Forums
New posts
Search forums
What's new
New posts
Latest activity
Members
Registered members
Current visitors
Log in
Register
What's new
Search
Search
Search titles only
By:
New posts
Search forums
Menu
Log in
Register
Install the app
Install
Audio and Video Talk
Valves / Vacuum Tubes
Gunter Steinhart tvp-77ul
JavaScript is disabled. For a better experience, please enable JavaScript in your browser before proceeding.
You are using an out of date browser. It may not display this or other websites correctly.
You should upgrade or use an
alternative browser
.
Reply to thread
Help Support AVForums:
This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
Message
<blockquote data-quote="fredeb" data-source="post: 1055861" data-attributes="member: 13623"><p>I have a sneaking suspicion that the resistor you have to replace is the 4.7ohm cathode resistor . You may as well replace them all with 5w wirewound types . Buy 10 , measure them all and use the 4 closest matching ones . To bias output tubes you read the voltage over those resistors . Should read 600mV .</p><p></p><p>I = V/R or Current = Voltage divided by Resistance</p><p></p><p>So ... 0.6V ? 4.7ohm = ~127mA</p><p></p><p>Each tube is biased to 127mA</p><p></p><p>If you want , you can replace those 4.7ohm resistors with 10 ohm resistors and adjust bias to 1.27V </p><p></p><p>1.27V ? 10 ohm = 127mA , just easier to calculate in your head.</p><p></p><p>Good to learn these things , then you can do it yourself .</p></blockquote><p></p>
[QUOTE="fredeb, post: 1055861, member: 13623"] I have a sneaking suspicion that the resistor you have to replace is the 4.7ohm cathode resistor . You may as well replace them all with 5w wirewound types . Buy 10 , measure them all and use the 4 closest matching ones . To bias output tubes you read the voltage over those resistors . Should read 600mV . I = V/R or Current = Voltage divided by Resistance So ... 0.6V ? 4.7ohm = ~127mA Each tube is biased to 127mA If you want , you can replace those 4.7ohm resistors with 10 ohm resistors and adjust bias to 1.27V 1.27V ? 10 ohm = 127mA , just easier to calculate in your head. Good to learn these things , then you can do it yourself . [/QUOTE]
Insert quotes…
Verification
Post reply
Audio and Video Talk
Valves / Vacuum Tubes
Gunter Steinhart tvp-77ul
Top