so you have an opto 6 in front of you
the first step is to get your bearings , place the board in front of you and start placing parts
on the work surface , it would be recommended to wear latex gloves for the entire operation
since the board is tin/lead coated to make soldering much more reliable.
try to avoid silver solder , use 60/40 rosin core (silver solder really does suck)
.032 is a great diameter of solder to use .
your soldering iron should be respectable , get the best you can afford (weller or haiko etc)
conical soldering tips (pointed) are not the best for soldering , use a fine chisel tip if possible ,
the heat transfer is best and solder flows much easier , 700f seems to work well with the large
pads and thick traces of the drip board.
the best order of things :
there is no special sequence how ever the #1 thing to remember is that most cases
do not have the mounting holes drilled in them for the opto 6
so , you will need to use the naked board as a hole template for the 8-10 standoffs
depending on the enclosure you use , you might need to avoid the horizontal edge mounting holes , the side brackets of the case walls will not allow you to use them ,
use a white or silver sharpie marker and place 8-10 evenly distributed marks in the standoff holes on the pcb marked with a octagon . (these are holes intended for mounting)
remember , for the collective cases enclosure , the three holes on the long edge indicate
the back rear of the enclosure , use tape to secure the pcb , about an inch of clearance is needed from the front panel . using tape to hold the board still can help this process.
next would be to add in this order :
standoffs / tube sockets /resistors / capacitors / jumps / terminals and transformers
it is best to add standoff from the get go to the pcb to support it while you install parts .
soldering from the bottom is the neatest , if you are going for that fresh pimp look ,
other wise you can solder from the to of the board , how ever you will have flux splatter etc.
soldering from top is easiest , bottom soldering is best if you fold the component leads after you install them so they hold themselves in place while you install other components .
installation of the transformers :
in this photo , lundahl transformers have been selected for this particular build .
taping the transformers to the pcb can help secure them while soldering to the pcb ,
these transformers are pcb mount , so there is no additional wiring to set once soldered .
you should note , it is best to solder one pin on each side of the transformer footprint ,
this way you may insure the transformer is seated properly , once achieved , solder all the pins.
installation of the tube socket notes :
all the tube sockets should be gold plated , it would be a shame to use anything but gold.
the contact to the tubes pin is essential for operation , absolutly avoid plastic sockets ,
for this build you will use
1 seven pin socket (not available in gold except on ebay)
3 nine pin sockets
2 eight pin sockets to mount the t4's (NOTE : THE OCTAL SOCKETS NEED TO BE ALIGNED PROPER TO THE PCB PIN OUT )
TAKE NOTE OF THE WHITE LINE ON THE OCTAL SOCKET FOOTPRINT BETWEEN PIN 1 & 8
you must place the key way of the octal socket to align between pin 1 and 8
failure to do so will disable the operation of the t4 optical cell .
on the nine and seven pin sockets , there is nothing special , if you want to preserve the gold on the top side of the pcb , solder from the bottom , also solder two pins and then press on the socket as you solder , a little tricky but it will insure your socket is not all lop sided .
two types of capacitors on the opto 6 , film and electrolytic .
film do not have a polarity , meaning you can place them in any orientation you feel .
electrolytic capacitors however will pop on power up if they are placed backwards.
a total of 5 electrolytic capacitors on the opto 6 .
C10 a small 50uf @ 35 volt capacitor
and four big blue atom capacitors . in the power section .
all capacitor locations have a big 'you cant miss it' plus symbol (+) to indicate the polarity of the position , align the cap to this .
by all means , try not to blow your face off by placing the blue polarized electrolytic atom capacitors backwards.
they should be oriented as shown in this photo ,crimped side of the capacitor is toward the front panel side of the pcb.
the two capacitors in the signal amplifier (the audio amplifier)
are rather important , normally they are just film caps rated for 400v and are .1 capacitors.
orange drops are a great sounding tried and true tube amplifier capacitor (same reason why guitar amplifiers use them)
they are very affordable and best to use for this application .
in the photo above Mundorf supreme .1 capacitors have been chosen ,
a beautiful and flawless capacitor , but could be more esoteric then any thing .
sometimes dripping with quality is a good enough reason ,
the output capacitor is treated the same , it is the last component that the signal goes through before the output transformer .
get the best you can afford , like the simple atom 10uf@450v in the bill of materials .
you cant go wrong with that .
if you would enjoy blowing your own mind , try the mundorf supreme 10uf or the mundorf silver and oil 10uf if you just need to get all best of the best .
PLACING THE RESISTORS AND OTHER COMPONENTS :
placing the resistors is an easy step , seperate your component bags from mouser or digikey into types.
resistors / capacitors / hardware / etc.
some notes on placing the resistors .
in the design there are on two 2 watt rated resistors a 4.7k in the power supply and a 22k resistor underneath the 6aq5a tube location , it is clearly marked 22K 2W (r34) pay attention to this .
always place the resistor with the value up and visable (if you are using labeled resistors like vishay etc)
this way you can check the value by reading the lable written on the resistor ,
most cases you can not check the resistance of a resistor with a multi meter once it is installed in to the circuit ,
place the resistors and fold the leads over to secure them , or solder them one at a time , if you function like that ,
make sure the hole is filled with solder and the lead is securely soldered to the pcb , please no gaps in soldering or half soldered leads , inspect each soldering joint . trouble shooting this is a pain , once the pcb is bolted to the case bottom ,
soldering from the bottom , as said is cleaner , and preserves the wicked look of the top side ,
in this photo the resistors are carbon composition and use a three band color coding system .
google resistor color band calculator if in doubt..
in the end your resistors should be placed and look as such :
gain reduction metering section
the metering section of the opto 6 is set up to monitor gain reduction only ,
externally you will connect this to a switch to select between output metering and gain reduction metering ,
this section contains the NE-2 voltage regulator bulb , this stabilizes the vu meter needle during GR metering.
nothing really special in this section to note , except the tracking option of using a resistor or a trimmer .
the trimmer will allow you to adjust the tracking of the needle to precision .
it is a pain to adjust and calibrate , so advanced uses might select this option ,
you will use the trimmer or the fixed resistor , not both .
how ever it is recommended to just use a fixed 33k resistor or a 56k resistor is using really slow T4b optical cells similar to the T4A type of optical cell .
the mica capacitor is originally a 470 pf , but in this aplication , it does not mater. 500pf is available and fine.
below is the metering hook up schematic to connect the reduction metering section to a toggle switch.
optionally , you may connect the reduction metering section directly to the meter if you do not wish to have a switch or monitor the output on the vu meter ,
simply connect the vu meter positive directly to the reduction metering section + same with the negative.
here is the traditional metering switch set up :
the blog will continue every couple hours over the next several days .
check back for more updates ,