i'm on a roll... the kgsshv

[GeorgeP]

Thanks for the advices.

I think it's also worth to note that the first fuse blew during operation. I left it on during night because I was listening to it before I went to sleep and forgot to turn it off (not the first time.) When I woke up, the amp was off and the fuse was blown. I was also using 3A fuse tho with two thermistors in series to get the surge down. I was blowing through 3A fuses with only one thermistor. I used 4A this morning because I couldn't find the 3A fuse...

The trafo was speced using Yun's BOM. 450V @ 125mA IIRC. There was always very faint hum with it, but I had to have my ear within inches of it to hear it. There was not loud hum whatsoever. ( It was humming loud this morning tho... I could hear it clearly standing 2 feet away from it.)

Not going to add more skepticism now.. I'll report back when I have tested it.

 

Did you happen to measure the offsets the second time your fuse blew? Curious to know whether one of them was sitting in the 400v range. If your traffo turns out to be fine you might want to sacrifice another fuse just to see (though there must be some type of short somewhere to blow the fuse).

[jwzhan]

Did you happen to measure the offsets the second time your fuse blew? Curious to know whether one of them was sitting in the 400v range. If your traffo turns out to be fine you might want to sacrifice another fuse just to see (though there must be some type of short somewhere to blow the fuse).

 

I just unplugged it from the circuit and tested it... exactly the same thing happened except this time it happened even faster. It blew through the fuse almost immediately. The secondaries shot up to 300V and died. Also, there was that burnt smell and loud humming again.

I'll use a low voltage trafo and the LTSpice model to check if there are any damages to the main circuit.

I guess SumR does suck... and I retract what I said earlier in the therad about having problem with everything except the SumR... I now have had problem with every single component the in the amp.... (I must have jinxed it.  )

Edited October 11, 2013 by jwzhan

[RiStaR]

May be hard to spot, depending if you have the onboard or offboard - but maybe check the 25 ohm resistors? This is the resistor that burnt out for me on the amp board (it took out an LED along the way or the other way round?) when I initially got it up. It's hard to spot/access between heatsinks for the onboard version

 

Mine has been running fine daily since replacing those.

 

Good luck!

[jwzhan]

hmm... burt smell is definately from the trafo... it wasn't even connected to the circuit when I tested it the second time... and I've had resistor burn problem... it didn't smell anything that strong..

[GeorgeP]

May be hard to spot, depending if you have the onboard or offboard - but maybe check the 25 ohm resistors? This is the resistor that burnt out for me on the amp board (it took out an LED along the way or the other way round?) when I initially got it up. It's hard to spot/access between heatsinks for the onboard version

 

Mine has been running fine daily since replacing those.

 

Good luck!

 

 

That was what I was thinking, but sounds like it is probably his traffo.

[eggil]

I have used SumR also but haven't had any problems. Yet

Left mine on all night by mistake and no problems.

The question is, who to order future trafos from.

[RiStaR]

I'm using a Toroidy that hasn't given me any problems, but its only been just under a year of daily use. Got it from a fellow forum member here.

[livewire]

I have used SumR also but haven't had any problems. Yet

Left mine on all night by mistake and no problems.

The question is, who to order future trafos from.

 

Sometimes ya get lucky.

Just curious, what is the current rating of your SumR?

Are you using inrush protection?

(sorry, didn't feel like reading back)

[eggil]

450x2 125 mA

15-0-15

No inrush protection

[jwzhan]

I sent an email to SumR regarding it. His answer did not instill confidence. He basically said he is now in the 4th (2013) edition of the trafo.. and he has made it overkill and it won't happen again.. Sounds familiar? I'm probably not going to get anothet HV trafo from them now..

eggil... I really do hope you got lucky.. because it sucks not to have an amp:(

[Pars]

Is Richard (SumR) handling these faulty trafos, or do you have to buy a new one from him? Doesn't sound good, whatever.

[jwzhan]

well... he did not suggest replacing it. The trafo was ordered Aug 2012, so it's just a little over a year. I wasn't expecting him to replace it anyway.

He was actually a little defensive when I told him that I just burned through his trafo and suggested to reinforce any future HV trafos..

It's because of his attitude that made me not want to buy more HV trafo from him... I know he definately can make high quality trafo that can withstand the abuse from these demanding amps... but I'm not sure he will, given his attitude.. Especially when he is already on the 4th edition trying to overcome the issue that has been present for a couple of years already.

I have my doubts on the 4th edition trafo, so my replacement will not be from him. I don't know who to buy from yet.. Palchiu is kind enough to lend me his 450V 150mA trafo for now; however, that trafo runs on 110V, not US 120V, so it might result in too much heat. But if it's good enough, I might just get a 120V version from whoever he is getting his trafo from.

Edited October 11, 2013 by jwzhan

[palchiu]

jwzhan,

 

Trafo's input voltage is set@115V, We're used same voltage as US.

[eggil]

And where did you get it from?

[palchiu]

And where did you get it from?

 

My power transformer?

[eggil]

yes

[nopants]

Seems more relevant to chime in here than the other thread, but I've noticed my megatron transformer from SumR started humming, which has turned into a buzz. Maybe I'm running it too hard? I used the specs from Tran's page: 

 

Pri: 110v/220v. Sec: 2x 420v/130mA, 16v-0-16v/500mA

[palchiu]

yes

 

Mine was custom order from a local transformer factory.

[insanity]

Guys looks like I have to bother you with another question. 

 

After moving the amp to another room to do a provisional listening setup until I manage to case everything up, a hum developed on the right channel. I still hear music on that channel, there is just a medium loud hum. When I disconnect the inputs and short them to ground, the hum is not noticeable anymore. 

 

Does this speak for a grounding problem, or could the input j-fets or anything else be broken?

 

Edit: If this helps: The hum gets louder shortly, when I power off the amp (this has something to do with servo, as the  Led D1 also lights up a bit more when powering off - but this is the same on both channels and not cause of the problem).

Edited October 12, 2013 by insanity

[livewire]

Sounds like it could be a grounding issue.

Move it back and see if the problem goes away (or not?)

[spritzer]

The SumR unit in my first KGSSHV blew up so Richard sent me two replacements to see what the hell is going on.  I'm working on getting them through customs now without it costing an arm and a leg. 

 

Seems more relevant to chime in here than the other thread, but I've noticed my megatron transformer from SumR started humming, which has turned into a buzz. Maybe I'm running it too hard? I used the specs from Tran's page: 

 

Pri: 110v/220v. Sec: 2x 420v/130mA, 16v-0-16v/500mA

 

That is too low for a Megatron.  I'd go with 420V/200ma as you are driving 8 EL34's.  How hot is the transformer at full load? 

 

I'll probably use a 2*335V/200mA Edcor transformer as I have a few sitting here and running it at +/-400V is a good idea in my book.  Less heat and all that... 

[nopants]

It gets somewhat hot, nothing crazy. However, it's encapsulated so that probably obscures my perception somewhat. This was using it in the open, I just shoved it into something loosely resembling a case. I'll get back to you with a number when possible. 

[insanity]

Sounds like it could be a grounding issue.

Move it back and see if the problem goes away (or not?)

after moving everything around a bit, the hum is still there. I noticed that even when I ground the inputs via 250ohm resistors, the hum shortly returned during the described turn off phase. I even switched the position of the two boards and the hum goes with the board. I think that makes a grounding issue very unlikely.

 

Furthermore the "hum" sounds a bit rougher than the classical 50hz hum we get to hear in grounding issues. 

Is there any particular device you would start on checking/replacing? Rather inputstage or output? The fact that grounding the inputs reduced the problem, make me think it is more input related.

 

Thanks

Edited October 12, 2013 by insanity

[insanity]

Looks like my nose (with a bit unexperienced brain) was right. Replaced the lsk389 and the adjacent mpsw06 and the problem is seems solved.

[jwzhan]

I sent Richard another e-mail, and he said replacing the trafo for me is fine. (Maybe I mis-interpreted his tone in the last mail?) He also asked me to provide some detail. Why not, I guess it doesn't hurt to have a HV trafo for back up. We'll see if it will be strong enough.

 

@insanity congrats on solving the problem.