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Page 67
9.5 Voltage Check
If you're using a Variac take into consideration that the voltages you'll be measuring are
going to be a percentage of the full DC voltages: for example, with the Variac at 90V AC
instead of 120, you can factor in that the DC voltages will be down by 25%.
Install the 5U4G rectifier tube.
Tubes Installed At This Point: All
Turn the Phono Stage on.
Worst Case Scenario
Installing the 5U4G rectifier provides the Phono Stage with the various DC voltages (including the
HT) that it needs to operate; usually, if there is a problem with the build, it's going to be noticed here.
It's possible that, if there is a major problem, the fuse will blow — or you may get a burning resistor
or even see some smoke.
If anything alerts you that there is something drastically wrong then turn
off the unit ASAP, unplug it, and contact us at [email protected] before proceeding. We'll be
happy to provide you with advanced troubleshooting advice. Note: we may ask that you send us high
quality digital pictures of the internals of the Phono Stage.
Make the following measurement: On the Phono board, measure the HT (+ and –): you should have
about 260V DC. Turn the Phono Stage off.
Well done if all these checks are good! Let’s move on to the sound check.
9.6 Sound Check
Now that we have a Phono Stage with a key correct DC condition it’s time to see if we can get some
sound. We recommend hooking up your turntable to your preamplifier and the rest of your system,
including a pair of "cheap" speakers! — to verify that it is working correctly.
When the Phono Stage turns on you may hear a hum for about 15 seconds; then it will
disappear. The reason for this is the voltages are settling: it’s kind of like throwing a rock in a
swimming pool; it takes a bit of time before the ripples (or, in our real world case, the DC
voltages) settle.
If this checks out, congratulations! You should have a working L5 Signature Phono Stage. Feel free to
contact us to share your excitement.
Summary of Contents for L5
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