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06-26-2009, 12:13 PM
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Junior Head-Fi'er
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Join Date: Jul 2006
Posts: 14
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Help!! Melos sha1 parts unknown!!
Hi all,
Let's take a look on the pics...
http://i780.photobucket.com/albums/y...o/R0011242.jpg
http://i780.photobucket.com/albums/y...o/R0011240.jpg
http://i780.photobucket.com/albums/y...o/R0011235.jpg
http://i780.photobucket.com/albums/y...o/R0011234.jpg
Hope you all can help me on this bit...
Bought this amp long time ago, found out the amp has got lots of hiss sounds, even when turn the volume off/switch to the other channel and I can hear the sound from the source...
Change all the caps to a better ones with dect step volume but doesn't help.
After a quick check then the tech told me it is a relays problem...
But now nightmare begins... by the time I take my unit back and switch it on,signal light is off and only the tubes are on, hook it up and find out there is only the hiss sound with the sound from the source(small hiss) from the monitors...Try all channels and headphone out & it doesn't got any good sign...
Could you all brothers help me with a schematic or any mods picture available?
Cheers!!
George Po
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06-26-2009, 01:21 PM
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100+ Member:
DIY tube amps can be SHOCKING
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Join Date: Jun 2001
Location: Tokyo Japan
Posts: 1,059
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Hey,
I did own SHA-1 before. Mine had a black faceplate.
So you get hiss in your music, correct? It may not be all that major. Mine had some noise like that, and all I did was replace the tubes. Try that. You might want to use 6922 or E88CC instead of 6DJ8 or ECC88.
If that ain't work, you should send into the professional restorer. This is probably the best, because I know Melos sometimes did unique patchworks different from one unit to another. You may get into more trouble fiddling with it yourself.
The tech should have the schematics. So ask him. If he ain't, beat him up. No self-respecting tech would mess with other people's equipments without some intel.
I have a schematics, but that's for SHA-Gold. It looks distinctly different.
T
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06-26-2009, 01:57 PM
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100+ Member:
DIY tube amps can be SHOCKING
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Join Date: Jun 2001
Location: Tokyo Japan
Posts: 1,059
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This is the signal relay (NEC MR62-* series). The transistor on the right should be IRD510 or equivalent.
This pair of Melos caps is highly likely for it's line out.
The pair on the left is LM317/LM337 from PSU. According to my schematics, the one of the lright is a pair of 2N6945 darlington transistors. But there is no proof that Melos actually used them as markings are sanded off.
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06-26-2009, 08:50 PM
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Junior Head-Fi'er
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Join Date: Jul 2006
Posts: 14
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Thx!! Brother Tomo. Anyway can I change the line out cap to other better one as I saw there is lots of mod are changed to solen 10uf, 250dc filmcap.
is your schematics for sha 1 or may I have a copy of it?
Cheers!!
George Po
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06-26-2009, 08:52 PM
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Junior Head-Fi'er
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Join Date: Jul 2006
Posts: 14
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Oh Yes!! I was using Jan Philips 6922 before things messed up.
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06-26-2009, 09:59 PM
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Headphoneus Supremus
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Join Date: Mar 2006
Location: San Francisco, CA
Posts: 6,643
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__________________
Home: ESI Juli@ (I2S) -> Buffalo32 -> Balanced Dynalo / Melos Maestro / SinglePower MPX3
Headphones: HP-2, RS-1, SR-200, Sennheiser HD-600, HD-650, Denon D-5000, AKG K271
Portable: 240GB diyMod 5.5G -> V-Cap Dock -> PPAS -> UE700
Office: Gamma1 -> PPAS -> K271
Feedback
Digital Audio Primer
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06-26-2009, 11:34 PM
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Junior Head-Fi'er
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Join Date: Jul 2006
Posts: 14
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THX for the link mate. But is sha 1 different from the maestro?
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06-27-2009, 12:46 AM
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500+ Head-Fi'er
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Join Date: Mar 2008
Location: Vancouver
Posts: 587
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Can someone who owns a SHA-1 tell me the value of these parts:
The two should be the same values.
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06-27-2009, 12:55 AM
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Junior Head-Fi'er
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Join Date: Jul 2006
Posts: 14
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Thx for the reply but don't know what you mean mate?
Anyway can I change the output cap from the melos stock to solen 10uf 400vdc as I saw some mod pics before.
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06-27-2009, 01:26 AM
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Headphoneus Supremus
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Join Date: Mar 2006
Location: San Francisco, CA
Posts: 6,643
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Those the input caps and are 1uF film (should be upgraded in quality).
What headphones are you using georgypo?
__________________
Home: ESI Juli@ (I2S) -> Buffalo32 -> Balanced Dynalo / Melos Maestro / SinglePower MPX3
Headphones: HP-2, RS-1, SR-200, Sennheiser HD-600, HD-650, Denon D-5000, AKG K271
Portable: 240GB diyMod 5.5G -> V-Cap Dock -> PPAS -> UE700
Office: Gamma1 -> PPAS -> K271
Feedback
Digital Audio Primer
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06-27-2009, 02:01 AM
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Junior Head-Fi'er
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Join Date: Jul 2006
Posts: 14
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Actually I was using melos sha 1 as a pre amp. coupling with melos cdtii transport, melos analog processor to aragon 4004 mkii and adam naf10 monitor...
I'm not a pro in headphone but I do love westone um3x.
And Yes, I change those input caps to wima already but don't know which one to replace the output caps(those two big ones) the best. Saw your one changed to some kind of 6uf 250v... But can dc cap replace ac cap? Gonna ask nikongod since his one has changed to solen 6uf 200dcv...
Anyway, is your melos hiss a lot? My cd is noisy as hell!! don't know what's wrong with the processor. As long as I play with the cd, the source is always leaking out to the monitors even though I turn down the volume knob or switch to other channel and it will never happens on other devices.
Cheers!!
George Po
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06-27-2009, 02:03 AM
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Junior Head-Fi'er
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Join Date: Jul 2006
Posts: 14
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To John,
Sorry that I don't know the value for those... I want to replace those but got no clue...
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06-27-2009, 02:09 AM
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100+ Member:
DIY tube amps can be SHOCKING
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Join Date: Jun 2001
Location: Tokyo Japan
Posts: 1,059
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George -
Are you talking about this?
This pair of Melos caps is not input cap. And, it is for your line out; not headphone out. I thought headphones are DC-coupled. So there isn't a point to upgrading these caps if you aren't using the line-out.
John -
I can't really tell from the picture, but it looks like ceramic or mylar capacitor. You know oblong thin cross section from the above. I guess, but there are two of these par tube. You should see another one right across to the other side of the tube connected to a straight copper pattern at the bottom.
Schematics for the amp doesn't show this. But this could be bypass for the tube heaters. Sorry, Melos board seems like double sided. I can't make anything out. (Plus they got a bunch of jumpers!)
T
P.S. Anyone know if there would be a problem in posting the schematics. You know trademark thing?
P.P.S. Melos board seems to marked with single or double digit numbers. I think these are component codes. Can you see what they are?
Last edited by Tomo; 06-27-2009 at 02:13 AM.
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06-27-2009, 02:32 AM
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500+ Head-Fi'er
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Join Date: Mar 2008
Location: Vancouver
Posts: 587
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Oh right, I forgot to highlight the other two at the board edge. Those two should also be the same value, but I don't know what value it is. I replaced all four of those with 0.47uF 150v iirc, and all four of the caps between the two tubes with 1uF 250v. The amp now has weird issues. Anyways, all this is off topic, I was just wondering if anyone had those values (so I could replace them and see if that helps)
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06-27-2009, 02:53 AM
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Junior Head-Fi'er
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Join Date: Jul 2006
Posts: 14
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Hi Brother Tomo,
Yes!! I want to change these!! As I treat this as my pre amp always.
Cheers!
George Po
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