Cliff 1959 Posted November 17, 2016 Share Posted November 17, 2016 I have an old Silverlit Sopwith Biplane new still in its box but there seems to be a problem with the charging ... the green light is supposed to illuminate to indicate a charge is taking place when the charge lead from the transmitter is plugged in but nothing happens. The batteries in the transmitter are new and the voltage output indicates this to be so, I've taken the back off and put my meter on the outputs from the board to the charging plug and I get no reading so presumably the problem is somewhere in the board? Any ideas anyone. Quote Link to comment Share on other sites More sharing options...
Denis Watkins Posted November 17, 2016 Share Posted November 17, 2016 If you have a multimeter Cliff, check the LED, set the multimeter to Diode, A triangle pointing into a bar symbol. The LED could have failed, and if it is in series, it will cut the charge current. The LED is biased so try your red and black probes both ways. If the LED is working, check the pins in the Tx output charged lead for being bent back and not making contact. Report your findings for us to go further Edited By Denis Watkins on 17/11/2016 21:40:26 Quote Link to comment Share on other sites More sharing options...
Cliff 1959 Posted November 17, 2016 Author Share Posted November 17, 2016 Hi Denis, Thanks for your interest, I set the multimeter to Diode and the display shows '1' I then checked the LEDs, the one that I know is working starts with a reading of around 1.8 and quickly drops to 1, the one that doesn't light up shows a reading of 1.642 and remains constant ... is this indicative of a problem? As for the output lead it's a socket on the end so no pins to bend, but there is no voltage showing from the charge lead soldered connections on the circuit board whether the plane is plugged in or not. Quote Link to comment Share on other sites More sharing options...
Cliff 1959 Posted November 17, 2016 Author Share Posted November 17, 2016 Also I've just noticed that when I switch the circuit on the green charge LED very briefly flashes as the slide switch moves across. Quote Link to comment Share on other sites More sharing options...
Former Member Posted November 18, 2016 Share Posted November 18, 2016 [This posting has been removed] Quote Link to comment Share on other sites More sharing options...
Denis Watkins Posted November 18, 2016 Share Posted November 18, 2016 Like Tom, I believe we have a board failure. Something caused the LED to fail. If you want to persue this, just replace the LED and check for dry joints. If a surface mount IC has failed completely there is little chance of replacing it, and of actually getting a replacement back on to the board. When you think a B6 charger is about £12 then repairs become uneconomic. Quote Link to comment Share on other sites More sharing options...
Cliff 1959 Posted November 18, 2016 Author Share Posted November 18, 2016 I've decided to fit a small external battery that I can charge from my big charger, problem circumvented! Edited By Cliff 1959 on 18/11/2016 22:56:01 Quote Link to comment Share on other sites More sharing options...
Malcolm Baird Posted November 19, 2016 Share Posted November 19, 2016 Hi Cliff - just read your diagnostics. I'd have thought that if the LED is flashing even briefly it (the LED) is probably OK. If the switch is part of the charger, most likely the problem is in the mechanical switch making intermittent contact. Depends on how sophisticated the charger is. If your charger has its own built in switch on the low voltage side, have you tried bypassing/replacing the switch? If it's the switch on the mains wall socket on the other hand, ignore most of what I just said. Most modern ('Switch mode' ) chargers have complex circuitry and lethal voltages, and can't easily be fixed. Best replaced. Older chargers (e.g. with a mains transformer in) have a high input voltage (240V mains - lethal), a transformer step down, and a low voltage output circuit to regulate the charging current. To check an LED properly, it needs to be out of the circuit. Then you should get approx 1.8 volts across it if it's red/green/yellow, and about 3.3V if it's blue or white. Use a 5V to 9V supply, and limit the current through the LED with a resistor. For a 9V supply use approx 200 ohms, and for a 5V supply use approx 80 ohms resistors (Ball park figures). Don't mess with the mains unless you know what you're doing!! Edited By Malcolm Baird on 19/11/2016 00:26:40 Edited By Malcolm Baird on 19/11/2016 00:27:05 Quote Link to comment Share on other sites More sharing options...
Cliff 1959 Posted November 19, 2016 Author Share Posted November 19, 2016 The flight battery charges from the transmitter via a little lead so now separate charger. As the green LED lights very briefly I agree, it must be working, the problem may lie in the switch but I've just finished removing the original battery (which is probably US now after six years of sitting in its box) and wiring up a socket for an external battery. This has got it working ok but it'll probably fly a little faster with the extra weight. Thanks for your very well thought out answer though. Quote Link to comment Share on other sites More sharing options...
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