JVC 838 LED mod and tuneup

[Maxx134]

So I had bought this JVC a long while ago on ebay and the seller sent it with 30yrs of dirt and dust and looked like it was abandoned in someones garage lol.
I hate those ebayer power sellers and that sell U a garbage and expect U 2 pay like it was new.

I then proceed to tuneup.
I took it all apart and cleaned first.
This unit had the most dam screws I seen yet just to remove chasis from outer box.
I changed the main cassette belt and lubed the metal chasis. Another 7 screws just for doing that!

I was lucky to see the heads and pinch roller had little use for a old box like this.
This unit has a truley metal feel and sound to the buttons as the almost all metal contruction looks indestructable.
I then boosted the power supply by adding an 3300uf capacitor to it which helps distortion/dimming at high volumes.
I then make the tweeter center caps silver instead of black, for a more prominent look.
Had to paint the woofer and tweeter grills as well.
I made mistake of using gloss instead flat

Finnaly get to the LEDs, first tapped off circuit board for the dial lamp power.
It is located by unscrewing the two left front switches and I will post a pic of exact location.
Then we have dilemma of controlling the lights..
No Problem, use bottom left pin of meter switch on main board, for a switch to ground control.
In will post another pic of that as well.

So what is final result?
I looks like I would havr invisioned it to be.
Lighted dial
Lighted VU meters
Lighted front controls
Lighted glass looking cassette door!

LOOK:

Another view :

 

[goodman]

Excellent work!!!

 

[Maxx134]

Excellent work!!!

Thanks Goodman, I like the cassette door best

 

[Reli]

hmm interesting, can you show a closeup of the meters? I am curious how many LEDs you used there, and which direction they are pointing.

 

[blu_fuz]

Best looking 838 I have ever seen!

 

[baddboybill]

That does look very sweet !! Love the blue LED's although I would have chosen green I think


Bad Boy Bill

 

[Maxx134]

hmm interesting, can you show a closeup of the meters? I am curious how many LEDs you used there, and which direction they are pointing.

Each meter has 3 high intensity flat square leds pointing diagonal into the meter from the top down and on the grove where the slimmer part gets bigger.
All LEDs should be positioned while on so you have optimal view how each slight angle looks.
Three more same Leds used on meters are used over area of the switches, so three on left and three on right.

Then the dial was left alone with original light working on the left,
While 3 high intensity flat side shooting Less where placed on the right side perfectly just had to remove the foam so U have the space,
But the angle here is very critical to get perfect so have a hot glue gun ready and position while light is on.
Wire from dial was run under the meters so not impede with string of running dial

Same 3 leds for the dial are used for the door in a groove near bottom.
Only trick is to run wire to back without impeding the door, so hot glue to the rescue again.

 

[Fatdog]

I like the idea of LEDs in the door, but the downside of it is when you need to disassemble the unit or just remove the door. A "quick-connect" plug would really come in handy for something like that. For my own tastes, I think I would have gone with some sort of green lighting if possible, like BBB said. It looks cool though.

 

[Maxx134]

That does look very sweet !! Love the blue LED's although I would have chosen green I think


Bad Boy Bill

Ur correct blue does not work good on the dial which has some yellow in numbers so either cool white or green is optimal so I chose cool white because of the big white meters and visually more impressive in luminance.
It is my phone camera that is making it look like blue when actually they are all the same cool white color.

 

[MONOLITHIC]

That does look very sweet !! Love the blue LED's although I would have chosen green I think


Bad Boy Bill

I agree with that... Green indeed!

Still a dope mod tho!


Sent from my iPad using Tapatalk HD

 

[Maxx134]

That does look very sweet !! Love the blue LED's although I would have chosen green I think


Bad Boy Bill

I agree with that... Green indeed!

Still a dope mod tho!


Sent from my iPad using Tapatalk HD

Hi this is a photo edited hue to show how it would look in green according to the type color green LEDs I have it would look like this:

 

[baddboybill]

That does look very sweet !! Love the blue LED's although I would have chosen green I think


Bad Boy Bill

I agree with that... Green indeed!

Still a dope mod tho!


Sent from my iPad using Tapatalk HD

Hi this is a photo edited hue to show how it would look in green according to the type color green LEDs I have it would look like this:

Now that looks Awesome!!!! reminds me of a Toshiba Bombeat


Bad Boy Bill

 

[Reli]

Looks great! But, I am a fan of leaving white meters white......so maybe make the tuner green, the tape door green, but the meters white......just maybe not quite as bright

 

[Maxx134]

Looks like I couldnt help it and modded it again.
Maybe I went overboard, but results were a sucess and
the unit's full potential is brought out as it sounds better to me than before.
On a suggestion from a friend and fellow collector,
I swapped out the speakers for a set of m71 speakers.
Here is the result videos:
https://www.youtube.com/watch?v=Gql71WZnBkQ&feature=youtube_gdata_player
Also made the metal dial pointer green..color matched to the green area below it

 

[Maxx134]

Also another video where I was initially testing.
The m70 type speakers were on the right side and I was
switching back and forth between right and left sides.

At around 2:50 mark you can here the difference in percieved clarity or sound.

https://www.youtube.com/watch?v=-7rPqBJ7coc&feature=youtube_gdata_player

The woofer and tweeter are designed to be together as a unit with the capacitor specified for the tweeter to blend with the woofers response curve.
The amplifier or radio in this instance only has to handle the speaker load, or impedance.
The m70 speakers can handle more power than the originals and are less a load on the unit as total impedance is slightly higher.
So in this case it is not only a perfect fit, but a nice upgrade as well.
Only noticable drawback is the unit does not drive the speakers as hard as an m70,
But that could be a good thing and a non-issue for normal use.

 

[Cpl-Chronic]

Looks & sounds pimp SON!!

 

[jrhepton]

Amazing box, what a great combination. One of a kind for sure, and what a sweet spacious sound!
Super job, especially compared to where you started!

:super:

Jason

 

[Maxx134]

Amazing box, what a great combination. One of a kind for sure, and what a sweet spacious sound!
Super job, especially compared to where you started!

:super:

Jason

Thanks for positive words.
this is my last video overview
https://www.youtube.com/watch?v=yOFzuxjtHuc&feature=youtube_gdata_player

 

[Maxx134]

Final pic:

Dial has black cover right corner where led shines so you can't tell where light comes from.
Switches left side have translucent protective cover inside that replaced dark grey felt ones.

SOLD..