NEAL 103 Cassette Deck

Currently working on this machine, just posting images for now ...

Main Circuit Diagram:

This is the schematic for the NEAL MKII, I suspect it is very close or identical to the NEAL 103?

 

Transformer: 

Secondary voltages (under load) at ..

(1) Vyy ~ 41.2v rms,

(2) Vxx ~ 10.3v rms.

Induction Motor Armature Current: 

Ia ~ 133mA (ac), and unloaded motor (primary tapped) voltage is approximately 116.2v, RMS. 

Main Board:

Identifying where each circuit is not going to be easy - there are no markings at all on either side of the board.

All electrolytic capacitors were replaced, this solved a line in distortion problem. 

The Power Supply Unit (PSU) on this NEAL 103 appears to be near identical to schematic of the NEAL 102 MKII. The original 'axial' 1000uF main power supply capacitor has been temporarily replaced with a radial type, in this case I've used a 2200uF.

I have no formal service manual for this NEAL 103.

New Old Stock Pinch Roller Mechanism:

On both the NEAL 102, and 103 models they employ their own unique pinch roller mechanism and pinch roller. The tyre had worn and was in a poor state, although tapes could still be played.

The old arrangement was removed, and a protruding 'boss' was ground down to make room for a mech that was originally in a TEAC A-109.

So far, so good.

Induction Motor Inpection Images

 

The motor was about 2.5% to 3% slow which was surprising, so I opened the motor up for cleaning and lubrication. 

 

To increase the motor speed, theoretically another pulley will have to be made with a 2% to 3% percent increase in diameter. 

Alternatively, increasing the supply voltage, or even lessening (if possible) the air gap between the stator and the actual rotating rotor would bring about the increase in speed. All of which are difficult to realise to get the desired, but small increase in motor speed. 

Internal labelling states this machine can be switched to either 230v or 115v, I initially suspected that this machine was wound or configured for 240v? I now suspect that back in 1975/1976 this machine was configured for the 240v UK mains voltage, and so this deck's pulley was made to accommodate for that small (default) increase in supply voltage? The UK now runs on a main voltage of 230v/50Hz rms. 

Returning the motor back to the deck after cleaning, and the speed was now hovering around 1.5% slow. I may look into this later, but thoughts also do surface that each transformer manufactured will not be identical. Small differences in primary voltage tappings from one transformer to the next will statistically occur. 

Motor Circuit Now Fused

 

Motor is now fused; there's no requirement to do this other than to easily monitor ac induction motor current, which is steady at around 133mA.

 

 

 

This NEAL 103 report may be updated without notices. (30/12/2025)