Quote:
Originally Posted by martthie_08
Suad, thanks!
pulled one of the HD IO out of the rack today to take some pictures.
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In comparison to 192, HD I/O has PSU divided into 2 PCBAs and mainboard relocated to front panel metal plate. Fan connector and regulator are in the upper right corner of mainboard (picture attached). I can barely see even on maximum zoom, but I think fan voltage regulator is marked U6 (same as on 192) and this little blue component that is barely visible on picture I suppose is thermistor (picture attached). If your HD I/O is still out of rack, it would be good if you take some detailed pics of that part.
Here is my suggestion how to proceed:
1. Detect what are sources of heat inside device
- make HD I/O connected to HDX card and working with Pro Tools running. Put top lid on but remove screws for easy lid removal.
- after 1 hour of operation, remove top lid and touch all relevant components and mark your observation how hot are the components (rate them as cool - warm - hot - very hot). Observe converters, FPGAs, voltage regulators (especially ones with heatsink) and PSU MOSFETs and heatsinks. I suggest to turn device OFF when touching anything on PSU.
2. Make some performance measurements of the stock fan (do this at the same time while doing step 1)
- make fan voltage graph by measuring fan voltage in 1 hour period every 5 minutes (start when device is completely cool). Attached graph for 192 with stock fan and thermistor
- during 1 hour temperature testing, with lid on, observe noise and airflow from the fan hole. There is no strict procedure for that. Use your senses. I test airflow with thin piece of paper...
3. Install new fan and observe performance with stock thermistor
- install new silent fan (I use Noctua A8-FLX). Avoid fans with less than 2000RPM. Don't use PWM fans. Modify fan connector to fit HD I/O header and leave RPM wire unconnected.
- observe fan performance during 1 hour operation as in step 1 (start with device cooled down). Does fan spin during first 5 minutes of operation?
- observe temperature of hot components. Does it getting even hotter?
4. Replace thermistor if needed - if your fan does not spin fast enough and HD I/O internals get much hotter than with stock fan
- remove stock thermistor and measure it's value on room temperature (192 has 10-12K)
- try thermistors of lower value - 6.8K , 4.7K...
- repeat tests and find sweet spot with best noise/cooling ratio. Keep in mind temperatures will be higher in crowded rack with limited airflow.
For 192 with Noctua A8-FLX I use 4.7K thermistor.
Cheers!
S