General Information on 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