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irishron40
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Joined: 22/09/2014
Location: Ireland
Posts: 254

Posted: 08:54pm 24 Oct 2023

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hi Can someone tell me the correct way to test a TL084 with a multi meter.
I wanna rule out a faulty one.

thank you. ron

irishron40
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Joined: 22/09/2014
Location: Ireland
Posts: 254

Posted: 09:18pm 24 Oct 2023

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am I correct in saying this?

using the ohm function for testing a TL084cn on my multi meter

pin 1 and pin 14 should have reading either way
pin 2 and pin 13 should not have reading either way
pin 3 and pin 12 should have reading either way
pin 4 and pin 11 should not have reading either way
pin 5 and pin 10 should not have reading either way
pin 6 and pin 9 should not have reading either way
pin 7 and pin 8 should have reading either way

ron

phil99

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Joined: 11/02/2018
Location: Australia
Posts: 2415

Posted: 09:32pm 24 Oct 2023

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For a breadboard test of any op-amp connect one input to a voltage divider (2 x 10k resistors in series to V+ ang Gnd.). The other input is connected to the wiper of a pot (10k to 100k) with the outer legs to V+ ang Gnd.
As you turn the pot slowly from one end to the other the op-amp output should abruptly switch from high to low or vice-versa as you pass through the mid point.

In-circuit testing depends on what the circuit is. Post a circuit diagram and description of what it is supposed to do.

Edit
The breadboard test needs to be done for each of the 4 op-amps in the package.
Edited 2023-10-25 07:43 by phil99

irishron40
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Joined: 22/09/2014
Location: Ireland
Posts: 254

Posted: 09:48pm 24 Oct 2023

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this is the charge controller circuit

its not switching the relay when adjusting the pots on the circuit board so I suspect the tl084 to be faulty

https://www.thebackshed.com/windmill/articles/TL084-Controller.asp

ron

phil99

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Joined: 11/02/2018
Location: Australia
Posts: 2415

Posted: 11:34pm 24 Oct 2023

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Voltages to record.

Output of regulator should be 8V +/- 0.4

With the battery supply set to 13.9V pins 3 and 6 should be about 3.3V

Adjust Low-V pot for the same voltage at the wiper as pin 6 then measure pin 7 while turning the pot back and forth a little either side of that spot. It should switch between 0V and 8V as you do that.

Adjust High-V pot for the same voltage at the wiper as pin 3 then measure pin 1 while turning the pot back and forth a little. It should switch between 0V and 8V as you do that.

Pin 13 should be 4V.

Adjust Low-V pot for 0V at pin 9 and adjust High-V pot for 8V at pin 10, the Dump-On LED should light and pins 12 and 14 should be 8V.

The transistor should have 0.6V on the base and 0.2V on the collector and the relay should now be on.
Edited 2023-10-25 10:13 by phil99

phil99

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Joined: 11/02/2018
Location: Australia
Posts: 2415

Posted: 03:41am 25 Oct 2023

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Multi-meter resistance measurements that you should get in circuit +/-10%. (no power)

IC Pins Result
6 - 3 0 ohms
7 - 9 0 ohms
8 - 12 0 ohms
3 - 11 3.3k - Black lead to 11 (Bat. negative)
6 - 11 3.3k
10 - 11 100k
8 - 11 110k
12 - 11 110k
13 - 11 4.6k
14 - 11 3.2k
5 - 11 8k to 18k varies with Low-V pot
3 - 11 8k to 18k varies with High-V pot
1 - 10 0.6V Diode range, Red to 1 Black to 10
Edited 2023-10-25 22:27 by phil99

irishron40
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Joined: 22/09/2014
Location: Ireland
Posts: 254

Posted: 07:24am 26 Oct 2023

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thank you all . some advise I can work with. thx

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