Yesterday I intended to record some on-the-air short wave radio transmissions. I installed batteries in a cassette recorder, loaded a cassette tape, connected the cassette recorder audio input to the audio output of the radio receiver, and started a recording session. After the recording session was complete, I rewound the cassette tape, and then attempted to play the recording -- the tape moved across the heads but nothing was heard at the speaker. Plugging in a set of headphones produced the same result -- nothing was heard.
Not knowing if the fault was a lack of recording or some inability to play a recording, I transferred the cassette to my CCR-82 Computer Cassette Tape Recorder, installed batteries in it, and then attempted to play the recording -- the tape did not move across the heads. Obviously a drive belt had broken. What to do, what to do? I went to the local WalMart and purchased another cassette tape recorder -- in fact, the very same model I used in the attempt to record the short wave radio transmissions. I installed batteries in it, loaded the cassette tape, and then played the recording -- sound emerged from the speaker and I listened to the recorded short wave radio transmissions. Obviously the original cassette tape recorder fault is some inability to play a recording. The original cassette tape recorder now is kept for cannibalization of parts in case the newly purchased units develops a fault. With the situation resolved, I turned my attention to the CCR-82 Computer Cassette Tape Recorder. I obtained a .pdf of its Service Manual and studied it. Disassembly is rather involved but the Service Manual has illustrations and thoroughly covers the dissassembly in three step: removal of the cabinet, removal of the PC board, and removal of the tape mechanism assembly. The tape mechanism assembly has 3 belts: main belt (Ref# 9), sub belt (Ref# 7), and belt for the tape position counter (Ref# 51). The main belt and the sub belt circuit the flywheel (Ref# 8) on separate tracks. I removed the cabinet, and saw that the main belt was off of its track on the flywheel. I measured the main belt -- 8 inches inside diameter (which likely is stretched), by 1 millimeter wide (.039 inch), by 1 millimeter thick (.039 inch). Then I placed the main belt back onto its circuit and rotated the flywheel by hand while engaging the play button. The tape capstan/pinch roller rotated properly and the take-up reel rotated properly. Then I loaded a cassette that had a recording on it, and pressed the play button. The recorded material was heard at the speaker. However, the take-up reel did not have sufficient torque to drive the forward spool within the cassette. According to the Service Manual, a torque of 30gcm to 65gcm is specified and, if the torque is insufficient, either the take-up reel or the forward clutch assembly must be replaced. Methinks the problem is insuffient tension of the main belt, which fails to pivot the forward clutch asseembly into position in order to engage the perimeter teeth of the take-up reel. A new main belt of proper inside diameter should correct this. I also saw that the sub belt was not found in its track on the flywheel. Some residue of its existance is seen within its track on the flywheel. Without further disassembly, my view is obstructed by the PC board such that I can't see any sign of the sub belt. It's likely that the sub belt, or residue of it, hides deep within the tape mechanism assembly. I believe its lack of presence explains why the rewind and fast forward actions don't take place. So I searched through Club 100 messages and found the subject of replacement belts was covered by two folks: David Ladd on December 9, 2010, and David Szasz on September 1, 2010. David Ladd cites the http://www.studiosoundelectronics.com/ link and part numbers: SBM8.0 - Main drive belt Inside Circumference 8.0", thickness .065", and SBM5.3 - Sub drive belt Inside Circumference 5.3", thickness .065". David Ladd's main belt information appears inappropriate based on my measurement of the existing and obviously stretched main belt found in my CCR-82 Computer Cassette Tape Recorder. An 8.0" Inside Circumference is to large, and .065" is too thick. David Szasz also cites the www.studiosoundelectronics.com link but he cites part numbers: SBO7.2 - Main drive belt Inside Circumference 7.2", thickness .039", and SBO4.7 - Sub drive belt Inside Circumference 4.7", thickness .039". David Szasz's main belt information is likely correct because it agrees with the 8 inch inside diameter measurement of my stretched main belt when a 10% stretch factor is assumed. At the very least, replacement of the main belt and the sub belt is needed. Compared to the expenditure of effort to completely disassemble the tape recorder in order to replace the sub belt, very little additional effort is required to replace the belt for the tape position counter. Until I completely disassemble the tape recorder, I won't be able to measure the existing belt for the tape position counter. Keeper of the Primordial Bit (born of the Big Bit Bang), -= Ron Wiesen =-
