Help please with my poorly Stasis 2

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#203
william2001 said:
With setting up an amp you will want two multimeters to watch the behavior. You need to look at 2 critical voltages at the same time as you slowly and carefully bring things to life. One meter connected to monitor the DC offset on the output (we want zero volts), and the other meter across one of your emitter resistors in the output stage to monitor the voltage across and hence the current through, calculated with ohm's law. P1 is the DC offset adjustment and P2 will establish how much current is flowing through the output stage. But go slow and understand what is going on so that you don't burn something (or many something's) when this thing wakes up.
Click to expand...
I’ve now bought an additional dmm
 
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#204
Good. I use some leads with small alligator clips on the ends to clip onto what I'm trying to measure. Some short jumper wires with alligators or spring clips on both ends work fine also. The point is, you don't want any slips when doing this... Slip = sparks = failed / damaged components = sadness and disapointment
 

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#205
all you need to change for Wakoo rails

changes in red

all resistors normal MF 0207 size, except those noted 3W

R29 changed to stay alive, while value set to have same currents through D5 and (D1+D2)

3W - don't want to touch their value, sorta hot-more current needed to keep OS cascodes firmly

transistors changed for more voltage capable ones

Q8 - no need to change - you can use 3MV rails, that one is always seeing same voltage

Q9 - same criteria, but why not changing it, counting on possibly greater current peaks with higher rails






STASIS-FE-REV-SCH-for-73Vdc.jpg
 
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#207
Zen Mod said:
all you need to change for Wakoo rails

changes in red

all resistors normal MF 0207 size, except those noted 3W

R29 changed to stay alive, while value set to have same currents through D5 and (D1+D2)

3W - don't want to touch their value, sorta hot-more current needed to keep OS cascodes firmly

transistors changed for more voltage capable ones

Q8 - no need to change - you can use 3MV rails, that one is always seeing same voltage

Q9 - same criteria, but why not changing it, counting on possibly greater current peaks with higher rails






View attachment 1277264
Click to expand...
You are THE man Zen . Very much appreciated, I will order those now .

Andy
 
#208
Zen Mod said:
all you need to change for Wakoo rails

changes in red

all resistors normal MF 0207 size, except those noted 3W

R29 changed to stay alive, while value set to have same currents through D5 and (D1+D2)

3W - don't want to touch their value, sorta hot-more current needed to keep OS cascodes firmly

transistors changed for more voltage capable ones

Q8 - no need to change - you can use 3MV rails, that one is always seeing same voltage

Q9 - same criteria, but why not changing it, counting on possibly greater current peaks with higher rails






View attachment 1277264
Click to expand...
I’m now struggling to find some of these components, might be that I’m inputting the wrong search term or something.
Tried mouser and digikey for the : 8k 2.1w resistors, 8k 2w , 1k 5.3w and gone no further as nothing is coming up 🤷‍♂️
I’ve found the ztx transistors ok and the heatsinks.

I need :
2 x 27k 0.5w resistors ( found these )
2 x 8k 2.1w
2x 8k 2w
2x 1k 5.3w
4x 1k 3w
8x 1k 5.3w

Sorry if I’m a dumb **** 😁
 
#209
Hi Andy,
I am at a friends place and able to log on.

You already have the 1K and 1K5 3watt resistors on the board.

So you just need :

27K 0.5W
8K2 0.5W
8K2 1W
ZTX transistors and TO92 heatsinks.

Search metal film resistors and select resistance value, wattage and 1% tolerance in the search table, it should come up with lots of options for you.

Gary.
 
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#211
gary s said:
Hi Andy,
I am at a friends place and able to log on.

You already have the 1K and 1K5 3watt resistors on the board.

So you just need :

27K 0.5W
8K2 0.5W
8K2 1W
ZTX transistors and TO92 heatsinks.

Search metal film resistors and select resistance value, wattage and 1% tolerance in the search table, it should come up with lots of options for you.

Gary.
Click to expand...
Gary to the rescue again 👍🏻
 
#214
TheFinisher said:
I’m now struggling
Click to expand...

Gary already saved you

Though, for your further reference - when you read "MF 0207", that means metal film resistor, body 2mm Dia, 7mm Length

various manufacturers are claiming 0207 having anything from 250mW to 600mW, and there are even 1W made of same size

in praxis - at least to me - it's all the same (except 1W), simply because I'm rarely putting more than 100mW through 0207

8K2 can be easily made of series 3K9 and 4K3, 0207, and you'll have enough Cojones that way

current is (73V-9V1)/8K2=7.78mA

thus heat is 7.78mA^2*8K2= 0.5W

so, for these, take either 8K2/1W or said two in series, certainly declared as 600mW each
 
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#217
Hopefully you all know at what point of the powering on I was at ( I was about to adjust the P2 pot ) the p2 pot was set at maximum resistance before powering up and I was to adjust it whilst my dmm was connected to the emitter resistor ( #9 on the heatsink ) but when turning the screw on the pot nothing happened, would this have been because a: R29 burnt out or b: the other components that I’m yet to replace were causing the issue?
or C: something else is wrong?
I have since tested the P2 pot again and it is working ie: I can still adjust its resistance.
 
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