This thread covers the belt replacement on Panasonic RQ-S and RQ-SX series with AR90 mechanism walkmans. The particular unit depicted is an RQ-SX1V, but the procedure is very similar to many others. NOTE1: The mechanism design on these models is particularly good because the pulley driving the table reels is decoupled from capstans, hence the wow&flutter is identical on both forward and reverse play. In many other slim-type walkmans (like SONY WM-EX series), the forward wow&flutter will be higher, due tot the fact that the FWD flywheel directly drives the geartrain. NOTE2: There is another type of mechanism in the RQ-SX series (SX10, SX60, etc.), depitected here: https://stereo2go.com/forums/threads/my-toughts-on-the-panasonic-rq-sx-transport.6138/ This one, although similar in the replacement prodcedure requires 2 belts. This type also requires a new clutch retaining disc to be installed. New retaining disc: https://fixyouraudio.com/product/panasonic-rq-sx10-clutch-retaining-disc-new-unused/ New belts set: https://fixyouraudio.com/product/belt-panasonic-rq-sx10/ NOTE3: Pinch rollers may need replacement if the walkman has been left with one roller engaged for many many years. You will see this as an indentation mark on the affected roller. You can purchase the belt from here (fits all walkmans with this mechanism): https://fixyouraudio.com/product/belt-panasonic-rq-sx11/ You can purchase pinch rollers from here: https://fixyouraudio.com/product/pinch-roller-6-x-5-x-1-5-mm-for-cassette-players/ Thanks @Emiel for pinch rollers dimensions ! 1. On some devices you will need to remove the gumstick battery door (it's not the case on SX1V depicted). To do this, you must pull the tab and slide the door out; 2. Proceed in removing all the screws that hold the back cover (a silver one also needs removing on some RQ-S); I recommend lying the screws in a sqaure format on the bench, to know exactly where each screw goes; 3. Pull the cover starting from the gumstick battery door. There are some clips as well on the side with cassette door latch; 4. Desolder the points indicate on the PCB (motor, solenoid, tape in/EQ switch, negative battery terminal, AM antenna). For this you can start by using a solder pump and finish with a solder wick. Be careful not to apply too much heat, as most connectors go into plastic; 5. Remove the head flex cable carefully with a pair of tweezers; 6. Remove the PCB as indicated in pictures, being very careful of the part connecting to the AM antenna (in the case of radio equipped models); note there are 3 screws holding the PCB, maked with red arrows; 7. Remove the cut washer from the motor pulley; Keep one fingernail on it, otherwise it may fly; It's not critical, the walkman will work without it, but for keeping it original it's better to pay attention; 8. Remove the upper part of the rotor by pulling it up with 2 plastic tools (spudgers) from opposite ends. Be very careful not to scrach the PCB with coils, as the magnet is very strong (neodymium); 9. Remove the old belt; 10. Clean all the pulley's grooves thoroughly (including the one on the motor), as the old belt will leave an oily residue; 11. Re-install new belt; 12. Re-install the PCB, connect the head flex cable; note the positive battery terminal must also be re-installed before soldering back connections; 13. You must adjust the tape speed: using a 3kHz test tape, adjust the trimpot near the motor connector; 14. Put the back cover back, noting the position of the internal switches relative to the case buttons; On these models, lubrication of the mechanism is usually not necessary, as it was done properly from the factory and they're also relatively new. If you do want to do it, the most important points are: - the shaft of the motor itself (you must remove the coils PCB for this), which needs to be oiled and upper part of bushing greased; - the capstan bearings;
I will add few things: 1. Don't use too much heat as it could destroy the soldering pads (done that). 300C should be safe and enough if you have good soldering iron. 2. On the belt replacement 2nd pic you see silver 2 tooth 'fork' like thing. It have to be on the center (because left or right position indicates which side it will start to play tape) before you solder board! I think it sometimes resets itself in SX with S mechanics (1, 5, 11, 22, 33) , but it doesn't in S series models I have. You will see that even of motor works, when you push buttons it starts for a second or two and stops. To set it corectly you need to move the gears. There is some chinese guy on youtube that has repair procedure for S35V and some other models and he shows it quite well. As much as I like those models, almost every one I have has a quirk. Some S15 develop a problem that after stopping they won't play again until you 'reset' tape, like it looses the sensibility of the tape for play (FF and REW works). S33 - the other way arround, after playing for some time it doesn't react on buttons and you can't stop it unless you remove batteries. S35 - have 3, only one was working ok. It felt on the ground ... I will try to revive it. S55 - nice, working, but rare and expensive. SX5 - nice, repaired, have problems with autoreverse. Vibration sound is nice SX33 - as with SX5 it's hard to open and close shell. When working it's nice sounding and rarely only has autoreverse problem.
@Raul Very good points ! I will add some info as well to clarify some aspects: 1. About the desoldering, you should add some leaded solder to the connections to lower the melting temperature before attempting the desolder. After that you should use a vaccum pump first and then use solder wick to clean the pads from solder. 2. The mode switch is indeed very important to line up with the mechanism fork. I wanted to put this info, but forgot because it seemed so obvious to me (but it's certainly not obvious to newbies). The fork is likely going to move, as you will have to rotate the black plastic pulley to clean it from the oily residue. Will attach 2 pictures to show the parts in more close detail (they're not from the same walkman, but very similar). Note that the mode switch in my picture is not centered (PCB picture is from different walkman), while the fork is centered. Both should be centered and you should be able to see the switch going into the fork through the inspection hole in the PCB.
Question: the pin for the positive battery terminal "door": should that be soldered to the PCB? With your instructions (and Marian's on FYA site) I was successful restoring a RQ-S25, but am having trouble with RQ-S15: when i reassemble i appear to have a "dead-short" situation: I soldered this pin to the main PCB, plus the side control board has 12 tiny solder points, instead of the S25 only has 3 solder points in the similar position. Immediately below is OEM S15 solder before repair: Below is "after repair" situation: The mechanical cleaning, motor lubrication, capstan pulley lube went great, but now when i test, it appears to have a "short"; positive batt terminal is immediately hot to the touch! Two areas of potential problem: 1) soldering the positive terminal pin and 2) this side board soldering. This is also a caution to others: be aware of the design of a particular model before you begin, the difference I experienced between repairing the S25 design(only 3 solder points in this area) VS S15 design (12 solder points in this area) will likely keep me from repairing any more units with this design... each S15 solder pad is about 1mm wide, with 1mm spacing... Thank you Raul for pointing out which SX models use single belt mechanism, great information! Thank you all for these tutorials, these make choosing and repairing these units straightforward!
I will check (probably tommorow) with working S15 but I think I always have had this pin soldered. I think there is small solder ball (picture is not sharp there) between pin on the left and this one you've pointed. Are you sure that it's not touching/shorting? And thanks, I has soldered board for S33 lately and it had short and I wasn't sure what was the problem. I will check if it's not with that pin.
i will check somehow, maybe remove this solder ball ... also worried i could have bridged over the top, too... it's so hard to see this area clearly... thanks
Yeah, the pin is soldered in my S15 that fully works. I would check if you haven't made big solder ball on the pin near screew, maybe that is shorting, it is on the right-top side of the board where the battery is.
Some success! found the short was between the battery door hinge and the body(electrical tech friend found this problem for me)... can see a piece of non-conductive tape glued to help insulate: however I believe when the battery door is reinstalled onto the brass hinge it would keep this metal from touching... Friend cleaned up the 12 solder points for the side control board... got rid of that little bead of solder too... With these two items cleaned up, the unit now will FF and REW just fine, will test the PLAY tomorrow... autostop isn't working, but possible problem is unit is still partly dis-assembled. I'm concerned with part of my repair: when i removed plastic washers from one of the spindles, I lost the small plastic washer, so i put one of Marian's blue washers on... should this work? it appears to lock just fine, and technically shouldn't touch the tape, but it's taller than the OEM original plastic washer... should this work? Last question, on this RQ-S15, there is a small adjustment screw near the headphone jack, I accidentally moved it when i was reaching for the screw head and didn't have my glasses on... I never noticed a screw like this on other units, anyone know what this is for? some of these small points could help anyone working on RQ-S or SX units.
It's important that the washer locks completely onto the capstan groove. I can see a gap on the washer: if you compress it manually with a pair of tweezers, does that gap disappear or not ? If not, sand the washer until you make it thin enough to fit perfectly. Doesn't look like an adjustment screw to me. It's not even clear if that is part of the mechanism or not, as it looks to be from the mech. Given there is non radio on this device and Dolby levels are not adjustable (there should be 2 adjustment for Dolby anyway), I assume the only adjustment is the tape speed, which is located on the opposite side.
More success! Found the capstan had some oil on it, cleaned up again and now it plays the tape! still not assembled, W/F is noticable, still to work on those washers, I wish there was a suitable new replacement available, I may possibly have a couple i could get from another unit... Question, how to safely clean a tape without damaging? can you use IPA? or will that damage tape? Is there a special fluid?
If there is too much oil the wow and flutter will be high. Clean it with IPA and give it time (at least 30 minutes of play) and check.
Valentin and Raul, thanks for both your suggestions, success today: I had not noticed the blue washer was so bad, i tried to compress, could not, so removed the blue washer, then cleaned the groove several times with a thread soaked in IPA... some kind of black grime was removed... The blue washer on the other spindle was closed perfectly: cleaned groove and replaced blue washer with OEM panasonic washer: I took your suggestion Raul and also removed a good bit of oil (maybe too much oil on shaft isn't so good...?) that appeared to have leaked out onto the spindle, again, and when i finally tested, playback is now good! I will confirm when i reassemble and get my fat hands off the internal parts while playing! Thanks to both of you for your advice. Then I should move on to an earlier project, EX-808 mike in SC
1 or 2 years back I've bought 3 Panasonics S60. Two of them I broke and third wasn't working, I've put it on pile of walkamns for parts. Today I looked at it and I saw that I didn't solder properly and belt slipped. I thought, why not try to repair it again. Put belt again, resoldered, cleaned it. Put tape, motor started but no Play/FW/REV .. Ok, Hold was on At first it played too fast on one side, ok on the other. Some forward/rewind and play time later it works nice (I will test it for longer though). I really thought it's a lost cause. I really love how small are RQ-Ses. And yesterday I brought to life SX5V. Only radio was working and I didn't know what was wrong so just in case I resoldered points, lubricated capstans and motor, cleaned it and it plays.
Thanks for this great post. I've already restored my quite battered RQ-SX10 transport in tip top shape... at least I hope. I prefer to unscrew the two halves of the motor assembly, when you slide out the coil pack you don't have to worry about damaging it anymore. I have two of these RQ-SXes bought for next to nothing to restore, both have been leaked massively... I have restored the SX10 and diagnosed the main fault in the electronics to a small voltage regulator... at least, what I thought it might be, project suspended because I had and still have other priorities... like stopping corrosion from eating other vintage electronics. I established that if I up the voltage in the part that was missing it I can make it working, so... at some point in the future I shall make them work again. I am wondering if it's a known issue as I have two that exhibit the same behavior pattern.
I've followed the tutorial with my RQ-SX11. Before I started the power worked, now it does not. I do not seem to have any shorts on my soldering. I'm running from the external battery pack. Does anyone know how I can go about trouble-shooting this please? I have very little electronics experience but do posses a multi-meter.
Start by double checking everything: - are all the pins you desoldered soldered back ? Solenoid, motor, battery terminals, tape in/EQ switches. - is the battery sidecar making a good connection with the terminals ? - are the battery terminals clean ? Is there any corrosion that should be cleaned ? If the walkman doesn't do anything at all, you most likely are not getting battery voltage on the main board or there's something you have not soldered back.
Thank-you! I was naive and thought I should see signs of life even without a cassette in place. With cassette it works! I'm very happy to find this brilliant tutorial and that the repair was possible to a beginner like me.
Two more things. 1. I am missing two screws from a long time back. I wonder if anyone knows the name and type/spec I need to replace them, please? See pictures 2. When I did the repair, i noticed a loose bit of plastic which subsequently dropped out. I looked and it must have broken off when I fitted the belt. I did not think it is possible to glue this back in and decided to go ahead and hope for the best. Does anyone know what its function was? It sits next to the belt. Please see pics.
