19th Oct 2020, 11:20 pm | #1 |
Pentode
Join Date: May 2017
Location: Ware, Hertfordshire, UK.
Posts: 215
|
Philco U647
hello all, a new protect ,or possibly bridge to far, the cabinet is good
the speaker needs a couple patches speaker transformer checks out ok But 35RE gone, 1d6 fitted, barretter and holder gone, dial lamp and shadow meter also missing. the chassis rubbers missing and its had a good bashing the centre sub chassis bent . so a capacitor dropper for LT a resistor for shadow coil ? the schematic u647 not very clear but u638 looks to be the the same radio (different cabinet ?)I've fitted new electrolytic caps (sticking out of the top (easy to get back out if it fails) isolation transformer variac lamp limiter , the capacitor dropper made the dim bulb not dim!, took two days to work that out ..so I have a second variac for LT (the isolation transformer probably is no longer doing it job)I had the make a wooden frame to hold the chassis Many hours spent, but this evening found MW 5 live ? no aerial turned of let cool down (voltages not GOOD) fire up plug in long wire crikey, lots of stations ..so I think that indicates major parts all ok. need to work out what to do next, its above my pay grade but seems to be a good performer dave |
25th Oct 2020, 7:34 pm | #2 |
Pentode
Join Date: May 2017
Location: Ware, Hertfordshire, UK.
Posts: 215
|
Re: Philco U647
hello all . the HT was low i have changed most of the capacitors in rectifier out put valve end (No room to get probes on valve pins) took a wire of
the block capacitor tacked new cap (higher value all I had) with a new resistor I got negative grid volts 0n 2151 .removed 1D6 I put a diode and a bridge for LT in an old valve base adjusted LT volts ,still low HT. turned wave change switch a few times All ok 210v in 250v dc out Then I plugged in a power/energy monitor. the set draws .2amp =200ma at 27 watts, (the LT is on a separate power supply) if that is correct the 1D6 rectifier is not up to the job should I be looking for another type rectifier, what valve ? thanks all |