Michelle's Bonkers blog

2018 begins with me looking around and wondering what the heck happened?

A bit of a dark time nearly thirty years ago, ensured I would end up on a journey. After some time of searching, I came to the conclusion that if I didn't ramp up the pressure, then time would render my search futile. So I stepped up the pressure on the hunt for a HS PX-303.

I very nearly had one... talking about it with one of my friends from the Netherlands, he said that his Mother had one... but when he next had the chance to talk with her, it had been thrown out three years earlier.

So I determined to get some other units on which I could prepare for the potential eventual day. I bought two P505 units which obviously needed new caps (from the fault descriptions on flea bay) and I started sourcing the bits and pieces I'd need, along with whatever spares I'd need for a PX-303 should the day come.

And then things went utterly bonkers.

A very kind soul offered me a deal... two PX-303's and if I repaired both of them, then I sent one back their way. That kind of deal I couldn't turn down.

Service manuals. Belts. Old lead acid batteries. Test tape, roller cleaner, contact cleaner and more. I've even decided to get some new tapes... twenty of the 799 Studio Masters are on their way. Might as well. The amount of customs and tax is going to be bonkers (there's that word again) so my credit card might as well be hung for a sheep as a lamb. Soldering test kits so I can practice SMD work before I even go near a unit. And then there's the small matter of recovering my main tape deck...

I had a Technics RS B605 and an RS B705. As a means of cutting down on some of the equipment, I exchanged some of my thirty year old equipment with a friend... for some bottles of wine. As you do. Unfortunately, instead of giving him the 605, I'd given him the 705. Cue a panicked phone call. The three head 705 comes back later in January to be swapped for the 605. (and it'll likely cost me a trip to the pub, as well as never living this down.) Maybe later I can upgrade it for another unit as the year rolls on... but I've got to work with what I've got.

So... the plan for January is to wait for the bits and pieces on order, to arrive. Catching everything that comes through customs is going to be a real pain. Practice soldering and study the service manuals.

First on the block will be the 705. New belts are on the way, and I should be able to handle the larger unit more easily.

Second will be the two P505 units. As well as caps, there are a few other faults. Some missing screws and one of the rivets on the hinge is missing.

Last will be the two PX-303 units. The snag is that there is precious little on YouTube about people repairing the PX-303. In fact, the only video that explicitly mentioned the PX-303 was one of mine... from February 2017. I start talking about it at 29:40-ish. - Well, that's about to change, because all this is going to be vblogged to boot.

Stay tuned for the ongoing adventures. With pictures... eventually

 

Finding things...

*) Tape Deck

This had been a long search. Turning up at Stereo2Go was the catalyst that propelled me from nowhere to light speed in about a month. After searching for years, I suddenly had two units, and a lead to a few more.

*) Power

The Aiwa units take 2v lead acid batteries, with an external unit for AAA. In the case of the PX303, the battery compartment is also the way to connect the transformer. The 505 has a socket on the side. The compartment is probably going to be the hardest thing to trace. It may actually result in going to the expense of getting some 3D printed... but only time can tell on that front. The lead acid units were also not easy to get hold of (had a few awkward moments dealing with ebay sellers and combined postage) but they were critical to getting the decks running in their full glory, rather than just running them off a bench supply. Two methods of using these are possible. First, charging with a 300Hz pulse circuit to rejuvenate the chemical composition. Secondly, gutting the thing and using the case to carry a completely new cell is an option. These are all mini adventures in their own right... particularly because I'm going to be reliant on other people as this is way outside my comfort zone.

Mains adaptors are hard to track. Fortunately, these can be replaced with other units that deliver 2v DC at 350mA. Not impossible to find, but difficult.

*) Belts

Remarkably, these are still being created. Care needed to be taken over source, however. Not all belts are made to the same standard. Unfortunately, my position was to try and take the units apart once only, but some people who could make belts needed to know the dimensions. That would have required taking apart twice at least (or having small parts laying around) and taking measurements of existing belts. Not only would the belts likely have already been stretched to an unknown quantity, but more critically, my ability to measure them would be questionable at best. It would definitely require belts from someone who already knew the dimensions and model numbers. Fortunately, this was straightforward.

*) Capacitors

It stood to reason that units this old would need capacitors replacing. Unfortunately, I came across an old list and ordered tantilums from the US, because the list had the part numbers for DigiKey, which made the whole thing easy. Again, this was partly because I wanted to have known good components on hand, for the time I took the unit apart. There was a newer list with some electrolytic part numbers that came up later, however, but it was too late for me. Ultimately, however, I need to get to grips with ordering capacitors. The shear number of caps available just made me want to run a mile. This is mostly down to my lack of experience. Time will hopefully improve this.

*) Consumables

I already had a demag tape. Had to replace the battery and do a little cleaning, but it works fine. I already had some long cotton buds hanging around from my days as a mobile engineer (board level) and some other bits and pieces. Isoprop is a standard. Still needed some contact cleaner and some rubber roller restorer, so those had to be ordered. The 3000hz tape also had to be ordered, becuase I didn't have a deck I could trust. A mobile phone app proved to be very adept, even when running on my Sailfish mobile phone. Downloading a reference audio file from a web site that generated files of different frequencies, proved that this would work.

*) Reference materials

Some were difficult to find. Still haven't been able to find the P505 service manual. The RS B705 was on a web site, and I found the PX-303 on fleabay. Cost a bit, but worth it. The service manuals are worth getting hold of, and printing large if possible.

*) Tapes

My small collection of TDK SA-90's are tucked up in their little box. Some of the commercial cassettes have degraded, most notably the pads have crumbled to nothing. I needed tapes that I could trust to stay together, but that I wasn't going to cry over, so I got myself some pre-enjoyed SA-90 tapes. For the heck of it, I also decided to get some metal tapes (because I couldn't afford any back in the day, and I was told that metal is better suited to live performance; which wasn't what I was listening to. How much truth there is in that, I don't know but I was too young to smell snake oil back then.) I've also decided to invest in some 799 Studio Master chrome cassettes, as people are talking about them and nothing is gained, if nothing is ventured.

*) Little extras

After watching a number of tear down videos, I saw magnetic mats being used. A brilliant idea whereby you draw on the mat and then place the screws at the appropriate place on the drawing. I had to get me one of those. Finding some of the screws is going to be difficult, as are the small rivets that are used for the hinges, etc. When you're dealing with Fleabay, there is no knowing what is going to be missing. One units is already suffering with a floppy hinge, and I'm not sure yet how I'm going to repair it.

*) Conclusion

I'm convinced that if I didn't act now, and instead left it another few years, then it is likely that the task would have been impossible. I have gone a little overboard on some of the spares, but I'm looking another twenty years down the road here. The chances of getting some of these belts, etc. are going to increase in difficulty exponentially. It is a chunk of money to find all at the one time, but once the foundation is made, then time will be on my side.

 

I agree. I do have an earthed mat which I work on, so static shouldn't be a problem if the surface can take a crocodile clip.

 

2017 for me was a pathological shopping year. collected many walkmans. It was also a donation year since some of them were so disappointing and useless, so i donated a lot of them to local goodwill.
in 2018 i will try to repair/ restore as many as possible. As usual Sergi will be a great help to me this year as well.

looking forward seeing your adventures/ repairs/ restorations with pictures and direction.

 

Power talkin'.

So, after badgering the heck out of a load of people on an electronics forum, the conclusion is that trying to rejuvinate/revitalize/resucitate the old lead acids is a shot in the dark. Or rather, the pitch black.

As a result, I decided to take one of the cells apart and see what was inside. After the dead, inert chemicals were gotten rid of, this is what was left....



A space measuring roughly 60mm x 15mm x 6mm ... give or take a prong.

Two options remain...

1) Find another cell that will deliver 2v and fit in that space.

2) Fit a voltage regulator circuit, and a usb socket to the arse end. - This will get around the need to feed it an endless supply of AAA batteries, or tracking down a commercial 2v DC power supply.

As I have the P202 units to mess around with, then these units will go first with the experiments (once the old lead acid batteries reach me, and can be gutted) ... and some voltage dropping circuits are on their way. The only ones small enough, appear to drop to 1.8V ... the variable version might be too tall.

I do have a query in with a company called Lighthouse in the USA, who have manufactured batteries for other Aiwa pieces of equipment. Maybe they can help.

 

So, after a while talking on the EEVBlog forum, here we have the intended source of power. A small battery meant for models...

RC Turnigy nano-tech 200mAh 1S 35~70C LiPoly Battery



It is 2mm too high, which I should be able to recover by removing the cap. Then I'm going to have to find out what circuitry is already in front of the battery, and then work out how to drop it to 2V (it supplies 3.7 at 200mAh, so dropping to 2V in theory might gain me the same run time as the original PB-3) and also allow the walkman to charge it, all within the remaining 7mm of space. So... no pressure then...

 

I think charging would be the major problem.

I have seen in other posts that someone is selling modified Aiwa batteries with a LiPo inside.
I believe they are charged through a Micro USB port.
It is much easier to design a charging circuit if the input voltage is higher than the battery.

p.s For really small batteries the cheapest source I have found are the £3 Chinese MP3 players on Ebay.
When I receive the famous "Round Tuit" I intend using this one to repair a Sony.

 

I started a bit of a discussion over at the EEVBlog a few days ago. It's still running, with a few videos of explosions being posted as well. - http://www.eevblog.com/forum/repair/rejuvenating-batteries/

I'm probably going to be using these - https://www.ebay.co.uk/itm/3-7V-500...501646-for-Recording-Reading-pen/262500045648

...with three 0.6v diodes to bring it down to 1.9v... unless I can find another dropping mechanism that doesn't waste power. But 500mAh is a good amount for that size. There was another battery suggested ... https://www.ebay.com/itm/3-7V-450-m...oth-mp3-mp4-/261285922057?hash=item3cd5dac509 but it is a little longer.

It will need a small external port (possibly where the black thing is in the battery case) to hook up to one of these chargers ... https://www.ebay.co.uk/itm/2pcs-5V-...ging-Board-Linear-Charger-Module/152070669880

I have been cautioned about using LiPos, as they are not the most stable and need care while charging. All this lot will take weeks to arrive, so who knows. I've run out of cash for this month, after just a few days in, so it will be early Feb before I can do more. Ultimately, finding a battery closer to 2v is proving difficult. There was the suggestion of posting a high res picture of the board, to see if people think that the unit can handle 3.7 volts. I did post some of the circuit and it does seem to be running at 2v... no one could see any obvious kicker components.

These poor P505 will deserve a medal by the time I'm finished with them!!!

 

Have you considered this? https://www.ebay.com/itm/Aiwa-Walkm...288394?hash=item41d5a5d1ca:g:KA8AAOSwh1hZ6zfF
You need to contact the seller and he will make and sell a battery for you. I am unsure of whether or not the battery is compatible with a px303 but i think it would be possible to reverse engineer them.

 

I've dropped him a note just now. I do have concerns about LiPo batteries, however, especially after what I've been reading. They seem to be the only ones that fit inside that space with any reasonable amount of power to them. Thanks for the heads up.

 

Hi Michelle looking at what you are doing to get your units working again with the batteries, nice good work hope it all goes well.

I have to say with LiPo’s the nominal is 3.7V but the voltage is actually 4.2V when fully charged, I know this as I fly radio control helicopters and use Lipo’s. Like people have said before LiPo’s are very volatile, handle with care.

Because I have loads of large ones I use on my helicopters i.e. 5000mAh 6S, I carry them around in armo boxes. I know you are only dealing with 200mAh – 500mAh 1S but you still need to be careful.

Personally I would look for something else rather than LiPo, good luck.

 

Thanks. That's good advice. I haven't found anything yet.

A colleague of mine went to Japan last year, and told me about sweet potato, I think it was. Going to contact them. To start, I'll try and track down that remote control. Can't find it on ebay or anywhere else I've looked.

I do know a few people in China, two of whom live in Shenzen... but I'm not sure they'd have much luck. They go round the Hong Kong retro events where it is a free for all. So I'm really putting the feelers out there now.

 

Well good luck with your hunt.

 

This looks to be the type of circuit you need

https://www.ebay.co.uk/itm/Lithium-...hash=item1ec4e0e4e7:m:mSIK97PGNNP9Sdp_L8zp79g

Probably too big to fit in the Aiwa case though

 

Should be fine, if you look at the ebay link previously posted:

 

I did contact the ebay seller as to whether they have PB-3 for sale, but the response wasn't comforting. Plus I'll have to wait until next month anyway now. I'll keep track and let you know what happens. Most things are going to take weeks to get here now.

 

My credit card tripped over today, so I put an order in with Mouser for more capacitors. Someone was kind enough to give me their last order sheet, which gave me the part numbers I needed so I could go straight to the ordering page and sling them all in a basket. One of the key parts, the small 100uF cap, is on back order, so who knows when they will reach me, however there is a chunk for me to do in the meantime.

Next week I should get the 705 back, in whatever state it's in. I believe it's working with the exception of the counter. Next week will tell.

The three 303 units are all in the state where they start working the moment they are powered on, but the silver one hasn't had the caps replaced yet. Work on this is going slowly because the small home office is in a mess and needs tidying up, before I can concentrate on things once more.

The P505 went for a walk with me last Sunday, along with Guardians of the Galaxy tape 2. The AAA batteries easily saw through two playings and I finished my walk before I ran out of battery, so that was good. I did, however, notice a muddy bass, and I had used tantilums to repair some of the caps on this, so when the Mouser order arrives, I'll replace these and see if I still have the same mud. Overall, the GoG2 tape performed well, but the hiss between tracks was obvious, and bearable, but obvious, if you know what I mean.

Interestingly, here is a comparison between the GOG2 (type 1) and 799 Studio (type 2) tapes from NAC for comparison. I won't actually be using the 799 until the RS-B705 deck is back with me, however.

Also in the post is a multimeter from EEV Blog. I was late to the party, so my multi won't be here for at least another month, maybe two, but at least I'll be able to throw out the two smaller, cheap multies I've been using.

Today has been work done on accessing the old forum posts. Attached are a few shots showing the initial layout and colours I've used. No search function yet. Tomorrow, I make a start on tidying up the office. Not much else I can do until the capacitors reach me.