Problems with amplifier MX50 SE - diyAudio
Go Back   Home > Forums > Amplifiers > Solid State

Solid State Talk all about solid state amplification.

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 5th May 2013, 03:20 PM   #1
diyAudio Member
 
Join Date: May 2013
Default Problems with amplifier MX50 SE

Hi
I bought two plates of this amplifier (ebay chine)
I've ridden and I've fed AC35+35 (DC50+50)
I have been burned when ignition resistance.
Turn repidamente.

I have not tried the other channel because I have fear of burning.

As I can find the problem.
Thank you.
Attached Images
File Type: jpg DSC_0180.jpg (505.8 KB, 342 views)
File Type: jpg DSC_0181.jpg (543.7 KB, 323 views)
File Type: jpg DSC_0182.jpg (407.4 KB, 306 views)
File Type: jpg DSC_0184.jpg (432.0 KB, 286 views)
File Type: jpg DSC_0186.jpg (519.0 KB, 281 views)
  Reply With Quote
Old 5th May 2013, 07:19 PM   #2
djk is offline djk
diyAudio Member
 
djk's Avatar
 
Join Date: Feb 2001
Location: USA
Post the schematic link, and identify the reference number of the burnt resistor please.
__________________
Candidates for the Darwin Award should not read this author.
  Reply With Quote
Old 5th May 2013, 08:57 PM   #3
diyAudio Member
 
Join Date: May 2013
burned resistance is 68 ohom

attachment scheme

Thanks
Attached Images
File Type: jpg Esquema01.jpg (154.6 KB, 213 views)
  Reply With Quote
Old 7th May 2013, 01:48 AM   #4
djk is offline djk
diyAudio Member
 
djk's Avatar
 
Join Date: Feb 2001
Location: USA
There are more than one 68Ω resistors, which one (use the reference designator on the schematic please).
__________________
Candidates for the Darwin Award should not read this author.
  Reply With Quote
Old 7th May 2013, 03:24 AM   #5
diyAudio Member
 
Join Date: Apr 2010
Location: Coffs Harbour
The resistor is probably R25 (closest to R23 and the PNP driver). The OP may be having a similar problem with the schematic as anyone else trying to follow it. It is bogus - I'd say intentionally, to foil copyists, as it specifies darlington drivers but the fitted transistors are apparently the Chinese versions of 2SD669/2SB649. Further, the part numbers are not reproduced on the overlay. There likely will be more errors to ensure failures if building from scratch using that version of the schematic.
__________________
Ian

Last edited by Ian Finch; 7th May 2013 at 03:39 AM.
  Reply With Quote
Old 7th May 2013, 08:59 AM   #6
djk is offline djk
diyAudio Member
 
djk's Avatar
 
Join Date: Feb 2001
Location: USA
Are those 669/649 full-pack? Or are they missing their insulators, I can't tell.

He has the C12 100F cap in backwards, the resistor is probably R29. Cap shorted, resistor burned.

http://www.ebay.com/itm/LJM-MX50-SE-...-/230909190448
__________________
Candidates for the Darwin Award should not read this author.

Last edited by djk; 7th May 2013 at 09:15 AM.
  Reply With Quote
Old 7th May 2013, 09:31 AM   #7
djk is offline djk
diyAudio Member
 
djk's Avatar
 
Join Date: Feb 2001
Location: USA
LJM MX50 SE 100W 100W Power Amp Kit Stero Amplifier Kit DIY | eBay
__________________
Candidates for the Darwin Award should not read this author.
  Reply With Quote
Old 11th May 2013, 04:39 PM   #8
diyAudio Member
 
Join Date: May 2013
Quote:
Originally Posted by djk View Post
Are those 669/649 full-pack? Or are they missing their insulators, I can't tell.

He has the C12 100F cap in backwards, the resistor is probably R29. Cap shorted, resistor burned.

LJM MX50 SE 100W 100W Power Amp Kit Stero Amplifier Kit DIY | eBay
You're right.
It was a mistake of mine.

I solder a capacitor backwards.

Thank you all.
Attached Images
File Type: jpg DSC_0201.jpg (542.0 KB, 186 views)
  Reply With Quote
Old 20th May 2013, 05:56 AM   #9
diyAudio Member
 
augustoriodosul's Avatar
 
Join Date: Jan 2011
Hi all,

I found it interesting parts welded far from the pcb, this should cause some loss in signal quality. I've assemble some of these MX50-SE but with SANKEN transistors - 2SA1186 Ft 60 MHZ and 2SC2837 Ft 70 MHz.The result is great mids and highs in a multi-amplified system. A simple amplifier, but it looks very good. Some pics in https://www.facebook.com/augustojose.hoffmann
  Reply With Quote
Old 20th May 2013, 02:56 PM   #10
diyAudio Member
 
Join Date: May 2013
I've installed everything and have already exploited the two channels of amplification.
I've ridden with NE5532 preamp.
Have coupled the midpoints of the two transformers at the output of toroidal coils.
First you burn an amplifier and then the other amplifier.
Before turning to audio cocnector touch several times to prove that it worked, and then burned.
The preamp volume was the maximum.
The toroid is in AC-DC-35 +35 50 +50.
The smaller toroidal AC-12 +12

That problem could happen?
Problems before the amplifier output directly to the PC and sounded good. Warmed much heat sinks but not burned. (Only burn the filter upside down )
Attached Images
File Type: jpg Esquema Union Transformadores.jpg (166.6 KB, 129 views)
  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
LJM MX50 kit amp augustoriodosul Solid State 151 18th December 2014 09:18 PM
MX50 LAST VERSION - probably the best Stee Solid State 7 12th March 2014 08:15 AM
Still have voltage problems with Simple SE BillEpstein Tubelab 6 15th July 2011 02:54 AM
Simple SE grounding problems.. hartze11 Tubelab 7 24th May 2010 05:33 PM
Final checkout problems with Tubelab SE Mazuki Tubes / Valves 11 21st June 2009 01:50 AM


New To Site? Need Help?

All times are GMT. The time now is 10:32 PM.


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