i'm on a roll... the kgsshv

[Lil Knight]

Would be awesome if you could come up with a simple, ready-to-use controller, instead of the Arduino. I have a couple of Bourns 256ppr encoder waiting for this attenuator..

[wink]

How about mounting the relay board on it's side?

That may give you room for a small potted traffo & rectifier/filter board for the relay board.

[wink]

Or, you could mount the traffo & regulator under the relay board.

[spritzer]

Trafo this close to the volume control will cause problems.

Edited August 19, 2013 by spritzer

[Kerry]

I agree.  I was trying to keep the front of the chassis free of any noise.  For the control board, I could mount it to the face of the amp and shield it from the amp boards.  I've got .75" there so I could fit it.  I was going to use .5" aluminum plate for the face and could mill the display into that so the electronics would be very flat.

 

I just bought a small 12V 1A  (70mm x 35mm x 30mm) switched supply that could sit under or above the Bias board.  Don't know how I feel about that.  It would not be part of the audio circuit (only control), but I'm worried about interference being induced into other components.

Edited August 19, 2013 by Kerry

[chiguy]

I'm guessing a shielded transformer is out of the question due to its increased size?

[holland]

That's jamming a ton of stuff into there.  I would be concerned about noise, although I have to say that I am doing something similar for a Dynahi (original boards).

 

Are 2 box solutions out of the picture?  I would pull the trafos out, and the regulator for the attenuator (noise doesn't matter much here, I think).  That should free up lots of room.  I'm guessing that's not the goal.

 

Can you tap the AC for the 15V PSU and run it to a different 12V regulator?

[particleman14]

you should check the values of the 100k feedback resistors.

 

the only possible way that resistor could burn up is lots of current coming back from the

outputs thru wrong value feedback resistors, then thru the 200 ohm resistors.

 

Thanks Kevin!  So rechecking the amp boards and schematics, all feedback resistors are indeed 100k and feed into the 200ohms. the values on both boards are the same, and the symptoms on both boards seem identical.  I am unsure how to proceed at this point as all the values seem check out on the boards.  

 

I have some new parts coming in just to try something/anything, but this build has been giving me quite the headache as I can't seem to figure out the root cause of the symptoms.  

 

Still have that 10k resistor heating up too much and the peculiar uneven led lighting .http://www.youtube.com/watch?v=LcVCWShWCHc   pretty stumped by this one!  I'll try to get some hi res pics of the amp boards (maybe another set of eyes can help out as I've checked the board several times now but no luck!) 

[JoaMat]

/

Edited November 11, 2015 by JoaMat

[spritzer]

I'd leave them open and look for shorts on the boards. 

[particleman14]

Thanks guys! busting out the dmm this weekend and will be going over each trace!  I'll have an update and some pics hopefully by Sunday.

[Kerry]

I have music

 

I had one error on the silk.  Had a 2k resistor instead of a 1k coming out of the 1k trim pot.  I couldn't adjust to zero.  Changed it out and it works perfect.

 

I scratched the solder mask on one of the boards and wanted to cover it.  I haven't had to do that yet, but I'm thinking some clear nail polish should do (could someone please confirm).

 

I've tested each board but not both together.  I've got to make the second power connector to the board and wire up the input section.

 

Here's a picture of the amp running...

 

 

 

I tried it first on some electrets and then on my 404s.  Very nice so far.

 

I let it heat up.  The sinks got to 129 deg. F.  once I case it up I think it will do a bit better.  Sitting on the table doesn't help and I will have another 20 lbs of aluminum to help cool.

 

The STN9360 transistors only got to about 100 deg. F, so we're good there.

[GeorgeP]

Really great, Kerry! Can't wait to see it all cased up!

[justin]

looks great..interested to know what kind of noise figures you get once its all cased

[Kerry]

So far it is dead quiet.  I'm curious how the noise will be once it's cased up too.

[holland]

looks awesome.  nail polish works on regular stuff.  i don't know about high voltage though.

 

how do you measure stat amps?  i haven't built one yet, and don't have stats...though i do have pcbs coming.  i'll buy the stats after i build an amp.

[Victor Chew]

Nice work Kerry.   Looking forward to seeing the finished product.

[eggil]

Those are beautiful boards. 120 degrees is pretty hot. Good thing you are not in SoCal!

[chinsettawong]

Nice work Kerry.  

 

By the way, the clear nail polish works.   

Edited August 21, 2013 by chinsettawong

[johnwmclean]

Beautiful work Kerry, I’m enjoying the updates!

[deepak]

Very nice Kerry

[johnwmclean]

This is a bit of topic, as it’s in regards to my BH, but maybe still relevant for KGSSHV builders, and I didn’t want to make a separate thread for my query.

 

My BHs transformers are housed in a separate plastic box. The psu and amp boards reside in separate metal chassis.

Earth ground is connected to the amp/psu chassis via its umbilical from the transformer box.

 

I’m upgrading and building a metal box for transformers, so I will need to connect earth ground in this box.

Here’s my query... Do I need to also connect earth ground to the amp/psu chassis as well, via the umbilical?

 

I know for a Beta22 2 box build the amp box is not connected the ground earth, but this being high voltage I want to be 100% sure. 

[holland]

This is a bit of topic, as it’s in regards to my BH, but maybe still relevant for KGSSHV builders, and I didn’t want to make a separate thread for my query.

 

My BHs transformers are housed in a separate plastic box. The psu and amp boards reside in separate metal chassis.

Earth ground is connected to the amp/psu chassis via its umbilical from the transformer box.

 

I’m upgrading and building a metal box for transformers, so I will need to connect earth ground in this box.

Here’s my query... Do I need to also connect earth ground to the amp/psu chassis as well, via the umbilical?

 

I know for a Beta22 2 box build the amp box is not connected the ground earth, but this being high voltage I want to be 100% sure. 

 

I'm probably not in the group you're targeting but I'll respond.  I earth both.  It's electrical safety protocol.  Any exposed conductive parts (metal) should be earth'd so as to not electrocute anyone accidentally, in case of a fault.  Fault current needs to go somewhere, and that place should be the safety ground.  You also don't want the chassis to float to some other electrical potential and do weird things.

 

HTH.

[Victor Chew]

John, I think I see 2 issues here. Firstly, whether you need to ground the PAS/Amp to transformer box and second, if not through the umbilical via another route. As regards first issue, my KGSShv offbaord is built in the same manner as your BH, Transformer in one box and PSU/amp in another. I connected earth ground to the amp/psu chassis as well, via the umbilical. Reasons why I did so is because, apart from the safety issues, DC offset was higher (prior to grounding to transformer box) and was oscillating a fair bit and I was also getting some noise. After the grounding (to transformer box star ground), DC offset was stable with little oscillation and the amp was dead quiet when volume was at max, of course, without input signal.

 

As regards second issue, my onboard, also in 2 boxes, I use a separate ground wire and connect them to chassis screws. Not very nice looking and would have been much neater to use the analogue type female ground jacks. 

[GeorgeP]

The T2 has the amp section in one box and the PSU/transformers in the other, and if I recall correctly the amp section had 2 separate grounds (circuit and chassis) that went via the umbilical cord to the PSU box where everything was then essentially tied to the earth ground. Not sure that answers your question though, but I recall Kevin and others placing some emphasis on ensuring the grounding scheme was adhered to properly.