Bias rocket 88.

Pål gundersen

Pål gundersen

Hi-Fi freak
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Skal sjekke bias på en rør forsterker. Den skal justeres til 200ma. (Egen stereo Jack hun kontakt på ampen) Har en eldre fluke 112 men den er det ikke Ma på. Kan jeg måle det med DC volt? Eller må jeg ha ett multi meter med Ma? (Milliamphere) Ikke noen ekspert på sånne rør forsterkere🤪
 
HasseBasse

HasseBasse

OVK-Generalkonsul of Jutland :-)
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Hjortshøj, Danmark.
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  1. Disconnect the speaker cables and the input RCA or XLR cables from the input jacks.
  2. Connect the provided Bias Cord into the bias connection jack. (If you have the Cary Audio MA-300 bias meter then skip to step 4.) It has a 1/4 inch mono ‘phone plug’ on one end and a pair of alligator clips on the other end. Plug the phone plug into the jack on the chassis. The red alligator clip is for positive electrical connections, the black one is for negative electrical connections on the milliampere (mA) meter.
  3. Set your meter to the DC milliamperes (mA) reading range. NOT to the MilliVolts (mV) range!
  4. Turn the bias adjustment screw on the chassis all the way counterclockwise so that the meter will read zero (or close to it) when you turn the power on. Some amplifiers will not go to complete zero.
  5. Turn on the amplifier power and wait 1 minute for the voltages to come up and warm up the tubes.
  6. We are not going to adjust the bias to its full recommended setting yet. Set it to about 10ma lower than needed as the bias will climb as the amplifier warms up and we don’t want it to go over the recommended setting. This also helps to put a gradual load on new tubes and allows them to warm up. Now SLOWLY turn the bias adjustment screw clockwise while you watch the meter for the correct mA reading. Now unplug the bias meter plug from the bias jack and move the meter’s plug to the other channels bias jack if this is a stereo amplifier. You will need to move the meter back and forth adjusting the bias a little at a time until set correctly. Using two meters is very helpful here.
  7. Let the amplifier run without an input signal for another 5-10 minutes and check it again. Readjust now to the recommended bias setting. You can find the recommended bias setting in your product’s owner’s manual. Adjust both channels until they each have the same reading.
  8. After another 5 to 10 minutes check and readjust the bias setting again, if necessary. New output tubes should be checked a couple of times in the first two weeks as they ‘burn in’ to their normal operating mode as they may keep changing over time. After that, check them within a month and then every 2-3 months just to be sure all is well.

    For bedre levetid på rørene, sett i unnerkant av annbefalet (190mA), ALDRIG over ;)
 
Pål gundersen

Pål gundersen

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HasseBasse skrev:
  1. Disconnect the speaker cables and the input RCA or XLR cables from the input jacks.
  2. Connect the provided Bias Cord into the bias connection jack. (If you have the Cary Audio MA-300 bias meter then skip to step 4.) It has a 1/4 inch mono ‘phone plug’ on one end and a pair of alligator clips on the other end. Plug the phone plug into the jack on the chassis. The red alligator clip is for positive electrical connections, the black one is for negative electrical connections on the milliampere (mA) meter.
  3. Set your meter to the DC milliamperes (mA) reading range. NOT to the MilliVolts (mV) range!
  4. Turn the bias adjustment screw on the chassis all the way counterclockwise so that the meter will read zero (or close to it) when you turn the power on. Some amplifiers will not go to complete zero.
  5. Turn on the amplifier power and wait 1 minute for the voltages to come up and warm up the tubes.
  6. We are not going to adjust the bias to its full recommended setting yet. Set it to about 10ma lower than needed as the bias will climb as the amplifier warms up and we don’t want it to go over the recommended setting. This also helps to put a gradual load on new tubes and allows them to warm up. Now SLOWLY turn the bias adjustment screw clockwise while you watch the meter for the correct mA reading. Now unplug the bias meter plug from the bias jack and move the meter’s plug to the other channels bias jack if this is a stereo amplifier. You will need to move the meter back and forth adjusting the bias a little at a time until set correctly. Using two meters is very helpful here.
  7. Let the amplifier run without an input signal for another 5-10 minutes and check it again. Readjust now to the recommended bias setting. You can find the recommended bias setting in your product’s owner’s manual. Adjust both channels until they each have the same reading.
  8. After another 5 to 10 minutes check and readjust the bias setting again, if necessary. New output tubes should be checked a couple of times in the first two weeks as they ‘burn in’ to their normal operating mode as they may keep changing over time. After that, check them within a month and then every 2-3 months just to be sure all is well.

    For bedre levetid på rørene, sett i unnerkant av annbefalet (190mA), ALDRIG over ;)
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Ok. Da må jeg få tak i ett annet multimeter ser jeg👍
 
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