From cbfsb!att!emory!athena.cs.uga.edu!mcovingt Mon Jul 15 15:45:45 EDT 1991 Article: 8311 of rec.radio.shortwave Xref: cbfsb rec.radio.shortwave:8311 sci.electronics:17778 Path: cbfsb!att!emory!athena.cs.uga.edu!mcovingt From: mcovingt@athena.cs.uga.edu (Michael A. Covington) Newsgroups: rec.radio.shortwave,sci.electronics Subject: How I Fixed My Sony 2010 Summary: How to replace FET that commonly fails. Keywords: Sony 2010 shortwave receiver sensitivity FET Message-ID: <1991Jul15.044316.2141@athena.cs.uga.edu> Date: 15 Jul 91 04:43:16 GMT Organization: University of Georgia, Athens Lines: 43 (Somebody please save this in an archive somewhere... it's a frequently asked question.) The most common component failure in the Sony ICF-2010 (ICF-2001D) receiver is probably Q303, the AM front end transistor. The symptom is loss of sensitivity (either sudden, or gradual and insidious). In previous net discussion people have said that the failure is due to static electricity, but mine went kaput while I was using an antenna well protected by diodes. Personally, I suspect Sony got a bad batch of transistors. Anyhow, the repair is easy and does not involve any adjustments or alignment. Here is the procedure: (1) Remove the back cover by removing the 7 screws that are marked with arrows. (One is inside the battery compartment.) Leave the computer batteries in place. (2) Locate Q303, which is well marked on the small circuit board near the antenna jack. The terminals are G(ate), S(ource), and D(rain), in that order. G is marked. (3) If you care to make a test, operate the radio in AM mode and measure the voltage from the drain of Q303, to the sleeve of the antenna jack (which is circuit ground). If substantially below 2.9V it indicates that Q303 is leaky. (4) Replace Q303 with the readily available MPF102 or any other low-noise N-channel JFET, making sure to get D, S, and G connected correctly. (5) That's all; put the radio back together and evaluate sensitivity. 73 de N4TMI -- ------------------------------------------------------- Michael A. Covington | Artificial Intelligence Programs The University of Georgia | Athens, GA 30602 U.S.A. -------------------------------------------------------