Vista 1 - Manual (Page 6)

ASSEMBLING THE KIT
If you purchased an unassembled kit, you will have all the parts, including tubes and printed circuit
board. Parts are in marked bags, with reference numbers and value written on a bag. Reference
numbers are the ones printed on the PCB, so locating parts positions should be very easy. PCB
layout printout is also part of this document and you can use it to locate parts. Output transformers
are purchased separately, and not included in the kit.
First step is to review all the materials received, compare to the part list and prepare all tools and
a well lit work area. Tools that you need are very basic – soldering iron, tweezers or flat pliers, and
cutters. You will also need solder wire and a digital multimeter. If you have an oscilloscope, that
will help in final testing and experiments, but it is not necessary.
- Start assembly with filament configuration jumpers, configuring heaters for your specific
application.
- Follow with resistors, keeping in mind that resistors should be slightly elevated off the PCB
(1/32” is sufficient). Main reason is that power resistors get warm and this will help air circulation
and prevent overheating. Also, some resistors have circuit connections underneath and there is a
possibility of malfunction if the resistor body touches exposed trace. This is not very likely, since
the PCB connections are protected by a solder mask and resistors have durable coating.
However, this could be a matter of safety and, also, troubleshooting of such problems is really
difficult, so it is better to spend some extra time up front to come up with great assembly.
- After resistors, install 2x2 headers for mode selection (Pentode, Triode, Ultralinear, FBK, etc.).
- Next step is assembly of all capacitors. Make sure to follow polarity directions for electrolytic
capacitors. All electrolytics have markings designating leads to be connected to the negative
voltage. Model 1 printed circuit board has a plus sign for the positive terminal of an electrolytic
capacitor. Positive terminal on the PCB also has a square pad around the hole, for easier
identification on the bottom of the board.
- After capacitors are installed you can proceed with connectors and, finally, with tube sockets and
volume control potentiometers.
Once everything is installed, take a short break and then come back and carefully inspect your
work. Check component locations and proper orientation of electrolytic capacitors. Inspect all
solder joints and make sure there are no solder bridges or splashes on the board. All joints should
look clean and shiny. If you are not sure that a solder joint look right, touch it with a hot soldering
iron again, until it looks right. Cold solder joints may create problems few hours (days, months)
down the road and are extremely difficult to troubleshoot.
Then, plug in the tubes, connect the output transformers and speakers (or dummy loads) and
proceed with slowly powering up the unit.
Bring the power for the filaments (Vf) first and make sure that all the tubes have about 16V on
their heater pins (depending on your supply, it may take up to a minute for this voltage to
stabilize). You should be able to see nice yellow/orange glow from the heaters.
Tubes that you received are already burned-in, so you can continue by bringing anode voltage
(Va) and measuring the most important in-circuit voltages (refer to the schematics section for test
points and voltage levels). If you followed all the instructions, everything should go smoothly and
now you can connect some music source to the inputs and start enjoying fruits of your hard work.
But, for now, keep reading the instructions…..
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