PL400 Series II WOPL Quasi Control Board
- Thread starter Sunnbobb
- Start date
First thing, the long white wire that you have running directly from the bulk capacitor bus bar lug to the copper plate under the input jacks. cut it somewhere around the middle of the control board, strip the end attached to the bulk capacitor lug and terminate this stripped end into the LEFT channel terminal position #5. This will establish a ground reference for the control board. Remove the white wire that you have going into the RIGHT channel terminal block position 5. leave this terminal block position blank, no connection. Then with NO inputs connected to either the left or right channel positions 1 and 2, measure the output offset and see if it now hovers very close to 0 volts. We can deal with the input wiring after you get this settled down.
![20240518_113621[1].jpg](/data/attachments/78/78306-967dffa6852172e4d98b03049ab4c7b7.jpg)
This diagram should help, it is for a 700B but the wiring is similar. Remove that white wire going to the RIGHT channel terminal position 5. That should be OPEN. The input signals only interact with terminal block 1 and 2 positions.
Ignore the input switch shown in this diagram, the 700B has this switch but the 400 S2 does not.
Ignore the input switch shown in this diagram, the 700B has this switch but the 400 S2 does not.
Hi all. I'm following these threads closely. (Trying to make a decision on my 400 II.)
I notice that the "white wire" ground problem, identified in posts #24 & #25, is precisely what is described in the WattsAbundant relay installation procedure. I take it, that instruction is wrong.
As shown here: 400 Relay Installation Procedure
You have to scroll to the bottom to open the PDF.
I notice that the "white wire" ground problem, identified in posts #24 & #25, is precisely what is described in the WattsAbundant relay installation procedure. I take it, that instruction is wrong.
As shown here: 400 Relay Installation Procedure
You have to scroll to the bottom to open the PDF.
Sorry, it is somewhat complicated.
There is the guy who wants to install the quasi comp board quickly with minimum alteration to the internal wiring. He gets one set of instructions.
Then there is the guy who wants to max out the quasi comp board performance and is willing to make some key alterations to the internal wiring. He gets the more advanced set of instructions.
In those posts you referenced, I was giving Richard the more advanced wiring tips.
Then there is the go for the full monte approach, bare metal upgrade. That follows the complete teardown, backplane installation along with control board. And after gutting it following the very detailed rewiring upgrade to make it into a full comp amplifier. That nets the best possible performance.
There is the guy who wants to install the quasi comp board quickly with minimum alteration to the internal wiring. He gets one set of instructions.
Then there is the guy who wants to max out the quasi comp board performance and is willing to make some key alterations to the internal wiring. He gets the more advanced set of instructions.
In those posts you referenced, I was giving Richard the more advanced wiring tips.
Then there is the go for the full monte approach, bare metal upgrade. That follows the complete teardown, backplane installation along with control board. And after gutting it following the very detailed rewiring upgrade to make it into a full comp amplifier. That nets the best possible performance.