I recently got my grubby paws on an Aiwa HS-JX505. Sound on it was terrible. Up to level 10 and right channel was definitely quieter than left channel and both channels were also extremely very low. So out with the screwdriver set we go ...







It is clear to see that we have a bit of a problem with a few leaky Nichicon electrolytic capacitors. I've identified that there are eight caps in all that will need replacing

2x 220mfd 2v
2x 100mfd 2v
2x 47mfd 4v
1x 100mfd 4v
3x 220mfd 4v

I can easily source the 4v caps, but after trying RS Components, Digikey, Mouser, and Farnell/CPC I am seriously stumped as to where to get the 2v caps from. I know I could probably get away with using 4v on 100mfd as they are reasonably spaced apart but the 220mfd are quite packed in with the rest. Can anyone here offer a suggestion as to where I may be able to source them? Source must be either in UK or willing to ship (at a reasonable price) to UK.

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Originally posted by rerooted:
looks like a nice clean soldering job you did. i do soldier occasionally but mine doesn't quite look like that.

quote:

I need: 2x 470uf 2v
4x 220 4v
4x 100 2v
2x 22 6v

Except the first two which are plastic wrapped, I know they are Aluminum surface-mount capacitors but thats it. I will be more then happy if you can help.
Thanks Regards TheLion

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Originally posted by TheLion:

I would really like to add couple of PX303 PCB photos but unfortunately I don't know how.

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Originally posted by plop:
It would be a great help to get an idea of what the existing components look like and also where in your PX303, before deciding the best way forward with component replacement. So to that end, a few photos of the PCB with the affected components marked up would be great. But in the meantime I can make a few limited suggestions.

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Originally posted by cooldude:
I have an Aiwa that has everything working except for the sound. There's absolutely no sound from the radio tuner. When I play the cassette I can hear a slight hum/buzz. Does it have the same problem as mentioned in this thread? Would replacing these caps fix the problem?
Thank you.

JX505 Deep Bass Mod

I managed to end up with another JX505 recently (a second bi-azimuth mech type ). It had a number of issues.

1. Very low volume

2. Leaked caps

3. DSL not working

4. FM radio not receiving any stations

After thoroughly cleaning this one, I replaced all the capacitors as per usual. EXCEPT for the two DC blocking capacitors. I decided to have a bit of fun. Instead of substituting the 220uF 2V for 220uF 4V (it is a tight fit but these do fit in), I decided to put in their place a couple of pre-used but tested ok 470uF 2V caps that I had knocking about.

The FM radio was still not working correctly, but with a test probe on pin 1 of the tuner flexible ribbon cable I was able to confirm that stations were being received. Therefore a break existed somewhere between this point and the ground on the headphones. Eventually after tracing through everything, I discovered the acid from the capacitors had completely eaten through the copper trace at the point where it connects to the copper coil by the headphone socket. This was repaired and once again it was possible to receive FM stations the usual way.

Compared to the 'regular spec' JX505 there is a subtle difference in the sound and even without DSL it is possible to recognise that there is a lower point from which the bass rolls off, but the sound is still quite neutral.  Engaging DSL and the bass is very deep. It is a very low and warm bass. The bass level remains consistent and balanced throughout.

What Did Your change of these Value's do to the Sound output ? what difference can you Hear versus a Standard 'Not Modified' Walkman

p.s. Are Only Aiwa's Walkman's Manufactured with bad Capacitors? or that have 'cap's' in them that dont last so long?

James,

The increase from 220uF to 470uF on the DC blocking capacitors has the effect of lowering the low end frequency roll off presented to the headphones. This is proved from the following equation :

F=1/(2CPiI)

F=Frequency (Hertz), C=Capacitance (Farads), Pi = mathematical constant, I = Impedance (Ohms)

For example for a standard JX505 with 220uF DC blocking capacitors you would get the following low end frequencies before roll off for headphones of common impedance values :

32 Ohm - 22.6Hz
24 Ohm - 30.1Hz
16 Ohm - 45.2Hz

With a higher value such as the 470uF as found already in the PX303 and PX505, you would get the following values :

32 Ohm - 10.6Hz
24 Ohm - 14.1Hz
16 Ohm - 21.2Hz

Now obviously these are the ultimate roll off values, so you wouldn't necessarily hear anything at these values themselves, but the bass range is essentially extended.

Compared to the standard JX505, the modified JX505 has a more extended and deeper bass. It is more apparent on closed cup or open ear type headphones, than in ear buds.

AIWA certainly has the reputation of being especially bad with leaked capacitors. Certainly when you compare them to Sonys of the same era. Not anywhere as many Sonys would have failed capacitors as the AIWA models. I've also found that owing to the way the surface mount capacitors are sited, these would inflict the most damage to the PCBs. Larger values containing more electrolyte tend to leak the most over the PCB. The lower values tend to just dry out inside.

Thanks Very much for this information.

I don't own any Aiwa walkman's - Mostly Sony's and a few other brands.

The computations is a good read & the Last paragraph is Most helpfull.

Remember that JX505 bought from German seller ? Well, i had time yesterday to take care of it. I knew i had to change caps. Although there were no sound issue exept may be with DSL(remember,could'nt figure out wether it was there or not) ,but for sure the big issue was when i wanted to record some radio stations , it oftenly gone erratic like the sound going mute and the display too was going crazy , i usually needed to remove batteries to reset the thing(even manual resetting was ineffective).

So , i changed all caps , they had all leaked of course , hopefully not all over the board so no need to dish-wash the board , some alcool and cotton buds were fine here.But the issue with erratic behavior when trying to record radio was still there... so it wasn't a cap issue ! I then decided to change the door cell and guess what ? It was the culprit ! Now it works fine. The DSL is still nothing compared with what offers my JX303 , on the 303 it's immediate and very loud , on MY 505 it still seems to come slower and is very discrete ,nothing as loud as on the 303 but i suppose it is normal , it's also much more enjoyable this way with a good headphone. Plop,did you noticed such difference between yours ? Other than that all seems to be fine so i suppose the DSL is the way it should be.

Something i have noticed too is a lower record level on the 505 compared with the 303(and others) , did you noticed that too ? Recorded sound is good but is lower , but i suppose it is normal too.

On this picture , you can see the board not fully yet cleaned , as you can see the DSL section seems fine. There is just one 6 legs chip (from the dolby section?) that seems to have suffered from acid. Next photo shows a cleaned board , but no water here , only 90° alcohol and a cotton bud. So don't know if it's related to my weak DSL ?

And here a look at the caps ,of course although you wouldn't tell they were all dead ,they had ALL leaked and needed emergency removal.

edit: as you can see , our 505/50 are adjusted the same in the record level section so i'd be curious to hear your answer Plop.

Hi cosmos,

Unfortunately for you, I don't record any tapes on my AIWA so I am not able to comment at this point about the recorded sound level on either of my two JX505. If I ever get round to doing so, I will let you know.

With regards to the 6 pin IC chip that you are referring to in your post, that IC chip controls the signal for the remote control.

DSL is quite complex on the JX505, since AIWA did not implement a dedicated DSL chip like say on the PX303 and so is a combination of various components. DSL is controlled by the 6 pin IC chip between the volume control and nearest to the power amplifier TA7688F chip. The 100uF 4V capacitor nearest to the internal battery contacts, is also part of the DSL circuit.

Circuitry can look deceptively clean. Alcohol will only serve to spread around on the PCB the slightly conductive residue from the capacitors. Worst of all is flux mixed with the capacitor residue. Washing the PCB is the only way to remove the residue. I've repaired many AIWAs with leaked capacitors, and at the beginining took the lazy route of just a basic mop up with alcohol to find I was only wasting my time trying to diagnose crazy faults like these. Nowadays I just wash, dry, reassemble then see if there are any issues afterwards. At least then I can rule out any weird short outs. I reserve the alcohol for flux clean up only.

Hi Plop and thanks for your answer ! I'm sure you're right , well it's a lot of work to wash and i won't do the same error i did with my JX303 so i'll see that later may be. This reminds me the fact that who could figure the recheargable battery was the cause in a strange behavior when all capacitors were replaced. When you know there's no effect on a JX303 and may be others. So a good wash is certainly the solution.

This evening i've been having a nice surprise i couldn't beleive my ears ! I decided today to charge the internal battery on my JX505 for some hours and...surprise !Heavy  DSL has awaken !!! It was weak before and now i understand it was not at its normal level , now it's heavy , strange , i will see if it stay forever at this level in the future , but it's a  thing that should be tried when something is still going wrong and you don't know why.  

By the way , i have received my second 505 today , in nice condition , clean inside and just a little swipping outside , without surprise the sound is weak(actually on one channel only) , DSL is weak and its too weak to handle a tape , it will need new caps ,unfortunately i think it's the second generation(no bi-azymuth), at least i think , i will have to check that.