Member buzzforb shared a link to a paper comparing resistors and their noise:
https://dcc.ligo.org/public/0002/T0900200/001/current_noise.pdf
https://dcc.ligo.org/public/0002/T0900200/001/current_noise.pdf
Please help:
Hello,
I’ve acquired a blue FSP assembled for MM from a member in Portugal. At the moment it’s undergoing transformation to Low MC maximum gain settings. I’ve changed Q1, Q2 quad with corresponding R2, R3 5R resistors. R13 also changed into 1.2k
One channel biases perfectly to TP 3.6V and 34.6V rails respectively.
Alhough the other is a little more stubborn.
VR2X is not changing rails voltage at all no matter how many turns I make. It stands stable at 30.5V. While with VR1 I have managed to trim the TP from 7V to 6.1V maxing out the turns.
VR2X is marked with T63YA 1210 2k2. It doesn’t make any maxing out clicks when turned on a bad channel, while on the correctly biased one – it does.
Could it be the culprit?
Incoming DC is 51.6V on both channels.
Hello,
I’ve acquired a blue FSP assembled for MM from a member in Portugal. At the moment it’s undergoing transformation to Low MC maximum gain settings. I’ve changed Q1, Q2 quad with corresponding R2, R3 5R resistors. R13 also changed into 1.2k
One channel biases perfectly to TP 3.6V and 34.6V rails respectively.
Alhough the other is a little more stubborn.
VR2X is not changing rails voltage at all no matter how many turns I make. It stands stable at 30.5V. While with VR1 I have managed to trim the TP from 7V to 6.1V maxing out the turns.
VR2X is marked with T63YA 1210 2k2. It doesn’t make any maxing out clicks when turned on a bad channel, while on the correctly biased one – it does.
Could it be the culprit?
Incoming DC is 51.6V on both channels.
There's possibly a problem in the non adjusting channel's power supply. Compare Vgs in Mosfets & JFETs as well as Vbe in transistors between the two shunt regulators when on. To find broken semiconductor(s) if any. Unless it's the trimmer itself. You can measure if the trimmer changes value with the Ohm meter when off.
You can't use it in this state. The non adjusted channel will be either distorted or muted. You can copy the set value of the working VR2X and replace the faulty one with a near there resistor at pins 1,3 for the time being. To hopefully have an about good test point reading until finding a new 2K trimmer.
The closest i can find in my country is this:
Adjustable multiturn resistor T93YB 2,2K R*T93YBK002.2
would it be ok changing both or even one faulty trimmer using this T93 model?
Adjustable multiturn resistor T93YB 2,2K R*T93YBK002.2
would it be ok changing both or even one faulty trimmer using this T93 model?
Thanks a million for all the help! One final tweak that needs to be done is input impedance as i'll be using a Denon 103 cartridge. Do i need to change two pairs of input resistors or only one, and which slots exactly? As there are two pairs of Z-foil 47R installed in slots R1 & R14 at the moment (MM setting).
so i should remove R1 & R14 and install Rx1 400R and set the jumper on S1 correct?
An externally hosted image should be here but it was not working when we last tested it.
