Where are we now ? It's been a while and took a bit of an effort to take this board back to speed but it's design at places totally sucks. I dont know why they made such poor signal flow choices.
a) post fade monitor b) mic level inputs only the channel faders never gets to 0 really .. so there's quite a few bugs with it's design. What i did do first was take it in pieces and even without looking replace ALL the electrolytics with good grade new parts. ALL of them . Second mission : replace all the lightbulbs in all 12 meters. Third mission : check all resistors , unsolder one side , measure and replace , i had bunches of them off their value by more than tolerance so that got also canned, long tedious , yes .. worth it , absolutely.
The 4 th mission was to invent a way to get line levels to work so i made a series of 10 modules . Each module is a simple 4 pole 2 direction pc mount relay. What i do is simply switch in a -20 db pad. Each channel has a switch and status led just above the vu meter. They need power on their own. You cannot use the internal power for this, draws too much, so i added a small 24 v psu and transformer. I mounted the small pc boards for the relays just at the back of the xlr connector held solid in place. Wiring is minimal and no signal travels anywhere , just the 24volt to actuate the individual relays. That took care of the issue and line levels is ok now. The next one was a bit more ambitious. Give it a real pre fade listen system. The first issue here is ok , you want switches to activate PFL .. but where to put them ? After carefull consideration i decided to mount them between the 2 sets of monitor select switches . It's crowded by 4 10k resistors. and thickness overall available for a push button impossible. I managed by switching the resistors from component side to solder side , then drill baby drill . I opted to get the signal right off the input transformer pc board. ( the following is less than optimal but it worked ) I took every line and took them to a new pc board , 2 uf cap and 10k resistor , made 2 buses ( 1 and 2 are separate , allows stereo ) and each of the lines are switched in/out from the new front panel switches ( i used molex 2 pins on each so i can take modules out without undoing everything. This in turn feeds a volume control , and switching for mon 1 2 out/ preface listen and feeds the 30w/channel power amp module and it's own supply .
The switches and volume control are sitting nice between channel 10's vu and the Master VU , with a suitable red button , it's hard to notice it's not original. I switched around a lot of jacks at the back to have a second mon 1 ,2 output and have 2 jacks for headphones. the crossover outputs were the easy target.
Think of the 1220 as a good mixer to fiddle around with .. i would not do what i did to a SSL or a Midas .. but hell it's good fun for the bucks . Also it's , once put to speed , an ok board to webcast with . I made a small adapter module for a telephone line that sits outside the board , i didnt want it in .Two 600 ohm transformers few resistors few zeners in a small metal box is all it takes. So basically the new setup has 2 cd players , computer ( that's 3 strips ) Strip 1 is main mic + guest mic , Second strip is telephone line and the mic on the DT-109 headphones i am using. Works out ok . Got a second computer doing the actual web streaming . Just having fun with an oldie.
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