Paul is a veteran broadcast professional of some 33 years. He has worked for both the Commercial Radio sector and for the BBC. His areas of expertise include Radio Programme presentation & production, Commercial Production and Voiceovers. He is also a technician who specialises in vintage electronics maintenance, in particular, DAT Recorder repairs. He also repairs more contemporary devices such as iPhones. He can be quite useful to know!
Viewers of ITV's "Emmerdale" will often see Paul sinking a few pints of Ephraim Monk in The Woolpack as one of the background regulars (he's an Emmerdale Extra!)
The following is a pictorial overview of a typical repair of a Sony DAT Recorder. It is not intended as a tutorial or a step by step repair guide!
Sony DTC-P7 - Sony’s only midi sized DAT Recorder was aimed squarely at the domestic market. The recorder uses the same mechanism as many of Sony’s full size models such as DTC-690, DTC-750 and consequently, they share common faults.
Top view of the P7 with its lid removed. The mechanism is seen on the left. The cylinder looking object is the head drum which houses two heads 180 degrees apart and rotates typically at 2,000 rpm. On the right is the main board with the power supply and audio section to the rear of the mecha.
This is the underside view of the mechanism with the drum drive board removed. The areas circled red are the entry and exit loading arms. Note, however, that the retaining clasps are missing. This is a common problem as the clasps are made from nylon and are prone to splitting. This causes the arms to become detached from the loading mechanism and therefore the tape cannot be loaded.
Close up of the nylon clasps prone to splitting at its weak points.
This is the topside view of the mechanism showing the take up and supply tables. The areas circled red are the back and forward tension levers. Note within the right hand circle the pressure pad which has worked free. This lever sets up back tension (along with the associated solenoid to the bottom right) and in this state will cause tape path instability.
So, with these issues corrected, it is time to look at the condition of the RF waveform. One of the issues with this set is that no audio was present when playing a tape. The most common causes of this are dirty or contaminated heads, head wear, tape path mis-alignment or a fault in the RF Modulator....or a combination of all of those! The photo below shows the location of the RF modulator, the metal can with the cluster of wires:
The can has to be removed and dismantled in order to access the PCB and associated components.
This is the component side of the RF modulator. The items circled red are electrolytic capacitors and these often fail with age. They become leaky and must be replaced. Whilst only one may have failed, I replace them all as a matter of routine.
When re-assembled, we can then setup the tape path:
The areas circled red and yellow are the entry and exit tape guides respectively. Each must be adjusted separately to achieve the waveform below. The LHS of the waveform is represented by the entry guide and similarly, the RHS is represented by the exit guide. Adjustment of these guides is critical and can only be achieved using an oscilloscope.