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I have an RCA RT2780 - receiver unit, and one of the resistors on the power supply board is burned so much that the color bands are not there anymore. The resistor is R202, if somebody has the circuit diagram for the unit, please let me know what the value is. Or maybe somebody can upload the diagram in PDF and post a link here. Also, the circuit board itself is marked as RT2770, so I suppose these units use the same kind of power supply board, which makes me guess that it should be pretty generic, easy to come across.

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  • Nyle Davis
    Nyle Davis Oct 16, 2013

    I have the same problem with my RT2770, which uses the same power supply board. R202 along with C211 make up the "snubber network" for the fast action diode pack (TO5 Tab mounted on 2nd large heatsink) labeled D207. This resister is so burnt, on my unit, the color bands are not readable, so the value can not be determined. Obviously, by size, this is a 1 watt resistor. This resistor goes out when C211 shorts out at high voltages. Normal testing will not show the short, since it is an arching short at high voltage. On my system C211 has no markings so I need this value also. From my knowledge of High Efficiency Switching Power Supplies, they use high frequency switching (pulse width modulation is used to vary signal width to increase amperage under load). Snubber networks are needed to chop off the hign voltage spikes that occur. These spikes vary as the input voltage varies. Typical voltage here in the US varies from 105 to 125 VAC. Therefore the spike voltages at the upper end can easily exceed 30 KVAC. Since I used to repair switching power supplies, the design engineers typically under rate the capacitor at 10-25 KVAC, which should be 35-50 KVAC. So when you replace this capacitor, get one with same capacitance rating (critical for resonance with the frequency of the design) but add 10-20 KVAC to the voltage rating from the schematic. I'm trying to find the value of these 2 components, so please share if you have this knowledge.

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The resister called for is R202, which is a 1 Watt resistor and makes up a "snubber network" with C211, which must be replaced as it shorted, which caused R202 to burn out. This short will not show on any tester as the short only occurs above 25 KVAC from the spikes that this system typically produces. Do not replace C211 with same value capacitor, because it will also fail. The MFD rating must be the same to resonate with the frequency, but up the VAC rating. Engineers typically design these @ 12-25 KVAC and you need a rating of 35-50 KVAC, since the voltage spikes easily exceed 30 KVAC.

Posted on Oct 16, 2013

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SOURCE: I need a new Resistor for my RCA RT2770 the number by the resistor is R202, does anyone know what size the resistor is?

I haven't found the answere yet, but my RT2870 uses the same power supply board and this appears to be a known issue with this power supply board. keep checking this thread:

http://www.hometheatershack.com/forums/rca/54253-rca-rt2870-turns-then-back-off.html#axzz2DvlVJuuL

if an answer is found, it will wind up being in that thread...

also, if you found the answer, please post it to that thread, thanks!

Posted on Dec 03, 2012

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