Quad fm4 signal strength

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23-Sep-2018 04:04 PM

Willy Van Win

Willy Van Win

Posts: 12

Hello, i have a FM4 with a not working signal strenght.

just the 2 lower grids are illuminated. Had desoldered N3 driver but have not taken attention how it was placed. on the N3 itself is no marking. on the pcb there is a marking with 1.

The N3 has a flat side and a side where you can see the smd components. Does anybody know  which side for pin 1 ?

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24-Sep-2018 03:54 AM

EJP

EJP

Posts: 1525

The component side goes to the rear of the tuner.

If you think the signal meter is showing under par you can adjust it via RV7, if you have it, but this is really best left to a professional tuner aligner.

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24-Sep-2018 01:52 PM

Willy Van Win

Willy Van Win

Posts: 12

FM4 was delivered at me faulty. No display.

When checking there was a faulty IC22 ( no 20Mhz ). After replacing ic22 i had a working display but no tuning. Seems IC9 was defect. Replacing ic9 solved the tuning. Tuner is working now, but signal strength is not working. Because ic9 drives N3, i suppose N3 is defect or the display itself has broken segments. I have only one bar left and right for the signal strength, i could turn off with RV7 the one bar but can not get moere than one bar. Is N3 still available ? Any suggestions ?

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25-Sep-2018 02:42 AM

EJP

EJP

Posts: 1525

You can probably get N3 from Quad but I suggest it is the display itself, which you can't. It isn't at all likely that 9 transistors or resistors have failed. You might check its tracks. You might also check that there really is 30V at pin 13.
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25-Sep-2018 04:04 PM

Willy Van Win

Willy Van Win

Posts: 12

I will replace the display and let you know.

I have a good spare one. On the other hand i had mounted the N3 the wrong side first. I had looked at some photos on the internet and thought the component side was at the front.

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