Installing Princeton Reverb Reissue Mod Kit Princeton Reverb Reissuev Fromel Mod kit installation

Warning skipping this next step could result in death

Using your multimeter set to DC measure the voltage between the positive side of C29 to ground. If the voltage is higher than 10VDC you need to drain the charge that's still in the caps

It's a good practice to keep your non-dominant hand in your pocket and only work with one hand in an amp that still has a charge. Then, if you do touch something that's high voltage while grounded the current will only go through one side of your body and miss your heart

Using your insulated pliers to hold the 5W power resistor touch one lead of the resistor to the negative side of the 22uf filter cap at C29 and the other lead to the positive side. Keep the 5W power resistor leads in contact with the leads on C29 for 30 seconds then measure the DC voltage on C29 again

Keep repeating the last step until the voltage reads below 10VDC

Once the filter caps have been drained below 10VDC it is safe to work on your amplifier

Remove the control knobs by loosening the set screws and all the nuts securing the pots and jacks to the chassis

Clip all the wire ties

Unplug the power and output transformer's leads by pulling firmly with steady pressure while gently rocking the lead terminal from side to side. As you remove each lead tag the wire with the number off the terminal connection it was removed from. You can either use masking tape and a Sharpie or I just mark the terminal number on the lead

Remove all the screws holding the PCB to the chassis

Pull gently on the main PCB to make sure it's not stuck to any of the standoffs that were folding the pcb screws

Disconnect the bias pot from the bottom side of the chassis

Disconnect the grounding lug screw near the pilot light.

Disconnect the ribbon cables between the main PCB and the control panel PCB

With the main PCB screws removed pull it up and back carefully, being mindfull of the wires running from the PCB to the tube sockets. You'll need to have the control panel side of the main PCB pulled up from the chassis to access the solder side of the main PCB

With the knobs, all nuts, and washers removed removed the control panel pcb should pull freely away from the front of the chassis and be removed

Do not put any pressure on any components, including the filter caps, while moving the PCBs

Be careful that your soldering iron isn't too hot. The solder pads and circuit traces on the PCBs are fragile and prone to curling and separating from the PCB.

Remove components with care, never using force. It's best to clip the component leads flush to the board on the component side and then remove the remainder of the lead and solder from the solder side with de-soldering braid.

If a pad comes off during de-soldering carefully scrape the trace next to the pad to expose the copper, bend the lead so it's in contact with the exposed copper trace, and solder them together.

On the main PCB remove R25, R17, and R27

Couple one lead of the 1M resistor to the bottom of R9 and the other into the hole on the left side of R25

Couple one lead of the 2.2M resistor to the 1M resistor that's going into the hole on the left side of R25 and couple the other lead to the right side of R57

Also couple one lead of the 56K resistor to the right side of R57 as well with the other lead of the 56k resistor going to the bottom hole of R17

Jumper R27 with a lead from a clipped component

This mod moves the phase inverter's power supply to an unused higher voltage power supply increasing clarity, clean headroom, and tone!

On the control Panel PCB remove: R52, R46, C19, C23 and C24

On the control panel board install: 10K in R52, 91K in R46, 270pf MLCC in C19, .047 in C23, and .1 in C24

Only follow this step if you have the Supreme kit

The electrolytic caps in this step are polarized, meaning they will only work in a circuit connected with their negative and positive leads connected to the corresponding negative and positive connection in the circuit. The PCB is marked with a "+" sign closest to the positive connection for the cap.

If polarized caps are incorrectly installed they can explode

Remove the filter caps: C29, C27, C26, and C28

Remove C1, C2, C7, C8, C9, and C18

Install 22uf/ 500V filter caps in C26, C27, C28, and C29

Install 22uf/ 35V caps in C1, C2, C7, C8, C9, and C18

The voltage rating on caps for C1, C2, C7, C8, C9, and C18 in the kits can be anywhere from 25V to 63V for this part depending on our supplier. This voltage rating is a maximum working voltage and for where they are used in the circuit they will see less than 10V.

Carefully put the control panel PCB back into the front of the chassis solder side up and fasten the washers and nuts onto the pots

Carefully put the main PCB back into the chassis and screw it back into the standoffs.

Reconnect the ribbon cables being mindful that they are properly aligned to the pins coming off the main PCB

Make sure the ribbon cables have a smooth path and don't have any kinks or sharp turns in the cabling

Reinstall the bias pot with the nut on the bottom of the chassis next to the power transformer

Dress the transformer leads. Poor lead dress is one of the main causes of noise in this amp. Instead of using new cable ties we're going to use proper lead dress techniques

Twist each pair of AC leads from the transformers: yellow, green, and black and white together. All leads and twisted pairs if possible should cross each other at 90 degree angles

Slide the chassis back into the cabinet from the back of the cabinet and secure the chassis with the two top screws