JVC 838 resto-mod long overdue!

[blu_fuz]

I have had this 838 for YEARS and never used it or cleaned it. I was thinking of selling it so I needed to replace the power switch and get the switches cleaned. The contacts in the stereo/biphonic switch and function switch were so bad it was making the box useless and sound like a blown speaker. The cassette wasn't working either.

Well, the cassette motor is dead. Voltage at the motor is 12.5v when you hit play/ff/rw but the motor doesnt do anything. After about 4 seconds you can here something faintly click and the voltage at the motor drops to 10.5v.

I left it alone.

I couldn't help but to make and install my own LED mod to the VUs and get the rest of the box working and cleaned up. A friend of mine had a pile of RGB 12v LED strip pieces that he gave me. I picked to light up the green because thats the accent color on the 838 anyway. Painted the grills and cleaned the roaches out of the case too. Enjoy!

 

[BoomboxLover48]

I also have one in mint condition that I rarely use and love the looks of it. After lots of repeated switches cleaning everything works. At one point I remember giving up.

Those stereo/bi phonic and function switches are so hard to clean. As I remember they are connected from the front switch by hard plastic levers.

I would try cleaning those tiny leaf contact switches on the deck gently with a 2000 grit automotive emery paper. One small stroke with gentle pressure should be enough. I've seen the same problem with some of my decks. The motor terminals show voltage and they won't turn for some reason. May be those commutator or brushes are dirty? No idea! In many cases it is not easy to open those sealed motors. I left them alone.

 

[Superduper]

Looking good. But you might want to cut the current a bit to the led's to take out the harshness. Might be a bit bright.

As for the motor, maybe it can be saved. Some RC forums suggest cleaning their motors by hooking up to 9V battery and dangling it in a cup of water while running. The water gets muddy/black from the gunk that gets cleaned out, and then it runs like new again after drying out. I suspect that if the motor was lubed and then spun by hand, it might work again. If it does, the dunk/clean method might get it back in shape (after drying and final lubing, of course).

 

[blu_fuz]

Good suggestions. I did try the 'sandpaper swipe' on the feeler contacts, no dice. Maybe i can try some of those other tricks to get the motor spinning.


You will see in my updated pics next that I did try 3 different ohm resistors and ended up sticking with the 100k ohm to dim down the brightness a bit. The LED strips are already in clusters of 3 so i decided to center them even though the two LEDs on the outside edges of each VU are only 1/2 way under the vu box corner. Looks nicer than I was expecting.


Right now I am pretty suprised how good the 838 sounds when all the switches are clean and working. The woofs still distort sooner than I would like. It performs better as a rock box.

 

[BoomboxLover48]

It will be even nicer with LEDs on those radio dials. The dials and VUs should have the same brightness.
[SIZE=11pt]There must be a way to reduce the glare right above the LEDs. May be something opaque, semitransparent, something to diffract, or scatter the light intensity above the LED and reduce the glare. [/SIZE]

 

[blu_fuz]

I want a white LED for the dial. I thought I had a spare M70 LED kit I was going to mod to fit the 838, but I can't find it. I'm content with how it is.

 

[BoomboxLover48]

To an older guy like me it looks like 3 fingers sticking up from each VU meter! Pardon me Joe!

Only A E Stereo did a good LED mod for boomboxes. I've never seen any good ones after that. Just my opinion!

 

[blu_fuz]

I feel the same way about not having such a spot lit point. My life is about doing a quality job, and quickly. There will always be something to fix, do, change, etc... If I had 3 days to leave this box tore apart and try a bunch of samples frosting plexi glass to diffuse the light I would. I'm good with how it stands, now onto the next one!

 

[BoomboxLover48]

I feel the same way about not having such a spot lit point. My life is about doing a quality job, and quickly. There will always be something to fix, do, change, etc... If I had 3 days to leave this box tore apart and try a bunch of samples frosting plexi glass to diffuse the light I would. I'm good with how it stands, now onto the next one!

Agreed!

 

[caution]

Looks really nice, I like that color!

 

[trippy1313]

Very nice job. I love the black/green. Makes me think of the "Green Hornet."

Very cool. How big are those speakers? Would M70 speakers fit and help it out?

 

[blu_fuz]

I have seen someone put M70 speakers in a 838, I bet it sounds better with them.

 

[floyd]

nice work joe! ,

i'm almost positive the 838 has 5 1/4 woofers and the m70 has 6 1/2 woofers , i been wanting to do a speaker swap in mine because i think the speakers are just too stiff and not very warm sounding . might see if a new set of high roll foams might help it sound better but these woofers are just too limited in the xmax that's why they distort because they have almost no cone travel and the power just compresses into distortion.

 

[BoomboxLover48]

nice work joe! ,

i'm almost positive the 838 has 5 1/4 woofers and the m70 has 6 1/2 woofers , i been wanting to do a speaker swap in mine because i think the speakers are just too stiff and not very warm sounding . might see if a new set of high roll foams might help it sound better but these woofers are just too limited in the xmax that's why they distort because they have almost no cone travel and the power just compresses into distortion.

Floyd said it! Those speakers are very stiff! This unit badly needs a speaker upgrade!
I hate those grills also.

 

[blu_fuz]

Rocked out some more this morning. It really needs better woofers. If i put the bass down to 1/2 way then you can really crank it.


I'm happy, but will consider a woofer upgrade that fits. Not much room in here and the magnet is less than 1/4" away from the chassis by the transformer.


Here are some HDR pics from my phone:

 

[BoomboxLover48]

Nice pics! Good job!

 

[Lasonic TRC-920]

Looking good. But you might want to cut the current a bit to the led's to take out the harshness. Might be a bit bright.

As for the motor, maybe it can be saved. Some RC forums suggest cleaning their motors by hooking up to 9V battery and dangling it in a cup of water while running. The water gets muddy/black from the gunk that gets cleaned out, and then it runs like new again after drying out. I suspect that if the motor was lubed and then spun by hand, it might work again. If it does, the dunk/clean method might get it back in shape (after drying and final lubing, of course).

That is interesting, never heard that before

Norm, you always got something awesome to add to the conversation!

 

[Lasonic TRC-920]

Nice upgrade Joe, if you find a suitable speaker for this, please post, I have an 838 that could use a speaker upgrade as well

 

[floyd]

basically the amp puts out 5 gallons of water but the speakers only hold 2 gallons , so three gallons are wasted . i know thats a stupid comparison but it holds water lol.

 

[Beosystem10]

That is interesting, never heard that before

Please, Chris, don't do that! There a very good reason you'd never heard of it; it's utter bollocks! Yes, it appears to work in a youtube clip but that's a brushless motor and it's completely sealed.