Ming Da transformer problem? - diyAudio
Go Back   Home > Forums > Design & Build > Parts

Parts Where to get, and how to make the best bits. PCB's, caps, transformers, etc.

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 7th May 2009, 01:52 PM   #1
diyAudio Member
 
Join Date: May 2009
Default Ming Da transformer problem?

I'm assuming for those of us Ming Da amplifier owners who have lost a power transformer (or are in the process of losing one) that we are S-O-L.
I've got a Ming Da MC-88C that recently blew a fuse. I found a fried screen grid resistor and replaced all of them while I was at it, and replaced the power tubes with a new matched quad, biased them to .41V and thought I was back in business. But evidently that wasn't the extent of the damage because the power transformer is seriously over-heating under load. It still plays and sounds great but after around 30-40 minutes the power transformer gets hot enough to burn you (I've only tested this once since I noticed it). Being able to replace known bad parts, and take measurements relatively safely, is about the extent of my knowledge. So, considering it still operates and sounds good, does that mean the transformer isn't a lost cause yet (assuming it is the transformer)? Is it possible that there is another problem causing the transformer to overheat, and there isn't even any damage to the transformer yet? I am addicted to the sound of this amp and am afraid to lose it. Any suggestions or comments would be greatly appreciated.
  Reply With Quote
Old 10th May 2009, 03:10 AM   #2
diyAudio Member
 
unclejed613's Avatar
 
Join Date: Dec 2006
you need to check your output tube idle currents. new tubes might be needing to be re-biased. most (not all) newer transformers have a thermal fuse in them. the temp rating of the thermal fuse is usually quite a bit below the melting point of the enamel on the wire. however, you have something drawing current. bad caps in the power supply could cause it, or like i said, your output tubes could be running a bit too much current.
__________________
Vintage Audio and Pro-Audio repair ampz(removethis)@sohonet.net
spammer trap: spammers must die
  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
Ming Da MC368-B90 ManUtd Tubes / Valves 2 18th October 2012 07:49 AM
Ming Da MC-34B fuse value? cscmc1 Tubes / Valves 1 26th October 2008 07:46 PM
Ming Da MC-7R transformers for Quad 22 clone. johnm Tubes / Valves 0 6th June 2008 06:43 PM
Ming Da MC34B....passive or active pre amp? Paul Dimaline Tubes / Valves 2 29th January 2006 07:35 PM
Transformer problem Semir Power Supplies 3 2nd January 2005 11:36 PM


New To Site? Need Help?

All times are GMT. The time now is 04:43 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