Author Topic: Equalizer Schematic Really low output  (Read 1501 times)

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Offline miguel

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Equalizer Schematic Really low output
« on: July 21, 2016, 04:06:17 am »
So i thought i repaired a klark teknik dn360 31 Band Graphic Eq but i just tested and audio output is really low i mean mV
I replaced both input  NE5532(I/o board) , Replaced  Both 7818(psu) regulators misc caps and one of 2 DG308A(Eq Board) All of these Shorted , Now unit turns on relays click no visual Overheat
So i pluged Xlr to Rca (i have low voltage Source but it works on my receiver )adapters and put some music , before turning on audio passes through. after relay´s click audio goes to the "inside" and comes out so so dim you nedd to turn the amp to 11 to barely hear it  so i need some expert help looking at the Schematic and take a look were most likely is the problem i have no Oscilloscope to test :( 
What i think may be the problem
#1 Bad conexion inside the relays , unlikely since bowth click , channel a and b but the do get warm
#2 Maybe the TL074 is not working properly
*Tested with simple led circit , it works
I assume all NE5534 are the frequency gain stuff so i assume if they don´t work only specific band will be missing (just my assumption)
#3 Rca voltage is too low and needs Xlr input
Schematic
http://www.cultureocentre.fr/sites/default/files/fichiers/notice_eq_klark_teknik_dn360.pdf
 Thanks apreciare the help
« Last Edit: July 22, 2016, 07:07:29 am by miguel »
 

Offline singapol

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Re: Equalizer Schematic Really low output
« Reply #1 on: July 21, 2016, 08:18:48 am »
Your url is not working.Delete 2nd. line or edit the url again.

Edit:   url does not work..error 404.
   
http://www.cultureocentre.fr/sites/default/files/fichiers/notice_eq_klark_teknik_dn360.pd
« Last Edit: July 21, 2016, 09:22:48 am by singapol »
 

Offline Andy Watson

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Re: Equalizer Schematic Really low output
« Reply #2 on: July 21, 2016, 11:56:43 am »
Working link and a bit more of the story in this thread:
https://www.eevblog.com/forum/repair/need-guidance-repairing-vintage-31-band-eq/msg984448/#msg984448

i have no Oscilloscope to test
Oh :(  What equipment do you have?

Quote
   
What i think may be the problem
#1 Bad conexion inside the relays , unlikely since bowth click , channel a and b but the do get warm
It could be damaged internally. The state of those burned tracks suggests that there was enough current to melt the internal parts of the relay. Without connecting the amplifier you should be able to measure the resistance between the contacts of the relay(s) to determine proper operation.

Quote
#2 Maybe the TL074 is not working properly
I assume all NE5534 are the frequency gain stuff so i assume if they dont work only specific band will be missing (just my assumption)
Maybe! You should be able to trace sensitivity back, from the output sockets, through IC4/IC10 etc.., all the way back to the input sockets (set the frequency controls to mid position). Do you have a signal source and amplifier? (I would caution against using your precious hi-fi for this - use something cheap that you don't mind sacrificing!)
Quote
#3 Rca voltage is too low and needs Xlr input
You are aware that the XLRs have an option to use balanced input signals? Does this unit have the balancing transformers?

 
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Offline miguel

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Re: Equalizer Schematic Really low output
« Reply #3 on: July 21, 2016, 07:24:32 pm »
Working link and a bit more of the story in this thread:
https://www.eevblog.com/forum/repair/need-guidance-repairing-vintage-31-band-eq/msg984448/#msg984448

i have no Oscilloscope to test
Oh :(  What equipment do you have?

Quote
   
What i think may be the problem
#1 Bad conexion inside the relays , unlikely since bowth click , channel a and b but the do get warm
It could be damaged internally. The state of those burned tracks suggests that there was enough current to melt the internal parts of the relay. Without connecting the amplifier you should be able to measure the resistance between the contacts of the relay(s) to determine proper operation.

Quote
#2 Maybe the TL074 is not working properly
I assume all NE5534 are the frequency gain stuff so i assume if they dont work only specific band will be missing (just my assumption)
Maybe! You should be able to trace sensitivity back, from the output sockets, through IC4/IC10 etc.., all the way back to the input sockets (set the frequency controls to mid position). Do you have a signal source and amplifier? (I would caution against using your precious hi-fi for this - use something cheap that you don't mind sacrificing!)
Quote
#3 Rca voltage is too low and needs Xlr input
You are aware that the XLRs have an option to use balanced input signals? Does this unit have the balancing transformers?

Thanks for the help excuse bad url
 This unit has no input transformers
Today i decided to test both NE5523 i just bought i used a simple circuit witch turns a LED on if opamp works , bowth work , even tested TL074 and it works
 So i decide to plug my laptop in since it has more power on the line out , turns out A channel works but it does attenuate the signal buy maybe 10db not shure if normal but it sounds Ok
Update , tested today with owners audio gear not even a sound came out when ON , i was able to hear on my own but at volume 11/10
B channel Does´t witch is to be expected from the blown traces even though i replaced  , i think relay must be the problem since it does´t sound with the EQ off (pass through ) or On internal  damage must be

Regarding all NE5534 do you think they are just  the Frequency ICs?

« Last Edit: July 22, 2016, 07:10:35 am by miguel »
 

Offline miguel

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Re: Equalizer Schematic Really low output
« Reply #4 on: July 21, 2016, 07:26:35 pm »
Your url is not working.Delete 2nd. line or edit the url again.

Edit:   url does not work..error 404.
   
http://www.cultureocentre.fr/sites/default/files/fichiers/notice_eq_klark_teknik_dn360.pd
Fixed thanks
 

Offline Andy Watson

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Re: Equalizer Schematic Really low output
« Reply #5 on: July 23, 2016, 01:41:43 pm »
Regarding all NE5534 do you think they are just  the Frequency ICs?
No. Most of them process the signal. ICs 2,3 and 8,9 form the filter in conjunction with the frequency selective ICs 12 through 26.
 
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