Today I want to share with you another interesting walkman that I got recently on a local auction site. It is the first JVC walkman in my collection; I bought it primarily because of the low price and the design, which is different than most walkmans. What I liked the most was the blue cassette holder with white squares, the matte gray metal and a general sense of quality. I was pleasantly surprised with it and have certainly become interested in having other JVC walkmans in the future. So, let's continue with the restoration process, which was pretty time consuming for this one; I would dare say one of the difficult ones, due to a large range of problems. The first and biggest problem were the CE brand capacitors that have leaked all over the board. Yet another problem with this board is that most of the resistors are carbon printed and corrosion from leaked electrolyte can also destroy them. It is to be noted a pattern that I have observed regarding these CE brand capacitors (which I have found to be leaky in other walkmans as well, especially the very small footprint ones): not all of them were leaky, but only the higher value ones (100uF and 47uF), which leads me to believe that the manufacturing technology was not that good for making large value capacitors with small footprint. Found this pattern in other walkmans that use CE capacitors, one worth mentioning being the Infinity Intimate Stereo. I did replace all capacitors anyway, except 2 of them (0,1uF) that I didn't have on hand and were not leaky. After the replacement, I noticed that 2 traces were completely corroded; I have repaired them with a fine wire. At this point in time I decided to make a test and see if the electronics side works. It did kind of work, but not as it should; the volume was low, especially on one channel. Started to troubleshoot using a test tape and oscilloscope. I found that the signal coming out of the head preamp was low, which made me suspect the feedback resistors, which were carbon printed on the PCB. After finding a schematic of the JVC CQ-F2, which is nearly identical to mine, I measured the resistance of those feedback resistors and found both to be too high. The final solution was to bypass them using normal through hole 0.25W resistors. I did find a third carbon resistor that was eaten away, in the muting circuit. Those 3 were the only affected. The next part was the mechanical: the belt was loose, the table reel gears were both cracked and the head screws were both loose. The reel gears were taken out and the hole was enlarged just a little bit with a 2mm drillbit. The next step was cleaning the reel tables shafts and relubricating them, before glueing the gears back to the reels. I also lubricated the capstan bushing, the intermediate flywheel and motor bushing at this point. After cleaning the pulleys' grooves, I found a belt from Marian's 13 belt set that would fit (it's thinner than the original 1mm, but it works fine). Next, I adjusted the azimuth, applied some glue to the screws, cleaned and demagnetized the head and pinch roller (which seemed that it was never cleaned before). The walkman was almost finished by now, the only thing that I did more was a clean to the housing and a polish to the cassette door window. Overall, I enjoyed repairing this walkman and especially enjoying the final result: a perfectly working JVC CQ-1K. Although it sounds about average I would say, the overall design and build quality makes it a very interesing addition to my collection. Hope you enjoy it !
Thank you, @autoreverser ! Indeed it is highly underrated, I would not have looked for JVC walkmans before having this one. After this, I found that there are a couple of other interesting models, which I will keep an eye on in the future.
I am currently work on one of these units for a friend. Doesn’t seem to be leaking from the caps. Had to re-install the play and reverse catch. And I’m having really low volume from the right channel. Other than that it seems solid. Any tips or more insights to getting the right channel outputting properly?
Really low volume from one channel is very likely caused by the output decoupling capacitor going very low in value (like 100nF). The leakeage may not be obvious, but I can almost guarantee you will find it when you desolder them (you will feel that nasty electrolyte smell and also green marks where the legs contact the seal). I recommend replacing all the capacitors in this unit, even the ones that do not seem leaky, because sometimes they become leaky after voltage is applied to them (unit is used). So even if some of them are not leaky now, they may become leaky after some usage. Not long ago, I guided a member in repairing a WM-DD10, which had some pretty strange symptoms and the capacitors did not seem leaky at first glance. However that DD10/DD11 is well known as having leaky capacitors and it was no surprise that replacing them all solved the strange problems. When I see a unit like this one, where 99% of the capacitors leaked, to me it becomes clear it is a common problem.
Thank you for the reply and the info! I’d rather it be the caps than the PCB itself. Do you recommend a source for caps and is the a cap upgrade that would still fit the operating specs?
Much time has passed and I forgot about the carbon printed resistors in the preamp circuit. Those could also cause a very low volume if the resistance gets too high. Either way, the capacitors need to be replaced anyway, because if the carbon printed resistors are bad, that's because of corrosion from leakead caps. Regarding your question, I don't recommend any upgrade, just replace the caps with ones with same capacitance and voltage rating (this can be higher, but the footprint will also be larger and may not physically fit). Note that the footprint is very small, 5mm height if I remember right. The source can be any electronics distribuitor, like DigiKey. I attached the schematic of the CQ-F2, which is nearly identical so can be used as a reference for component values. The resistors I had problems with are the ones marked red. All those that are drawed in a rectangle are carbon printed resistors, so if you see corrosion around other ones, you have the values here.
Thank you so much! I’m gunna order some caps and give it a shot. And I’ll check back in on this thread soon
