Smoking HOT X-BoSoZ HELP!

[steenoe]

?

where is the pic?

Just needed someone to want to see it Here you go, my oldest son (more or less my printed pic!!!) He is holding a very strong fish that we really respect...... After the pic was taken, it was duely released.... Like we do with every catch we make....

 

[anatech]

Hi Jason,
Did you ever get anywhere with this?

-Chris

 

[jleaman]

I'm actually hoping to order new 1.5k @ 3watt resistors soon, i have to place a F4 order list for resistors and stuff so i'm going to replace them then elivate them up higher, I did spend a while going over every soldering joint and did some touch up. I'm going to replace the resistors to some more measurements then post it.

I was going to ask a question, but it might be stupid, HOWEVER.. it might not be..


I was reminded that it is best to place the volume control after the output, so in therory when connecting the source, in my case a nice sony cd player with hi-output it would drive the pre-amp to full power. Now in stead of using a Volume pot i'm using a relay based volume control, i wonder if this is what caused the problem ? i have never heard of placing the volume pot on the out put, only on the input. I can't remember but i think it was explained, i was a little confused.

Could this be the problem ?

I do not have any shorts as i tripple checked every fet, i know for a fact i have no shorts to the chassis or between any fets.

Jase

 

[anatech]

Hi Jason,
I see an unbuffered volume control as next to useless. That's my opinion, your pot should be on the input.

Now in stead of using a Volume pot i'm using a relay based volume control, i wonder if this is what caused the problem ?

I'm not that familiar with this unit, but if it shorts to ground it may cause you grief.

-Chris

 

[Zen Mod]

Hi Jason,
I see an unbuffered volume control as next to useless. That's my opinion, your pot should be on the input.


I'm not that familiar with this unit, but if it shorts to ground it may cause you grief.

-Chris

it can't be a problem neither input or output shorting to ground

 

[anatech]

Hi Zen Mod,
Thank you for the diagram.

Where are the 1K5 resistors that get too hot??

-Chris

Edit: This just appears to be a beefy diff pair section without a VAS, just a cascoded diff pair.

 

[Zen Mod]

..............

Where are the 1K5 resistors that get too hot??

-Chris

.............

they're two in parallel...... in mosfet drains ;
in that schematic represented as 680E

Edit: This just appears to be a beefy diff pair section without a VAS, just a cascoded diff pair.

yup............. what else ?


EDIT:
ya know Papa- he crippled every stage he can .....

 

[mpmarino]

post 45-

that schem is quite easy to follow.

nice job

 

[Zen Mod]

post 45-

that schem is quite easy to follow.

nice job

somewhat simplified KK's commercial drek drawing , without colours;

I have somewhere later, final schm , how I tweaked his original rip off schmtc and pcbs

it was friend's ,not mine ;

zilch support , false values of some parts in schmtc , traces were peeling off after few desoldering, tiny pads for output caps etc.......

pattern was nightmare , nice lookin' pcb ( for amateurs) on top , hell from bottom.............

 

[jleaman]

I'm not sure if it shorts to ground or not, however i could take it out and try another type i'm thinking about purchasing the Russ & Brian one. I hope to order parts soon to test this out.

For now im running my aleph's with a passive pre-amp works flawless for now.

 

[Zen Mod]

I'm not sure if it shorts to ground or not, however i could take it out and try another type i'm thinking about purchasing the Russ & Brian one. I hope to order parts soon to test this out.

For now im running my aleph's with a passive pre-amp works flawless for now.

you deserve that or not , I'll tell you:
if everything is AS you wrote- that all mosfets and other parts are OK,just resistors are smoking, then you probably have sort of heavy positive bias on mosfet's gates.........

if attenuator is on input, disconnect it and check attenuator's output, regarding DC offset
so........ if I'm still invisible , let someone else quote me ;

it's never been easy to help you .

 

[flg]

And the 27 Ohm Source R Voltage =

 

[anatech]

Hi Zen Mod,
Thank you. Now I understand.

-Chris

 

[mpmarino]

let someone else quote me ;

The only Zen you can find on the tops of mountains is the Zen you bring up there.

Like this?

 

[jleaman]

And the 27 Ohm Source R Voltage =

Well i do have all the same parts as russ and brian are using, I even went over each resistor and checked.

 

[Blues]

For those waiting for jleaman, you can also check out Eric Clapton's Crossroads live concert on msn.com

Now playing: Buddy Guy!

 

[anatech]

I think Jason has his hands full. No reason to rush him. Mistakes happen this way.

It's Saturday night here. I expect Jason will need a few days to get his parts.

Jason, while you are waiting, please check to make sure your mosfets are still okay and not damaged. Retest for a matched set.

The fault that people can not solve is the fact they did not confirm. So test everything and write it down, check it or list the result when it's been tested.

-Chris

 

[jleaman]

I think Jason has his hands full. No reason to rush him. Mistakes happen this way.

It's Saturday night here. I expect Jason will need a few days to get his parts.

Jason, while you are waiting, please check to make sure your mosfets are still okay and not damaged. Retest for a matched set.

The fault that people can not solve is the fact they did not confirm. So test everything and write it down, check it or list the result when it's been tested.

-Chris

Yup i did this fets are all ok, that is the first thing i did, ill see if i can get some resistors. put them in then measure for you..

Jase

 

[Vix]

i have never heard of placing the volume pot on the out put...
...
Could this be the problem ?

Jase

Jase, maybe you should have a look at the original BOZ and Bosoz articles. Shorting inputs, or outputs, as already mentioned, can't be a problem. If you have troubles with volume pot on the output, you could put in on the input. However, you must add a buffer, so the pot position does not influence the amount of NFB.

 

[Vix]

you deserve that or not , I'll tell you:
if everything is AS you wrote- that all mosfets and other parts are OK,just resistors are smoking, then you probably have sort of heavy positive bias on mosfet's gates.........

if attenuator is on input, disconnect it and check attenuator's output, regarding DC offset
so........ if I'm still invisible , let someone else quote me ;

it's never been easy to help you .

Easier?