Equalizer Schematic Really low  output  - Page 1
Forum section: electronics / repair

author: miguel
author_rank: Newbie
timestamp: July 21, 2016, 04:06:17 am
content: 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 mVI 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 OverheatSo 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 testWhat 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 worksI assume allNE5534are 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 inputSchematichttp://www.cultureocentre.fr/sites/default/files/fichiers/notice_eq_klark_teknik_dn360.pdfThanks apreciare the help

author: singapol
author_rank: Frequent Contributor
timestamp: July 21, 2016, 08:18:48 am
content: 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

author: Andy Watson
author_rank: Super Contributor
timestamp: July 21, 2016, 11:56:43 am
content: 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/#msg984448Quote from: miguel on July 21, 2016, 04:06:17 amOhWhat equipment do you have?QuoteIt 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.QuoteMaybe! 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!)QuoteYou are aware that the XLRs have an option to use balanced input signals? Does this unit have the balancing transformers?

author: miguel
author_rank: Newbie
timestamp: July 21, 2016, 07:24:32 pm
content: Quote from: Andy Watson on July 21, 2016, 11:56:43 amThanks for the help excuse bad urlThis unit has no input transformersToday 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 worksSo 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 OkUpdate , 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 11/10B 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 beRegarding all NE5534 do you think they are just the Frequency ICs?

author: miguel
author_rank: Newbie
timestamp: July 21, 2016, 07:26:35 pm
content: Quote from: singapol on July 21, 2016, 08:18:48 amFixed thanks

author: Andy Watson
author_rank: Super Contributor
timestamp: July 23, 2016, 01:41:43 pm
content: Quote from: miguel on July 21, 2016, 07:24:32 pmNo. 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.