The fuse location works. But I don't like it.
Instead drill out the ends of an old fuse and insert a 1r0 1% resistor and re-solder the ends.
Insert those into the LV fuse locations and measure the voltage drop across each resistor.
This gives the total quiescent current, not the output bias current.
You can measure the voltage drop across the Output Source resistors and convert that to currents for each device.
But the tolerance of those resistors is probably +-10%
You could remove them and match them up to 0.5%, to make source resistor measuring more accurate.
Instead drill out the ends of an old fuse and insert a 1r0 1% resistor and re-solder the ends.
Insert those into the LV fuse locations and measure the voltage drop across each resistor.
This gives the total quiescent current, not the output bias current.
You can measure the voltage drop across the Output Source resistors and convert that to currents for each device.
But the tolerance of those resistors is probably +-10%
You could remove them and match them up to 0.5%, to make source resistor measuring more accurate.
Yes sorry, not been on here for a year nearly and I am using a mix of iPhone and laptop lol, just having my tea in Kilmarnock premier inn, I stay away from home in Scotland all week!!
Thanks again on the great info my friend 🙂
Thanks again on the great info my friend 🙂
275mA through 1r0 is <76mW
You could use 250mW, or 400mW, or 500mW, or I use 600mW metal film for almost everything.
You could use 250mW, or 400mW, or 500mW, or I use 600mW metal film for almost everything.
Are you ever on the east side?
And I had to find a use for the box of 1000 1r0 I bought.
I'm only half way through them.
And I had to find a use for the box of 1000 1r0 I bought.
I'm only half way through them.
I cover the whole of Scotland, I am going to wick and Orkney wed, Thursday lol!!
Couldn't spare me a couple could you haha!!
Kindest Regards
Danny
Couldn't spare me a couple could you haha!!
Kindest Regards
Danny
When I didn't know what I was doing as regards Q C, I set the voltage on the first pin on MOSFET to 0.150mv what would that be in milliamps? Any idea lol, I wish I had more brains on what am doing inside amps!!!
I seem to remember that the Source Resistors and the output resistor are all 0r22, the black wirewounds. Maybe 1W devices.
Check your resistances.
Check your resistances.
Hi Andrew, and good morning.
How do I convert the voltage to mA if I read off the resistors?
Sorry if it seems like a silly question
Regards Danny
How do I convert the voltage to mA if I read off the resistors?
Sorry if it seems like a silly question
Regards Danny
They are the black wirewounds in my amp! Are they bad! And are they bad for braking down??
Regards
Danny
Regards
Danny
Hi me again!!
If you could send me any info I may need regarding setting up and best parts to replace on my sugden p128 monos, please email me if its easier on bdanny77atyahoo.co.uk
All info greatly received!
Very Kindest Regards to Andrew and all on the forums
Danny
If you could send me any info I may need regarding setting up and best parts to replace on my sugden p128 monos, please email me if its easier on bdanny77atyahoo.co.uk
All info greatly received!
Very Kindest Regards to Andrew and all on the forums
Danny
Use Ohm's law.
V = I*R
or re-arranged to
I = V/R
This is a far better method than using an ammeter inserted into a circuit.
The black wirewounds are good and reliable.
But their values could be anywhere in that +-10% tolerance range.
I always select any paired resistors so that later measurements can become useful.
It's no good measuring the imbalance in emitter current of an LTP pair using the degeneration resistors for Vdrop if the resistors are at either end of the +-1% tolerance.
Similarly the output Source resistors can easily be selected to better than 1% total range (+-0.5%) and with care better than 0.1% total range (+-0.05%).
Absolute accuracy is unknown and unimportant.
V = I*R
or re-arranged to
I = V/R
This is a far better method than using an ammeter inserted into a circuit.
The black wirewounds are good and reliable.
But their values could be anywhere in that +-10% tolerance range.
I always select any paired resistors so that later measurements can become useful.
It's no good measuring the imbalance in emitter current of an LTP pair using the degeneration resistors for Vdrop if the resistors are at either end of the +-1% tolerance.
Similarly the output Source resistors can easily be selected to better than 1% total range (+-0.5%) and with care better than 0.1% total range (+-0.05%).
Absolute accuracy is unknown and unimportant.
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Hi Andrew and thanks for the info above and email! Did you get chance to find any links for me yet, there is no rush at all though, as will not be finishing them off till Sunday / Monday.
Regarding the ohms law math, is * times and / divide?
Also regarding reg to 0r1 resistors did you say use them so the voltage would be straight convert into mA?? As voltage divided by 0r1 would be the some figure yes??
Why is this so hard for me to grasp! I have been into messing with hifi since I kid for god sake!! Lol
Kind Regards
Danny
Regarding the ohms law math, is * times and / divide?
Also regarding reg to 0r1 resistors did you say use them so the voltage would be straight convert into mA?? As voltage divided by 0r1 would be the some figure yes??
Why is this so hard for me to grasp! I have been into messing with hifi since I kid for god sake!! Lol
Kind Regards
Danny
This weekend at some point i will be installing new multi-turn 10k and 500r pots for QC and DC offset, new mains cables as old ones where really thin!!! New Blue neons for front panals, Fancy new Gold speaker binding posts, Fancy new Silver Input sockets plus internal Platinum input cable and new speaker cable of good quality 🙂 then set them up bob on!!
then enjoy my new, good old Sugden P128.
Will upload pics if i ever find out how to!!
Full re-cap and some other parts plus connectors etc about £160 dont think thats to bad really do you?
Regards to All
Danny
then enjoy my new, good old Sugden P128.
Will upload pics if i ever find out how to!!
Full re-cap and some other parts plus connectors etc about £160 dont think thats to bad really do you?
Regards to All
Danny
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