Hi, I need some tech help.

As some of you are aware, Aiwas from a certain time period tend to have massive capacitor failures, often needing recapping.

I have obtained quite a few Aiwas for cheap (some as low as US$1 for a U07, $2-3 for Tp-S30,JX707 and JX2000) and nearly all of them have the same problem: Low Audio hum, or in some cases, no sound at all.

Now I've tried Re-capping most of them, but success rate is often low. Apparently if the unit started out with audio hum, recapping will reduce but not eliminate it entirely.

I was successful in a full repair for a G101, bringing it from no audio at all to full working order.

Then the JX2000 which started off with no sound, but after a recap there is still a bit of hum. At least it sounds great. I'm planning to check this one over to see if any more improvements can be made (maybe with tantalums?) Will be needing input on this one.


The JX505, on the other hand is perfect cosmetically but the Capacitors inside have leaked everywhere. Worse than plop's 505. Despite cleaning it up and installing new caps it screams with dolby on and volume is too high, radio works but the soundstage is very narrow compared to my JX2000. Oh, and it's too loud. Cassette mode hisses and hums like crazy.

The U07, despite being mechanically perfect, Barely improved from a re-cap. The board has a ridiculous amount of factory flux on it.

The TP-S30 works but buzzes rather loud if the volume knob is turned, and hums as well. Recapping also barely helped. Quite a bit of factory flux too.

The J09 is on the other hand, electronically sound and only needed a new belt and LOTS of cleaning.

All of the newer aiwas like the PX-347, rx648, JX769 do not suffer from electrical problems.


On the other hand, the Sony walkmans that I find tend to only suffer from mechanical probelms that are easily resolved like belts. Now what I'd want to know is that whether the audio hum that still lingers in my Aiwas to be either:

1. I did not re-cap it properly. (Not very likely)
2. The capacitors I used were not of high enough quality (I used smt caps for some)
3. The traces on the board have been affected by corrosion, and cannot be seen
4. There are probelms with the pre-amp or some other IC.
5. Other components (like smt ceramic caps or through hole ceramic caps) have failed.
6. Aiwa uses substandard solder that corrodes/degrades.


If the caps are not of high enough quality, I'm wondering if replacing with tantalums will help. I buy my caps locally and some may be old stock, so that may be the cause. But I've checked this by replacing with different caps again.

I also have a JX707 waiting for new caps. Great condition, but missing a battery holder, and does not seem to hum. Dead right channel, BBE and DSL.
I could use service manuals for the 707 and 505/JX2000. And the user's manuals too because I have no idea how to set the clock (seriously.)


I need to know why I have this issue, and what steps I can take to improve them.

Wow, so apart from the D6C you seem to be really getting into the spirit of re-capping your Aiwas

There are quite a few models mentioned in your post, but I will try and tackle questions on the models that I have already worked on. ie the JX2000/JX505 and JX707.

In general, what capacitors are you replacing with? I presume same capacitance and same or higher voltage? Yes capacitors can go bad - even unused old ones. Thankfully you're likely to notice they have failed before you have installed them into a prized circuit board. If in doubt check the values match the advertised value with a capacitance meter before installing. Or replace with newer stock if really paranoid.

JX707

These are a real pain at the best of times to work on, as I am sure you have now found out. The likely reason why BBE or DSL isn't working is that the switches for these can develop dry joints especially when you struggle to wrestle the board off the chassis. Worth checking the joints are good on the circuit board. Also for BBE and DSL the IC chips can also get dry joints too! I got that on my first ever brand new (at the time) JX707 I bought from a dodgy electronics shop in HK in 1992. So, your dead right channel is likely down to dry joint, possibly the headphone jack or even on one of connections to an IC chip. If the BBE and DSL are working, but don't display on the LCD that they are, then it is likely due to the flexible PCB at the hinge. The angle of bend is very sharp, and it is a known failure point on the JX707 series.

JX505/JX2000

First of all make absolutely sure that all traces of cap juice and crud is off the board on all the components. Use as much sodium bicarbonate and PCB cleaner (I use IPA) to clean this off as is required. If leakage is as bad as you say the acid will have leaked to even some of the least expected parts of the unit.

Once you are satisfied it is completely clean, then you will need to check the areas where most of the acid was found for signs of corrosion on the traces. Any traces corroded will need replaced or strengthened. I was very fortunate that none of the traces on my board were affected. YMMV. Also check to see that no other component was damaged eg resistors or ceramic capacitors. I had a couple which were slightly corroded, but they still worked. Any that are badly corroded will need replacing. If any IC chips are corroded, then the PCB is pretty much a write off. At best you may as well keep it for spares. I did also re-tin some connections on the board that looked decidedly dry/oxidised.

If you are having volume control issues, check that the pot is not shorted out eg contaminated with acid or cleaning product.

You can replace with tants, but they are expensive and on the audio path they may not have the desired acoustic reproductive qualities of their electrolytic equivalent. Be sure to check the polarity. Tants have a tendency to ignite or violently explode if incorrectly installed.

I could scan you my user manuals for the JX505/707, let me know which pages you are particularly interested in (I don't fancy scanning the whole manual) There are no free scanned copies of the service manuals available for the JX505 or JX707 on the internet - at least that I've found.

The part of the service manual I'd need is the schematics board diagram, especially to check for broken traces, then the electrical adjustments. Oh, and I need to know how to set the clock.

707:
The LCD seems fine, and luckily the ribbon cable seems ok. Maybe find ways to strengthen it. The silver coat of paint behind the LCD rotted away so I've re-painted it with tamiya silver.

505: Most of the solder has turned dull, and some black due to acid attack, but I did clean it a bit with alcohol. Soldering on it produces fumes. Should try what you said, but I think that this one will require too much work (nearly all solder points are dull). Also repainted the LCD.

JX2000: Will give this one a cleanover and see what happens. Also repainted the LCD (I'm seeing a trend here). This one can barely close because the caps are larger values than the originals (Hate tight space.)


I'm still wondering why Aiwas all suffer from this compared to Sony units. Yes, bad batch of caps but stretching so many years?

Sorry I don't have the service manual for the JX505, just the user manual.

To set the clock for the JX707, press and hold 'MEMORY/SET' for about 5 seconds, and then using the tuner buttons press UP to set hours and DOWN to set minutes. Press 'MEMORY/SET' to confirm the time. Without digging out the unit or user manual, I believe it is the same process for the JX505 as well.

If it is producing fumes rather than burning roisin, then it sounds like you haven't neutralised all the acid with sodium bicarbonate.

If you are having problems closing the JX2000, then you need to get the smaller Panasonic 4v caps from Digikey. No issues closing when using them. BTW the through hole 4v 220uF Panasonic caps for the JX707 from Digikey have to be perfectly aligned for the PCB to just about close if you decide to use them. I have yet to find a shorter alternative.

I have yet to see any Aiwa where the silver backing on the LCD has come off. These ones that you have, sound like they really have been previously badly stored.

I get all of these Aiwas from flea markets, and while they are ridiculously cheap, the humidity of this country has affects them moreso than others.

I've come across rustbuckets and near-mint examples. I've got a near brand new WM-EX1 for about $7 and a well used but restorable TPS-L2 for 3. My JX707, despite being nearly perfect cosmetically, has the LCD silver rot.


Aiwas used to be very popular in asia and had a very strong reputation here. If you desired a walkman, you wanted and got an Aiwa. There also used to be an Aiwa factory here- My PX-347 is singaporean.

Btw pressing Memory/set on the 505 and then hour/up resets the display. Maybe it's something else.

Just checked the JX505 user manual. Yep procedure is the same as per for the JX707.

Preset 1 - Current Time, preset 2-4 hour only adjustable (For timezone setting), preset 5 customisable both hour and minutes

In "off mode" ie no tape playing or radio, press preset "1" and press and hold 'MEMORY/SET' for about 5 seconds, and then using the tuner buttons press UP to set hours and DOWN to set minutes. Press 'MEMORY/SET' to confirm the time. Repeat for preset 2-5 if required.

If doing this this resets the display, then maybe there is bad connection somewhere on PCB.

i have been following you all along. i don't have the problems with my 505 but this is the first time i have ever got the clock to work. i douldn't figure it out at all but now i know it's not that bad....thanks much. thanks all..

yup I've got my clock to work now too.

ON my 707:

I've just opened the thing up (much easier than some of the others) And fixed the broken right channel just as you said (a bad joint.)

Here's the sit-rep: Radio works fine. BBE sounds worse with it on. DSL is dead. Cassette has motor buzzing sound. Volume is super-loud (can still hear sound at 0!). No signs of electrolytic leakage.

I think it needs a re-cap, But Since the space given is ridiculously small I may not be able to get such puny caps locally. I'm wondering how installing tantalums will affect the sound.

I think for the JX707, you should be able to replace most of the caps with tants as they are used for noise filtering on the VCC line for the IC chips, except for the through hole 220uF 4V cans. These are the two audio caps post amplification. They are also the two caps that would give you the most trouble closing the JX707 if their replacements aren't exactly the same size or smaller. There are also SMT caps that should be replaced on the RF PCB (the PCB with the clock) as this is where the JX707's main logic processor is located.

Can the battery which keeps the clock and radio memory intact on both these when changing the battery's be replaced. Is it soldered to the unit. And also, what type of battery do they take.

They can be replaced, button cell type. They are similar to game cartridge cells, but I cannot remember the exact model. I believe the JX707's cell is soldered on but can be removed and replaced easily. For the 505 and 707, the cells are in the cassette door behind the "Amorphous HX" label, and are rather easy to access.

Derek, this is a very special type of Lithium polymer rechargeable battery by Panasonic CL1220. It is no longer manufactured anymore. There are direct replacements, but to be honest technology has moved on and the better alternative with a higher charge capacity is available from Digikey manufactured by Sanyo - ML1220. Part number is SY104-ND. This is the only source I have found with this battery and the correct axial solder legs.

Interesting. Never knew they were rechargeable.Did a search on the CL1220 and a guy on a Nintendo forum replaced a CL1220 from a cartridge to a more available CR1220. Although it worked, that CR1220 is not rechargeable. I wonder if this will have any ill effects. Either way, it looks like it's better to buy the correct rechargeable replacement.

It is confirmed in the JX707 user manual that the CL1220 as having a lifespan of 1 hour from when the lead battery expires to allow the user the chance to change or charge the lead battery. From other sources, the capacity of a CL1220 is only 6mAh, compared to the 15mAh of the ML1220 which should result in >2 hours before the memory is lost.

Replacing with the cheaper non-rechargeable single use CR1220 is not a good idea, since the unit would be trying to put a charge over the cell when supplied with power from the main batteries.

We are constantly reminding it is not wise to charge single use batteries. Also once the single use battery has expired, you have the trouble to dismantle and replace the dead battery. Just replace with a rechargeable battery and minimise the trouble of replacing.