Re: ITT SL 530 Cassette Recorder Check Out
Hum still present when on batteries but as before intermittent in nature.
Internal microphone recording checked OK.
Opened up the unit and tried to see if could either induce hum when no hum present or make hum go away when hum was present, by disturbing various cables and connections.
With hum present could make it worse by disturbing screened cables (to heads and microphone) and/or just putting hand close to areas of the PCB (which may well be normal). With hum not present could sometimes make it come and go by tapping areas of the PCB.
Neither of the above was very conclusive. Gave the PCB a good visual under magnifying glass, but no obvious dry/bad solder joints found.
Have now got the PCB hinged back to inspect the components side, had to disconnect various wiring including the heads wiring so not really practical to do live operational checks with the board hinged back.
The PCB is marked SL 520 so hopefully the SL 520 schematic I found will match it.
|