Marantz PM66 KI tweeks - Page 41 - 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 23rd June 2011, 04:41 PM   #401
diyAudio Member
 
Ben Hanke's Avatar
 
Join Date: Dec 2007
Location: Vancouver, BC
Send a message via MSN to Ben Hanke Send a message via Skype™ to Ben Hanke
I've not taken measurements while it's switched on before, besides when doing the idle current adjustment, and I'm not sure where's safe to put the probes without potentially causing more damage. The twin PSUs are kicking out about 33v, and the relay clicks as normal so I suppose the voltages can't be too crazy. I might try taking the FK smoothing caps out and put the original Elna caps back in there temporarily, just to eliminate any doubts about the leads. They were the last thing I changed.
  Reply With Quote
Old 23rd June 2011, 04:49 PM   #402
diyAudio Member
 
Ben Hanke's Avatar
 
Join Date: Dec 2007
Location: Vancouver, BC
Send a message via MSN to Ben Hanke Send a message via Skype™ to Ben Hanke
While I'm on the subject of those caps, I was playing about with a circuit simulator looking at the smoothing effects of different values there. The design calls for 12,000uF but my FKs are only 10,000uF, and 22,000uF seems like the sweet spot for low ripple. If I do end up fixing this and later decide to increase the value there, where do you guys think would be the most effective place to put those FKs in my system? (CD63 MkII KI included).
  Reply With Quote
Old 23rd June 2011, 04:53 PM   #403
SimontY is offline SimontY  United Kingdom
diyAudio Member
 
SimontY's Avatar
 
Join Date: May 2003
Location: Sheffield, North England
Send a message via MSN to SimontY
Hmm, first place that springs to mind is smoothing for the output stage, +-20V in the CD63 - if they'll fit. I guess they won't so they'd have to go on leads or something. I don't know what else you could do with them.
  Reply With Quote
Old 25th June 2011, 08:20 AM   #404
diyAudio Member
 
Ben Hanke's Avatar
 
Join Date: Dec 2007
Location: Vancouver, BC
Send a message via MSN to Ben Hanke Send a message via Skype™ to Ben Hanke
R764 (330ohm/2w) went to the great circuit in the sky with an impressive fireworks display. Now, if I measure its resistance with my DMM, the value gradually climbs and then goes infinite. Relay no longer clicks, of course.

I tried measuring the voltage across it very for a couple of seconds with the power on and the reading climbed past 100v (really? seems like a lot) and the resistor lit up like a bulb. I suppose R764 has taken a bullet because of a fault elsewhere.

Last edited by Ben Hanke; 25th June 2011 at 08:24 AM.
  Reply With Quote
Old 26th June 2011, 06:31 AM   #405
diyAudio Member
 
Ben Hanke's Avatar
 
Join Date: Dec 2007
Location: Vancouver, BC
Send a message via MSN to Ben Hanke Send a message via Skype™ to Ben Hanke
I replaced the resistor, swapped the original smoothing caps back in but now the fuse blows immediately instead :-/

I really miss listening to music.
  Reply With Quote
Old 27th June 2011, 04:42 PM   #406
diyAudio Member
 
Ben Hanke's Avatar
 
Join Date: Dec 2007
Location: Vancouver, BC
Send a message via MSN to Ben Hanke Send a message via Skype™ to Ben Hanke
I think it's fried, and I'm concerned about pursuing it further in case I blow the thermal fuses in my PSUs. I've got a main board from a spares/repair amp coming, and I've found a local parts supplier. I've swapped out my FKs and tested them and they seem fine, although the left one was holding a worrying negative charge when I first pulled it. I think when I get this new board, assuming there's nothing wrong with it, this time I'm going to concentrate on getting the small things right first, in more than one sense. I'm going to start with precision trimpots, small caps and resistors, keeping the leads short so I can get the big caps closer to the PCB.
  Reply With Quote
Old 28th June 2011, 04:58 PM   #407
diyAudio Member
 
Ben Hanke's Avatar
 
Join Date: Dec 2007
Location: Vancouver, BC
Send a message via MSN to Ben Hanke Send a message via Skype™ to Ben Hanke
While I wait for a new board, I'm building a Lightspeed LDR attenuator kit from Uriah Dailey at BuildAnAmp.com to try instead of the standard Alps pot. It seems to be working perfectly so far except the resistance at min volume is only measuring 12.5k per channel, but if I can get that to up to 50k then my hope is that I will be able to install it directly at the main PCB input and run a very short signal wire down from the input selection switch.
  Reply With Quote
Old 28th June 2011, 05:27 PM   #408
SimontY is offline SimontY  United Kingdom
diyAudio Member
 
SimontY's Avatar
 
Join Date: May 2003
Location: Sheffield, North England
Send a message via MSN to SimontY
I heard the Lightspeed attenuator once compared to two other preamps and it seemed to produce a much bigger soundstage. Very interesting volume control.
  Reply With Quote
Old 29th June 2011, 03:22 AM   #409
diyAudio Member
 
Ben Hanke's Avatar
 
Join Date: Dec 2007
Location: Vancouver, BC
Send a message via MSN to Ben Hanke Send a message via Skype™ to Ben Hanke
Great! Well that's exciting. Lots of people seem to rave about it. I think it's supposed to add some low order harmonic distortion. If my DMM readings are to be believed then the channel matching should be better than my Alps at normal listening volume too, which should help with imaging. I think I got the wrong end of the stick about the resistance when I posted earlier, and the Lightspeed board is probably good to go in as it is.
  Reply With Quote
Old 30th June 2011, 03:31 PM   #410
diyAudio Member
 
Ben Hanke's Avatar
 
Join Date: Dec 2007
Location: Vancouver, BC
Send a message via MSN to Ben Hanke Send a message via Skype™ to Ben Hanke
I tinkered some more with my broken amp and found that the transistors have failed, which explains why the fuse has been blowing immediately on power up. Now I'm concerned for my 805s. I hope the output protection circuitry saved them from a dose of DC.
  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 se problems, information wanted alan_w Solid State 8 6th August 2012 05:13 PM
Quad II Mods/Tweeks slurb.net Tubes / Valves 62 16th June 2012 12:32 AM
wanted marantz pm66 amp paul.42 Swap Meet 0 6th April 2009 08:09 PM
Tweeks on tubes - bring out the demagnetiserss ashok Tubes / Valves 36 3rd August 2004 05:34 PM
expert tweeks for PA? Pbassred Multi-Way 4 7th December 2003 08:57 PM


New To Site? Need Help?

All times are GMT. The time now is 01:38 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