Hello to all,
I'm looking for help regarding which bias trimmer resistor replacements (RT301 & RT351) to purchase as the original carbon trimmer resistors are no longer available for Sony ta-n55es power amp.
The sony part number (1-237-455-11) in the service manual only states that the resistance of the trimmer is 500 ohms , now i don't know the power rating as this is not stated.
Should i purchase a 0.5w bourns 25 turn pot to replace these or do i need extra power rating ??
Can anybody who has done the repairs on the TA-N55ES or similar amp help me with which part to purchase to replace?
Its really annoying the Sony do not include the power rating for the said parts, unless its not important ?
Thank you in advance.
I'm looking for help regarding which bias trimmer resistor replacements (RT301 & RT351) to purchase as the original carbon trimmer resistors are no longer available for Sony ta-n55es power amp.
The sony part number (1-237-455-11) in the service manual only states that the resistance of the trimmer is 500 ohms , now i don't know the power rating as this is not stated.
Should i purchase a 0.5w bourns 25 turn pot to replace these or do i need extra power rating ??
Can anybody who has done the repairs on the TA-N55ES or similar amp help me with which part to purchase to replace?
Its really annoying the Sony do not include the power rating for the said parts, unless its not important ?
Thank you in advance.
I have had a N55. A 0.5W potmeter is sufficient.
One can calculate the exact power rating if a circuit drawing is available.
If the bias current is, say, 10mA, potpower is (10E-2)exp2 * 500 = 0.05W.
One can calculate the exact power rating if a circuit drawing is available.
If the bias current is, say, 10mA, potpower is (10E-2)exp2 * 500 = 0.05W.
Thank you Marbravo for your reply and help 🙂
Would you replace with a single turn pot or multi ?
The pin layout is important too.
Would you replace with a single turn pot or multi ?
The pin layout is important too.
The power rating requirement is minimal, the bias current is not flowing through that pot, only the bias network current, which is a lot less than that stated 10mA.
A 25-turn pot is probably a better quality pot than a single turn one.
If it fits physically, then it should be OK.
Peter
A 25-turn pot is probably a better quality pot than a single turn one.
If it fits physically, then it should be OK.
Peter
Thank you both for your reply , its greatly appreciated 🙂
The pin orientation is important , so i would need to identify the pins for the new replacement pots are of the same orientation as the original carbon pot.
There are 3 terminals on the original pot.
The pin orientation is important , so i would need to identify the pins for the new replacement pots are of the same orientation as the original carbon pot.
There are 3 terminals on the original pot.
Thank you both for your reply , its greatly appreciated.
The pin orientation is important , so i would need to identify the pins for the new replacement pots are of the same orientation as the original carbon pot.
The pin orientation is important , so i would need to identify the pins for the new replacement pots are of the same orientation as the original carbon pot.
Between two pins you will measure 500Ω independent of the position of the wiper. Notice where these fit in the pcb. Make a drawing of it. 90% change that the middle one is the wiper.
10mA if no 'rubber zener' is used, otherwise as stated by orbanp in #4.
If so, 0.1mA is running through the trimmer. Yields 0.000005W
10mA if no 'rubber zener' is used, otherwise as stated by orbanp in #4.
If so, 0.1mA is running through the trimmer. Yields 0.000005W
