How to change the cassette deck belts on the Panasonic RX-DT707 "Cobra Top" from early 1990's? I ordered the replacement belts from Thakker e-bay store. The set includes 4 belts, 2 for each deck. Cost as of May 2024 is $19.50US + shipping. Webspareparts also sells the belts sourced from Germany. As does DechTech on e-bay. Are they all sourced from the same manufacturer? Probably. The belts consist of a large flat belt and a smaller round belt. This small round belt is, instead of round, square, in the replacement package I got from Thakker. This is a basic quick overview to help those who are looking to see what it takes to replace the belts. Make sure to have a quality synthetic oil for lubricating the bearings, motor and capstans at the same time. (I developed the habit of using gloves so as not to add skin oils to new belts when working on anything like this. Also useful as one can clean hands from accidental grease contamination with alcohol or cleaners periodically throughout the process.) Remove the 8 long screws. All 8 are the same length. The 2 on the handle once removed will allow the handle to come off. I found an old credit card to be a good tool to open the case. There are no wires connecting to the speakers. Instead there is a connector with pins. Remove the 6 screws holding the combo deck. The deck then simply lifts up as it has electrical connectors. No wiring to de-solder. The decks come out like a cartridge. Very convenient. Both deck units are connected with a white plastic bridge. 3 screws hold the top plate with motor. With screws removed this plate is still held in place with raised screw post stand off's. Nice. Just lift off slowly and the belt will come away too. Lift away the top plate with motor and the belt comes away too. Removing the old round belt. Other replacement belt packages may use a round belt? It should be a round belt not a square belt in my opinion. Intensive cleaning with cotton tip and 70% alcohol of the belt path pulleys. Remove all old black rubber residue. Critically important step! Go slow. Make sure to clean this pulley too. Carefully. Form cotton swap end with pliers then moisten with alcohol. This way the cotton is shaped to fit into the groove. Old belts kept. Deck 01 belt had very low W&F measurement. Better then the new belts. I was questioning whether to put the old ones back in for deck o1. (Deck 02 belts were degraded and poorer W&F. New belts improved W&F a lot). 4 conductor ribbon cable to motors. PCB has hole through. Use solder pump to clear holes and clean up pads. Maybe to install a 4-pin connector would be a good idea for solder free removal? I would like to so that just for the sake of it... Motor speed adjustment procedure is detailed in the Service Manual on pages 50 / 51 (Google for service manual which is freely available as a .pdf file). I did a lot of different WFGUI tests and stop / start / rewind etc., and the new belts are still settling in. EDIT: to add pieces of the service manual with speed adjust: Will re-test again after some hours of play time. Basic quick preliminary results as follows: Deck 02 test results WFGUI and test tape 3150hz 3140.6 0.1023 0.1985 3140.9 0.1245 0.2803 3140.6 0.1431 0.2803 3141.7 0.1132 0.2803 3141.3 0.1496 0.2849 3140.6 0.1294 0.2885 3140.9 0.1062 0.2885 3140.0 0.1462 0.2885 3141.1 0.1115 0.2885 3140.5 0.1510 0.2885 3139.7 0.1064 0.2885 3140.0 0.1116 0.2885 3140.5 0.1520 0.2885 3140.1 0.1174 0.2885 3141.2 0.1437 0.2885 3140.9 0.1316 0.2769 3140.8 0.1113 0.2769 3140.3 0.1280 0.2779 3140.7 0.1218 0.2779 3140.3 0.1248 0.2779 3139.9 0.1280 0.2779 3140.8 0.1320 0.2779 3140.4 0.1317 0.2779 3139.9 0.1044 0.2779 3140.8 0.1360 0.2779 3139.9 0.1358 0.2779 3140.4 0.1113 0.2779 3140.3 0.1280 0.2686 3139.6 0.1107 0.2686 3140.5 0.1535 0.2918 3140.3 0.1617 0.3008 3139.6 0.1314 0.3008 3140.4 0.1488 0.3008 3139.8 0.1367 0.3008 3140.8 0.1268 0.3095 3140.0 0.1182 0.3095 3139.5 0.0950 0.3095 3139.9 0.1397 0.3095 3140.0 0.1505 0.3095 3140.0 0.1013 0.3095 Deck 02 test results WFGUI and test tape 3000hz: 2986.6 0.1166 0.2004 2986.0 0.1079 0.2021 2986.2 0.1067 0.2021 2985.5 0.1058 0.2021 2986.0 0.1064 0.2345 2985.6 0.1103 0.2345 2984.9 0.1168 0.2429 2985.4 0.1022 0.2429 2984.8 0.1266 0.2429 2984.9 0.1126 0.2429 2984.1 0.1067 0.2429 2983.9 0.1100 0.2429 2983.8 0.1165 0.2429 2983.8 0.1182 0.2429 2983.5 0.1000 0.2429 2983.4 0.1146 0.2429 2981.8 0.1169 0.2346 2982.9 0.1087 0.2346 2981.4 0.1277 0.2379 2982.3 0.0991 0.2379 2981.2 0.1138 0.2503 2980.7 0.1289 0.2503 2980.8 0.1050 0.2503 2980.1 0.1133 0.2503 2980.6 0.1130 0.2503 2979.8 0.1088 0.2503 2979.6 0.1173 0.2503
Hello everybody. Does anybody know if the connectors shown in the following pictures are soldered or not? The service manual only says "remove the connectors....". But no matter how hard I try they won't go out, and the only thing that I wouldn't want to to is to break any of those little cables..... Thanks in advance.
I don't remember exactly, even looking at my own pictures But I know I left them in place because I found it was not necessary to remove the wire ribbons to perform the repairs shown above. I did de-solder the motor wires however. That was necessary.
Thanks a lot for your answer. In fact, some time ago I also did a repair in a 505, without removing those connectors. But it pisses me off that the service manual states in one of the steps that those connectors should be removed........ and we can't do it.
Hello again....... Can anybody help with this mystery? Without the cassette, pressing the Play (to the left) button it turns in the right direction (to the left). But with the cassette, pressing the same Play (left) button, it turns to the right, as you can see in the video. WTF????? (Pressing the Play (right) button, as well as the Rewind and Fast Forward, everything works OK.)
One can only assume... that this behavior is due to the lack of a cassette - causing the sensor to indicate no cassette - and it behaves this way from a design glitch or from a necessary engineering work-around. For the above ribbon cables, yeah, those plastic connector things do come apart, don't go back together easily at all and break easy too. Best to work as though they can't be taken off. I had a junk Technics cassette deck from early 1990's I found last year that had the same, or very similar, connectors. I did pop the ribbon wires out... some of the little metal contact pins fell out. I tried to get them back. Getting toothpaste back into the tube would be easier. Just a mess. Deck was garbage anyway so that was that.
Thank you for your reply. But what happens is that precisely when the deck in question does not have a cassette attached, and I press the sensor with my finger to make contact (and “trick” the cassette deck), the take-up hub turns in the right direction. However, when it has a cassette in it, the same take-up hub turns in the wrong direction. All this problem only happens when trying to play the cassette to the left. That's what's driving me crazy. When playing to the right everything works OK. Kind regards.
Sounds like you have to flip the cam that rotates the tape head. When changing the belts one has to observe the directionality of this cam and make sure it does not rotate out of alignment. Kinda hard to explain. But I think this happened to me too. I had to take the deck apart again, de-solder the motors, get the board out, rotate the cam and pulley etc., I can't even remember exactly but it was easy enough. Basically need to to flip it the opposite to how it is now. It sounds like this is the same issue. The symptom is that the cassette deck is basically "confused" and plays the tape on the wrong side / direction?
Dear Hyperscope, two things I must say: 1.- I didn't change any belt. I replaced a whole deck. More specifically, Deck 1 (play back only). 2.- Excuse my ignorance, please. What is that "cam" you refer to? As usual, thanks again for your answers. Kind regards.
If you didn't change any belts or remove the capstans for cleaning then it is less likely or improbable the cam got out of alignment. It happened to me because I had the cassette deck 1 and 2 all apart for cleaning, oiling and new belts. I was not careful enough and let the pulleys turn such that the cam moved and it flipped the head over as if to play the other side of the tape. The cam is the mechanical rotating part that flips the tape head over. There is a right way and a wrong way for it to be in as a default. It has to be in that default "whatever it is" mode. It is linked to the cassette mechanism pulleys. I had to get back in there and dial the flywheel around somehow and click it the other way. Sure enough that was all that was wrong. I only half grasp how it even works to be honest. I just shuddered and was glad it worked ok after
I think I give up. Not playing "Deck 1" in the left direction should be enough for me. I'm not young anymore and it's being a real struggle for my eyes. If I sell this 707 one of these days I will have to mention this little problem in the auction. Anyway, thank you very much for your answers. Kind regards.
These Panadonic "Cobras" are one of the few great sounding boxes that are worth working on though. I'd guess for something like 99% of boxes ever made... it's just not worth the effort to work on them...unless sentimental... to get the rubbish audio quality output... when / if it is even working again. The old "Choose your battles wisely" saying.
