Author Topic: FM reception lost a few moments after heated rear windows switched on  (Read 414 times)

carrera

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As title really, I had forgotted the DE Aero had this problem until an early morning start this week

https://www.saabscene.com/threads/rear-window-demister-and-fm-reception.134165/

Seems to suggest a filter has failed

Can anyone confirm this, any other experience or advice
9-5 Aero Estates, 2002 Cosmic Blue, 2003 Steel Grey, 2003 Graphite Green, 2004 9-5 Glacier Blue 2.0 saloon, 2004 Nocturne Blue 2.2 diesel estate, 2006 & 2008 Black Aero saloons

sgould

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Re: FM reception lost a few moments after heated rear windows switched on
« Reply #1 on: 20 August 2022, 04:49:34 PM »
Is this the saloon?  I assume so if the heated screen affects the radio.

Could be the filter behind the panel on the LHS, or it could be a single split in a heating element.  I've not looked behind the panels on a 9-5 for a long time, but the 9-5 saloon seems to be very similar to the 9-3 we have. 

On the 9-3 the filter is a  small bump in the earth with.  But, we had a rear screen shatter.  It was replaced and we immediately had the same problem as you have with the radio.  No FM when the heated screen is on. Well all you got was hiss...

 I have put a picture below of the replacement screen on a frosty morning. It shows one element has failed.  The screen was replaced under the fitters warranty, without the filter wire being changed, and the radio is OK again.  So check the elements.

The only difference in the screens is that the 9-5 elements are full width and the 9-3 has two vertical elements to spread the heating current for some reason. You can see that the broken element has increased the current in the remaining central elements and cleared the middle of the screen.

Also a photo of the earth filter...



« Last Edit: 20 August 2022, 08:47:36 PM by sgould »
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carrera

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Re: FM reception lost a few moments after heated rear windows switched on
« Reply #2 on: 20 August 2022, 05:30:54 PM »
 :thumbsup:

Cheers, that sort of confirms the diagnosis, with great pictures too.

Looks like I need to rob something else out of the DE shell that donated the engine for the black saloon. There's always something else left, I should get the stepper motors for the heating system while I have the tools out. It's almost a shell only, if you need anything I should have it, if only I can find it

But then again, I do think that not all the elements are working  :(
9-5 Aero Estates, 2002 Cosmic Blue, 2003 Steel Grey, 2003 Graphite Green, 2004 9-5 Glacier Blue 2.0 saloon, 2004 Nocturne Blue 2.2 diesel estate, 2006 & 2008 Black Aero saloons

carrera

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Re: FM reception lost a few moments after heated rear windows switched on
« Reply #3 on: 31 August 2022, 11:40:13 PM »
I have robbed the filter and amplifier from the donor car.

All heating elements seem to be fine, but a few cooler mornings are  needed to be sure
9-5 Aero Estates, 2002 Cosmic Blue, 2003 Steel Grey, 2003 Graphite Green, 2004 9-5 Glacier Blue 2.0 saloon, 2004 Nocturne Blue 2.2 diesel estate, 2006 & 2008 Black Aero saloons

carrera

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Re: FM reception lost a few moments after heated rear windows switched on
« Reply #4 on: 04 September 2022, 03:32:57 PM »
Found a few moments to swap the filters over this afternoon

Unfortunately, no change, though they did look different, strange considering they both came of 2006 cars

Removing the speaker grilles is a scary process, if you really don't want to damage them  ::)
9-5 Aero Estates, 2002 Cosmic Blue, 2003 Steel Grey, 2003 Graphite Green, 2004 9-5 Glacier Blue 2.0 saloon, 2004 Nocturne Blue 2.2 diesel estate, 2006 & 2008 Black Aero saloons

carrera

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Re: FM reception lost a few moments after heated rear windows switched on
« Reply #5 on: 13 November 2022, 11:05:13 AM »
A bit of progress on this today

With "twin" to compare with I could see that a resistance of 10 ohms was high, measuring across the two connection points on the HRW

It was then a matter of testing each element in turn, helped by the fact that I suspected which element may be high resistance

Element number 9 showed 1.5 ohms about 6 inches in, 6.8 ohms 8 inches in. There was no visible break, so I decided to simply get about an inch of bare wire and stick it in place with some insulating tape

Heath Robinson works, the DAB and FM signals remain in place when the HRW is switched on. The ultimate test will be in the morning when I suspect there will be heavy condensation

Then I need to figure out a permanent repair, or is the old silver paint still the best method ?
9-5 Aero Estates, 2002 Cosmic Blue, 2003 Steel Grey, 2003 Graphite Green, 2004 9-5 Glacier Blue 2.0 saloon, 2004 Nocturne Blue 2.2 diesel estate, 2006 & 2008 Black Aero saloons

carrera

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Re: FM reception lost a few moments after heated rear windows switched on
« Reply #6 on: 13 November 2022, 11:29:02 AM »
Wandering around WIS looking for radio/phone/audio information and this popped up

9-5 Aero Estates, 2002 Cosmic Blue, 2003 Steel Grey, 2003 Graphite Green, 2004 9-5 Glacier Blue 2.0 saloon, 2004 Nocturne Blue 2.2 diesel estate, 2006 & 2008 Black Aero saloons