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MCI JH-16 Series Tape Machines

The MCI JH-16 Series machines have either a JH-10 (silver top 1971-'73, with all AC motors), JH-100 (yellowish top 1973-'75, with AC reel motors, and a DC capstan motor), or JH-114 (yellowish or seahawk grey 1975-'79, all DC motors) series transport. They all came from the factory with input and output transformers on each control card, and a head coupling transformer on the reproduce card. After sale, some machines may have had either the input, output, or both transfomers on the control card removed. This was thought to improve the "sound." When done correctly (with additional electronic balancing circuits), this modification will make the circuit a little more transparent. However, removal of the transformers changes the input/output impedance, and the frequency response of the circuit. Most engineers prefer the characteristic "warm sound" of the transformers.

All JH-16 machines from 1971-'78 did not have and cannot be retro-fitted for "quick-punch" circuitry. Starting in 1978 and continuing into '79 the QUIOR (quiet initiation of record) "quick-punch" circuitry was delivered as a standard circuit on the machines. Any machine that has a Bias card with "PC 9000-139" has the QUIOR circuitry integrated onto it. Also, the erase head and the record head were placed closer together on the headstack than on non-QUIOR headstacks.

JH-10 and JH-100 machine cabinets have the audio cards mounted side-by-side in a fold-down rack. The JH-114 machines, and some late JH-100 machines are in the JH-24 cabinet, with sliding drawers, one drawer for each bank of 8 channels of audio electronics.

JH-16 series audio electronics channels consist of a Buss board for each set of 8 Strip boards. Each Strip board hosts (from top to bottom):

  • Control card
  • Reproduce card
  • Record card
  • Bias card
MCI JH-24 Series Tape Machines

JH-24 Series machines (1980-'88) have a JH-114 series transport (it's brown, and matches the color of the cabinet), with balanced differential (I.C.'s) inputs and outputs. After 1982, a 4 to 1 step-up transformer was added to the Cue circuit to improve signal-to-noise in Sync mode.

JH-24 Series audio electronics channels consist of a Buss board for each set of 8 Strip boards. Each Strip board hosts (from top to bottom):

  • Reproduce card
  • Input/Output
  • Record/Cue card
  • Bias card
Important Miscellaneous Facts
  • There were NO MCI JH-116 machines, or JH-124 machines, every made; these are not valid MCI product model numbers!

  • Before 1980 all the electronics were referred to as JH-16 electronics. Prior to 1974, all discrete components were used on the Reproduce, Record, and Bias cards. These are referred to as non-QUIOR (Quiet Initiation of Record). After 1974, two I.C.'s were added to the Control cards, and after 1978, 2 I.C.'s were added to the Bias cards.

  • All JH-16s, with JH-10, JH-100, and early JH-114 transports, used either Nortronics or AMC Erase heads (non-QUOIR). Late model JH-16s (1978-'79), with JH-114 transports, and all JH-24 machines, were Woelke (ceramic) Erase heads (QUIOR). The QUIOR circuit ramps the Bias and Erase current on and off for smoother, seamless punch-in/out.

  • All Record and Reproduce heads were either Nortronics or AMC.

  • JH-16 Series Record and Reproduce heads were low impedance (z). The JH-24 Series Record head is the same low impedance (z) as the JH16 Series (same head).

  • The JH-24 Reproduce head is a different head and is high impedance!!

  • The head assembly from the JH-16 Series machine will not work on a JH-24 Series machine, and visa versa!!

  • The headstack from a MCI JH-10 transport will not interchange with JH-100 or JH-114 mounting system. The Headstack from JH-100s and JH-114 transports will physically interchange, although the heads and head mounting position may be different.

  • JH-16 and JH-24 Audio cards and power supplies ARE NOT interchangeable. Only JH-16 (1978-'79) and JH-114 transport system cards, power supplies, and motors are interchangeable with JH-24 (1980-'88) JH-114 transport system cards, power supplies, and motors.

  • JH-10 transport system cards, power supplies, and motors are incompatible with other MCI Transport systems (i.e., JH-100 and JH-114 transport systems).

  • JH-100 transport systems are incompatible with JH-114 tranport systems, only the capstan motor, control logic board, solenoid driver boards, or lamp driver board are interchangeable.
The pictures below are of two different types of remote connectors for JH-24 Series. The silver connectors were used on 1980 - 1982(ish) JH-24 remote controls. Note that the same silver connector was used on JH-16's throughout the '70s.