A

lot

of

enthusiasts

ask

us

to

replace

the

entire

set

of

resistors,

capacitors

and

semiconductors

on

the

seven

circuit

boards!

This

is

a

major

overhaul

using

100s

of

modern

components,

(1%

tolerance

low

noise

metal

film

resistors,

polyester/polypropylene film capacitors, low noise, high beta transistors, and new diodes/rectifiers.

Before you opt for this option and any Quad 33 service we offer, is important to make sure your 33 is mechanically

in good working condition. The push button switches and horizontal and vertical edge connectors, must be fully

functional. This is because these parts are no longer available as NOS items. It would be futile for you to spend

more to replace all the electronic components in your 33, only to find a short while later, that a mechanical switch

or edge connector, (MS&EC) has failed. The only replacement MS&ECs available today, are used items from donor

33s! From our point of view too, we can’t be expected to replace MS&ECs under warranty, as there is only very

limited and expensive source of 33s with viable spares.

What we do if you choose this option:

After verifying that your 33 'parts to keep' are  in good condition (we will inform you if they are not); we strip all the existing

components from the seven PCB boards.*  We then clean off the solder and flux residue and re-populate each board with

new high quality components. For example, the resistors we use are 1% metal film types. This allows the DC operating

points and gain setting components to be optimised and reduces the inherent noise.  Likewise for the capacitors and

semiconductors.

The legend light is modified to a diffused dull orange LED circuit. This gives a pleasing legend similar to the original

incandescent lamp.

We modify some components in value and rating to improve performance, this includes the PSU smoothing capacitors,

rectifiers, bias resistors and response tailoring components. Nothing drastic, just sensible improvements so the system still

has the smooth original sound as it was when first un-boxed.

The push button switches are individually dismantled, contacts cleaned and reassembled. A similar dismantling action is

carried out on the slider pot. If the switched volume control and tone pots are in good working order, we clean the wipers

and tracks with contact cleaner/lubricant. If not, they are replaced with modern nylon spindle controls. The edge connectors

are checked for integrity and cleaned.

Everything is then assembled back in place and the system is then checked for correct operation on. Finally a full listening

test, PAT and bench soak test is carried out.   

‘Soak test‘ meaning: Powered up, playing music or a continuous sine wave into speakers or dummy load

for several hours at a stretch.