ZM, I’m grateful for the help.aha
yup , problem often is my multitasking
in fact , I am the problem , due to multitasking
just confirm - you're having 0R47 resistor mounted now ?
Welllll, very good question. Yesterday morning I would have answered yes. But after spending some time measuring and pre-checking everything in the afternoon, I noticed I had bought, and stupidly installed, 0R.47 resistors.
So the correct ones are on the way.
No short answer, in a couple days I will have 0R47’s mounted.
In a couple of days I will be installing the correct 0R47 5w resistors.well , now I'm confused .....
is that a typo , for my eyes (what you wrote ) 0R.47 is pretty close to 0R47 (means 470m)
what you really meant to type ?
Would the Babelfish J be happy with 18 V rails? I need a summer amp and a mini Aleph J was the plan but the Babelfish has cascodes and that seems interesting. No rush on this as I do have a backlog of projects but I am retiring the end of this summer and expect to find time to clear up that backlog over the next year.
ZM, I guess I picked the wrong week to stop sniffing glue (movie reference)!!
I don’t know what I was thinking yesterday. I have the correct 0R47 resistors soldered in.
Below is a marked up schematic of what is soldered in now. Can you take a look and let me know what needs changed? Looks like I’ve taken some values from two different schematics.
I don’t know what I was thinking yesterday. I have the correct 0R47 resistors soldered in.
Below is a marked up schematic of what is soldered in now. Can you take a look and let me know what needs changed? Looks like I’ve taken some values from two different schematics.
Enlarge thumbnail. Press right button on mouse and drop down menu opens: 'save to desktop' from drop down menu. Saves on my iMac {OS 10.11.6} as a .jpg
ZM:
That is one hell of a good logo!
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here it is , finally ;
look at attached schm , I believe I edited everything ;
note - input JFets doubled , doubled current through them (LTP) , BD140 cascodes instead of eeenyweeeny BC critters
few resistors marked as 1W - you can easily buy metal oxide ones , tiny as regular 600mW metal-films ; up them smidge above pcb
for more necessary info about general approach (how to connect Daughter boards , recipe for eternal life and no need for Viagra ....) read these posts:
#21 (important Snake Oil notes)
#80 (how to actually do it ; imagine 2 daughter boards per side , paralleled)
Greedy Boy Coasttocoast asked for something with 38Vac rails ........ that would be aroundish 47-48Vdc
same applicable
Boyz - you're nutz ........ who need that sort of power ?
I’m not sure how I got sideways/confused, so best to go back to the beginning.
I received the balance of resistors I needed and swapped everything to exactly match this originally provided schematic to match my original power supply.
Been really giving my Hakko 808 some good use!
Here is a pic of the completed board. In wanting to stay with all PRP resistors I had to get a little creative with the 3ea 1W ones.
Going to put some power to it later today when I get back home and see what happens!
give me few hours and I'll post schematic I promised (or triple check already posted , whatever)
got sidetracked these days ......... you know - that thing Muggles calling real life
Oh great! Thanks for taking the time to help me.
Lazy ZM
see enclosed (repeated) schematic
looking at it , I can see that I didn't made (miracle!) any serious mistake ...... but looking at pic of your pcb , I see that YOU made few ....
most important thing(s):
-source resistors for 6 pairs of outoput mosfets , as I marked them , are 1R ..... and you change them to 0R47 ; OK with me ......
-now , BIG BUT! : according to source resistors of 1R , 6 of them in each half , demands that in SENSE group ( resistors in series with output) we have 6pcs of 0R47 , or 12pcs of 1R ........ practically half value of all source resistors (in one half) paralleled ........ and that is your mistake , as far I can see from pics..... you have too few of 0R47s in SENSE group
-Conclusion - if you have 6 mosfet vertical pairs ,each mosfet having 0R47 source resistor , in SENSE group you need to have either 12 paralleled 0R47 , or 6 paralleled 0R22
had few mishaps with values of trimpot and resistor in input JFet drain , corrected , red marked
rest is OK
see enclosed (repeated) schematic
looking at it , I can see that I didn't made (miracle!) any serious mistake ...... but looking at pic of your pcb , I see that YOU made few ....
most important thing(s):
-source resistors for 6 pairs of outoput mosfets , as I marked them , are 1R ..... and you change them to 0R47 ; OK with me ......
-now , BIG BUT! : according to source resistors of 1R , 6 of them in each half , demands that in SENSE group ( resistors in series with output) we have 6pcs of 0R47 , or 12pcs of 1R ........ practically half value of all source resistors (in one half) paralleled ........ and that is your mistake , as far I can see from pics..... you have too few of 0R47s in SENSE group
-Conclusion - if you have 6 mosfet vertical pairs ,each mosfet having 0R47 source resistor , in SENSE group you need to have either 12 paralleled 0R47 , or 6 paralleled 0R22
had few mishaps with values of trimpot and resistor in input JFet drain , corrected , red marked
rest is OK
Attachments
Fantastic! We are getting close. Thanks for looking this over and being patient with me.
Please indulge me a couple more questions.
So I need to swap out TP1, 20 Ohm trimpot with a 200 Ohm trimpot, and change R7 to 390 Ohm.
On the daughter boards I have 1 Ohm/3W resistors and a 180 Ohm resistors for each mosfet.
On the front end board I have OR47’s for positions R31-R36. So I need to swap these out for 1 Ohm?
Thanks
TP1 was marked as 500R , now going to 200 ..... though - you can leave 500 in , just having less turns to fiddle with
having 1R on daughterboards (that's my bad , I understood that you have them ALL 0R47) , leave those 0R47s on main board and do not touch source & sense resistors at all
remember ........ as I wrote in previous post - if you have 6 of 1R under mosfets , you need half of that in SENSE group ....... and that's exactly 6 paralleled 0R47s
so , to repeat - now I have necessary info that I can say that source and sense resistors are good
having 1R on daughterboards (that's my bad , I understood that you have them ALL 0R47) , leave those 0R47s on main board and do not touch source & sense resistors at all
remember ........ as I wrote in previous post - if you have 6 of 1R under mosfets , you need half of that in SENSE group ....... and that's exactly 6 paralleled 0R47s
so , to repeat - now I have necessary info that I can say that source and sense resistors are good