the vehicle and every USB port on the MB used. Only 5 free ports (USB3 and USB2) on a USB hub under a cover in what was the old cigarette lighter / ashtray enclosure at the front of the vehicle are available for flash drives and other external media. Another 3 are available behind the centre console for future expansion if needed.

The hubs are all powered. I have had problems with some hubs running “some” USB hardware. They would suddenly disappear and reconnect at random times and this is definitely a HUB fault/incompatibility issue.

Some Hubs when externally powered “BEFORE” the PC has powered on (+5v USB has appeared from the MB) will bleed voltage back to the MB and other USB devices on the line. This can cause “SOME” USB devices to power up incorrectly and lead to strange issues with USB devices not ready or not functioning correctly.

Since selecting the correct hubs and ext power setup this system has NEVER had a single USB issue of any kind under any condition on a cold boot or resume from hibernate or sleep.

Originally Posted by Mickz

Since selecting the correct hubs and ext power setup this system has NEVER had a single USB issue of any kind under any condition on a cold boot or resume from hibernate or sleep.

What are the "correct hubs"?

Originally Posted by elpres

What are the "correct hubs"?

This was basically beg, borrow and purchase a few hubs until I found ones that worked with all the USB devices I have installed.

In the end I found the small 4 port extension repeater HUB from Jaycar with a hardwired quality 15 foot lead was one of the best for running from the trunk mounted PC to the front centre dash area. It becomes the main distribution HUB for the other HUBS and devices running at the front of the vehicle.

I was initially running another two standard 4 port hubs off this HUB with HI-DEF webcam, USB radio, keyboard, mouse, touch screen, GPS, OBD2 USB to serial convertor and two USB micro controllers with no external power to the HUB. The cable and repeater were that good; however the MB was designed to supply high current from its USB ports to allow this to work.

The HUBS I’m now using are the original 4 port repeater HUB and a 10 port HUB, both from Jaycar, and a 4 port USB-3 repeater HUB from Jaycar mounted in the ash-tray.

Now I can’t remember if the 4 port repeater HUB back-feeds from its external +5v supply, I’m sure the 10 port does, however this is of no concern to me as the +5v supply for the HUBS (all are now powered) is supplied from the +5v output rail from the M4-ATX supply, with suitable protection for accidental shorts to ground and (God forbid) the Vehicle +12v line. This +5v output to the HUBS is switched via a tiny 12v relay controlled from the M4 +12v output rail. This is to stop any USB device from feeding back into the +5v rail before the PC has started. This can sometimes happen with USB OBD2 interfaces and independently powered Microprocessor interfaces devices. By taking a few precautions everything can be made to work faultlessly. How much effort you need go to is dictated by the complexity of the installation and the Hardware you are trying to use.

These HUBS can run everything I have thrown at them.