TABLE OF CONTENTS Restoring Hammond X66 Table of

TABLE OF CONTENTS Restoring Hammond X-66 Table of Contents. Description Nbr of Slides Level Part Two. - Scanners - Reverb - Arpeggiator - Tab Controls - Tibia Flute Filters - Preamps - TWG / Dividers - Special Effects - Sforzando - Percussion Keyers 13 6 3 2 8 7 4 6 Part 2 ***** *** *** 1

SCANNERS Restoring Hammond X-66 by dan. vigin SCANNERS SERVICING Servicing scanners is not complicated but requires some work methods. The easiest way is to remove the complete scanners block from the console. Not so difficult, first mark off all wires, unsolder wires and the scanner unit can be now extracted from the console and put on the workbench. Part 2 2

SCANNERS Restoring Hammond X-66 by dan. vigin SCANNERS SERVICING The console looks empty so and provide adequate room to dismount later on the flute filters board located just behind the scanners block. X-66 is featured with 3 scanners: - TAB scanner on the left - CELESTE in the center CELESTE - DRAWBARS on the right TAB DRAWBARS Part 2 3

SCANNERS Restoring Hammond X-66 by dan. vigin SCANNERS SERVICING Start removing the three scanners from the chassis. The inside of the TAB one was sticky (caused by excess of oil) and exhibits verdigris stains. Enough for an overall cleaning. The mechanical parts can be easily disassembled. Pay special attention to avoid any damage to the rotor contact spindle during dismounting. Protect this spindle afterwards with foam or the like. TAB scanner Rotor contact spindle Part 2 4

Spindle SCANNERS Restoring Hammond X-66 by dan. vigin SCANNERS SERVICING Unscrew the 16 screws fixing the stationary plates. All pieces can be now removed and cleaned with acetone. Do not break the lub strings! Lub strings Leave all small pieces in acetone can during about 30 min. and clean them to refind a ‘like new appearance’. Start re-mounting in the reverse sequence. Part 2 5

SCANNERS Restoring Hammond X-66 by dan. vigin SCANNERS SERVICING The first scanner unit is completed. Protect Rotor spindle After Part 2 6

SCANNERS Restoring Hammond X-66 by dan. vigin SCANNERS SERVICING The ‘Celeste’ & ‘Drawbars’ scanners are almost identical and featured with two rotary pickup arms i. s. o. one as for the ‘Tab’ scanner. Rotary Pickup arm Celeste Rotary Pickup arm Drawbars Part 2 7

SCANNERS Restoring Hammond X-66 by dan. vigin SCANNERS SERVICING It is very difficult and not recommended to dismount those two scanners because some parts on the rear side are riveted. Rivets Part 2 So, the only way is to firstly clean with air-pressure and try to clean with alcohol from the front side. Insulating resistance between both rotary arms is 200 MΩ ! Any little conductive layer between both rotary arms will be lower than this value and will create problems. 8

SCANNERS Restoring Hammond X-66 by dan. vigin SCANNERS SERVICING For better understanding, here is a cut of dual scanner. Part 2 9

SCANNERS Restoring Hammond X-66 by dan. vigin SCANNERS SERVICING Correct scanner operation is also greatly depending on the vibrato gang switch. As expected, contacts were dirty, full of dust, etc. . and need some maintenance. Unsolder all wires coming from scanners, quite easy to get it on the work-bench. All stationary stems and switching leaves cleaned and correctly repositioned Part 2 10

SCANNERS Restoring Hammond X-66 by dan. vigin SCANNERS SERVICING Once again, this operation is not complicated but requires some work method and patience. Before During cleaning process Part 2 11

SCANNERS Restoring Hammond X-66 by dan. vigin SCANNERS SERVICING Upon completion, inject 12 Vdc on each solenoid to confirm proper alignment and operation. With ohmeter, check for correct On/Off DC resistance that should fall in the range of 0. 5 Ω or lower. Elco's of 100 µF were replaced on each solenoïd. Simply re-install the gang switch in reverse sequence as usual. After Part 2 12

SCANNERS Restoring Hammond X-66 by dan. vigin SCANNERS SERVICING Since all phase shift line units were removed, it would be unfortunate not to check the values of cap's. All cap's were measured and the good news is that only one single capacitor was found out of specs. Cap's testing Part 2 13

SCANNERS Restoring Hammond X-66 by dan. vigin SCANNERS SERVICING The vibrato drive amp's located at the rear side of the scanners block require some actions. Cap's within specs All "MALLORY" elco's were found doubful during tests and were systematically replaced. However the three output cap's (top of picture) were still in perfect condition and were not exchanged. This completes the scanners chapter. Mallory cap's replaced Part 2 14

REVERB Cap's within specs Restoring Hammond X-66 by dan. vigin REVERB SERVICING REVERB circuits implmented on X-66 console are rather basic and can be summarized as follows: Part 2 15

REVERB Restoring Hammond X-66 by dan. vigin REVERB SERVICING The complete chain was operative but with some background noise that was confirmed on the scope. ? Before Reverb spring after cleaning Drive amplifier Before Output preamp After cleaning and replacement of all elco's in drive amp and output stage ( 6 in total ) and full control, normal operation was restored without any problem. Part 2 16

ARPEGGIATOR Restoring Hammond X-66 by dan. vigin ARPEGGIATOR REPAIRS In the Service Manual of X-66 it is stated: 'Do not attempt to disassemble Arpeggiator'. If you have a new one on hand, no problem, if not you have no other choice than to disassemble it to fix it. Removing arpeggiator from the upper keyboard, sliding the assembly from its support is quite easy. Part 2 17

ARPEGGIATOR Restoring Hammond X-66 by dan. vigin ARPEGGIATOR REPAIRS Where is the 'dangerous/critical' point ? Here is the answer. The arpeggiator is composed of 61 slices (one per contact) that are overlaped together by means of male/female small plastic clip-ons that break at once because of the mechanical traction caused by the bundle of yellow wires. Breakage points Part 2 18

ARPEGGIATOR Restoring Hammond X-66 by dan. vigin ARPEGGIATOR REPAIRS When sliding the arpeggiator out of its support, the mechanical tension applied on plastic clip-ons is sufficient to break them. With aging, ABS becomes more and more really 'brittle'. Part 2 19

ARPEGGIATOR Restoring Hammond X-66 by dan. vigin ARPEGGIATOR REPAIRS To restore adequate mechanical strength, small strips of 3 mm width were cut off from fiber-glass material (epoxy plate). Those epoxy strips are firmly fixed where needed with resin epoxy cement in order to re-position the contacts correctly and to refind so the mechanical strength. This operation is not easy but I have not found a better issue to cure this problem. Fiber-glass strips sealed by epoxy cement Part 2 20

ARPEGGIATOR Restoring Hammond X-66 by dan. vigin ARPEGGIATOR REPAIRS Let the epoxy cement dry during 24 Hrs. Afterwards, each contact has to be measured one by one. The coloured wires remained unsoldered but it was absolutely necessary to remove all yellow ones. That's where the fault lies. After a thorough check, the arpeggiator has been re-installed and operated quite normally. Final check before re-installation Part 2 21

ARPEGGIATOR Restoring Hammond X-66 by dan. vigin ARPEGGIATOR REPAIRS Carefully and slowly slide the arpeggiator assembly back in original position in its support. Now, it's time to rescrew the whole assembly on the upper keyboard. Final re-installation Again, to my opinion, this is probably the most delicate part on X-66 restoring. Part 2 22

TAB CONTROLS Final re-installation Restoring Hammond X-66 by dan. vigin TAB CONTROLS There is not so much to tell about Tab Controls. Tab controls are only a matter of mechanical contacts. As expected a lot of poor contacts were found (my ohmeter was even 'crazy' sometimes). First and easiest thing to do was to replace the diodes on both solenoïds that exhibit strange shape. Part 2 23

TAB CONTROLS Final re-installation Restoring Hammond X-66 by dan. vigin TAB CONTROLS Afterwards, it is highly advisable to measure the values of all resistors around Tab Controls. When looking to the X-66 schematic diagram, we can notice at once that any major change of value of those resistors may affect the overall 'balance' of the output signals. Some of them were replaced (quite easy). Part 2 24

TAB CONTROLS Restoring Hammond X-66 by dan. vigin TAB CONTROLS More complicated is the cleaning of the spring contacts and fixed contacts of Tab Controls. Most of contacts exhibit traces of oxydation and verdigris. Those contacts were cleaned from the rear side with alcohol. Same lubricant as for drawbars was used and normal functions were so refound. Oxydation and verdigris Part 2 25

TIBIA FLUTE FILTERS Restoring Hammond X-66 by dan. vigin TIBIA FLUTE FILTERS Flute filters are located just behind the scanners unit. It is quite easy to remove the complete assembly, put it on the workbench (before re-installing the scanners block) for a thorough check of those filters. Flute filters Most cap's were measured and found still within specs. Coils were intact. Flute filters board There a few resistors in these filters (3. 9 K, 2. 7 K, 1 K). It's wise to check them also. Part 2 26

TIBIA FLUTE FILTERS Restoring Hammond X-66 by dan. vigin TIBIA FLUTE FILTERS The switching relay installed on the right end of the flute filter does merit some attention. Each contact of this relay is in series with the flute filters when Tibias tab is ON. The capacitor (1000 µF) in paralell on the relay coil was replaced (leaky). Tibias relay After cleaning and tests Again overall cleaning and inspection is required. Technical details on 'how to clean' those relays will be covered in the 'Sforzando' chapter. Part 2 27

PREAMPS Restoring Hammond X-66 by dan. vigin PREAMPS The X-66 console is featured with 'several' Preamps. The same principle of operation is often implemented: - One driving preamp to feed the next insert circuit with sufficient signal. - Filters, Reverb, Scanner… entailing losses of signals. - Recovery preamp needed to restore a valid level output. Part 2 28

PREAMPS Restoring Hammond X-66 by dan. vigin PREAMPS The major advantage of X-66 preamps is the fact that those specific circuits are exclusively composed of 'discrete components', hence quite easy to fix, modify or improve. Most important preamps are scanners and expression preamps located just on the upper part of the scanner unit. Expression preamps The two others are the console output and reverb (already covered in Reverb chapter). Scanners recovery preamps Part 2 29

PREAMPS Restoring Hammond X-66 by dan. vigin PREAMPS The console output preamp is installed vertically on the left side of the scanner unit. Transistors replaced One of the fourth transistors was found defective (noisy). So, all of them were replaced. Elco's were systematically replaced. Other components were found normal and still within specs. Output monitoring can be easily done via this board (ref. Fig. 4 -1 A of SM). Console output preamp Elco's replaced Part 2 30

PREAMPS Restoring Hammond X-66 by dan. vigin PREAMPS The scanner recovery preamp board exhibited some signs of fatigue (noisy, unstable output signal. . ) During tests, five transistors were found doubful and replaced by BC 107 types. Other components were found normal and still within specs. Output monitoring can be easily done via this board (ref. Fig. 4 -1 A of SM). Transistors replaced Part 2 31

PREAMPS Restoring Hammond X-66 by dan. vigin PREAMPS The expression preamp is probably the most important one in the X-66 console. It is composed of 5 transistors and has also a function of 'mixer' just before feeding the console output preamp. Expression Preamp board Transistors replaced Cap's replaced Part 2 32

PREAMPS Restoring Hammond X-66 by dan. vigin PREAMPS Some active components (like transistors) and caps were replaced in this expression preamp. As a consequence of all those changes, the overall 'balance' did not meet fully my expectations. Several values of resistors composing the input mixer were modified according my personal feeling in this expression preamp. As previously said, since X-66 is mostly designed with discrete components (some exceptions in the dividers, percusssion switching. . ), then it is quite easy to modify the tonal balance accordingly. The modifications of resistors are described on the next slide. Part 2 33

PREAMPS Restoring Hammond X-66 by dan. vigin Part 2 34

PREAMPS Restoring Hammond X-66 by dan. vigin PREAMPS There are many other preamp in the X-66. Most of them are based on similar basic principle. It would be too much time-consuming and useless to explore all of them in details during this presentation. A few days more would be necessary… This completes the Preamp chapter. Part 2 35

T. W. GENERATOR/DIVIDERS Restoring Hammond X-66 by dan. vigin TONE-WHEELS GENERATOR & DIVIDERS The TWG of X-66 is only providing sinus top-octave signals that are later on 'squared' and routed through dividers chains. The role of each 'flip-flop' divider is to divide by a factor of two the incoming signal. The so-divided signal is routed later on to the next one for another division by two and so on. The output signals from the dividers are sent to the proportional keyers. This means that the level of the signal is firstly defined by the position of the drawbar and is triggered by the corresponding key-contacts. X-66 has been so designed to eliminate any 'key-click' contrarily to B 3, C 3, A-100 series. The signals available at the outpout of the proportional keyers are filtered later on by the flute filters in order to get at the output a pure sinewave signal. Part 2 36

T. W. GENERATOR/DIVIDERS Restoring Hammond X-66 by dan. vigin TONE-WHEELS GENERATOR & DIVIDERS Part 2 37

T. W. GENERATOR/DIVIDERS Restoring Hammond X-66 by dan. vigin TONE-WHEELS GENERATOR & DIVIDERS The TWG was in poor conditions and was not lubricated since years. After cleaning and proper oiling, it was back to life and was running normally. "It was noticed in the past that owners of X-66 are injecting 'gallons of oil' at scanner block and purely forget the TWG in the base. " Anyhow, no major problem that unit, adequate voltages and frequencies were noticed. Part 2 38

T. W. GENERATOR/DIVIDERS Restoring Hammond X-66 by dan. vigin TONE-WHEELS GENERATOR & DIVIDERS The table on the left shows the measurements collected at the TWG receptacle before re-installing in the base. Part 2 39

T. W. GENERATOR/DIVIDERS Restoring Hammond X-66 by dan. vigin TONE-WHEELS GENERATOR & DIVIDERS When checking all dividers, I found one missing output signal on divider #7 of G# board. This means no sound when keying this low-end G#. No output signal at this point Instinctively, any techician will replace the two transistors. There were OK ! So the problem lies in the divider IC. Since those IC's are no more foundable, the only solution was to reconstitute this IC to get this divider operating again. No other choice. Part 2 40

T. W. GENERATOR/DIVIDERS Restoring Hammond X-66 by dan. vigin TONE-WHEELS GENERATOR & DIVIDERS Then, the first thing to do is to recompose the inside of this IC and try to rebuild it. Here is the inside. Part 2 41

T. W. GENERATOR/DIVIDERS Restoring Hammond X-66 by dan. vigin TONE-WHEELS GENERATOR & DIVIDERS All discrete components were assembled on a small board and resoldered on the frequency divider board. Part 2 42

SPECIAL EFFECTS Restoring Hammond X-66 by dan. vigin SPECIAL EFFECTS The Special Effects panel on the right-end side was also in extremely poor conditions: broken knobs, scratches, dirty, stained, simply ugly ! The S. E. panel has been totally dismounted for several reasons: - to clean and repaint the front panel. - to renovate the circuits boards and lever switches - to eliminate the magnetic particules from the S. E. chassis. Part 2 43

SPECIAL EFFECTS Restoring Hammond X-66 by dan. vigin SPECIAL EFFECTS Renovating the S. E. panel is rather easy, it's again a matter of taking the time to do it in the correct way. BEFORE AFTER Part 2 44

SPECIAL EFFECTS Restoring Hammond X-66 by dan. vigin SPECIAL EFFECTS The boards and lever switches were fully cleaned because traces of magnetic particules (conductives) were found in this S. E. block. All elco's were replaced (specially Mallory one's). AFTER Lever switches cleaned and tested Part 2 45

SPECIAL EFFECTS Restoring Hammond X-66 by dan. vigin SPECIAL EFFECTS The S. E. metal chassis was really covered with magnetic particules (dendrite formation). Here again air-pressure becomes an essential tool to remove them. Those conductive particules may generate problems (cfr. percussion noise in B 3's. . ) This metal frame and board was found covered with magnetic particules. This completes the S. E. chapter. Part 2 46

SFORZANDO Restoring Hammond X-66 by dan. vigin SFORZANDO The Sforzando presets on X-66 console are mostly driven by three switching relays IBM 769023. However, SFZ relays do merit more attention than Tibia Filters relay. Tibia relay has no connection in 'Rest' position while three 'SFZ' relays do! This difference is not negligible at all since all signals are indeed passing through those contacts while being in 'Rest' position. This means that contacts in 'Rest' position have to be carefully cleaned and measured. Part 2 47

SFORZANDO Restoring Hammond X-66 by dan. vigin SFORZANDO Under normal use, signals are routed to drawbars while SFZ relay is not activated. Contacts in 'Rest' position must be carefully checked. DC resistance of contacts should be around 0. 3 Ω. Poor contacts may generate intermittents, noises, cracks, pops, distortions, crosstalk… Part 2 48

SFORZANDO Restoring Hammond X-66 by dan. vigin SFORZANDO The three SFZ relays can be easiliy removed from their socket without any tool. Just unplug them. Like always, first clean them with air-pressure but it is not sufficient. Then a little strip of blotting paper impregnated with alcohol is slided between the airgap in rest position. Part 2 49

SFORZANDO Restoring Hammond X-66 by dan. vigin SFORZANDO This cleaning process requires some dexterity. bent. Closed visual inspection is needed The moving parts of those relays are delicate and should not be When this strip of blotting paper is in position, contacts have to be closed by hand the piece of paper slightly slipped back and forward. It's surprising to notice the gross black marks left on the blotting paper. Part 2 50

SFORZANDO Restoring Hammond X-66 by dan. vigin SFORZANDO When completed, re-check the contact values in both 'Rest' and 'On' positions. Be sure that DC resistance stays in the range of 0. 3 Ω. Take the time to also measure the DC resistance of the relay coil (between 48 Ω and 52 Ω). It is also possible to extract each moving contact for proper cleaning (not easy and not recommended). After contact cleaning Part 2 51

SFORZANDO Restoring Hammond X-66 by dan. vigin SFORZANDO Pinning: most of male pins on the back side of those relays also exhibit some traces of verdigris that have been simply removed with alcohol before re-installing on the relay socket. The whole behaviour of X-66 console greatly depends on the SFZ relays ! This completes the Sforzando chapter. Cleaning pinnings Part 2 52

PERCUSSION KEYERS Restoring Hammond X-66 by dan. vigin PERCUSSION KEYERS The Percussion Keyers boards need to be reworked. Each P. K. circuit is using three capacitors : one elco and two tantalum types. The 100 µF elco's were in bad conditions and the tantalum ones were even worst. So all of them were replaced by new ones. This means 216 capacitors to be exchanged. New capacitors Old capacitors Part 2 53

PERCUSSION KEYERS Restoring Hammond X-66 by dan. vigin PERCUSSION KEYERS Nothing really complicated but it takes time. Removing each PCB from their support is rather easy. Unsolder the old cap's and replace by new ones. Special attention to correct polarity. Transistors and adjacent components were still within limits. Access to copper side is quite easy. Part 2 54

PERCUSSION KEYERS Restoring Hammond X-66 by dan. vigin PERCUSSION KEYERS Here is a view of all P. K. boards equiped with new cap's. As a general advice, it is strongly suggested to replace all tantalum capacitors. They are all noisy, leaky. . and create many troubles. Tantalum cap's This completes the P. K. chapter and Part Two. Part 2 55