MFB 545 - Bass driver oscillatie

Alles over onze geliefde MFB boxen in deze categorie.

Moderator: Moderators

Gebruikersavatar
markkelsall
Berichten: 29
Lid geworden op: 05 apr 2017, 18:08

11 apr 2017, 22:07

Unless you know of someone who wants to sell a pair of 545's??
Gebruikersavatar
Thomas
Site Admin
Berichten: 11843
Lid geworden op: 16 jun 2005, 14:55
Locatie: Lochem, Gelderland
Contacteer:

12 apr 2017, 07:28

I would be happy to adopt the faulty pair and sell a perfectly serviced pair instead ;)
Thomas Baur
webmaster http://www.mfbfreaks.com
De Enige Echte Philips Motional Feedback Website!
Gebruikersavatar
markkelsall
Berichten: 29
Lid geworden op: 05 apr 2017, 18:08

12 apr 2017, 21:46

HI Thomas

Thanks for the offer but I think he'll want too much for them, although Denmark is a bit closer to you than to me!

How much would you want for your 545's?

Mark
Gebruikersavatar
Thomas
Site Admin
Berichten: 11843
Lid geworden op: 16 jun 2005, 14:55
Locatie: Lochem, Gelderland
Contacteer:

14 apr 2017, 08:58

Hi Mark,

Denmark, hmm, could be interesting.

I'll send you a PB about the 545's!
Thomas Baur
webmaster http://www.mfbfreaks.com
De Enige Echte Philips Motional Feedback Website!
Gebruikersavatar
markkelsall
Berichten: 29
Lid geworden op: 05 apr 2017, 18:08

15 apr 2017, 16:32

And here is a link to a Youtube video clip of the bass oscillation

Thoughts please

Note also the LED's. Only two lit

https://youtu.be/5-sVpiFLyfE
rob040
Berichten: 518
Lid geworden op: 07 mei 2007, 12:24

16 apr 2017, 12:29

I can't play the video, since it is a private one...
Gebruikersavatar
markkelsall
Berichten: 29
Lid geworden op: 05 apr 2017, 18:08

16 apr 2017, 19:17

My mistake. Try again!

https://youtu.be/5-sVpiFLyfE
Gebruikersavatar
Thomas
Site Admin
Berichten: 11843
Lid geworden op: 16 jun 2005, 14:55
Locatie: Lochem, Gelderland
Contacteer:

17 apr 2017, 10:10

That looks a lot like the MFB sensor is generatief faulty feedback, possibly a bad BFW11 fet inside the woofer. I say possibly, there could be more causes for this problem.

About the LED's, in the video the automatic led is not working, this is a setting of the top right input dial knob. It is set to asymmetrical input and always-on situation, thus bypassing the automatic power-on circuit.
Thomas Baur
webmaster http://www.mfbfreaks.com
De Enige Echte Philips Motional Feedback Website!
Gebruikersavatar
markkelsall
Berichten: 29
Lid geworden op: 05 apr 2017, 18:08

17 apr 2017, 12:01

Thanks Thomas

I have sent you a PM.

Mark
Gebruikersavatar
David
Berichten: 5541
Lid geworden op: 05 dec 2012, 11:03
Locatie: Utrecht
Contacteer:

17 apr 2017, 13:28

I don't think it's a bass driver oscillation. It looks like an acceleration sensor issue.

There is an easy way to verify this: by disconnecting the feedback signal. The easiest way to do this is by woofer dis-assembly and then take the feedback wire off (desolder 1 signal lead).

If, when powered on, the woofer stays stable, most likely the sensor is faulty.

It could also be the input circuit on the 545 but that is less likely.

A woofer swap would be more conclusive but also more work, and after finding where the problem lies, you would need to swap the woofers back as the alignment is woofer dependant.
MFB Collectie: Aanwezig...
Overige hobby's: flipperkasten, auto's, watersport, aquaria, zendamateur
Plaats reactie