Help with hardware info /schematic for fan cooling?

[Vox]

Greetings to all for 2026!

I've had my HDR-FOX T2 for years, its sat under 3 generations of T.V and had 3 hard drive swaps with no issues. For a few months now I've noticed at about 22.00 hrs each evening I can no longer select MHEG text. First thought was it had been abandoned by the BBC. I put up with this switch off at about the same time until my partner said text services worked on another T.V. Here's my story:

I powered the Humax box off and on and text services were restored. I started thinking software glitch, need firmware update etc until it also ocurred to me these boxes have a cooling fan. I removed the box and the case was quite warm with no sign of the fan running? I'm on to something now. The 22.00 Hrs nightly loss of text service ocurred after the box had been running 4-5 hours for evening T.V viewing.

The fan is 12V on a 3 pin connector and I suspect they are using PWM speed control? I have no schematics and there's a risk I could kill the box by poking about. I tested the fan on a bench supply and it ran silently at reduced voltage. Since the box electronics seem to have survived without a fan for months, I considered a fan running continuously at reduced voltage was better than nothing. After testing voltages on SMD electrolytic caps I found one near the fan connector that provided 5 volts during power on and zero in standby. My fan is now wired to that cap and runs silently at 5 volts. For an intake room temperature of 19.5 deg.C, the fan exhaust temperature is 38 deg.C. and the cover lid is cool.

I don't like taking chances with circuit hacks working in the dark when I don't know the circuit configuration. If anybody has a circuit schematic or link for the fan control, I would revisit the fault. In the past people have complained the FOX-T2 fan was noisy. These are small 12V fans and running mine at 5V continuously for power on is a simple solution if it provides sufficient airflow. The fan is cheap and easily replaced if its life is reduced. I couldn't find a thermistor on the board, unless they are using their CPU core temperatures to control it?

 

[MymsMan]

No hardware changes needed.

If you install the customised firmware you can also install the fan package and specify how fast you want the fan to run avoiding the the standard humax setting of only starting the fan when the HDD temperature reaches 55C

 

[Black Hole]

In addition to the above: HDR-FOX Hardware: Commissioning, Disassembly, Repair (which is pinned near the top of the HDR-FOX section of the forum [ie this section] and, frankly, should not have escaped your attention!).

 

[Andybrody]

The fan is 12V on a 3 pin connector and I suspect they are using PWM speed control? I have no schematics and there's a risk I could kill the box by poking about. I tested the fan on a bench supply and it ran silently at reduced voltage. Since the box electronics seem to have survived without a fan for months, I considered a fan running continuously at reduced voltage was better than nothing. After testing voltages on SMD electrolytic caps I found one near the fan connector that provided 5 volts during power on and zero in standby. My fan is now wired to that cap and runs silently at 5 volts. For an intake room temperature of 19.5 deg.C, the fan exhaust temperature is 38 deg.C. and the cover lid is cool.

I don't like taking chances with circuit hacks working in the dark when I don't know the circuit configuration. If anybody has a circuit schematic or link for the fan control, I would revisit the fault. In the past people have complained the FOX-T2 fan was noisy. These are small 12V fans and running mine at 5V continuously for power on is a simple solution if it provides sufficient airflow. The fan is cheap and easily replaced if its life is reduced. I couldn't find a thermistor on the board, unless they are using their CPU core temperatures to control it?

Hi Vox,
I have just laid my hands on a HDR that has not been used for approx. 18 months (dates on recordings on HDD) have just found out after loading custom firmware (fan package) that the fan is not working at all. The fan is fine in another working unit so it appears that there is a power fault on the unit.
Did you find a source for a schematic.
Can you tell me which capacitor that has 5 Volt when on and zero in standby.
Was there any capacitors with 12 Volt or 9 Volt when on and zero in standby.
Any help you can advise would be greatly appreciated.

 

[Black Hole]

I couldn't find a thermistor on the board, unless they are using their CPU core temperatures to control it?

To answer this, the only source of on-board temperature data is the HDD diagnostics.

Can you tell me which capacitor that has 5 Volt when on and zero in standby.
Was there any capacitors with 12 Volt or 9 Volt when on and zero in standby.
Any help you can advise would be greatly appreciated.

I have done some work on this in the past, and there are unused internal USB points on the PCB.

 

[Vox]

Hi Vox,
I have just laid my hands on a HDR that has not been used for approx. 18 months (dates on recordings on HDD) have just found out after loading custom firmware (fan package) that the fan is not working at all. The fan is fine in another working unit so it appears that there is a power fault on the unit.
Did you find a source for a schematic.
Can you tell me which capacitor that has 5 Volt when on and zero in standby.
Was there any capacitors with 12 Volt or 9 Volt when on and zero in standby.
Any help you can advise would be greatly appreciated.

Where software and hardware designs need specific information I do not have I'll use other methods. Logic says it's just a standard type 12V fan in either 2, 3, or 4 wire versions. I may be wrong about this 3 wire being PWM controlled (as is the case for 4 wire cpu fans) and the third wire could just the tacho sensing the fan is running? Simple logic says disconnect the fan from whatever was controlling it and as long as its rotation isn't being sensed to trigger a shutdown warning, connect it to a voltage source available on the board. The ducting for this fan is designed to pull air over the hard drive and at the side from the pcb chips. Since many including myself are probably using newer 'Green' video streaming hard drives, their power consumption is less than older drives that used to be fitted which reduces cooling demand on the fan. That just leaves the main board chips to cool.

Working in the dark without engineer level documentation you can find +12V and +5V power sources on the the power supply connector but I've not found 9V. The board seems to use a common ground plane as 0V. If you want 9V try a cheap adjustable d.c-dc switchmode buck converter on the +12V rail, the fan only takes about 15mA at 5V and 35-40 ish at 12V. Although for such low fan current you could probably use a series resistor rated for the wattage and fixed to the chassis if it gets warm. Ideally you need a voltage source that powers on and off from standby to on, so the fan only runs continuously when the box comes out of standby. I'm not bothered running the fan in standby because circuits are in low power sleep mode and it would just clock up fan hours. Standby to on function seems to be done on the main board not the power supply and that's what I found probing various capacitors. I'll upload a photo next time the cover is off. Until then it's in use and upsets my household when I take it out! I would like a schematic diagram just to confirm the capacitor my fan is now tagged on to. I know it's not on a signal rail because its voltage is held steady both on and off fan load but I don't know what device is switching the line from standby to on and what current it can take?

There are no engineer level schematic drawings or parts lists in the link added by Black Hole but the info. is useful if you just want to dissassemble and replace modules, which is what most shop repairers do these days. I attempt repairs at board level using SMD work station repair kit if I have supporting information and data to do it.

Andybrody makes an important point. I've never checked the fan operation after firmware mods. but I suspect my unit with its lower power HDD has been working without its fan for a very long time. It's quite hard to see the fan rotating. I painted one of the blade surfaces with a white correction pin and can now see it through the case. Whatever purists think about my hack, a cooling fan that's always going to work independently of critical on board circuitry is a better reliable option. If the fan seizes after 3-4 years it's cheap and easy to replace.

It may be imagination but I think the box selection and scrolling functions are quicker now it has cooling, which may be because it's cpu is cooler and not auto speed throttling at higher core temperatures if that feature is enabled?

Thanks for replies.

 

[Black Hole]

The thread I referred you to tells you how to test a fan. We have no published schematics so everything that's been done so far is by reverse engineering. I was working on a CPU fan add-on but that went by the wayside – there's no easy way for a non-engineer to pick up the existing fan power for it. If you look hard enough you'll find a discussion about it, several of my units are retrofitted. The obvious pick-up point for non-PWM 12V or 5V is the HDD power.

As for whether the unit runs faster, indeed it could be that there is throttling. Also the performance is critical on the HDD responsiveness.

There's no point getting shirty, everything we know is already on the forum for you to find (and you seem to be trying to reinvent the wheel).