Heathkit Troubleshooting Tips Last updated: Thursday, 4 December 1997 Made some internal changes to speed up image loading and corrected some of the obvious spelling errors. There's been no technical changes since 29 March 97. -------------------------------------------------------------------------------- Note: This file (HECO_FIX.HTM) is rather long (about 50 KB, or 1400 lines of text). To save online charges, you may download it and the associated image files to your local drive and read it off line. (Please respect the copyright notice at the end of this text.) The required image files are: HECO_AD1.GIF (1922 bytes) HECOGR78.GIF (1183 bytes) HECOH9A.GIF (1705 bytes) HECOH9B.GIF (2225 bytes) HECOIG28.GIF (3986 bytes) I will update this information as necessary if I make any significant changes to this file. --Bill -------------------------------------------------------------------------------- Introduction From 1973 to 1978, I worked as an electronics technician at the Heathkit Electronics Center (store #45) at 9207 Maple Street in Omaha, Nebraska. It was the first "mini-store" that Heath Company tried. A mini-store is a Heath store with three or less employees. A full-size Heath store usually had eight or more employees. People in those stores could be in sales or a specialized area of service. In Heath's first mini-store, the three of us (that includes the manager) did sales and service. Since I was more of a "techie" than the other two, I spent most of my time repairing the products. (The other employee, Vern, spent his time between TV repair and sales. The manager, Joe, managed.) Because we didn't have enough people to specialize, I ended up working on a wide variety of Heath products. To help me keep track of the problems associated with each product, I kept notes in a little black notebook I purchased from Lefax®. When I transferred to Michigan, I transcribed those notes to an H8 cassette and left a copy in Omaha for my successor. I was told that it came in handy several times. Over the years, the tape had gotten lost. However, I've managed to hang onto the original document and have laboriously transcribed it again--this time for the Web. Some words of caution: It's been a long time since I've serviced Heath products and have forgotten a lot of the details of some of the circuits described here. Though I've cleaned up some of the grammer and spelling, I've left the original notes intact if I could no longer recall what the note was about. The original writing may make sense to an experienced technician still servicing electronics. Some of the fixes listed in here weren't authorized by Heath Company and I doubt that they or anybody else will support them. They were fixes that got the unit back to working within specifications and back to the customer in a timely manner. Also, many of these fixes are model number specific. What would work for an SB-104, for example, would not work for an SB-104A. So here's the Legal Copout: Don't attempt to use these service procedures unless you have a strong background in electronics and can analyze the circuitry. (I may have made some typographical errors when transcribing this information and missed them during proofreading.) A strong background in electronics would include attending a two-year technical school, three years training and experience with military digital electronics, a couple of mail-order courses in computer and RF communications engineering, a First Class Radiotelephone License with Ship's Radar Endorsement, and CET certification. (What, me brag?) In other words, don't blame me if applying these troubleshooting tips gets you upset in some form. With that bit noise out of the way, here's the notes from my little black book. Have fun. (By the way, I didn't single-handedly come up with all these ideas. Many were suggested or inspired by others--or are factory-authorized modifications. I just noted them down at the time. I'll try to give credit where credit is due if I can remember who the contributor is.) --Bill -------------------------------------------------------------------------------- AA-Series Amplifiers AA-22 SPST pushbutton power switch breaks down quite often. AA-29 Hum and noise audible w/volume turned up and covers taken off: This is normal (approx. 3mV @ 8 ohms measured with IM-48). AD-Series Audio Equipment AD-17, AD-19, AD-27, and Other Systems w/BSR-500 Changers Slow Speed and Slow Changer Action: Changer may even stop during change cycle. Check idler wheel height adjustment. Replace idler wheel if it has a "hardened" appearance. Clean idler wheel, pulley, platter, and changer mechanism with a non-lubricating solvent (Print-Kote®). Don't use tuner contact cleaner as it usually contains silicon lubricant. Soak the bearing assembly in solvent (the assembly at the base of the spindle). Lightly oil this bearing assembly and the cam next to it