eXStatA Build Thread II - Page 18

Quote:

Originally Posted by pabbi1 

So quiet - listening to my eXStatA while building a new prototype. And waiting to hear some responses... certainly there are more than a couple of builds almost done?

 

OY!

Built a epsilon24 power switch unit today. :p Still need to make a mouser order for some caps, but I need to create a mouser BOM for EHHA rev.A as well. Hoping to get a working exstata hybrid by the end of next week. :)

I'm almost done and have just tested the amplifier board but seem to have a problem with the right amp so would greatly appreciate some help trying to solve the problem.

Using the procedure from Cavelli Audio web site to test the amp board, I've come up with the following readings:

Rail Voltages: both +/- are 308V

Left Amp:
* Voltage between output terminals adjusts OK using P2: varying between 0V to 0.15V

* Output+ to gnd: varying between 0V to 0.15V

* Output- to gnd: varying between 0V to 0.13V

Heatsink of Q14L hotter than Q13L

Right Amp:

* Cannot adjust voltage between output terminals to lower than around 15V (P2 at it's limit). Voltage is varying between 14.5V to 15.5V

* Output+ to gnd: varying around 15.5V

* Output - to gnd: varying between 0V to 0.5V (??)

Heatsink of Q13R hotter than Q14R (opposite to left amp)

Also:

My input jfets readings are paired at 10.6 & 10.8 and 11.2 & 11.49 but didn't note which side got what.

The heatsinks at Q11/Q12 L&R are grounded.

I'm using a 369JX transformer which is quite warm to the touch - don't know if this is normal.

Is it a clue to whats wrong with the difference between Out+ to Out- (to gnd) on the right board (15.5V and 0.5V respectively)?

cheers

Tim

Quote:

Originally Posted by pabbi1 

So quiet - listening to my eXStatA while building a new prototype. And waiting to hear some responses... certainly there are more than a couple of builds almost done?

 

OY!

Hi,

I am having a very hard time finding P Channel 500V Mosfet around here.  This is the only component that I can't find.  Can someone who has some extras share with me? 

On the other hand, can I run the amp without using regulated supply?  How many mA does this amp draw in total?

I would really appreciate any help.

Wachara C.

Wanted to say thanks again to all and Alex.  

I've had the SS eXStata running since last Friday, waiting on some hook-up cable to replace what I'm currently using and a better attenuator before it's finished. Still need to build the final case. 

I think I prefer the SS to the Hybrid-not sure why, still listening to both. But I like the SS sound.  

chinsettawong - I have one P-channel 3P50 500V spare if you PM me your address, I'll send it to you.

chinsettawong:

i think it s 30ma and 35ma. you can check on the website

marcus1: what is the voltage drop across the PSU s resistor R1?

what about adjusting p1 on the amp boards?

I agree.

Quote:

Originally Posted by noobula 

I agree.

Dear sir, I find your opinion deeply insightful, and I wish to subscribe to your newsletters.
 

Hi tomytank,

Thank you very much for your generousness.  I will send you a PM.

Wachara C.

^^you could always use a MTP2P50EG in that position, people had success with them. Farnell has some in singapore.

Actually, or this: http://cgi.ebay.com/Power-Mosfet-P-CHANNEL-FET-3P50-500V-3A-18nC-9-5pF-x2-/180509125144

You guys are great. I received the connectors from Frank today. Everybody helps...  I am just amazed at this community.

BTW, I just started my first Cmoy (actually 2 of them)......in between 120 + hours of work last 14 days.

I figure I'd try that before going with the eXStatA build..I am starting to look for parts and having Pabbi's proto will help me a lot by comparing while I build my own

Sorry it is going to take me much longer than you guys.      *hides his face in embarrassment*

Chinsettawong,

Sent this morning, please look out for it.

Quote:

Originally Posted by chinsettawong 

Hi tomytank,

 

Thank you very much for your generousness.  I will send you a PM.

 

Wachara C.

 

Hi Tomytank,

Thank you so much.  I really appreciate it.

Wachara C.

If anyone is still needs 6s4a, I have another batch - just have to sort and test, along with a bunch of other triodes.

Oh, and a little pron, just for good measure.

nice going Al!!

I brought out the a set of exstata SS boards I needed to test out as well today.

Going to try and test them out later tonight. Which reminds me..Brian..you get those SS boards out to me yet?!