11.( )[500,600] Remove the screws holding the original circuit boards to the module noting how these are installed, save the hardware,
and 'fold back' the boards. This will help you determine which wires can be removed from the original PCB and marked for later
installation into the PA-7. Several wires are still hooked to both circuit boards. NOW, carefully inspect the Figures A, B and C to decide
how much labeling you want to do as you remove them. As you remove them from the original PCB, mark them with masking tape, etc.
to identify where they were connected to the original caps, fuse holders, boards, etc. In other words, the wires connected beneath the
module are removed along with the module for now, then reconnected to the same points. However; it is better to remove the wires for
B+,B-,ground and output right at the original circuit board, keep records. Table 1 and Figures A, B and C explain the connections
between the PA-7 and your amplifier.
12.( )[500,600] Remove the 4 screws securing the module base feet to the chassis. Remove the module from the chassis, if this is your
plan. If there are still wires connected which prevent this, remove and label them. It is your responsibility to keep records.
13.( )[All except DH-200] Since the XL-280 and XL-600 have good quality RCA jacks you might elect to keep the originals. >You will
use the small 22ga wiring for inputs from RCA jacks to the PA-XX boards.< There is a wire connecting both old RCA jacks to the
adjacent ground lug. Clip this wire at the RCA jacks, even if you keep the originals. Now remove both original RCA jacks. Install the
two new jacks as shown in step 7, but the twisted wires from the RCA jacks to the PA-7 boards have different lengths in different
amplifiers(DH-500/XL-600 = 2 - 11" pairs(two different color wires), XL-280 = 2- 14" pairs, DH-220 = 1 - 11 in. pair and 1 - 17" pair).
Make sure the original ground wire, from the star ground between the filter caps, is still connected to the ground lug between the RCA
inputs on some amps.
NOTE[DH-220 & XL-280]: Prewire the jacks before installation as outlined in step 7. It is very hard to get a soldering iron in the
limited space around the jacks, once installed. If it is easier for you, temporarily remove the large power supply cap in front of the jacks.
IMPORTANT NOTE! [for original DH-500 with PC-10 PCB only] Strip both ends of a, most likely black, 14" wire(1/4" on one end,
1/2" on the other). Insert and secure the short end to the chassis ground lug between the RCA jacks and solder the other end to the center
of the 'secondary star ground' connecting the large filter caps. Temporarily loosen the screws where the wire connects to each filter cap
which will help you get enough heat on the star ground wire. Run this wire straight forward from the rear and tightly against the chassis
bottom; tape to the bottom if you like. Then run straight up to the star ground wire.
IMPORTANT NOTE! [for XL Series amps only!] These amps (not all but most) have a thermistor in the input ground circuit.
Remove this device and replace it with a piece of wire. You will find the device on the power supply board of the XL-280, where the
star ground is connected to the chassis ground via the chassis ground wire. This is the board on the top of the four large power supply
caps. In earlier versions, a foil was cut on the board and the thermistor spanned the cut, i.e. one of it's two leads was soldered to each
side of the cut. In later versions, the thermistor was mounted on the bottom(component side) of the board between the rear pair of filter
caps. Very early versions did not have the device, so don't change anything. In the XL-600, the device, which looks like a black-matte
Nickel or Quarter with lead wires, was connected to a terminal strip near the power supply caps. The upshot of this is that we don't want
this device between the chassis ground lug and the power supply star ground.
14.( )[DH-200/220/500 only] Remove the fuses from the dual fuse holders on the floor of the amp. Save the fuses. Since the PA-7
already has the rail fuse holders mounted to the circuit board, you may eliminate clutter by removing the pair of twin fuse holders from
the chassis bottom. If you don’t want to remove them clip wires from each end. The wires you are clipping may have been labeled
previously. You may transfer a given label to the other wire connected to the opposite end of the same fuse holder. See Fig. B which
shows clearly how your amp is wired - you may not feel the need to label wires.
15.( )[DH200/220/500 only]The speaker fuse holder has 2 wires attached. If you are eliminating the speaker fuses carefully desolder or
simply clip and remove the wires along with any capacitor mounted to the fuse holder. Remove detached wires from the red speaker
post. If keeping original binding posts and speaker fuse you can leave the wire connected from one side of the holder to the appropriate
red speaker post. On the other side/end you can leave wires formerly connected to the original driver circuit boards. Just remove from
original boards and reconnect later - your choice. Replace the wires with heavy wire provided in the kit if you prefer.
16.( XL-280/600 only] The kit has heavier wire for replacement purposes. If you want to use it, now is your chance. Desolder and
remove the wires connected from the speaker fuse holders to each circuit board at the fuse holder end. Go back to the last step, read it
over and perform the same functional steps for your amplifier. Your goal is replacing the wire between the fuse holder(relay board in
XL-600) and the output posts.
17.( )[DH-500/XL-600 only] These amps route the output signal through a relay which provides DC protection. If you wish to remove
it from the signal path simply wire around it, i.e. wire the output posts either directly to the PA-7 (eyelet 8) or via the speaker fuse
holders. To retain it, connect the heavy wire provided from the relay’s output to the output posts. Simply trace the wire's path and replace
it. NOTE: Catastrophic failure of the power amp could destroy the speakers if the relay is removed. It is very,very rare though.
