[n3rdling]

That's trevornetwork, please be careful people.

 

[gilency]

That's trevornetwork, please be careful people.

Who is he?

 

[livewire]

Let's just say that he is not well liked elsewhere due to previous deceptions. Also there are red flags all over that auction of his.

 

[dukja]

OK, thanks to Spritzer's help.  I have been working on the SRM-1 MK2 PP I got from crumpler like crazy.  Certainly gain a lot of knowledge about it.  I finally found a dead resistor that cause the offset calibration issue.   After swapped in and listen to my 1st Stax set for 5 mintutes.., and new problem shows up.  Oh well.
 
I can't believe people selling such gear and claim it to be working condition.  Either being really newbie in headfi so he cannot hear any apparent problem or ...   
 
I'll keep working on this amp but I also got NEW 323s coming from Japan.  That should give me some reference for comparison with SRM1.
 
Since new 323s will be wired for 100V, does anyone know that if they can be rewired to 110V?
 
Second question, anyone can recommended a good step-down transformer so I can use it without re-soldering?
 
Thanks a lot!!

 

[svyr]

>After swapped in and listen to my 1st Stax set for 5 mintutes.., and new problem shows up. Oh well.


mmm? what problem? also what resistor (number and value) died on your srm1/mk2 pp? It might be pointing to a larger issue and you could potentially be better off replacing other parts near it.



>Either being really newbie in headfi so he cannot hear any apparent problem or ...


Let me put it this way - if you didn't try to retune the bal/offset, would you have noticed it?

 

[dukja]

Hay, thanks for the help.  Spritzer was out so I have not got any more help yet.
 
The R119 died (the schematic shows it for L channel, but it is actually R channel on PCB).  There is no burnt mark. It just read as open.  The R219 was fine.   I checked most bipolar transistor using the diode mode on my nice DMM and they seemed to be fine.  Most "big" caps and resistors that see HV have been checked.  Oh, the DC out of transformer is a little bit weak (308VDC from 243VAC out of yellow wire) I did learned a lot debugging this amp. 
 
After replacing the equivalent resistor, both balance/offset calibration can be dialed in to ~0VDC.  It sounds OK (the bass is rich but less controlled comparing to beyer T1), but about 5 minutes, the left channel sound faded away.  I can adjust the offset pot to get the sound level up, but the sound will fade again later.  I think it is due to some failing component so that the bias point of the FET was swinging.
 
I can turn it on and listen for a few minutes and the volume will fade and I will hear the distortion at loud bass.  (literally broken sound).
 
Still I got some quick comparison of Stax gear with my T1 + Phoneix.  It was interesting and I can see the different presentation.  I like it so far and am willing to spend more money to buy a new Stax amp. 
 
The money I spend to buy this NON-functioning amp from the headfier (claimed it perfectly function and then refuse to take the amp back even I pay for both way shipping) is petty much vanishing in the air....

 
Quote:

>After swapped in and listen to my 1st Stax set for 5 mintutes.., and new problem shows up. Oh well.


mmm? what problem? also what resistor (number and value) died on your srm1/mk2 pp? It might be pointing to a larger issue and you could potentially be better off replacing other parts near it.



>Either being really newbie in headfi so he cannot hear any apparent problem or ...


Let me put it this way - if you didn't try to retune the bal/offset, would you have noticed it?

 

 

[Michgelsen]

Make sure you leave negative feedback then, even if that's all you can do...

 

[svyr]

Hay, thanks for the help.  Spritzer was out so I have not got any more help yet.
 
The R119 died (the schematic shows it for L channel, but it is actually R channel on PCB).  There is no burnt mark. It just read as open.  The R219 was fine.   I checked most bipolar transistor using the diode mode on my nice DMM and they seemed to be fine.  Most "big" caps and resistors that see HV have been checked.  Oh, the DC out of transformer is a little bit weak (308VDC from 243VAC out of yellow wire) I did learned a lot debugging this amp. 
 
After replacing the equivalent resistor, both balance/offset calibration can be dialed in to ~0VDC.  It sounds OK (the bass is rich but less controlled comparing to beyer T1), but about 5 minutes, the left channel sound faded away.  I can adjust the offset pot to get the sound level up, but the sound will fade again later.  I think it is due to some failing component so that the bias point of the FET was swinging.
 
I can turn it on and listen for a few minutes and the volume will fade and I will hear the distortion at loud bass.  (literally broken sound).
 
Still I got some quick comparison of Stax gear with my T1 + Phoneix.  It was interesting and I can see the different presentation.  I like it so far and is willing to spend more money to buy a new Stax amp. 
 
The money I spend to buy this NON-functioning amp from the headfier (refuse to take the amp back even I pay for shipping) is petty much vanishing in the air....

 


 

wow, that's not sounding good at all. I suggest you also try Dr Gilmore (kevin.gilmore, or was it kevin_gilmore). He and sprizer helped me fix my SRM-1 (more like fixed remotely with soldering and measuring ) and figure out that after fixing a dead resistor the rest of the problem was in large DC offset in my MD11 dac lol ...

For the power in, I had All the power caps showed around 330v DC from 240v AC in. (large C005,etc in the psu section)

I presume read as open you mean inf resistance (yep,that's pretty dead)...

Sort of sounds like something overheats (or maybe dodgy/damaged cap or diode nearby the dead resistor)...then again that's my reply to everything electronics )...Not sure if it could be an overtightened pot, but you could try replace the sections around the dead resistor on both channels - i.e the transistor (see http://www.head-fi.org/forum/thread/223263/the-stax-thread-new/15345#post_7396494) and the cap / couple of resistors around it and the diode (1n4007 is a replacement for every diode except the 1s1153. the 1s1153 are likely replaced by a 1n914. <--- thanks kevin and spritzer)...Same goes for the pots, but I wouldn't have a clue what the suitable replacement is.



>The money I spend to buy this NON-functioning amp from the headfier (refuse to take the amp back even I pay for shipping) is petty much vanishing in the air....

heh, well, look at how it may sound to him - "i got your amp, opened it, turned some weak single turn pots and stuck some probes into it then soldered it and it doesn't work"
IDK if leaving negative feedback will do anything since can quite easily leave some for you to reciprocate...

 

[dukja]

Guys thanks for the hints and condolence.  I don't intent to revenge for my loss, but definitely will leave some warning for future headfier to learn about.   The true character of people quickly shows even with only a few hundred bucks involved.  (Sorry, I am a rich cow to milk.

  No, definitely not.

)
 
I'll keep debugging it just as a good exercise for my future DIY project.  Thanks a lot for your help!  It may be more fun and rewarding than just use the gear. 

 

[spritzer]

Quote:

Since new 323s will be wired for 100V, does anyone know that if they can be rewired to 110V?

I just bought a SRM-323S for the sole reason of documenting how this is done.  It was childsplay with the 323A so hopefully the new amps are just as easy to modify. 

 

[dukja]

I just order mine today.  Please keep me updated on re-wiring transformer.  Thanks a lot!!
 
Quote:

I just bought a SRM-323S for the sole reason of documenting how this is done.  It was childsplay with the 323A so hopefully the new amps are just as easy to modify. 

 

 

[svyr]

Guys thanks for the hints and condolence.  I don't intent to revenge for my loss, but definitely will leave some warning for future headfier to learn about.   The true character of people quickly shows even with only a few hundred bucks involved.  (Sorry, I am a rich cow to milk.

  No, definitely not.

)
 
I'll keep debugging it just as a good exercise for my future DIY project.  Thanks a lot for your help!  It may be more fun and rewarding than just use the gear. 

m, warning type feedback is good. Usually means if people intended to deceive they can only do it a lot less times in total (once people might give them the benefit of doubt, second time - they'll start a poo-storm)

yay, spritzer! Any suggested course for dukja on what to measure/replace, or did I poke a hole in the right area of the sky ? (congrats on the 323s new toy btw)

 

[vvs_75]

[size=9.5pt]If you paid via Paypal I would start a despute case  right away.  Main reason the product is not as described. Put everything as it is and hope that paypal will rule in you favor. It does not work  in 100% cases but worth a shot. I just won two cases like that within last two month. And got all my money back.  Good luck! [/size]

 

[spritzer]

Quote:

yay, spritzer! Any suggested course for dukja on what to measure/replace, or did I poke a hole in the right area of the sky

? (congrats on the 323s new toy btw)

 
I'm still trying to narrow down what needs to be fixed as that busted resistor could be a clue.  It is a part of the input stage so if the 2SA1156 is busted then that would explain a lot of things.  Most of the transistors in there are cheap to replace except for the J109's which are beyond rare these days...
 
As for the 323, it will be sold as soon as I'm done with it.  I need more Stax amps about as much as a hole in the head...

 

[dukja]

Unfortunately, I try to be cheap and use "gift option" with bank transfer.  This is very bad decision for someone I don't know much.  I learned my lesson and will not make the same mistake again. 

  Paypal will not accept dispute for "gift option" and my bank will not help either.
 
Quote:

[size=9.5pt]If you paid via Paypal I would start a despute case  right away.  Main reason the product is not as described. Put everything as it is and hope that paypal will rule in you favor. It does not work  in 100% cases but worth a shot. I just won two cases like that within last two month. And got all my money back.  Good luck! [/size]