MV-32/64 Multiviewer
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Installation
Issue 1 Rev 11
Page 26
© 2014 Snell Limited
3.8 Thermal Protection
The multiviewer and the MV-Power backup power supply units contains thermal shut down
logic and protection circuits to prevent overheating.
Backup Power Supply Unit (PSU) Thermal Protection
The backup power supply thermal protection operates under the following conditions:
75°C ±5°C (TSW1) detection is on the heatsink of power transistor
85°C ±5°C (TSW2) detection is on the heatsink of power diode
Under the above conditions the output voltage is shutdown. Recovery is automatic when the
temperature drops.
Multiviewer CPU Thermal Protection
Before the temperature in the rack reaches the PSU shutdown conditions, there are three
CPU initiated responses intended to reduce the power consumption of the rack considerably
and so slow any internal temperature rise due to abnormal cooling scenarios.
The first response depends on the temperature detected in the immediate vicinity of the CPU.
If it remains above 60ºC for more than one minute then all the scaler devices will be shut
down (video inside the tiles will disappear). An on-screen warning message will appear and
persist before this occurs (while the temperature is above 55ºC).
The second action is in response to the detected failure of three or more fans. If this persists
for more than one minute then an on-screen warning message will appear indicating the
failure. If it continues for an additional minute then the scalers are shut down to prevent the
temperature from rapidly increasing.
Finally, if 75ºC is reached in the vicinity of the CPU for more than one minute then the CPU
shuts itself down. The system cannot start itself again after this (a power recycle is required
after the conditions causing the problem have been dealt with).
If the temperatures continues to rise then the PSU's thermal shutdown protection will come
into effect.
While the multiviewer is in this thermal fault state, the front red fan LED will blink twice in one
second, remain off for another second and continue to repeat this. If the front red LED blinks
on for one second and off for one second it indicates a less severe condition; that at least one
fan has failed.
Note:
The CPU initiated thermal defence actions are in firmware versions 2.0.93 and later.
