This thread is intended to be a list of common problems found on walkmans and portable recorders in order to help buyers make a better decision and not spend a lot of money on something that they won't be able to fix themselves or are not willing to pay for a professional service. A lot of sellers speculate on this vintage equipment, because there has been an increase in interest in regard to this kind of stuff. You must pay careful attention, because some sellers can try to trick you into thinking that some of these common problems are in fact not problems at all and the respective units had that behaviour from the factory. They'll argue that "all X units do that, check YouTube videos". However that argument does not stand, because the fact that all X units make a particular noise (like the clicking of a DD broken center gear) does not mean it's not a problem, but rather it means that all X units have that problem. For the sake of keeping this thread clean, I ask you not to post anything besides adding new devices and their specific problems. Note that by common problems I mean significant problems, something like a belt replacement is not considered a common problem and not worth mentioning a unit just for that. List of AIWA capacitors: https://www.stereo2go.com/topic/ind...7178235650847317&board_oid=522740502721869426 FixYourAudio belts can be found on https://www.fixyouraudio.com/ DeckTech belts can be found on ebay here: https://www.ebay.com/str/manatreereplacementparts?_trksid=p4429486.m3561.l161211 Pinch rollers which I mention by model name (like TPS-L2 type) can be found at FixYourAudio. Some other rollers on which I only mention dimensions can also be found at FixYourAudio, some not. Please don't post asking for links, as I want to keep the thread clean. If belts/rollers dimensions are not mentioned, it means: - either they are readily available on FixYourAudio/DeckTech or other sellers just by seraching the model number; - or I have never replaced those items on the specific units, so don't have the dimensions (but may be added later); Same goes for the Dolby levels, if not mentioned I either don't have the spec or they're not adjustable. TO BE NOTED Dolby levels mentioned here are using a 200nWb/m ANSI tape. If you have any questions, create a separate thread and ask them there. Thank you ! NOTE: This thread will be constantly updated, both with new units added, items added to a specific unit or links to more detailed information about a problem or a tutorial on how to fix it. REQUESTS: 1. Please do not include boomboxes or decks, as the list will be long enough with walkamns and portables alone. You can create a separate thread if you have a lot of info on that. 2. Maintain the formatting style and limit the posts to 1 per device or per device type. Thank you !
AIWA HS-P303/Kenwood CP-D3 - capacitor leakeage, need a complete re-capping. Not the easiest one to do, as the caps are very close to each other, traces are thin and the likelyhood of damaged traces is high; - the volume potentiometer is also affected by corrosion, it will need to be cleaned thouroughly or even disassembled and cleaned with a cotton swab; - Dolby level trimpots will likely need cleaning; after this, the levels will need re-adjustment with a calibration tape; - belt is usually still good; replacements are availble, but not for this specific model; you will need to choose one with same dimensions; - pinch rollers are usually still good;
AIWA HS-P20/HS-PC20/HS-P202/PC202/HS-J20/HS-R20/HS-J15/HS-J202/HS-J202M/HS-J800/HS-T202/HS-T202M/HS-T800/HS-J150/HS-J150M/HS-J380/HS-T150/HS-T150M/HS-T380/HS-T120/HS-T120M/HS-T280, HS-J505, HS-J303, HS-J800 These walkmans share the Alpha-1 mechanism. - known capacitor leakeage problem. All capacitors should be replaced as even in cases where they are not leaky (like on the Dolby C models with Nippon Chemicon), they measure low on capacitance and high on ESR. Here you can find all the details regarding capacitors: https://stereo2go.com/forums/threads/aiwa-hs-p202-mkiii-restoration.1718/ - potentiometer will need cleaning, as it's located very close to leaky capacitors; - Dolby levels are off and will need to be adjusted; - belt repalcements are available from https://fixyouraudio.com - a mechanism cleaning and re-lubrication is recommended. - the clutch retainer may break and require repair: https://stereo2go.com/forums/threads/aiwa-hs-p202-pc202-clutch-repair.8730/ Pinch rollers: 8 x 5 x 1.5mm (outer diameter x total height x pin diameter) Dolby adjustment: Levels are 100mV RMS at the Dolby points (no load) on the PCB with 200nWb/m ANSI calibration tape.
WM-EX3, WM-EX5, WM-EX7, WM-EX9, WM-EX900, WM-EX910, WM-EX2000, WM-EX527, WM-EX550/552, WM-EX560/EX562, WM-EX570, WM-EX610, WM-EX615, WM-EX651, WM-EX660/662, WM-EX631, WM-EX650/652/654, WM-EX655/668, WM-EX670, WM-EX672, WM-EX674, WM-EX677, WM-EX678, WM-EX910, WM-EX921, WM-GX688, WM-GX670, WM-GX788 - many of these units can have a broken clutch gear, details here: https://stereo2go.com/forums/threads/wm-ex-series-tac-tac-sound-repair.7108/#post-54878 - belt is a very elastic type and will need replacement more often than other units; can be found at fixyouraudio.com - pinch rollers are usually good, although new ones can be found at fixyouraudio.com - units that have a gumstick battery compartment may have significant corrosion on the terminals; - it is highly recommended to lubricate the motor, as it's very prone to wear (details in note 2); - a less common problem is wear on the main FWD flywheel driving gear which will cause an higher frequency tac-tac sound; wow&flutter will also be increased in such scenario; Solution is to replace the flywheel with one from a donor unit. NOTE1: Given the 50-50 chance of having a bad clutch, don't spend a lot of money on those walkmans as you will need both a donor unit and possibly paying for a repair if you're not able to do it yourself. It is pretty involved for a newbie, especially on some of them like WM-EX3/EX5/EX7, which also happen to be the most expensive ones in the list. NOTE2: The motor used in all EX series is prone to wear, as the motor usually comes with bushings dry or poorly lubricated from the factory. Motor lubrication tutorial: https://stereo2go.com/forums/threads/how-to-diassemble-and-lubricate-sony-wm-ex-fx-motor.7940/ Do keep in mind there are many different types of motors used in EX series, so look for details such as how it is mounted to the chassis, number of pins (some have 4, some have 8) and locations of pins. In some cases you will need a replacement motor from the exact same unit. Thanks to @Emiel I think the list is now complete or close to being complete.
SONY DD series (WM-DD, WM-DDII, WM-DDIII, WM-DC2, WM-D3, WM-DD100, WM-DD30, WM-DD33) - all units will have a broken center gear; if it has not been replaced, you can be sure it needs replacement; sellers pretending the unit is working perfectly, although never serviced are lying; It is important to use the new design made by Marian Mihokm (fixyour audio) and also sand the retaining disc before installation, otherwise a periodic gear engagement noise will be present and the FF/REW may slip; https://stereo2go.com/forums/thread...-wobble-problem-and-solution.7387/#post-53936 - sanding the inside of the gear may be necessary as metal disc is eccentric in many cases; - when replacing the center gear, it is of utmost importance to relubricate the mechanism, check the plastic slider and do the maintenance required on it; - the capstan ring needs to be replaced and the motor position may also need re-adjustment; - small reel gear (attached to supply reel) is prone to breaking, especially on the WM-D3. - adjustments on the center gear arm may be necessary for the FF/REW to work properly; - PLAY/FF/REW buttons not latching is a common problem; some levers need to be cleaned of grease; https://stereo2go.com/forums/threads/sony-dd-series-play-ff-rew-buttons-not-latching.7524/ - FF may not work properly due to a broken table reel shaft retaining tab; can be solved by glueing it; - potential problem with a bent pinch roller bracket; https://stereo2go.com/forums/threads/wm-dd-azimuth-instability.7590/ - Dolby levels are almost always off (sometimes by a significant amount), needing adjustment with a 200nWb/m ANSI tape; - some capacitors need to be upgraded to larger values in order to have proper bass response. - azimuth may need adjustment, even if lock paint is intact since head bridge sits at an angle; - WM-D3 will need the rec safety tab lever to be adjusted and sanded in order for cassette door easy opening; - on some WM-D3 units the gain resistor in the sample and hold circuit will have to be increased (165K) to get correct VU-meter readings; - WM-D3 jacks are prone to cracking, will require glue; - WM-D3 has a common problem (caused by leaked batteries) causing no sound: https://stereo2go.com/forums/threads/sony-wm-d3-no-sound.9548/#post-80408 Given how many items are already listed, you can see for yourself why a complete service is the way to go on these DDs; WM-D3 small reel gear (comes with counter belt): https://fixyouraudio.com/product/sony-wm-d3-small-reel-gear/ Small reel gear for other DDs: https://fixyouraudio.com/product/sony-wm-dd3-small-reel-gear/ Capacitor upgrade kit for DDIII (different for other models): https://fixyouraudio.com/product/sony-wm-dd3-capacitor-upgrade-kit/ Dolby adjustment: WM-DDII, WM-DD100 - 44mV RMS (no load) at indicated Dolby points (see service manual) with 200nWb/m ANSI tape WM-DDIII - 100mV RMS (no load) at pins 13 (L channel) and 4 (R channel) of the NJM2063 IC with 200nWb/m ANSI tape WM-DC2, WM-D3 - 340mV RMS on LINE OUT (loaded with 47kΩ) with 200nWb/m ANSI tape
SONY WM-2/WM-5 - contrary to what I have stated in other threads (will edit them), both of these units have a normal center gear, identical to the one used in the DD lineup, which is broken by now. - there seems to be a very early version which uses a thicker center gear (the one depicted in the WM-2 service manual), but not all WM-2s have that. So just check: if you have the full plastic one there is no need to replace it (there's no replacement available for that type anyway). However disassemblying the mech, cleaning and re-lubricaing is still neccesary. - all other problems mentioned in the DD series will also apply here; The idea is expect a broken gear when you buy such a unit. If you're lucky, you might get the one with thicker gear, but that's not a guarantee. - WM-5 may use CE brand capacitors will also have leakeage. If so, replace all capacitors. @Emiel will provide more info about this on his "DD portables overview" thread: https://stereo2go.com/forums/thread...rview-contributors-and-reviewers-wanted.7410/
SONY D6/D6C - common problem with servo IC burnt (CX20084), causing the motor speed to be too high and/or motor running all the time, even when in STOP mode. Issue is caused by powering the unit with reverse polarity (plug is center negative, as most cassette units in that era) or with higher voltage. Using only NiMH re-charghables is the preffered solution to avoid problems with this IC, as the absolute maximum rating of Vcc is not available due to the lack of a datasheet; there isn't any protection, Vcc of servo IC is connected directly to battery terminals/DC in jack; - potential FF/REW problem, identical to the TPS-L2/WM-3: https://stereo2go.com/forums/threads/sony-wm-d6c-no-rewind-ff.4687/ - rubber set needs to be replaced: https://fixyouraudio.com/product/sony-wm-d6c-cassette-player-walkman-complete-rubber-set/ - Dolby leves, rec levels and bias will need adjustment for optimal Dolby encoding/decoding; - potted modules tend to fail, especially on older units (muting module, 2 EQ modules, servo module in D6); Replacements are available on ebay: https://www.ebay.com/sch/scribbler_92/m.html?item=263851487685 - battery holders are sometimes missing, as their cover; a 3D printed version of the cover is available on the store mentioned above; as for the holder, I have seen a 3D printed version, but do not know if one is available for sale; In any case, if the unit is missing any of the 2, the value is obviously lower; - on older units, especially on those with many hours of use do expect head wear: both the parabollic amorphous and the 35711 amorphous heads can present signs of wear, usually in the form of pittings in the area where the tape rides; those can be lapped, but obviously the value of the unit will drop significantly; The sendust head (pointy shape) used in the D6 can also present signs of wear; Pay attention as head wear is usually not visible in pictures unless they're macro; - the only permalloy head on these units is marked "35712" and can only be found in the latest made units; because of that, it's unlikely these will have any wear, because of low usage (the professional market was already using DAT by that time); - potential problem with broken clutch gear: https://stereo2go.com/forums/threads/tps-l2-broken-clutch-gear.9534/ - newer units with double sided SMD PCBs suffer from capacitor issues; When buying such a unit, it's important to note that despite the hype going around this unit, it does NOT perform similarly or better than a mid-range or high-end deck; frequency response is much better on a deck, because bias frequency on this unit is only 64kHz, many decks having 85kHz/105kHz; most decks have HX Pro, which increases the SOL significantly; high-end decks also have auto-calibration feature, meaning they'll auto-adjust the bias and rec level to each particular tape; this cannot be done on this unit, as there is only one set of adjustemts (for all 3 tape types!); Although a very good walkman, the real prices are much lower than what you see in most ebay listings; Dolby adjustment: 340mV RMS on LINE OUT (loaded with 47kΩ) with 200nWb/m ANSI tape
SONY WM-7 - a very complex unit which most of the time is sold as non-working; Just because it's a SONY and it's more high end, does not mean it has much value unless fully restored; Note that even a working one will need to be serviced; - biggest issue on these are the magnetic clutches integrated into the table reels; Hexagon that gets into the magnet gets rounded and needs to be glued at times, while a thorough cleaning is necessary. Too much friction or inconsistent slippage will create a very high w&f situation. - Dolby modules are potted and will often fail because of that and will need de-potting; Symptom will be intermittent Dolby: the decoding will work for some time after you start the unit, will work intermittently and then stop working (sound will be the same as with Dolby OFF); This is a step that should be done even if Dolby is working now as it may start acting up in the very near future. - the head azimuth may need adjustment: it has 2 adjustments one forward and one reverse; - the head switch that switches the signal from forward to reverse may need cleaning, sometimes requiring disassembly to be able to clean it well; - battery leakeage is common on this unit: depending on the damage, the battery springs may have to be replaced and other damage on the PCB repaired (especially the tape speed trimpot that will need a very good clean); - some units may have capacitor leakeage depending on brand used; - out of round gears will increase wow&flutter; there is no solution to this problem apart from using a thicker belt (0.8mm) and fully re-lubricate the mechanism; - motor may need to be refurbished (uses MNF-1600B motor); - this unit is sensitive to the type of belt used; https://stereo2go.com/forums/thread...cess-capacitors-on-a-walkman-wm-3.3073/page-2 https://stereo2go.com/forums/thread...-disassembly-and-maintenance.7424/#post-54312 When unit is having high w&f don't jump on replacing the pinch rollers, they're not the problem. Rather investigate the problems mentioned with clutches, eccentric gears and old grease. Belt: 70mm x 0.8mm (inner diameter x thickness) https://fixyouraudio.com/product/sq...8-for-cassette-players-and-cd-players-8lkb2l/
SONY TPS-L2/WM-3 - the battery cover latch is often missing and requires replacement with a 3D printed part available on ebay; - rubber set replacement (2 idler tires, 2 belts) is a must, even if the unit has not been used; set available on fixyouraudio.com - if the unit has been stored in a high moisture environment, there is a chance the motor is seized; a guide of disassemblying the motor is available; However, I do not recommend you do this unless you have experience with disassemblying motors, otherwise chances are you will damage it; - in some instances, some capacitors can fail on this unit and you may get no sound or no sound on one channel; however I don't recommend replacing capacitors just for the sake of it, but only when there is a problem; - if the unit has not been used in a long time, there is a chance the FF/REW won't engage; a lever is stuck due to old grease, it needs cleaning and re-lubricating, tutorial available below: https://stereo2go.com/forums/threads/sony-wm-d6c-no-rewind-ff.4687/ - potential problem with broken takeup reel gear; - motor may need repair; https://stereo2go.com/forums/thread...cess-capacitors-on-a-walkman-wm-3.3073/page-2 https://stereo2go.com/forums/thread...-disassembly-and-maintenance.7424/#post-54312 - potential cracked clutch gear: https://stereo2go.com/forums/threads/tps-l2-broken-clutch-gear.9534/ - a full service is always recommended on these units, even on the ones that work;
SONY TCD-D3/TCD-D7/TCD-D8 - very complex unit with a lot of common problems; even ones that are sold as working will fail for sure in the near future if not serviced; - the biggest problem on these is lubrication getting hard in the mechanism and gearbox, causing all sorts of problems, including (but not limited to): backtension too high (which will wear the head drum or make some functions not work), mechanism errors, a broken gear beacuse mech unable to move while motor runs at full torque, eating tapes, not ejecting a tape, etc; - given what was stated above, a full cleaning and re-lubrication of the mechanism is an absolute must on this unit; the oil used and the quantity are critical for the unit to work; chances are if you haven't worked on such a unit before, you won't get it right; - LCD backlight inverter is a known problem and often fails; the replacement part is not available, so recommend keeping the backlight on for only a couple of seconds at a time to prolong the life of the inverter; - loading guides often fall off their posts and need to be glued back; - some electronic modules can fail, so a unit that is not powering on or restarting itself is to be carefully considered before buying, as replacement parts are not available and donor units are needed for some parts; - when a seller states such a unit works, all functions must be tested: play, ff and rew; It must be tested in play for a longer duration like 30 minuites, as intermittent problems that appear only after running some time do exist; - if FF does not work or is showing "Blank", there is a serious problem; there is not a single cause for this problem and fixing it may not even be possible in some instances, so don't get fooled if the seller is trying to convince you it's no big deal; - I don't think there is a need to go further on this one, the above list speaks for itself: servicing this unit is a must even if it does (seem to) work ! Also note there is a significant difference in price between a fully serviced unit and a just working one. Just because it's rarer than other walkmans and it's DAT does not mean it's worth $500. Keep in mind that sealed DAT cassettes are pretty rare and expensive as well.
JVC CQ-1K/CQ-F2 - capacitor leakeage problem (uses CE brand caps); - potentially damaged carbon printed resistors (can be replaced with normal resistors); - broken table reel drive gears; those will need to be repaired, new ones are not available and will never be; - a new belt and pulley grooves cleaning is necessary; - head azimuth may need adjustment and locking the screw with lock paint or glue; Belt: 70mm (inner diameter) x 1mm (thickness) - https://www.ebay.com/itm/324233009181?var=514036305869
JVC CQ-(F)7K/CQ-(F)5K, CQ-R7K, CQ-V9 - capacitor leakeage problem; note the PCB on this one is a giant flex one glued onto an aluminium substrate, so traces are very delicate and can easily break when desoldering old capacitors; - clutch wheel needs to be repaired as it will be broken; - the motor will need lubrication (especially the bottom bearing); - a new belt will need to be installed; the entire mechanism has to be disassembled to replace the belt, so don't go for a generic cheap one; choose one that has been specifically designed for this unit; the one from DeckTech works perfectly; - repair is pretty involved and it's not as simple as many think. Most are sold in non-working condition or with some kind of issues, like poor FF/REW torque or motor squeeling; Clutch repair: https://stereo2go.com/forums/threads/jvc-cx-5-cx-7-cx-f5-cx-f7-cx-r7-cx-v9-clutch-repair.8461/ Pinch rollers: 7mm x 6mm x 1.5mm (outside diameter x total height x pin diameter) Roller tire is same as WM-700 series, but you will need new hubs as original ones can't be reused.
AKAI PM-01/Infinity Intimate Stereo/Cybernet MiniConcert(IntiMate)/KLH Solo - capacitor leakeage problem; I only repaired the Infinity in the series mentioned above, but given they're all made by Cybernet, chances are the problem is present in all above mentioned models; - there are 2 belts that will need to be replaced; you will not find anything specific made for any of these models, so you need to go by diameter; the small one needs to be a little lose and tighten only when unit is in play (don't have the dimensions as I used a generic one in this case); - the clutch spring will need to be shortened to apply more pressure in order to bring the takeup torque to decent levels; details in my thread about repairing the Infinity; Ideally the spring should be replaced with a thicker wire diamter one, as in the units that I repaired the takeup torque is still not as high as it should be (slipping at the rubber instead of clutch itself); - rubber parts will need cleaning either with alcohol or something like Rubber Renue; - a lubrication of rotating parts and the motor are necessary; - FF and REW idlers clutches retaining plates are often cracked and will need to be repaired; the 2 idlers should freely rotate on the shafts, if there is any resistance it means the clutch retainer has popped off; - on the Infinity, the Dolby NR system will need adjustement for proper Dolby decoding; Belts: capstan 90 x 1mm (inner diameter x thickness) - https://www.ebay.com/itm/324233009181?var=514036305877 clutch 38.5mm x 1mm (inner diameter x thickness) - https://www.ebay.com/itm/324233009181?var=514036305853 counter 38mm x 0.5mm (inner diameter x thickness)
SONY DD1/DD10/DD11/DD22 - known capacitor leakeage problem; a repair kit is available on ebay; - rubber will need replacement (capstan ring and belt); - a general cleaning including switches, potentiometers is needed, especially in the parts where leakeage has occured; - Dolby levels may need adjustment for proper Dolby decoding (DD1/DD10 only), although less of a problem compared to DD units mentioned at post #5; To be noted rubber ring is different than the one used on walkmans mentioned in post #5. Dolby adjustment: 100mV RMS (no load) at indicated points (see service manual) with 200nWb/m ANSI tape. Note not all units from these series have the levels adjustable.
Pioneer PK-5AW/PK-R7AW/PK-3/PK-F9 - a new belt will be needed; - pinch rollers are likely to need replacement; closest I could find are the ones mentioned at the bottom, which will require adding 2 nylon washers; Black washers from this set (https://fixyouraudio.com/product/washer-set/) are to be used and hole needs to be enlarged with 1.6mm drillbit; - motor governor will burn if the unit is powered with reverse polarity or higher voltage; also look for the capacitor put in parallel with the DC input jack, that may be blown as well; - the headphone amplifier may have problems if unit has been powered with reverse polarity/higher voltage; - complete re-lubrication of mechanism recommended; Recommend to NOT lubricate the motor, because of the small flywheel which is part of the pulley. Because of that, getting oil into the top bushing is hard. By any means DO NOT put force on the pulley or try to remove it, the entire shaft will come out since this is a coreless motor (similar to MNF1600B, but smaller). Hence why it's best to leave the motor alone (just clean old belt residue), since it's very unique to this walkmans and you will need a donor if motor gets damaged. Also note the PK-3 and PK-F9 use a different motor than the PK-5AW and PK-R7AW. Belt: 52.5mm x 1mm (inner diameter x thickness) Pinch rollers: 8mm x 6mm x 1.5mm (outside diameter x total height x pin diameter) + 2 x 0.2mm nylon washers Dolby adjustment: 100mV RMS (no load) at indicated points (see service manual) with 200nWb/m ANSI tape.
SONY WM-(F)10/WM-(F)10 mkII/WM-F10 mkIII/WM-10RV/WM-F15/WM-(F)20/WM-30/WM-50/WM-70/WM-W800 - potential problem with the table reels outer toothed ring; if that is the case you're in bad luck as the only fix would be with expoxy; note the sellers are unlikely to mention this problem and present the unit as working in perfect condition; https://stereo2go.com/forums/threads/sony-wm-10-take-up-reel-advice-needed.3625/#post-56073 - corrosion in the battery compartment is very common in these units; however note that this is not the only potential cause to a unit that does not power on; - some units will not power on: this can have many causes like DC-DC converter, leaf switch, etc. - possible motor problems; https://www.tapeheads.net/showthread.php?t=76685 - potential problem with output power amplifier; - intermediate pulley sitting at an angle may cause problems in some units, a problem that's hard to adress; Due to the potential problem with the toothed rings, I think this model is not worth a lot, although it is rarer than other models; There are units on ebay that have been listed for a long time and never been sold, but sellers are not giving up on price; be circumspect on those and ask questions; Most of the ones that are for sale do not work and on this one it's likely you will need more than just a belt replacement (which is the only easy thing that a newbie could probably do on such a unit). A unit that does power on and has sound is obviously more valuable than one that doesn't even power on. Dolby adjustments: 44mV RMS at indicated points (see service manual) with 200nWb/m ANSI tape Note not all units in these series have the levels adjustable.
SONY WM-A602/WM-B602/WM-B603/WM-BF608/WM-AF604/WM-150/WM-170/WM-171/WM-F180/WM-F181/WM-190/WM-506/WM-550C/WM-2091/WM-F2095/WM-EX48/WM-EX49/WM-EX49C/WM-EX50/WM-FX50/WM-GX50/WM-GX51 AKAI PM-R42 - a small gear, which is part of the clutch needs to be replaced, as it's going to be broken; replacement available here: https://fixyouraudio.com/product/sony-wm-a602-clutch-gear/ - a couple of SMD electrolytics capacitors leaking, will need replacement; - motor magnet can get damaged if the unit has been dropped; at that point the motor will have to be replaced; - it is recommended to lubricate the motor if it's noisy or wow&flutter figure is high: https://stereo2go.com/forums/thread...-type-motor-in-sony-walkmans.7943/#post-59754 - table reel driving gears might be cracked and need repair by enlarging the hole and glueing them to the reel shafts; Replacements are available here if you want or need to replace: https://www.ebay.com/itm/335392051559 - the belt will need replacement with one designed specifically for this unit; available at https://www.fixyouraudio.com/ Thanks @Emiel for providing additonal information on units using the same mechanism ! Now the list is likely complete.
Panasonic RQ-SX series (AR10 mechanism) - problem with clutch retaining washer; New metal one can be found here: https://fixyouraudio.com/product/panasonic-rq-sx85-clutch-retaining-disc-new-unused/ - problem with rubber rings on capstans (on units that have them); - potential problem with gear shrinking; - potential problem with REV flywheel gear breaking (rare); - re-lubrication of main rotating parts recommended; - re-lubrication of motor recommended; NOTE: On units with rubber rings on the capstans, NEVER clean them with anything containing alcohol. Use Lenor for cleaning. Pinch rollers can be cleaned with IPA, but be careful to only touch the rollers.
TC-D5/D5M/D5Pro/D5Pro II - biggest problem on this unit is old rubber; some replacements are available for idlers, but a good quality capstan ring is still not available; The 3 belts can be replaced with generic ones, as they don't drive anything that influences wow&flutter; Good replacements are also available from DeckTech; Capstan ring and idler gears are the ones that will have hardened and present cracks; the idlers can be sanded if the glaze/cracks are only on the surface, but that's not always the case; - lubrication of all rotating parts is necessary, as these units are very old and have seen a lot of use; - Look for head wear, as the units are pretty old and many have been used by reporters or in a professional environment, which means a lot of hours; Despite the sendust head used in TC-D5M is the most prone to wear, the ferrite head is the most problematic in practice because it can't be lappeed. The ferrite head has worse frequency response extension than the sendust. - Dolby levels, rec leves and bias will need adjustment for proper Dolby decoding/encoding; - potentiometers and switches will need to be cleaned; - potential problem with frozen takeup reel bushing, which will need careful cleaning and re-lubrication; - CX184 headphone amp can go bad; pay particular attention to units that have sound on line out, but no sound on headphones (on one or both channels); Thread about rubber parts: https://stereo2go.com/forums/threads/sony-tc-d5-d5m-d5pro-d5pro-ii-new-rubber-set.8115/#post-74545 Sellers ask a lot on these, however as in many other cases, the real average completed sale prices are much lower than the average listing price. Only buy unit in working condition or if it has electronic problems which you are able to fix yourself or you're willing to pay a professional service. If the unit has mechanical problems, there are chances the capstan ring is degraded beyond repair and there is nothing that can be done about that. Also pay careful attention to the variants with ferrite head, ask seller for recording of unit playing a cassette if possible and notice if the sound is muffled or any channel imbalance. NOTE: Dolby levels vary depending on feedback network of CX174, so check service manual of your specific unit and convert if necessary.
Marantz PMD430 Generally speaking a portable without many issues apart from needing maintenance/calibration, unless it has been powered with reversed polarity. Note, as many portable of that era, plug is center negative. Unit has many unique features like dBx NR (for both REC and PB), external bias adjustments, 3-heads with off-tape monitoring. - most units that are sold as not working will have a burnt motor governor and possibly a burnt CD4011 in the VU-meter LED drive circuit; this happens due to powering the unit with reverse polarity; both parts are readily available; - a new belt set will be needed if the unit has a lot of hours on it; when replacing the belts, a relubrication of the rotating parts is also necessary; - there is a crosstalk between SOURCE and TAPE when recording on this unit, which is a design limitation; this makes the recording monitoring functionality more or less useless, because the crosstalk will distort the signal badly being out of phase with the source; - the noise floor of the unit is not the greatest; however, given the unit uses mostly off-the-shelf components there is room for some modding; - the headphone amplifier is very weak and will distort easily at higher volume levels due to inability to provide higher current; probably it was designed for high impedance headphones, which draw a lot less current; - pay specific attention to the cosmetic condition and mods at the inputs/output and the cassette door, if its latch has been cut; this indicates the unit has been used professionaly and has a lot of hours on it;
