Thread: Panasonic RF-D1
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Old 7th Feb 2019, 3:10 pm   #1
Julesomega
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Join Date: Dec 2012
Location: Stockport, Greater Manchester, UK.
Posts: 414
Default Panasonic RF-D1

The RF-D1 was an early portable radio for the new DAB system in 2004. I was given mine by a friend who had not managed to scan for any stations, and I found it had good sensitivity and pleasing audio, I only wish it had a DAB-derived clock. Two common faults may be encountered with the RF-D1, and the more serious will have caused the failure of any units which have seen regular use.

First is failure of the voltage regulator, which uses a power device with no heatsink. The mains adaptor gives an input voltage of up to 11.5V, leading to dissipation of 2 or 3W in this device, which may die from the heat generated, or more commonly can melt the solder on its leads and drop off the board. Replacement is quite straightforward but requires some ingenuity to provide meaningful heatsinking.The other reported fault is that the processor freezes and the display shows "F76 PDET". The reported solution to the problem is to press the Power and Menu buttons simultaneously for a few seconds, a couple of times if required. I have not encountered this problem. Panasonic have a good reputation for build quality so it is always worth trying to repair this model.

The supply regulator uses a PNP TO220 transistor type A2057 as the series pass element Q315 configured for low dropout, and any PNP TO220 type can be substituted. I long ago fitted a small heatsink.

Mine failed last week so I opened it up for a look and could see a scarred blob on a sub-board and a bulging 470 electrolytic which is across the supply rail. The blob had been a reverse-pol protection diode which had died valiantly, either because I had reverse-pol'd it when trying to run it on the bench PSU, or because of the electrolytic. Another SOT23 diode was fitted, anode to Gnd but a resistance check showed a dead short across it. It was still shorted when the diode was removed, and it turns out that the diode is switched into use only when the external power jack is inserted. This changes some internal switching which is hidden from view. The 470 was replaced and the board fuse which had failed, power applied, and when the 'on' button was pressed it sprang to life.

The only remaining job was to reassemble the boards into the radio, which was fraught with aggrevations so I offer my advice based on hard experience. To dismantle you need a #1 Philips for the body and PCB screws and a #0 for the three screws which hold the tuner PCB. Remove also the handle support piece which lies above the Ae skt, and remove the F-skt to withdraw the RF input board. Before replacing the main PCB ensure that the wire from the telecopic antenna is not trapped under the RF board, and the two wires from the battery compartment are not trapped under the main PCB. The front panel has a divider board which projects onto the main PCB: a line is marked on the PCB to show where it lies so ensure that no electrolytics are lying across the line and make sure Q305 and heatsink are clear.

The date codes on the speakers are 240604 in mine, btw. References to the faults can be found on forums from 2005 such as
radioandtelly.co.uk
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