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TOPIC: PROBLEM WITH FAN CONTROL

PROBLEM WITH FAN CONTROL 28 Dec 2020 23:22 #1

  • ea3in
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I am using pins 3 and 14 to feed the fan

The fan works if I feed it directly from a 12v power supply
When enabling Ext Ctrl I can measure 0.5V at pins 3 and 14 against gnd
Is it correct?
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PROBLEM WITH FAN CONTROL 29 Dec 2020 06:19 #2

  • Rome
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ExtCtrl has pins with the open collector, which are controlled by ULN2003A, you can check its working current in the datasheet.
Did you enable a Thermostat checkbox on the ExtCtrl tab in ESDR2?

Probably you have damaged a ULN chip.
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PROBLEM WITH FAN CONTROL 29 Dec 2020 08:45 #3

  • ea3in
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Than you Rome

The radio was new from the box. No possible damage before this first attempt to control the fan
Maybe I am not measuring what I have to measure (I am using a multimeter betwen 3 & 14 to the chassis
How can I check the othe pins?

If it is damaged, what can I do?


PA keying is working fine
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PROBLEM WITH FAN CONTROL 29 Dec 2020 13:50 #4

  • Rome
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You are doing the check the right way.
Did you enable the Thermostat checkbox?
Do you have a voltage between 14 and 15 pins? You should have a supply voltage there. If not, then most likely the fuse was damaged.

ULN chip can be damaged by a short circuit, it can happen even during the first try.
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PROBLEM WITH FAN CONTROL 29 Dec 2020 16:58 #5

  • ea3in
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Hello

Yes, Thermostat is enabled

Voltage between pins 14 and 15 is zero or 0.5 V.
Can the fuse be replaced if this is the problem?
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