[daltonlanny]

*** SEE POST # 11 BELOW ***
Hello,
I recently bought a nice balanced Beta 22 with separate dual power supply, and really good parts such as black gate caps, etc., off headfi.
It worked perfectly and sounded beautiful until the other night.
I screwed up and did not turn the volume all the way down or the unit off when exchanging headphones with the 1/4 trs jacks.
I smelled and saw smoke come out the top cover and turned it off immediately. The unit was still playing normally believe it or not!
I took the top cover off, and all 4 of the boards appeared normal except for one. On one board R32 is basically fried.
I assume that there is possibly some mosfets, and possibly some other resistors bad on that board. The other boards may be fine.
I am a buyer and not a builder.
I am not very skilled at soldering, desoldering, replacing parts, and measuring parts.
I am looking for someone out there who is willing to repair or replace the board, and check out the other boards in the amp to make sure they are ok.
If the board has to be replaced, I would atleast like to have the Black Gate and Nichicon muse capacitors removed from the bad board and transferred to the new board.
I will gladly pay all necessary costs.
So far, no luck finding anyone.
I would really hate to scrap this fine amp.
If you arw willing to help me out, please pm me.
Thanks for your help.

 

[daltonlanny]

Anyone???

 

[tomb]

Sorry no one's responded, especially after I told you to post over here.  Have you tried AMB's forum, yet?
 
Another possibility is to contact MisterX.  He builds and sells them.  I'm not sure if he would be interested in a repair, but it's worth contacting him.

 

[FallenAngel]

  Sorry no one's responded, especially after I told you to post over here.  Have you tried AMB's forum, yet?
 
Another possibility is to contact MisterX.  He builds and sells them.  I'm not sure if he would be interested in a repair, but it's worth contacting him.

 
Him and I have been chatting about this for a bit, and yeah, I'm a little concerned that nobody posted, but his initial post asked for PM.
 
I'm happy to build another board to help him out and fix the amp, as he knows. I recommended getting someone in the US to do it as Canada has nasty taxes that will make it cost extra for me to do it.
 
DIY guys, please help out. It's simply building a board, hopefully salvaging the electrolytic caps and probably the heatsinks. That's like 1/3 of the costs right there.

 

[daltonlanny]

Thanks tomb and FallenAngel.
I really appreciate you guys and your help.
I really am having a really hard time getting anyone willing to offer to repair it.
I did also post on the AMB forum too, and have had a couple of responses off of the AMB forum, but who knows, right?
Nothing is set in stone as of yet.
If it falls through, I may have to come back to you.
Again, if anyone is willing to help me out, I am ready to get it done.

 

[Avro_Arrow]

If you are lucky you might get away with just replacing the output MOSFETs and resistors.
I was not so lucky. I tried to repair a B22 board and it just kept blowing the outputs.
I recommend building a new channel.
 
Good luck!

 

[Zashoomin]

I might be able to help so I sent over a PM.  

 

[daltonlanny]

Update:
Sent my balanced beta 22 to Jeffrey (m1abrams) for repair a couple of weeks ago.
He is hagak on the AMB diy forum.
He has agreed to repair the blown board, increase the gain on all the boards from 5x to 8x, replace the dual 50va toroidal transformers with dual 100va ones, that I pirchased and sent to him, and will possibly do a few other minor things for me.
He has ordered the parts for the bad board and for the gain increase, and will hopefully get them Monday.
I really miss the amp, and looking forward to getting it back at home!
Will keep everyone updated.
Thanks m1abrams!

 

[daltonlanny]

Got my fully balanced beta22/sigma 22 back from m1abrams.
It works perfectly and sounds awesome.
Excels with my modded Hifiman HE-6.
The new 8x gain is a needed shot in the arm when using single-ended dources with the HE-6.
Jeffrey did an outstanding job getting it back up and running, and was very reasonable on all costs.
Thanks m1abrams! Much appreciated.

 

[m1abrams]

Lanny,
Glad it is all working well for you.  Enjoy it!

 

[daltonlanny]

Hello all,

I hate to revive this thread. I really do.
I honestly thought I would never have to.
I need help again.
My friend borrowed my Beta 22 for the weekend, and he blew a board on my amp Saturday night.
I specifically gave him instructions on when plugging in or unplugging headphones with 1/4" plugs to turn the amp completely off.
Well, he forgot to do it just one time, and damaged one of the circuit boards.
Never again will I loan it out to anyone to use.
The amp still works normally, believe it or not, even though smoke came from that one board and R32 is toasted on that one board.
The other boards appear fine.
I am afraid to use the amp, because of possible further damage that could occur.
Can someone out there please help me out with this board?
I would appreciate it very very much.
Thanks.

 

[Jose C]

If you manage to get it repaired again, ask to change the output resistors to 1ohm or 2.2ohm, like Ti Kan advises on his website.
It should prevent this problem in the future.

 

[daltonlanny]

Anyone out there willing to help me?
If not, I will probably just sell it or scrap it, cause I'm sort of tired of fiddling with it, and having to worry about something burning up inside it all the time.

 

[cfcubed]

Posted the below at the other forums you posted this plea to.   Again I'm way too backlogged with work to take this on, but between you wanting it re-cased & it now needing work IMO may be best to sell it off.
 
This is always disappointing to see because its so avoidable.  Besides lowering volume whenever inserting/removing cans & following proper pwr-on/pwr-off order there's something else that should be done & should be well-known to those working on TRS jack β22s.
Only my 1st β22 had 0.47Ω R34s & R35s.  Early on in all the hub-bub WRT β22s & TRS jacks decided any β22s that passed through my hands had ≥ 1R R34s & R35s.  This must work because brought TRS 2-channel β22 to a meet once & some guy removed my headphones as slowly as physically possible & with volume up.   As if he was trying to burn the amp.  Was too far away to stop him but let him know about it.  Amp was fine.  Wondering what values your β22 has.
 
Some Ti quotes (β22 parts page + post here elsewhere):
 
Notes about R34 and R35:
The default value for these resistors is 0.47Ω. If you have TRS headphone output jacks, the value may be increased to 1Ω to 2.2Ω for added protection. This is because TRS plugs create momentary short circuits while being inserted or removed, and could potentially damage the output MOSFETs.
 
Originally Posted by amb
Note that increasing the value of R34/R35 will impact your output stage bias adjustment. Ohm's Law says V = I * R, so if you want 120mA of quiescent current, and R is 1 ohm, then you need to adjust VR2 to get 120mV across R34 (and R35).
 
Think β22 w/TRS jack builders / repairers should not consider using default value 0.47Ω R34s & R35s & should retrofit any that pass their way to ≥ 1R.
Doing that may prevent us seeing any more of these sorts of posts    BTW I'm waaayyy back-logged w/work or I'd help this guy out.

 

[cfcubed]

The repaired indicated in the other forum that he did suggest raising the resistor values.   So it appears it may have went sort of like this:

 
BTW should correct my statement:  All β22s that have passed my way have 1R R34s & R35s.  Did this even to a 4-channel/balanced build I sold because IIRC when the guy came to try it out / buy it his headphone XLR jack & wire looked wonky.   When I asked he said it did had issue whens wiggling.  This issue was it was shorting

Caught it & now test any/all DIY headphone jacks/cables before they come in contact with my amps