REL Q150E mk2 very light hum - diyAudio
Go Back   Home > Forums > Loudspeakers > Subwoofers

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 14th May 2013, 10:39 AM   #1
diyAudio Member
 
Join Date: Nov 2009
Location: UK, Manchester
Default REL Q150E mk2 very light hum

cheers!

got it faulty and repaired (one of the 4 mosfets was out along with 2 fuses). Now it works fine, though some very light buzzing/ hum is still there. It's not audible, only if in some 10-20cm from the sub and could be felt with hand.

1. It's there with no RCA or Neutrik cable connected.
2. If I short the RCA socket it's still there.
3. Connecting with no Earth or switching it off on the sub does not affect on the hum.
4. Same hum was there when I connect another speaker.
5. It's about 48vdc on the PS caps. Tried to connect the scope and it was 100mv p2p offset, is that fine?

Any ideas what's wrong here? I have a second sub (Quake) and it's dead quite.
Should I try to swap the main ps caps (2x 6800uf)?
Attached Images
File Type: jpg IMG_1051.JPG (498.8 KB, 118 views)
File Type: jpg IMG_1052.JPG (516.9 KB, 109 views)
File Type: jpg IMG_1047.JPG (786.3 KB, 103 views)
File Type: jpg IMG_1042.JPG (786.6 KB, 100 views)
  Reply With Quote
Old 14th May 2013, 04:32 PM   #2
diyAudio Member
 
Inductor's Avatar
 
Join Date: Feb 2006
Location: Cascais
Look at the related links. Keep us posted.
the dreaded Boston acoustic VR2000 sub woofer hum
Definitive amp and sub blown
__________________
NEXT-proaudio Portugal
  Reply With Quote
Old 17th May 2013, 12:29 PM   #3
diyAudio Member
 
Inductor's Avatar
 
Join Date: Feb 2006
Location: Cascais
This was a note from Bose Panaray sound system 502 array bass box and controller (Service manual and bulletins):
Quote:
402, 502, 802 II Controllers
Power Supply Noise
Units Manufactured before 4/96

Symptom: Noise or hum from outputs.

Reason: The transformer could be causing the problem.

Solution: Replace transformer with new type.

If a customer returns a unit for service because of a problem with noise or hum replace the transformer with part number 180128-1 (100V/ 115V) 180128-2 (220V/ 240V). This service
bulletin supersedes service bulletin 181472.
__________________
NEXT-proaudio Portugal
  Reply With Quote
Old 24th May 2013, 01:02 PM   #4
diyAudio Member
 
Join Date: Nov 2009
Location: UK, Manchester
thanks for the clue!

unfortunately I don't have any similar spare 2x36vac toroid.
The one I have is 2x18vac 100VA, I wonder if I could use it just for a test?!
  Reply With Quote
Old 4th June 2013, 05:14 AM   #5
diyAudio Member
 
Join Date: Nov 2009
Location: UK, Manchester
cheers!
tried the following with no luck:

1. Swapped the toroid to 2x33VAC 1.2A, same hum.
2. Removed 2 x 6800uf caps and put temporary 2 Nichicons KG 470uf (the only 50v I had), same hum there...
3. Removed the amp board from the back panel to clarify if that is related to grounding or add any noise/ hum and still the hum was there. Magic

looks like the problem is somewhere else...
One thing I didn't mention is that IRFP9240 I've replaced is not matched with other 3 mosfets and shows different voltage across the power resistor, however I doubt this could affect on any buzzing noise?!
  Reply With Quote
Old 6th June 2013, 03:49 PM   #6
jlithen is offline jlithen  Finland
diyAudio Member
 
Join Date: Nov 2009
Location: Vaasa
Anybody have a service manual for this one?

I have the same one with same symptoms on my table.

Turn on pop can maybe not be avoided with this simple relayfree design, but the slight crackle is certainly something extra.

Somebody tried to repair it before me and replaced a handful of caps.
He said they had leaked. Not sure if it is true. Caps don't leak easily in linear applications.

I am a bit surprised that there is no auto-on and the manufacturer states in the manual how safe it is to have it turned on all the time.
I unplug 90% of my things when I leave my home and I have good insurance

Hope we find a solution together!
  Reply With Quote
Old 6th June 2013, 09:13 PM   #7
ReTrO is online now ReTrO  England
diyAudio Member
 
ReTrO's Avatar
 
Join Date: Dec 2003
Location: High Wycombe, Bucks, UK
Isn't the Q150 a BK Electronics build? They should be able to help you out if it is.
__________________
Richard Wilson
  Reply With Quote
Old 7th June 2013, 09:47 AM   #8
diyAudio Member
 
Join Date: Nov 2009
Location: UK, Manchester
well I haven't found any service manual for REL subs at all unfortunately.
yee, I replaced all elkos as well, unfortunately that didn't affect on anything at all.

ReTro
it doesn't look like BK inside, perhaps you know the model?
  Reply With Quote
Old 13th June 2013, 07:22 AM   #9
diyAudio Member
 
Join Date: Nov 2009
Location: UK, Manchester
Quote:
Originally Posted by Inductor View Post
as it was mentioned, it was some issue with voltage regulator there, so i've tried to find out something relevant in my Q150. It turned out that without any manual or circuit it's nearly impossible to determine smd chips. There are 3x ZVY415 that act like some pre regulation stage I suppose, but I couldn't find anything similar in the web at all. Same thing is with transistors that are most likely used for regulation - DH S48.

One thing I noticed is that if I touch the axle of frequency pot (Rolloff), it starts to hum much louder. Could the problem be here
Attached Images
File Type: jpg IMG_1317.jpg (726.8 KB, 51 views)
  Reply With Quote
Old 14th June 2013, 07:07 AM   #10
jlithen is offline jlithen  Finland
diyAudio Member
 
Join Date: Nov 2009
Location: Vaasa
Are you sure those 14-pin chips are not LM324 Opamps?

The others I could not find either.

I was going to separate crossover and poweramp to see which one is actually fried. But without the schematic it was not obvious to me how to do it

The power FETs might get "hissy" and "poppy" if they have run hot, so I was thinking about replacing them too. But it is a slim chance and I am getting really tired of this cheap crappy amp module

Anyway my friend is willing to spend up to 200euros on the sub to get it working, so I ordered a D-class board with crossover from ebay.

I know it will mean buying a suitable transformer for more than 50euros too, but I think it will be below specified budget.

This should give about 150W rms, instead of the factory amp which gives max half of that
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
REL Q-Bass Sub JannaCassandra Subwoofers 0 26th May 2011 03:28 PM
Loud buzz/hum on my Technics SL-1400 MK2 with Shure VT15 type IV running type III sty ufotrekker Analogue Source 3 25th February 2011 09:40 AM
Improved PSU for Technics SL1210 MK2 and SP 10 MK2 (and others) beetle Analogue Source 21 19th January 2010 11:25 PM
Amp emits deafening hum when I switch the kitchen light off! rwtomkins Solid State 8 7th September 2008 03:59 PM
rel sub's Cheap Shot Multi-Way 8 23rd July 2004 03:46 AM


New To Site? Need Help?

All times are GMT. The time now is 04:27 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2