National RX-5700, info before I buy?

[dusty_bottoms]

I'm currently looking at a few larger at home boomboxes to play with and maintain, and the three that I'm between right now are the Panasonic 5500, the 5350, and the National 5700.

Since there's fairly limited information on the 5700 online, I was curious if anyone has any experience with one and what they can tell me. What are some common faults, what can I expect from buying it, what does the boombox expect of me to keep it running, etc. I'm hoping to find something nice that'll last a some years with care and attention, but I'm sure with all old electronics, they're bound to irreparably die at some point.

I'm pretty good with a solder, but I still generally favor simpler mechanical boxes, hence why I avoid boomboxes with soft touch or anything other features that'll end up confusing me when I open it up to fix something. Mo wires mo problems. I'm pretty good with a solder, but I'm not really equipped or skilled enough to do any electrical maintenance besides replacing components on the PCB, the less time I have to spend identifying which parts to replace the better.

I'm hoping to find a box that's big, nice, durable, and I can mostly maintain with my skills and hopefully only needing to send to a professional or replace the box in a few years.

 

[Tinman]

I'm going to say that most vintage boxes are very similar as far as the problems you run across and the common failures.
Obviously belts are a wear item like belts or brakes on a car, eventually they're going to go bad.
With the age of these boxes, pots and sliders need to be cleaned (if they haven't already).
Other than that, you can have any one (or more) of the hundreds of electrical components go bad at any time, electrolytic capacitors being the most common.
Personally I've had bad luck with Panasonics and their brand of caps leaking in the boxes I've owned.
Currently I have two 7700s, a National/Panasonic 5350 and a Panasonic 5350 that's waiting to be gone over.
I recapped both 7700s and the Nat/Pan 5350.
I've also owned a 5150 and 5250 in the past that I replaced a couple dozen leaky caps in each.
Basically, in my opinion, the 5700 is going to be similar to any other box you're considering so pick the one that you feel you're going to enjoy the most.

 

[dusty_bottoms]

Cool, thank you. Do you have any advice for buying them used/broken?

I'm asking most particularly for the 5350 since new and fixed ones cost way too much for what is a several decade old product imho, I mostly look at ones with broken tape decks since it seems like the connections to the PCB are fairly limited and besides replacing the motor everything is just mechanical which are pretty easy to diagnose and replace.

Is that a pretty good idea?

 

[Superduper]

You won't find much information on the 5700 because that one was released only in Japan, nowhere else. Up until recently when eBay began opening up to the Japan market, very few were ever imported. It is however roughly about the same size as the RX-7000 so it's decent size. The grill mesh is fabric if I recall correctly. It's one of the japan domestic panasonics worth getting because unlike many that only have 76-90 tuners, this one has a full 76-108. For regular use, you should however, retrofit the transformer to the AC mains voltage of your location. Also almost all panasonics suffer from serious controls oxidation and this one is no exeption. Often the oxidation is so extreme as to render the unit almost unusable. You are almost certainly going to have to go through the unit and deoxit everything. However, it is, in my opinion, a very aesthetically attractive unit though and worth having in a collection.

 

[dusty_bottoms]

You won't find much information on the 5700 because that one was released only in Japan, nowhere else. Up until recently when eBay began opening up to the Japan market, very few were ever imported. It is however roughly about the same size as the RX-7000 so it's decent size. The grill mesh is fabric if I recall correctly. It's one of the japan domestic panasonics worth getting because unlike many that only have 76-90 tuners, this one has a full 76-108. For regular use, you should however, retrofit the transformer to the AC mains voltage of your location. Also almost all panasonics suffer from serious controls oxidation and this one is no exeption. Often the oxidation is so extreme as to render the unit almost unusable. You are almost certainly going to have to go through the unit and deoxit everything. However, it is, in my opinion, a very aesthetically attractive unit though and worth having in a collection.

Where can I learn more about the transformer adjustment? Also would it lose its ability to be powered by batteries?

 

[Reli]

A 5700 is not a good box to start with, the buttons often stop responding. And it's 100 volts only, so you will need to buy a stepdown converter unless you plan to just use batteries all the time.

Since they were only sold in Japan, the sellers are usually Japanese too, and buying from Japan isn't worth the risk and the hassle, in my opinion

 

[dusty_bottoms]

A 5700 is not a good box to start with, the buttons often stop responding. And it's 100 volts only, so you will need to buy a stepdown converter unless you plan to just use batteries all the time.

Where would I find more info on fixing panasonic controls, I've hear people talk about deoxing and cleaning the controls endlessly but I haven't heard anything about what you'd need to do if they actually failed, I'm guessing there's no replacement besides taking the parts out of another one?

 

[Reli]

Replacing controls is rare, and not worth worrying about unless it happens. Sliders are the most likely controls to fail, especially on JVCs and Lasonics.

 

[Superduper]

We're not going to rehash cleaning controls with deoxit. It's literally discussed here hundreds if not thousands of times. You'll have to do just do the research and search our archives. Nobody wants to type up the same thing over and over again. Search and you will find. In a nutshell, deoxit is a brand name product sold by Caig that helps remove oxidation from metal contacts. There are other products by different manufacturers that do the same thing.

Yes, as Reli stated, the controls stop responding but that's because the controls have oxidized and need cleaning. Japan is a series of Islands and water, salt water, from N/S/E/W. Every direction. So everything gets oxidized, on steroids. As for the transformer, changing it will just mean that the boombox can operate safely on the AC mains voltage in your region. Because this boombox originates from Japan (as does many RX-5350, RX-5500, RX-5600, RX-5650, RX-5400/5450 etc.) they operate on 100V. If your region is USA, then your voltage will be 115/120V so operating that boombox, unmodified, at this voltage means that the boombox will be exposed to 20% higher voltage and 60hz as opposed to 50hz in Japan. This usually results in shorter lifespan if not immediate damage, and you will typically notice distortion lower in the volume control range. Retrofitting a proper 120V primary transformer will ensure that the boombox sees the proper voltage and operate properly in your region without requiring using a step-down transformer, and done properly, has no effect on battery usage. If this information is confusing and flies over your head, you may be better off having a shop do the conversion for you. The transformer is not something you want to mess up on because we are talking about AC mains voltage, not the typical 12-15 volts you'll see on the secondary side of the transformer, which is pretty much everything else on the boombox after the transformer.