This is the second of four HS-PX310's which I'm trying to get going - partly for the challenge and becuse I had one new and it was excellent...until it malfunctioned. The first restoration ended in disaster (see here http://stereo2go.com/forums/threads/aiwa-hs-px310-restoration.4833/), I got it working really well for 30 minutes before it all went wrong so it's been parked. I'd already replaced all the capacitors on machine two, cleaned everything and put on a new belt but it buzzed as before. I then noticed four of the resistors looked pretty bad (see below) so removed them and swapped in some nicer looking ones from my spares machine. I'm an electronics novice, I don't technically know that much apart from what I've learnt over the last few weeks here and on YouTube. So replacing these very tiny components was really pushing my skills. I used hot tweezers to remove and a fine tipped iron to reapply. It made no difference. Whilst feeling a bit down about the first player I popped a cassette in the other one and twiddled the volume, low and behold the music came through strong after a fizz and a few seconds. I had 10 minutes of perfect play and then it literally fizzled out again - this is what it does. I assume one of the new capacitors is the issue? Any advice greatfully recieved!
If you did a full re-cap, I would not worry about a Bad capacitor, although it does sound like a capacitor issue... Re-flow ALL the points for the headphone jack! When you say 'fizzling": is this going over the music? or just noise? Resistors do go Bad..., but they are tough guys and I have yet to find a Bad one in my resto projects I have a similar headache with my "dream-boombox": now waiting for a "freeze-spray" to (hopefully) narrow down what the f@#$ is going on
Thanks for the reply. I did remove clean and re-solder the headphone jack flex - but it still cuts in and out. Basically I get this: ...background hum, then a brief crackle crackle - perfect music for 20 seconds - crackle crackle, hum for a minute or so, crackle crackle - perfect music for 20 seconds - crackle crackle, hum...and so on I've also found that if you leave the battery plugged in with the machine off the headphones crackle. I've ordered an ESR meter.
The ESR meter was of limited use with such small capacitors. I removed and redid all the caps being very careful to clean and make good joints. The result was no hum...and no sound either! Also like my other machine I managed to make it constantly autorevesed and all the buttons stopped working too! I found reason for the autoreverse issue - see my other thread - I think this may account for the buttons on these machines failing generally. Next I got the multimeter out and started prodding around - I accidentally found that connecting the mute contact and earth brough back the music. I don't know why but it works - so I made a small link. As with my other machine, after 5 or 10 minutes the sound fizzles out, however, I've found that I can bring it back for a few seconds by turning the volume down or up... Capacitor issue?
Hi there, I have had a few adventures with these models and their sisters& brothers, what you would find extremely useful is a good working model and then you can use it to agree values on that PCB when comparing the suspect PCB, sometimes this makes it sooo simple to render the perfect repair and all ills disappear! (Yes it can happen), An E.S.R. meter is not always the best bet in case of these figure on lots of Age related corrosion and breakage between the upside and lower side of the p.c.b Continuity meter/ohm meter I use to fairly good effect prefer the bleep over silent checking of the p.c.b. I would rather not look at any thing else when I'm looking at the p.c.b. so a background bleep letting me know the pathway I just checked is intact is what I do with these because like I said in my humble opinion corrosion is chief culprit, this notwithstanding the other usual suspects dead/leaked capacitors and belts/belt mush clean! Take your time with these plug the digy holes uniting upside/down side should mostly get it, mind switches enclosed or otherwise they all will need cleaning, And if you are this committed to fixing you might as well lubricate that which requires it, remove in areas it's not required, spit and polish, fresh Batteries enjoy! Labour of love Kind regards Warren
Thank Warren, I'm actually quite enjoying this challenge - the occasional bursts of music from a long lost tape is worth the effort. The sound quality is tremendous - I'm one step away from success...and failure! I now have both machines at the same point - both fully function but after 5-10minutes the music fizzles out. My conclusion is a common component is failing but I don't think it's one I have put in. It could perhaps be any number of resistsors, but on my spare machine the Tantalum capacitor had broken up in situ - maybe heat? Looking at its location in the circuit it could be responsible for the music disappearing - the fact that it has failed on the spare machine makes me wonder if they are a weakness? Can anyone tell me from the photos below - is it a Tantalum 4v 22uf capacitor? One thing I have notice with these machines, when playing, is that the music is very loud when on low volume - maybe there is an issue (capacitor maybe?) causing an overload on the transistors after a period of time? Any comments gratefully received!
Oh forgot to mention, there are change over switches linked the mechanism there is one switch in particular which disconnects the amplifier when it's rewind or forward but ensures the sound signal can pass when in a certain position, the middle I think! Do note that some of these switches look the same on the outside but the internal switching arrangements are different! Easy to get into a tis with that one, Hopefully now you won't If you have doubts about a switch take it apart (VERY CAREFULLY) and scrape the contacts clean, Regards the tantalum capacitor value, I don't know off the top off my head that value and I cannot remove it from the board to measure the value or I risk messing mine up, if you're handy though no with electronics and soldering make a simple oscillator but leave the capacitor in that oscillator as a couple of wires what you then do do is put your oscillator on on the capacitor under test and listen to the tone it emits if you then take this to known values you can compare what you're hearing tells you it also serves to test a capacitor at the same time good luck mate they are a challenge to work on
That is a very strange looking capacitor. Tantalum capacitors are nomally rectangular plastic blocks. Electrolytics, metal cylinders. The gact that it is shown polarised on the schematic indicates one of the two. If you want to try a temporary replacement you could fit an electrolytic. Using a higher voltage doesn't matter. They just tend to be bigger. Using a slightly higher value probably shouldn't matter. Capacitors tend to have wide tolerances e.g 20%. 3.9uF or 4.7uF are standard values. Just a thought. Do you have an items list to go with the schematic. That might give more detail.
Of course, thanks Longman - there is a list with the manual. Just looked and it says Tantalum 22-4, so I assume 22uf 4v... which I’ve just ordered 5 of! Something it taking out both channels in a capacitor failing type way - this could be it... we’ll see!
I think if another possibility! Is it not the case that just nestled behind the headphones socket there is a plunger type switch which as far as I know detects if a jack plug is inserted or not, I have not traced it but the functions on the player still work without a jack plug so I imagine it would be tied into control of the sound out, look at this as well, maybe even arrange a temporary short, don't forget to remove after testing! Happy to give some pointers! Kind regards Warren
Thanks Warren, I have wondered about that bit. The way it fizzles and pops before cutting out to me suggests something going out of tolerance. It takes about 7 minutes to do it the first time then only 10 seconds or so after - I assume the offending part has heated up. We’ll see what the new cap does, after that I will have to check every other component!
Well from what you've said sounds like you are fairly convinced it's capacitor trouble well it could be, I noticed someone mentioned freeze spray now that will definitely work to reveal problem area's! As long as it can be applied in only small areas at a time! Tantalum caps tend not to be as short lived as the electrolytic types so it's rare to get failed totally but I have to concede anything is possible doing this level of service, took me ages to realise that The case needed to be installed in order for the - negative path to be complete, on one particular Repair havethat I got involved with early when I started looking inside these things, seen loads of examples like this so yep follow your own instincts you might get it right first time! Anyway any knowledge amassed I will await eagerly to read about please keep this adventure well documented as you have begun to, I certainly am enjoying hearing about it Kind regards Warren
I agree Tant caps are meant to be reliable, but do claim a life of around 20 years - though not much to go wrong with them. You shall have an update by the end of the week!
Too true, if you manage to get it sorted (I am sure you will) Then it should be good for another 10 years! Look forward to the update, chance's are though is that you'll want to put your feet up after this one! Kind regards Warren
Double check the polarity before fitting the new capacitor. From what I remember Tantalums normally have the + marked. That still makes me wonder what was fitted in there in the first place. Any normal Tantalum would have a polarity marking.
Hi there, I think it's the shape is different at one end on these small orange tantalum's denotes orientation, On some other tantalum's there is a line that denotes the positive end
...well I've been listening to this machine for 30 minutes now - a bit of crackling every-so-oftern but it's still going. I've been using NiMH batteries, I've got load of them from my kids Lego trains - could these be an issue - if for example I've accidentally been putting in ones that aren't charged properly? What happens when the batteris run out audio wise?
Hi, yeah not having full power can cause weird faults although in fairness a brand spanking new electronic item should have been designed to cope with the discharge curve/trace of the intended power source, The situation is slightly different with these used machines, as old components are at their extreme end of tolerance and inevitably have a knock on effect! personally I try to arrange a reliable power supply, usually mains derived, then that is one less thing to consider when investigating fault finding! Regards your question about what happens,,, I can't honestly tell you what happens when the power runs down because so many things happen simultaneously! And this also is determined by layout components, so on and so on,, One clue I can give is in the analogue stuff there will often be balanced points at various nodes within the circuits, changing the source will change the relationship and the balance points, Some circuits cope and continue to operate even with minimal power,, Some do not cope Sony have impressed me in this regards I have measured a battery with 0.7v Less that half the 1.5v twas when new and the Sony was Still able to power the motor, amplifier, and logic quite impressive level of efficiency if you ask me! Have you de-magnetized the head or are you not a believer in it? Kind regards Warren
I can test the behaviour with low battery on my almost fully functional HS-PX410. If I remember correctly, the volume goes down, noise goes up, maybe it starts slowing down - it's some time I used it. I was using it powered by a pair of AAA NiMH batteries (Eneloop).
I now have two machines working, one very reliably but when it gets to the end of the tape it doesn't turn over. The second works well but the motor is almost always running - a switch somewhere. Both discharge the battery overnight when it's left in. I have got all the buttons working on all machines - re-soldering the buttons seems to work quite well. I manged to get the audio working on both by jumping the mute and earth found on the base of the circuit board (see photo 2). I think the problem with loss of audio was to do with the mute circuit but I don't know why? I think the mute circuit is to mute the sound of the motor? The first photo below shows the two suspect items which deal with the mute... Still got work to do but I do have working machines - kind of!
