Champ 600 Upgrade Kit Installation
These upgrades improve the tone of the factory design of the Fender® Champion 600 Reissue amplifier; they do not change the circuitry from stock. We are simply using higher quality, better sounding components of the same value (except the preamp filter cap, which is slightly reduced in value) to improve the tone and feel of the amplifier.
You've probably noticed that the Jupiter tone caps are much larger than the capacitors they are replacing. This is because they are full-sized components, designed for optimal tone and for use on hand-wired, point-to-point vintage style circuit boards. Though this presents a challenge on a printed circuit board amp such as the Champion 600 Reissue, the end result will be worth the effort. Due to these and other challenges, it is recommended that these modifications be performed when you are at your best and able to take your time. You may wish to download a pdf version of the Champ 600 schematic.
Disclaimer: Specialty Guitars, LLC is in no way liable for damage caused to yourself or your amplifier in installing this kit. We recommend that you educate yourself on the proper discharging of filter capacitors before beginning work on your amp. If you do not feel confident to install this kit, including taking the necessary safety precautions, we strongly recommend that you take your amplifier to a qualified amplifier technician.
Step By Step Instructions
Remove back panel. Unplug the speaker cable from the chassis and gently remove both tubes from their sockets. The metal shield must be removed from the preamp tube by turning slightly counterclockwise and pulling down. Pull down on each tube while working it in a gentle circular motion. Remove the four screws holding the chassis to the cabinet (two on the back and two on the sides) and slide the chassis out of the cabinet. Sliding the chassis out can be difficult as it can be a tight fit, so take your time and work gently.
The tone and coupling capacitors to be replaced are C1, C9, C8 and C2.
Remove all of these caps by gently desoldering from the top of the board. Remove excess solder from the through-holes using a solder sucker and/or solder wick, or whatever means you prefer. Once the old capacitors are removed, take the twisted pair of green wires that go over the top and very gently pull back behind the J20 ribbon connector.
Start by installing the 250pF silver mica capacitor (C1). Trim the leads to approximately 3/8". Install as shown in photo and carefully solder from top side of board. After the solder cools, bend slightly at an angle toward R8.
Next, prefab the leads of the 3 Jupiter Tone caps, with the vertical line on the cap's print denoting the
location of the outer foil of the capacitors, in the orientation as shown in the photos. It is imperative that C8 (.1 mF)
and C9 (.05mF) be lifted off the board somewhat. Their leads will have to be bent underneath the bodies of the
Be sure to "dry fit" the components before beginning to solder.
Cut four 3/4" lengths of the white spaghetti insulation included with your kit and install on the leads of the .05mF and the .1mF Jupiters. C2 (.02mF) may sit on the board, but it is recommended to put a dab of silicone under it to keep it from vibrating. You may also install white spaghetti insulation on its leads, but it is not necessary.
Now, install and solder C2.
Next, install and solder C9, paying attention to the lead orientation with regard to the board mounting screw
Finally, install and solder C8 as shown in the photo. Once soldered, the components can be moved slightly to adjust them into optimal position. It is recommended to put a dab of silicone between C9 and C8 and between C8 and C2.
Now, gently move the twisted pair of green wires back into place over C8 and C9. Some repositioning of the caps may be required. It is again recommended to put a dab of silicone on the twisted wires where they touch the top of C8.
Next, we want to remove the factory 22mF filter capacitor in C7 and install the 10mF capacitor included in the kit.
At first, this may seem like going backwards, because more is better, right? Sometimes, yes, but in this case, it is
not. Installing the smaller value filter capacitor will allow the preamp section to be more touch responsive.
Fortunately, it is possible to get at the leads of C7 from the bottom of the circuit board. From the bottom of the circuit board, desolder and remove C7. Some rocking of the component's body may be necessary to break free of the silicone or adhesive that has probably been applied.
You may trim the leads of the 10mF cap as shown in the photo, which will make the fit between the top of the cap and the amp's cabinet very tight. You may want to consider cutting the leads longer, and installing the capacitor so that it is lying at an angle towards C3. Add a dab of silicone between the board and the cap's body to hold it in place. Solder the supplied 10mF in place, paying close attention to the polarity markings on the circuit board. Installing the capacitor backwards could cause it to malfunction and explode.
If you have purchased a kit that includes the Weber upgrade speaker, with the chassis still removed from the cabinet,
gently remove and unplug the factory speaker as shown in the photo. Carefully install the Weber speaker in the same
orientation as the original. Install the screws, turning a little at each time on each one. Do not overtighten!
Now fasten the speaker cable connectors to the Weber speaker, matching red to red and black to plain.
Finally, install the JJ 12AX7 preamp tube and replace the metal preamp tube shield. Install the JJ 6V6 and slide the chassis back into the cabinet, being careful not to bend or damage the tubes. Reinstall the side screws first, making sure not to tighten all the way. With the chassis in proper position, install the two faceplate screws, then tighten the side screws until secure. Reconnect the speaker cable, and screw on the back panel.
One thing that this amplifier invariably needs is power tube bias adjustment. The Champion 600 Reissues that we have seen have had the 6V6 power tube biased for too much power dissipation. The correct power dissipation for a 6V6 is considered to be between 12W and 14W (12W for vintage 6V6s and up to 14W for some of the newer 6V6s). The Champion 600s that we have seen were biased for between 15.5W and 16.5W. This is simply too high and does not sound optimal. We have found that the installation of a 200 Ohm to 240 Ohm 2W resistor in series with the factory installed 470 Ohm resister in R10 will achieve approximately 12W to 13W power dissipation.
There is much more that can be done should you wish to take it further. This amplifier, like all single ended amplifiers, would greatly benefit from hum reduction achieved through a DC filament supply. You will find that there are countless threads on countless message boards dealing with modifications to the Fender® Champion 600 reissue and if you wish to carry things further we suggest that you search out some of these threads.