[Premium-Rx] wj 205 / A10R14: how to estimate the nominal value of a burned carbon resistor
Peter Ratuschni
zpz at gmx.de
Thu Jul 10 17:06:27 EDT 2014
Hello,
the repair of the 205-3 makes some progress. At least the power supply is working now and even with most semiconductors replaced the +/- 18V rails did not need any adjustments.
Now I am going through all boards searching for failed components before reinstalling them in the receiver.
Due to the former overvoltage condition the value of resistor R14 on board A10 / CEI 76179 cannot be identified any more.
The first or last ring is yellow - but all the used Allen Bradley carbon comp resistors in the unit have a fifth yellow ring. So this probably does not mean anything about the nominal value. Measuring this burned resistor gives 37 ohms.
Because I have found a lot of 47 ohm resistors in the unit which were 10 to 50 percent higher in value, one could guess that R14 was lower than 37 ohms. But with a really burned out resistor the change in value may be reverse - who knows?
I will try to overload one of these desoldered 47 ohm resistors and see what happens.
Or is there a chance, that anybody can lookup the value? A10 is one of the few boards in this receiver where all components are labeled. R14 is between C3 and Q2.
b.r.
Peter
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