"New" RC-838 some questions.

[Simagus]

I just got this unit in an auction a few days ago.
Initially it has a number of issue, very noisy sliders, the Mono, Stereo, Bifonic switch only worked on some settings.
I took it apart and cleaned all of the sliders with switch cleaner on a cue tip, then blasted the switches on the other side of the board with switch cleaner.
This has solved the above issues.

Although I now notice the radio is in mono! It wasn't before I took it apart. Line in and cassette are both stereo.

My questions are, what exactly it the "Expand" and "Biphonic" settings supposed to do, it seems to just make it sound worse, a bit muffled with less treble.
On some classical music it did seem to expand the sound a little but anything with bass sounded a bit muffled and worse than the stereo setting.
I can't really tell if it is doing what it is supposed to be doing.

Also it struggles a little with bass when the volume is turned up, is there anything I can do to improve this? Recap the main board?
Are there any replacement woofers I could fit to improve the sound? ( I know some people like to keep them stock but I'd like to make it sound as good as possible, I am keeping it for myself not to resell)

Final question, I see some people have fitted LED's into the VU meters, how is this done? Where is the power drawn from.

Any thoughts or help on any of these would be appreciated.

 

[floyd]

These boxes don't have much power and the speakers are not that great . a speaker swap will make it sound better but the power is just not there.
I consider it a looks only box . too bad jvc could have done much better
. most of jvc 70s boomboxes are kinda weak sounding . I love jvc but I would never buy another 70s box from jvc unless it's just for looks.

 

[Hisrudeness]

It would be a shame to alter it as it looks like it’s survived it‘s years in good condition. (1978/79) but it’s your box.
As Floyd says these aren’t particularly powerful and a change of speakers isn’t going to do much. The amp chip produces what it produces. However this model is important amongst collectors because it was one of the first with bold styling and a street look. The Biphonic thing was a bit naff but they were experimenting then and what was a failure then is quaint now. Leave it in the ‘Stereo’ mode and it’s ok.
An M70 probably would have served you better as it has quite a bit more power, not as rare and around the same price in the UK.
Anyway..enjoy your purchase.

 

[Simagus]

Yes, fair points. I will leave it as stock for now, it is an old machine like you say.
The radio issue was just the FM push switch playing up a bit.
Does anybody know what the Level On Off switch it supposed to do? I assumed it just switched the VU on, but if I switch that off it alters the sound when in "expand" or "biphonic" mode. It is that that makes it sound muffled.
I might put this up for sale and try and get an M70, that is originally what I wanted but the prices on eBay are a bit much £500+.
I paid £100 for this.
And it does look amazing.

 

[floyd]

Jvc does have one great 70s box the jvc 3090 en . it's a tv box but the sound is fantastic. They are also rare and expensive.