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Blackbird

Moondog 2A3 Monoblocks

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4 hours ago, Les Lammers said:

 Find a reputable repair shop. Now is not the time to DIY. 

 

They are already at the shop...  😉

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9 hours ago, Les Lammers said:

 Find a reputable repair shop. Now is not the time to DIY. 

Reading is fundamental 😄

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By virtue of my post (from an earlier page) being quoted, I understood "right off" that he was reading through the thread and was at that point inspired to offer his opinion, before having finished catching up.  Done it many times myself...  Slack given.

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4 minutes ago, glens said:

By virtue of my post (from an earlier page) being quoted, I understood "right off" that he was reading through the thread and was at that point inspired to offer his opinion, before having finished catching up.  Done it many times myself...  Slack given.

 

I was guilty of this as well.  But I kept quiet.  😇

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I wouldn't poke fun if it wasn't relatable (we've all done it). Meant in good fun.

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Have your technician consider replacing the Solen Caps with modern 900 VDC rated Wima DC LINK film caps, with 4 Pins per cap, as shown, not two.   

 

                               2016627816_10uF.thumb.jpg.07220df443da4729cd26710594b79206.jpg

 

 

The ones I have are MKP4s, but DCP4s seem to be the new replacement,  $4.35 each, 138 in stock at Mouser.

 

https://www.mouser.com/ProductDetail/WIMA/DCP4N051007GD4KYSD?qs=DFPBcxnBxXiv2uqVo5TkuQ%3D%3D

 

This will likely be far-superior choice on the basis of reliability and sonically speaking.  Have tech note ESR rating !!!   Mouser has them, industrially priced, not audiophile priced.  Hard to beat !! 

 

Jeffrey Medwin

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I don't know yet what the new replacement will be for all of the new parts.  He will let me know soon and I trust that he will use the best of parts.  Once I get the Moondogs back, I will take a few photos of the amplifiers' inner.

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On 6/15/2019 at 12:58 AM, Blackbird said:

Well, I have had these pair of Moondogs for 18 years.  This is the first time I am having problem with them about two weeks ago.  Tonight was the first time I opened them in so long I don’t even remember.  I played music on these pair almost every day with my Klipschorns.

 

I'd talk to the tech about replacing all the film capacitors, including the Jensens. 

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13 hours ago, Les Lammers said:

 

I'd talk to the tech about replacing all the film capacitors, including the Jensens. 

We can check the power supply , etc., film caps with an ESR meter, and get some idea as to their functionality, and IF they need to be replaced. 

 

The trade off is, when replacing caps.. the amplifier is no longer a stock Moondog sonically.  Maybe worse, maybe better, depends totally upon cap choices !!  

 

From a reliability point of view, I would prefer the 900 VDC rated WIMA DC LINK caps in the power supply, over the stock 630 VDC rated Solens, on a long term use basis.   Just think, that 10 uF / 900 VDC $4.35 part I showed you all has a ESR of only 8.8 milliOhms !! 

 

The Jensens, if coupling caps, play a large part in the sound of the amp, and one would have to be careful in wholesale replacing them !!!   Something like a Mundorf Silver and Oil may be an OK substitute in 2019. 

 

Its a very slippery slope, replacing caps !!! 

 

Jeffrey

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Posted (edited)

My Moondogs are in the hands of my technician. All I can do now is wait for them to comeback and see the result.

Edited by Blackbird

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I finally got my Moondogs back.  They were burned in for about 3 days.

 

All of the caps have been replaced.  All of the sockets and pin holders have been tighten.  The technician told me that according to the schematic, two resistors were wrong.  R10 was suppose to be 2K not 1K and R13 was suppose to be 1.8K not 1K.  Other then that they sound incredible!  The longer they are burned in, the better they get.  Sonically, they sound better then before.  They cost me a total of $450 for parts and labors.  I am extremely happy with the sound.

 

Here are photos of both amps.

 

Moondogs Right.jpeg

Moondogs Left.jpeg

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13 hours ago, Blackbird said:

I finally got my Moondogs back.  They were burned in for about 3 days.

 

All of the caps have been replaced.  All of the sockets and pin holders have been tighten.  The technician told me that according to the schematic, two resistors were wrong.  R10 was suppose to be 2K not 1K and R13 was suppose to be 1.8K not 1K.  Other then that they sound incredible!  The longer they are burned in, the better they get.  Sonically, they sound better then before.  They cost me a total of $450 for parts and labors.  I am extremely happy with the sound.

 

Here are photos of both amps.

 

Moondogs Right.jpeg

Moondogs Left.jpeg

 

Congratulations !!  The tech, conservatively, kept essentially the same parts types ( Solen supply caps ) so there is no issues of re-voicing the amps, which is good.

 

Enjoy your music, now that all is fresh and working as originally intended.

 

No need to leave amp "ON" all the time, if that is what you were doing previously. !!  Its hard on tubes, etc. 

 

 

Jeffrey Medwin

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10 hours ago, Jeffrey D. Medwin said:

No need to leave amp "ON" all the time, if that is what you were doing previously. !!  Its hard on tubes, etc. 

 

Actually, as far as I can remember, I have only left the amps on twice (without turning them off) for a periods of maybe two to three weeks each time.

 

11 hours ago, Jeffrey D. Medwin said:

The technician told me that according to the schematic, two resistors were wrong.  R10 was suppose to be 2K not 1K and R13 was suppose to be 1.8K not 1K.

 

I forgot to mention that he replaced the R10 and R13 resistors since they have the wrong values.  He also replace all of the 10uF/400V caps with 10uF/630V caps.  As of today, the amps are almost dead quiet.  The sonics did not change but got better.

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Thosse are beautiful inside. So much neater than mine... just spent a couple of hours listening to mine, too. Love the Moondogs!

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there are two versions of Moondogs

magnequest iron (older ~1998 ) and electra print iron (most common) and some component values are different

 

this is magnequest

moondog magnequest.JPG

 

this is electra print

moondog electra.JPG

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4 hours ago, awsjr said:

this is magnequest

moondog magnequest.JPG

 

That is interesting.  The schematic Marvel provided is Electra Print but the technician replaced R10 and R13 with the resistors from Manequest parts list.

 

erik2A3 confirmed that my Moondogs indeed have Electra Print OPTs.  I trust the technician but I am wondering why he replaced R10 and R13 from Manaquest parts list?

 

My Moondogs seemed to work great and sonically better then before.

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There is a plausible reason...too tired right now to explain!  Glad you're amps are up and running again and that you're happy with them!  The net values of resistance are actually very similar.  It's not related so much to the output iron brand.  I happen to be working on a pair of Laurel IIs right now, and am just totally impressed by the massive size of the MagneQuest OPTs on the amps.  They are enormous and very Impressive.   

 

It's so great to see these great amplifiers from W. Labs during it's prime.  

 

 

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Erik, I've always wanted to spend the money to put the grid chokes in mine, but never had the cash. You told me at one time that mine had Magnequest trannies, but it there an easy way to know?

 

Bruce

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Bruce,

 

You might recall we've visited the subject of your OPTs a number of times.  So, yes, we could probably go back to that old link you provided earlier and have a look at the color coding on the secondary winding of the transformer.

 

If you'd like to compare them to my Electra-Print, we can do that too.  Tell you what:  I'll have a look at the inside shot you provided earlier in this thread, and tell you what to look for.  Or, have a look at the picture of these recently repaired and re-capped Moondogs.  Do you know where the secondary winding combinations are?  

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Hebe, that means I'll ha e to turn them off and open one up... I'll get to that, or find a pic of the inside of one I've made. Thanks Erik., it's not really important. As yoh said, either one is good, and I'm listening as I type this.

 

Bruce

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