help for mfb 587 midrange

Bonjour Neodyne

It can be a number of things.
The amplifier, the relais or the speaker itself.

The easiest way to find the fault is exchanging
parts with a correct working 587 set.

When you have discovered what the faulty system
is we can discuss the repair in detail.

[%sig%]

thank you... I have to look at the relay and the contact of medium was in bad condition!! still thank you
neodyne, alias : www.gillesaguilera.com

I have to check the loudspeaker midrange, it is ok. I have to check the potentiométre for the power, it is ok. I have to check the relay, it is ok!! the sound leaves the loudspeaker, but it is much weaker on the midrange

Hi There Neodyne
The only thing you have to do is take out the bad C2414,C2408,C2411 and C 2204 and replace them for a new one. That will do the job for you.
Good luck.
Cheers
Wim

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Bericht bewerkt (22-11-2003 16:20)

super is to repair!!!! thank you very much!!! C 2414 IS dead

Your welcome.
Cheers
Wim

Wim,

Wederom lof in alle talen!

[%sig%]

in French,on known as: it is better a person who knows, that 100
people who seek...

thank you still

In holland we say ask a mfbfreak what the problem is, and they tell you what to do.
Wim :D:D:D

Dear All
I have a Philips 22AH587 MFB BOX the mid tone speaker is not working just like that. I am looking for a service manual. I found one in Dutch (I prefer German or English.) However it will be possible with that :
http://www.mfbfreaks.nl/pdf/mfb/587/Service587.pdf
In this threat the suggestion was to exchange these capacities:
“The only thing you have to do is take out the bad C2414,C2408,C2411 and C 2204 and replace them for a new one. That will do the job for you. “
Is my assumption right that this numbers are the numbers in the service manuals
You think that helps? Can it be that transistors will be bad too?
Sorry if the questions seem to be stupid 🙄
Please feedback to claude.vanoni@bluewin.ch
Thank You
C. Vanoni

Yes, this might do the trick.
These small Electrolyt capacitors may drop to zero and mute the amp.
I've experienced myself a non functional sqeeker due to C2204 wich has dropped in value to zero.
Another sqeeker didn't work due to a broken wire inside the sqeeker, this is also possible to fix although this one is tougher to crack

besides that, there is a known problem with the relay contacts, they will get somewhat dirty over time and the result is malfunction of the tweeter and / or sqeeker.
A ferm knock on the housing will reveal if this applies on your set as well, if the tweeter and / or sqeeker come back on then you have to clean the relay contacts or replace the relay.

Another thing is the wiring, it's wire-wrap and sometimes it will also help to solder all the wire wrap connections.
A bad wire-wrap reveals itself when you touch the wiring while the box is playing (with an opened backplane) and nasty scratcing occures.

renewal of all the small electrolyt capacitors is a good thing, and renewal of the little transistors is never a bad thing, however it is less noticeable.

Dear all
Dear Remi

Finally I started today to repair my Philips 22AH587 MFB BOX. As I have already reported the middle tone speaker was not working. I opened the box, I tested the speaker alone. It worked! Then I decided to unsolder the relay to test it. Contacts have had >80 Ohm resistance. I clean the contacts. After that, the resistance was 0 Ohm! 🙂 I reassembled the box and it worked perfect. I assume my other box will have the same problem because sometimes the bass and middle is not working. Switch off on helps then.

I like to thank that guy who provided the service manual (without that a successfull repair is impossible) and I thank Remi for the support here.
MFB is prefect sound and fun!!

Best Regards
Claude

you're welcome!
nice to hear that it turns out so well 8)