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NCC Mark 1 Issue Number History

These Mark 1 controllers are now too old for factory service.

Warning: this listing was originally generated for 4QD internal use only, so is not as fully detailed as it should be if it were intended for general circulation. Also 4QD’s policy is one of continual improvement, so changes tend to be small and frequent. Also changes usually first appeared as a build modification on an the earlier board issue! This makes change history difficult to document fully, but it does improve the product! The history is however included here as it may be useful! No liability is accepted for the accuracy of the information in it!


The NCC series consisted of two different circuit boards:

  • Board 1 (part number for the bare board is 30-35) for the NCC-35 and NCC-50.
  • Board 2 (part number for the bare board is 30-36) for the NCC-60, NCC-70 and NCC-100.

These two boards were handled internally on a common computer file, consisting of three sections:

  • Common section
  • NCC-35 only parts
  • NCC-60 and NCC-70 parts

The issue numbers used therefore applied to both boards, so issue numbers tended to alternate. The ‘Bare Board’ is 4QD’s part number 30-35 for the NCC-35 and 30-36 for the NCC-60/70. This was etched in the copper of the circuit board, with the issue number, in the format 30-36-08, where the last -08 is the Issue number. It is on the component side near the aluminium heatsink block.


There have been no fewer than five different models in the NCC family.

  • NCC-35
  • NCC-50
  • NCC-60
  • NCC-70
  • NCC-100


The smallest board in the family, uses two MOSFETS.


Now discontinued, the NCC-50 used the same board as the NCC-35 but had four MOSFETs in place of two, so giving twice the current. It was an uprated NCC-35, but somewhat ‘overstretched’ the relays handing capacity. In the early days we used a relay manufactured by Schrack and MOSFETs were not as good as they now are. As MOSFETs improved, the available current increased and we started to get relay contact failure. Then Siemens bought Schrack and this particular relay was discontinued. Its replacement was of lower current carrying ability so the NCC-50 was dropped in late 1998, issue 14.


This is essentially the same as the NCC-70 but without the thermal sensor and parking brake driver. Discontinued in Autumn of 2001 (Issue 24 board) for no better reason than our range was getting too large!


The modern commonest member of the family. 4 MOSFETs, two drive, two regeneration.


In the early days (when MOSFETs were not so good) one customer tried an NCC-70, liked it but said, could we make one with slightly more current. The -100 was the result. It uses 6 MOSFETs (same as the Pro-120). However, it stretched the circuit board and main capacitors rather too much. It was discontinued soon after the Pro-120 was released, around NCC issue 08.


The board numbering system was implemented slowly: early boards did not have numbers or used a different identification, so it can be difficult to identify some early issue numbers. Key features are italicised.

Quick link to issue numbers

Click on the Issue number you want
01 02 03 04 05 06 07
08 09 10 11 12 13 14
15 16 17 18 19 20 21
22 23 24 25 26
  • Issue 01

    NCC-70, Board Part number 30-36-01, Aug 1993

    • This had a 4 pin control connector.
  • Issue 02

    NCC-35, Board Part number 30-35-01, Oct 1993

    • 6 pin control fitted.
  • Issue 03

    NCC-70/100, Board Part number 30-36-03, Dec 1993
    Last long board

After issue 3, the shape of the circuit board was changed: subsequent boards were shorter and fatter.
Early boards had been pre-select reversing. Later boards were ‘Dual ramp’.
Early boards also sensed pot fault at the bottom end of the pot. Later boards sensed at the top end of the pot, allowing the bottom end to be a direct battery negative connection to simplify external wiring.

  • Issue 04

    NCC-70/100, Board Part number 30-36-04, May 1994
    The board was actually marked ‘MkIV’

    • Dual ramp reversing fitted, hi-end pot fault.
  • Issue 05

    NCC-70/100, Board Part number 30-36-05, June 1994
    Board marked ‘MkIV’.

    • Details exactly as issue 4 but corner holes moved, holes for 100n in relay end (not used).
  • Issue 06

    NCC-35/50, Board Part number 30-35-06, Dec 1994
    The board was marked ’30-35-05′

    • Overvoltage clamp fitted. A relay track was wrong and had to be modified.

  • Issue 07

    NCC-70/100, Board Part number 30-36-07, Jan 1995
    The board was marked ’30-36 MkV’

    • First board to have regen current limit fitted.
  • Issue 08

    NCC-35/50, Board Part number 30-35-08, May 1995
    The board was marked ’30-36-08′.

    • Hiside zener moved (circuitry slightly re-configured), Input buffer feedback changed from ramp o/p, deadband reduced.
  • Issue 08

    NCC-70/100, Board Part number 30-36-08, May 1995
    The board was not marked.

  • Issue 09

    NCC-35/50, Board Part number 30-35-09 was marked on the board. NCC-35/50, 16 November 1995

    • New thermal sensor fitted on this and subsequent boards.
    • Board modified so that it was easier to accommodate series wound motors. The board had a cut which was to be bridged for PM motors.
    • A production fault meant that the hiside drive track needed separating.
  • Issue 10

    NCC-70/100, Board Part number 30-36-10, Feb 1996
    Board was unmarked.

    • Clock decoupling capacitor fitted, but subsequently removed!
    • Rev end decoupling.
    • track routing near relays altered
    • SCS hiside pullup.
    • The track break which was fitted for series wound motors is now removed: the track is cut in production where necessary.
  • Issue 11

    NCC-35/50, Board Part number 30-35-11, May 1996
    Board marked ’30-35-11′
    As issue 10 except that during the life of 10 or 11 the reversing threshold was changed: a 1K resistor was changed to 1K5. This alters the reversing threshold from around 6v to around 4v. It is inconsequential except on 12v controllers where the various joystick interfaces on occasion did not pull the reversing input high enough to engage reverse.This resistor is behind the expansion connector, just below the main capacitor.

  • Issue 11

    NCC 70, Board Part number 30-36-11, Dec 1996
    Board marked ’30-36-‘
    The board still had space for 6 MOSFETs, although the NCC-100 was now discontinued. No NCC-100 were built from this batch.

  • Issue 12

    NCC-35/50, Board Part number 30-35-12, Sept 1997
    Board was unmarked.

    • Pump ignition fitted.
  • Issue 13

    NCC-70, Board Part number 30-36-13, July 1998
    Board marked ’30-36-13′
    This board no longer had spaces for more than 4 MOSFETs (the NCC-100, which used six devices, had not been produced since May 1997).

    • Pump ignition fitted.
    • Battery tags moved closer to motor tags, so that uninsulated connectors have less chance of contacting components.
  • Issue 14

    NCC-35/50, Board Part number 30-35-14, Nov 1998
    Board marked ’30-35-14′

    • Current source moved to more room to fit TO5 on high voltage versions.
    • Current limit capacitor was 100n, now changed to 1ยต0
  • Issue 15

    NCC-70, Board Part number 30-36-15, Dec 1998
    Board erroneously marked ’30-36-13′

    • Current source: still more room

  • Issue 16

    NCC-35, Board Part number 30-35-16, Mar 1999
    Board correctly marked ’30-35-16′

    • Retrack current source
    • Reposition electrolytic leads at reversing end end (some caps had leaked).
    • Reverse/ignition diode added, so ignition can be used as ‘go forward’ and reverse as ‘go reverse’ for push button operation.
  • Issue 17

    NCC 60/70, Board Part number 30-36-17, May 1999
    Board correctly marked ’30-36-17′

    • as issue 16
  • Issue 18

    NCC 60/70, Board Part number 30-36-18, Aug 1999
    Board correctly marked ’30-36-18′

    • New current limit circuit. The old current limit was a problem with certain makes of LM339, which had excess sensitivity to negative going spikes on the inputs so that the conventional 1N4148 input clamp was inadequate.
    • Thermal sensor circuit modified, mainly to reduce component count. New circuit is not as sharp in operation as the old, so the current does not reduce as quickly with increasing temperature so the heatsink can therefore get hotter and give more current.
    • 6 way expansion connector re-configured to allow use with tachogenerator board.
  • Issue 19

    NCC 35, Board Part number 30-35-19, March 2000

    • This is the NCC-35 version of issue 18.
  • Issue 20

    NCC 60/70 Board Part number 30-36-20, May 2000

    • Changes are minor, to do with the expansion connector. There was also a change in an earth track as one customer managed to blow controllers (hi-side) by some interaction between the controller and his wiring!

  • Issue 21

    NCC-35. Board Part number 30-35-21, May 2000

    • NCC 35 version of issue 20.
  • Issue 22

    NCC 60/70 Board Part number 30-36-22, Oct 2000.

    • Changes are minor: the only significant one is the addition of a 10K resistor across the main capacitor to discharge it. Without this, the main capacitor can hold its charge for hours after disconnecting the battery and damage can then occur with mishandling the board which is still live while the capacitor is charged.
    • Around May 2001, a resistor was changed from 10K to 22K. See NCC Series, key components, Item 24
  • Issue 23

    NCC-35. Board Part number 30-36-23, Jan 2001.

    • NCC-35 version of Issue 22.
  • Issue 24

    NCC-70. Board Part number 30-36-24, June 2001.

    • The only change to the board is the addition of 10R resistors in the high side MOSFET gate drives.
  • Issue 25

    NCC-35. Board Part number 30-36-25. March 2002

    • Change made to capacitors in output timing circuit: one capacitor reduced and a second added. Slightly improves switching ‘cleanness’.
  • Issue 26

    NCC-70. Board Part number 30-36-26, May 2002.

    • Power supply current source replaced by a TO220 (TIP 42) – 36 and 48v previously required an untidy extra heatsink.

In early 2003, the NCC was redesigned as the Mark 2 NCC. In mid 2005 this was redesigned as the VTX.