Marantz PM66 se problems, information wanted - 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 13th April 2007, 12:22 AM   #1
alan_w is offline alan_w  United Kingdom
diyAudio Member
 
Join Date: Apr 2007
Default Marantz PM66 se problems, information wanted

I have been doing some research on this amp as my own has been having some problems, in that the right side output channel is at a lower volume than the left, which wasn't the case about 2 months ago.

Whenever I put in this amp into google it comes up with this website, and from what I have read I assume that this site is full of people who know far more than I ever will about this subject, so, like a moth to light it drew me in.

I am not totally sure what the problem actually is yet, I have ruled out the CD player (Marantz CD-48), the speakers (Kef Q35) and the cables (QED) and narrowed it down to the amp right hand speaker channel.

I have been told that Leaky electrolytic filter caps will result in audible hum, as there is no hum that rules that out. The thing is, the sound is good on both channels, but the left channel is quite a bit louder than the right, meaning that the balance has to be almost all the way to the right to actually balance it.

Does anyone have any ideas/hints/tips? Where can I get a schematic from so that I can start detailed diagnostics?

If it helps, I took some photos of the insides of the amp, mainly to document, but also incase it showed anything obvious up.

Thanks for your help, I appreciate it.
  Reply With Quote
Old 13th April 2007, 01:21 AM   #2
Leolabs is offline Leolabs  Malaysia
diyAudio Member
 
Leolabs's Avatar
 
Join Date: Dec 2004
Location: Bukit Mertajam
Send a message via MSN to Leolabs
Leaky signal/feedback caps or dirty volume/balance control.
  Reply With Quote
Old 13th April 2007, 09:41 AM   #3
alan_w is offline alan_w  United Kingdom
diyAudio Member
 
Join Date: Apr 2007
Sorry, I forgot to include the link to the photos. Probably won't help but I include them anyway (tried to look for a way to edit the OP but couldn't find one).

http://alan-wall.fotopic.net/c1254209.html
  Reply With Quote
Old 6th May 2007, 05:59 PM   #4
Juko is offline Juko  Netherlands
diyAudio Member
 
Join Date: Jan 2007
I had the same problem with a Yamaha amplifier. Cleaning the speaker protection relay-contacts solved the problem.
  Reply With Quote
Old 15th July 2012, 08:29 PM   #5
diyAudio Member
 
Join Date: Jul 2012
I have just experienced a similar problem (10% volume from right speaker vs 90% volume from left speaker) on my Marantz PM66 SE. Did your problem ever get resolved? If so, any pointers?
  Reply With Quote
Old 16th July 2012, 06:45 AM   #6
Mooly is offline Mooly  United Kingdom
diyAudio Moderator
 
Mooly's Avatar
 
Join Date: Sep 2007
Electronic faults causing gain problems are very rare, the causes are usually simpler.

First steps would be to use a scope and known signal source which would find the problem area in seconds but I'm guessing you haven't got one

So you need a test CD with a test tone of around 100 to 1Khz and a DVM that can read AC voltage reasonably well. It doesn't need be accurate so much as have good resolution at low levels. It should be able to resolve a voltage of say 1.22 volts and not just show 1 or 2 volts.

You would then check (no speakers connected) at the amp outputs first with the test tone playing and confirm that there is a difference between channels. Set the volume to give around 10 volts AC.

Assuming there was a difference then you next check the AC voltage at the input to the volume control to "split" the amp in half and determine where the problem is.

Most faults like this are caused by faulty controls such as balance, volume etc and by cracked (damaged) print.
__________________
-------------------------------------------------------
Installing and using LTspice. From beginner to advanced.
  Reply With Quote
Old 16th July 2012, 07:13 AM   #7
diyAudio Member
 
Join Date: Jul 2011
Check the input selector, if it is mechanical problem is there. Probably oxidation and contacts of gold are full of black film over it. Use contact spray to clean the input switch, or if you have knowledge disasemble switch and clean the contacts. 10 years is enough to make that film on gold contacts.
  Reply With Quote
Old 6th August 2012, 11:33 AM   #8
diyAudio Member
 
Join Date: Aug 2012
Thumbs up Dry Joints Galore!!!

Just repaired a Marantz PM66-se audio amp with no speaker relay operation and discovered -38 volts on L751 output coil (Left Channel). Traced fault back to input of channel and found R719 68ohms O/C emitter resistor for Q701, to find Speaker relay intermittently working and sometimes clicking off... dry joints galore on main board was the cause,also the "source direct button cut out left channel....you guessed it, dry joints on Source relay board!!

  Reply With Quote
Old 6th August 2012, 05:13 PM   #9
diyAudio Member
 
Join Date: Dec 2010
Location: wigan
I was about to say lots of dry joints but was pipped to the post.
  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
Marantz PM66 KI tweeks Fidelity Audio Solid State 506 25th January 2014 04:26 PM
wanted marantz pm66 amp paul.42 Swap Meet 0 6th April 2009 08:09 PM
marantz pm 75 coaxial information kdlsrinu Solid State 0 10th August 2006 06:45 AM


New To Site? Need Help?

All times are GMT. The time now is 02:37 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