The title says it all, today i scored a dirty Hitachi for 5 EURs. I wanted this machine for quite some time, because i thought it tobe a good loud box to use at a skate park or for bbqing...

Actually i'm a bit disappointed. I mean,you can't be wrong for that little money but it does not have the bass i expected.

In fact my home stereo speakers are similar in size (Jamo Cornet) ...


So i opened the radio and guess what the quad-amp system is: two cheap NEC µPC1278H chips, each delivering 2,5 Watts to the speakers. That is pretty much ok for the outer midrange speakers (10W max.), but a radio of that size with woofers rated at 20 Watts max. should put a bit more power to the woofers. They don't even move at all, i've seen a 3D70 its amp was torturing the woofer like a car audio sub.

The tuner works nice with the missing antenna it gets all local stations clean. Reception is good on all bands. Tapedeck is a simple construction with only one motor for both decks. Didn't test it yet. Simple erase magnet, no autoreverse or counter. They saved money where they could; the outer speakers are mounted with only two screws. The LED meter is mono only (just one chip although there are LEDs on both sides). At least there is a line-in and an equalizer.

Some components wear a production time stamp which says Nov.1990. I wonder what it cost new, back in 1991.

If you want i can take photos of the guts...

hi there, i believe i have the same one (twin deck with two woofers and 2 buttons to switch surround and 3d on and off) if so my one does pump like hell its really loud but the highs get blurred if you have the bass over half at high volume, if you look downward on mine the woofers they move back and forth a lot even the outside ones pump pretty hard.

Interesting. If you get a chance, tell me the model nr of your Hitachi. Must be a stronger one. These tiny amp chips don't make woofers "woof".

Mine has become a bit better since i fired it up first. It came out of my trunk and we have -5°C outside. That was obviously too cold for the box to perform well. Now it is loud with some bass. Radio music sounds ok, Drum and Bass isn't what the 3D88 is made for. The amps distort a bit too early, then you can see the power LED dim with each bassdrum. Speakers move visible, but far from what they should be capable of.

ah ha! i have a few answers for you, i will get to the model number of mine in a sec but first you have a few symptom that mine did, mine was a £1 from ebay a wrong tittle thing with a lot of work needed but it was local so i went for it and picked it up, anyway dust gets in the woofers badly and because they are so thin it seems to restrain them some what so get those out and give them a very good but carefull clean that will help, also the lights dimming happens on mine so i tried batteries and no dimming i think either my transformer is week or they wernt that good when new but anyhow it pumps harder on batteries,i know you might not have got this far yet but if you find the tape decks are stiff to operate then you may need to dissasemble the deck as on mine the little plastec guides that allow the selectors to slide had snapped of on both decks i found one but had to make the other also i put new belts on mine and that cured the speed from being too slow (belt slipping) also alighnment etc....
anyway my model is TRK-3d80e twin drive.

hope this helps.
ps if you nead more detailed help with anything 3d isolater seems to be the resident expert on these devices.

quote:

isolater seems to be the resident expert on these devices.

Yeah, i've already noticed that doing a search for Hitachi 3D models.

Now yours is a different model (earlier?), i've cleaned mine up internally. Wasn't too easy to get the top levers back to their switch positions. There was indeed a lot of dust on the woofers. I thought they could blow that off if they moved enough

The dimming light is caused by a weak transformer. It is rated with only 27 watts input - i've seen smaller boomboxes with more rated input. Also the power supply section's capacitors are small: only 2200µF. That is the bare minimum to avoid humming noise.

I'll connect my 3D88 to my car's battery later. Let's see what it can do. If it is still insufficient, i'll probably use some old PC speaker's amp board to crank the woofers and old Laptop batteries for power. The compartment is large enough for that.

Remember, i don't want to use this one in my flat, it's just for summer outdoor fun and y'all know skateparks are loud and dirty...

sounds cool, although i havent blown a woofer on the 3d80 i did burn one out on the little 3d just by cranking it too loud and ended up transplanting a voice coil off an old car speaker to get the woofer running again sounds same as before now, but i dont think them woofers are very strong

quote:

I wonder what it cost new, back in 1991.

BBDB info:



1990
1991
1992


BxHxT = 65x21x22 cm

TRK-3D88w,e Double Cassette Radio FM stereo, MW and 2 SW bands (2.3 - 22 MHz). 14 watt output or 200 watt PMPO through 3D Super Woofer Twin Drive System with 6 speakers. 5-band equalizer. Surround sound. Built-in microphone. Double cassette with auto-reverse (deck 1), high speed dubbing and continuous play. WxHxD: 65 x 20 x 24 cm. Net weight: 6.6 kg. Operates on 110-127-200-220-230-250 volt, 50/60 hz or 8 batteries $172,81


*TPR* edit:---picture changed.

what is the difference between the 3d80-88 cos i have the 80 and it looks just like the picture.

my 3D88 looks like this:

no piezo or fake tweeters, just loads of black plastic.

yeah that is slightly different to mine, the 80 has a tape counter and 2 piezo tweeters it is advertised as having 6 speakers, perhapse that explains it may have a more powerfull amp to drive the tweeters.
ps that seems to be in good condition about the same as mine i dont think i have seen any better good score, i do have a smaller 3d in mint condition but that was a story of luck

quote:

my 3D88 looks like this:

true,I took the wrong picture above.


welcome to the board echoes...

Thanks for the welcome, i'm here for quite some time...

The condition of my 3D88 isn't as good as it looks in the picture. The grills are all dented. There are deep scratches in the tuner window. Cassette decks work, but the doors don't open by the push of a button. Antenna is missing. I've seen Hitachi 3Ds in good shape several times before, but the sellers would not give them to me for the money i wanted to spend. A few weeks ago there was a mint 3D7, seller asked 60 euros. There was also a smaller one for 15 EUR, average condition.



I'm curious about the 3D80's amp chips. Does it need 8 batteries, like mine?

Hi Echoes & welcome to s2g.
Personally, I think you've made a wise choice for your first boombox, but I'm just ever-so-slightly biased

Let's see...
The 3D80 has 3 amps. Two 3W chips for left & right & a 2x4W chip BTL single channel setup for the two centre woofers.
You're right, the woofers in these don't move as much as those in the earlier single 6½" woofer models (like the 3D70 you mentioned & also the 3D8 & 3D7), but if they're both driven together from a similarly powered BTL setup, then I presume they'll move about half as much to shift the same amount of air?
I did a direct comparison between the 3D8 & 3D88 here, & found the 3D88 to have slightly more bass than the 3D8. If I remember right the 3D88 woofers moved a fair bit.

In other 3Ds I've had which were very dirty, the woofer made horrible cracking noises because dirst was trapped inside the woofer, between the coil & the magnet. Careful blowing out with a can of compressed air sorted out the problem.
Also regular thrashing makes any woofer move a little more freely, so years of inactivity will be a factor with yours.

More power on batteries than on AC power & dimming lights sound very much like the AC transformer is on the way out.
I do have one or two 3Ds & the AC power going wrong isn't as uncommon as it is on others. Thankfully, most (including your 3D88) work with 12V external DC input. My advice would be to get a beefy 12V dc power supply like this one & use that.

If none of this works, I suspect something is not quite right with your 3D88.

However, don't expect gut-wrenching bass. They just put the speakers in the plastic cabinet - no acoustic loading, so bass output is limited. If bass is your thing, check out the JVC Kabooms.

The 3D80 & the 3D88 were almost identical (radio, amps, speakers), but the 3D88 had a slight styling tweak & more toys on the tape deck - auto reverse on one & full auto-stop.
Neither of these had any real tweeters, the piezo-looking things on the 3D80 are fake.

Here's the data sheet on the 3D80, which may be of help considering how similar it is to the 3D88:

Cool, thanks isolator. Actually my 3D88 does not have an autoreverse tapedeck. It is a 3D88E, to be exact. And it has 2 identical dual amp chips, all the outputs are capacitor coupled (330µF for the mids and 1000µF for woofers), so no BTL. Wonder if they lied in their specsheet or changed their radios durig production.



I know the Kabooms, just don't like their look. To use them outdoors you need a 15VDC supply. 12V car battery is not enough voltage, resulting in less output power. And 10 D-cells are expensive and you need new ones every 2 hours

And it is a bit too large to carry around.

Fair enough about your 3D88.
I have no idea about any possible changes to the spec on yours...


btw, the manuals say Kabooms work on 12V DC input, not 15V...

with regards to the kaboom voltage it is indeed 12vdc for the car jack and 15vdc for batteries x10 but the reason for this is that batteries unlike car 12v loose volts as they loose charge and so they compensate by having a higher power to start with so there is no difference in output between batt and car.

the mains however is a different matter i have been studying the schematic for a "safe" way to enpower the backlight on batteries as they are only leds i cant understand why they are not powered by the batt.

anyway its rather complex the ac transformer together with the sensing switch on the socket supply a rectified 12v to a "ac/dc" track on the board and also the B+ track (so the amp gets the same power supply regardless of source) but the "ac/dc" track anables some transistors to switch on the backlight and standby light and also the clock rest screen,
there is also a feed to the micon so i wonder if the amps run with lower power when operating on batteries to conserve life or if its just a feed which turns off the low battery warning circuits (these would seem to be active on car jack also) now im sure you know where this is going!

by giving this "ac/dc" feed of 12vdc (same as the rectifier does when running on ac) it would be possible for the unit to run on batteries but with the backlite enabled and also some other less disirables like the standby light and clock but the most inportant thing is that if there is a limp mode on batteries it would dissable it at the expense of shortened bat life.

now im not sure if the batteries could even run it on full power or if it would cause damage when the batteries run flat with no "low shutoff" so if anyone else would be interested in hunting the schematics to see as i know other members have kabooms so it might be to their advantage also.

another thing i noticed is a diode would be needed to stop the batteries or dc from backfeeding the transformer when running in modified battery mode.

any ideas would be appreciated

Excellent price!

I always thought these 3D88's looked like weapons of some sort... Hand held photon torpedo launchers or something...

Ok ok... I know its after Christmas, I'll lay off the Egg Nog now!