2024-12-29 - Replacing Belts in a Panasonic RX-FW29L Cassette Recorder ---------------------------------------------------------------------- Years ago, I got an old Panasonic RX-FW29L cassette recorder that has just been lying around collecting dust ever since[0]. It was still in working condition, at least partially. The left side worked without any problems, but on the right side, the spools weren't turned, so the tape wasn't pulled back into the cassette. I figured there was probably a bad belt somewhere inside, so I decided to take it apart. Disassembly ----------- WARNING: This device does plug directly into mains power, so make sure that you don't electrocute yourself. If you don't know how to stay safe when working on such a device, please don't kill yourself and let someone else do the work instead. The first step is to remove all the screws on the back[1], including the ones inside the battery compartment[2]. I also removed the antenna[3], but I think that wasn't actually necessary. [4] shows all the screws that came out. Note that one of them is a bit shorter, so take care to put that one back into the correct place (I forgot which hole that one belonged to, but it should be obvious if you have to take the same cassette recorder apart). Once all the screws have been removed, it is possible to take off the entire front of the recorder[5] (both cassette doors have to be open for that to work). The front is held on by two cable bundles[6][7] which have to be unplugged in order to remove it completely[8]. The carrying handle[9] can also be slid out once the front has been removed. In order to remove the mechanism, the red plastic on the right side needs to be removed first[10]. Two of the screws are readily accessible, but one is hidden behind the tuning wheel at the top, which makes it a bit annoying to unscrew. The tuning wheel needs to be removed together with the board it is attached to[11]. There is a hole in the board through which a plastic piece can be pushed down to allow the board to slide out[12]. This part is quite annoying because the board is wedged in very tightly. Once the board with the tuning wheel and the screw behind it have been removed, the red plastic piece can finally be moved to the side[13]. Once that is gone, four screws in the mechanism must be removed[14][15] and the black plastic piece on the left side underneath one of the screws must be taken out[16]. This allows the mechanism to be partially taken out, although it is still held by four cables[17]. Take note of the gray cable at the right because it needs to be put back the same way it was before during reassembly[18]. At this point, I could already see the bad belt, or rather, the lack thereof[19]. The remains could be seen lying at the bottom[20]. In order to fully remove the mechanism, the cable bundles need to be unplugged. The gray and black bundles on the right are also glued in[21], but the glue can simply be broken off (I don't think the glue is too important, so I didn't add any fresh glue during reassembly). The mechanism can then be taken out completely[22]. Note that there is a spring on one of the wheels (the one where the belt was missing/destroyed), which will fall out when taking the mechanism out[23]. In the picture, it is the wrong way around, but more on that later. I think this wheel is the slipping clutch that is used to turn the spools at the correct speed[24] (the two parts of the wheel are pushed together by the spring, with a piece of felt in between), but I'm not an expert, so I'm not entirely sure about that. Belt Replacement ---------------- Since the old belt had completely disintegrated and there was still some sticky residue left on the wheel, I had to clean that off before the new belt could be inserted. Cleaning the second wheel that the belt wraps around was a bit difficult because it's located underneath the big metal wheel. I fortunately managed to find a matching belt in my collection of random belts. I forgot to measure its circumference, but I did note down that it was a square belt with a thickness of 1mm (don't take my word for it, though, because my notes weren't particularly great, and I'm not entirely sure if I interpreted them correctly when writing this article). If you need to buy a replacement belt and don't have a reference for it, you could probably take a piece of string and lay it around the wheels to figure out what the approximate circumference should be, then buy a belt with the proper thickness and a circumference slightly less than what was measured with the string (so it isn't loose). In order to replace the belt, the belt going around the larger wheel has to be removed first[25], after which the replacement belt can be inserted[26]. It's a bit difficult to get the belt underneath the large wheel because there are some obstacles in the way, so you need to poke around quite a bit before it sits properly. The belt around the larger wheel seemed to be fine still, so I left that alone, but there was a belt on the other side of the mechanism that was already a bit loose[27]. It still worked, but since I had everything disassembled already, I decided to replace it as well (mainly because I got a collection of belts a while ago, so I didn't have to buy any replacement). The mechanism needs to be turned around to access the small plastic wheel that this belt is wrapped around[28]. There are two smaller belts which can be seen on that side of the mechanism, but those are only used to advance the tape counter, so I didn't replace them even though they were fairly loose. UPDATE (2024-12-30): Just to clarify, the tape counter is still working, the belts are just a bit loose. I don't think the loose belts are much of a problem in this case, though, because they only have to move a tiny wheel for the tape counter. Mechanism Reassembly -------------------- Once the belts have been replaced, the mechanism can be reattached to the rest of the cassette recorder. Make sure to reattach the four cables, and put the black and gray cables on the right side into the correct places again where they were originally glued. Particularly watch out that the gray cable goes back as shown in [18] before screwing the mechanism back in. Another important note is that the spring which was mentioned earlier needs to go into the correct place. I originally put the larger side onto the plastic wheel[29], but that caused the spring to rotate with the wheel and cause clicking sounds[30]. Turning it around resolved those issues[31][32]. When reattaching the red plastic piece on the right side, it's quite difficult to push the board with the tuning wheel back in. I used a screw driver to push down on the little plastic clip so the board was easier to push in, but it still required a lot of force[33] (of course, only do that after screwing in the screw that is hidden behind the tuning wheel). Volume Slider and Carrying Handle --------------------------------- Before reattaching the front part of the cassette recorder, it might be helpful to look at the volume slider on the left side, which was a bit scratchy in this device. It is an interesting sort of potentiometer because the resistive track is visible from the outside, there is no cover over it[34]. In this case, that was somewhat convenient because it meant that I could clean it reasonably well without having to take out the entire circuit board it is attached to. I cleaned it with isopropyl alcohol and added some silicone grease[35], as explained in one of my previous articles[36]. Adding the grease might have been a bad idea since the missing cover on the potentiometer means that more dust might get stuck on the grease, but I can't say for sure. Don't forget to stick the plastic slider back on after cleaning the potentiometer[37]. One last issue I noticed was that the plastic holding the carrying handle was broken partially, so I glued that back on[38]. I don't think it really is critical, though, since the front of the cassette recorder slides over the top and prevents the carrying handle from breaking out completely[39]. Final Reassembly ---------------- There isn't really much left to be said now. Just make sure to reattach the two cable bundles from the front part before putting it back on. One last tip is that it's best to push the top in first so the buttons there go through the holes in the front part, and then push the rest in[40]. I think that's all I had to say. Have fun repairing obsolete devices. [0] gopher://lumidify.org/I/phlog/2024-12-29-cassette-recorder/recorder.jpg [1] gopher://lumidify.org/I/phlog/2024-12-29-cassette-recorder/back.jpg [2] gopher://lumidify.org/I/phlog/2024-12-29-cassette-recorder/battery_screws.jpg [3] gopher://lumidify.org/I/phlog/2024-12-29-cassette-recorder/antenna.jpg [4] gopher://lumidify.org/I/phlog/2024-12-29-cassette-recorder/screws.jpg [5] gopher://lumidify.org/I/phlog/2024-12-29-cassette-recorder/half_open.jpg [6] gopher://lumidify.org/I/phlog/2024-12-29-cassette-recorder/front_cables1.jpg [7] gopher://lumidify.org/I/phlog/2024-12-29-cassette-recorder/front_cables2.jpg [8] gopher://lumidify.org/I/phlog/2024-12-29-cassette-recorder/open.jpg [9] gopher://lumidify.org/I/phlog/2024-12-29-cassette-recorder/carrying_handle.jpg [10] gopher://lumidify.org/I/phlog/2024-12-29-cassette-recorder/red_plastic.jpg [11] gopher://lumidify.org/I/phlog/2024-12-29-cassette-recorder/red_plastic_board.jpg [12] gopher://lumidify.org/I/phlog/2024-12-29-cassette-recorder/red_plastic_board_removed.jpg [13] gopher://lumidify.org/I/phlog/2024-12-29-cassette-recorder/red_plastic_removed.jpg [14] gopher://lumidify.org/I/phlog/2024-12-29-cassette-recorder/mechanism_screws1.jpg [15] gopher://lumidify.org/I/phlog/2024-12-29-cassette-recorder/mechanism_screws2.jpg [16] gopher://lumidify.org/I/phlog/2024-12-29-cassette-recorder/mechanism_black_plastic.jpg [17] gopher://lumidify.org/I/phlog/2024-12-29-cassette-recorder/mechanism_removal.jpg [18] gopher://lumidify.org/I/phlog/2024-12-29-cassette-recorder/mechanism_gray_cable.jpg [19] gopher://lumidify.org/I/phlog/2024-12-29-cassette-recorder/missing_belt1.jpg [20] gopher://lumidify.org/I/phlog/2024-12-29-cassette-recorder/missing_belt2.jpg [21] gopher://lumidify.org/I/phlog/2024-12-29-cassette-recorder/mechanism_gray_cable_glue.jpg [22] gopher://lumidify.org/I/phlog/2024-12-29-cassette-recorder/mechanism_removed.jpg [23] gopher://lumidify.org/I/phlog/2024-12-29-cassette-recorder/mechanism_spring.jpg [24] gopher://lumidify.org/I/phlog/2024-12-29-cassette-recorder/slipping_clutch.jpg [25] gopher://lumidify.org/I/phlog/2024-12-29-cassette-recorder/belt_replacement1.jpg [26] gopher://lumidify.org/I/phlog/2024-12-29-cassette-recorder/belt_replacement2.jpg [27] gopher://lumidify.org/I/phlog/2024-12-29-cassette-recorder/other_belt.jpg [28] gopher://lumidify.org/I/phlog/2024-12-29-cassette-recorder/belts_other_side.jpg [29] gopher://lumidify.org/I/phlog/2024-12-29-cassette-recorder/spring_wrong.jpg [30] gopher://lumidify.org/9/phlog/2024-12-29-cassette-recorder/spring_wrong.ogv [31] gopher://lumidify.org/I/phlog/2024-12-29-cassette-recorder/spring_correct.jpg [32] gopher://lumidify.org/9/phlog/2024-12-29-cassette-recorder/spring_correct.ogv [33] gopher://lumidify.org/I/phlog/2024-12-29-cassette-recorder/red_plastic_board_reattachment.jpg [34] gopher://lumidify.org/I/phlog/2024-12-29-cassette-recorder/volume.jpg [35] gopher://lumidify.org/I/phlog/2024-12-29-cassette-recorder/volume_greased.jpg [36] gopher://lumidify.org/0/phlog/2023-10-15-speakers.txt [37] gopher://lumidify.org/I/phlog/2024-12-29-cassette-recorder/volume_slider.jpg [38] gopher://lumidify.org/I/phlog/2024-12-29-cassette-recorder/carrying_handle_broken1.jpg [39] gopher://lumidify.org/I/phlog/2024-12-29-cassette-recorder/carrying_handle_broken2.jpg [40] gopher://lumidify.org/I/phlog/2024-12-29-cassette-recorder/front_reattachment.jpg