Hey Guys.

I just registered for this forum, i am Patrick from Austria / Tyrol and i am a big fan of 80's Ghettoblasters.

I got myself a good condition Crown SZ-5100 which i want to modify to my needs.

I experience a lack of bass and highs, i read this is common for this type of model, so i want to change the AMP IC's to better rated ones, change all the capacitors and resistors, put some higher grade 20cm Speakers in it and reflow all the solder on the PCBs.

Also i want to put in a Lithium Polymer 4S Battery (14,8V   5000mAh) to have it portable and rechargeable.

When i am finished with the above mods i will hardwire a bluetooth receiver to the PCB so that no ugly cable has to be connected to the EXT. MIC. Input.

Does anyone have a Service Manual or info on the AMP IC's used and can recommend me better IC's to use with it ?

Maybe also someone knows better capacitors for better Frequency response on the Filter part of the PCB ?

Thanks again for helping me out.

hi RyuX and welcome to the forum. you've got a hell of a project, so good luck with it. btw i appreciate the fisheye-like effect of your pic: when you're finished, your modded Crown will definitely be a different unit to say the least 

I just made a list of all Capacitors i will change (all except the ceramic ones, the marking on them is not clear).

I could not find a replacement for the AMP IC (which is BA-5408) there a two stereo IC's in the unit, i wonder why ? (one BA-5408 should bring 2x 5W power output)

I might replace them with the BA-5406 which has the same pinout and operating voltage but with less THD (BA-5408 has 0.3 % - BA-5406 has 0.1% THD)

I also found some nice 20 cm replacement Bass Speakers, i dont know how they will sound on the weak amplifier of the Crown, also i am not sure what kind of filtering was applied before/after the amplifier.

If i am not excited with the outcome of the mod i will just put a new amplifier (12Volts) in the Unit and use the Headphone out as Inputs for the new amplifier (i should be able to fit pretty good one inside the case).

I will also reinforce the case on the inside with fiber glass because i see that the back already has cracks in it (pretty poor plastic quality - and the age..)

Finding better tweeters will not be much of a problem, because the ones used are the least quality i've ever seen (the tweeters on a old Gameboy DMG are 10 times better).

i can already see that alot of money will flow into this unit, and that i will never be able to sell it again, but thats not a bad thing, i might keep it as my personal 80's reminder and one hell of a project over the winter months.

i payed 160 euro (incl. shipping) for the Crown SZ 5100. At least the tape decks and radio receiver etc. are in good working condition.

The bad thing is that the Crown has such a poor build quality that the backside broke because of shipping. But i will also try to imitate the broken out pieces with fiber glass and have them painted.

So far so good, if anyone has a little more information for me, please feel free to reply.

I will post photos along the way

Greets from Austria

Patrick

Hi! and welcome Patrick, The SZ5100 is an amazing looking box, I had one myself but like you I was a bit underwhelmed by it's performance and what was inside! I could be wrong but I don't think anyome here has tried to modify the standard amp so you're exploring new ground here! Its like a muscle car with a small crap engine, do you spend time and money trying to tune the original one? or do you swap it for a bigger better one? Unless you are looking for an experiment/electronics project I think you'd be guaranteed better results with a new amp, woofers and tweeters! Its a huge half empty box, imagine what you could fit in there

hey smeats1976

Well yeah, i will do both i guess. I will replace the BA 5408 AMP IC's with newer BA 5406 but they will also serve as a kind of preamp because i will put a 2x 150 Watt (30 RMS) Amplifier in it to run my new Bass and Tweeter Speakers.

Also i ordered a Crossover Network to have tweeter and bass signal seperated, which will also help sound quality.

I will start molding the inside of the Case with Fiber Glass and acrylc glue to reinforce it.

I also started to reflow all the solder joints on the PCB today.

All in all this will be a project that will cost alot more than i aimed for, but i guess in the end i will have a unique nice box that i can keep a while and have alot of fun with

The only part that still gives me headaches is if the Lithium Polymer Battery (14,8V and 5000 mAh) will be strong enough to drive the whole thing, and if it can drive the whole thing, for how long. You got to know LiPo Stuff is ratter expensive (you need a Balancer/Charger and good Quality battery).

Also i am glad that all of the potentiometers and EQ pots still work, because it will be almost impossible to get a fitting replacement for those (if someone knows replacement numbers please write them down).

Greets Patrick

PS: These are the Bass Speakers i will use, should be a direct replacement according to diameter. I think they will also look very cool because of the slick black ghetto look.

can't wait to see this finnished! You'll need to add some weight and line with sound deadening "dynamat" type material to the cabinet ( and try and make seperate enclosures for speakers) or I think it will just vibrate, rattle and fart your tunes out!  Then you may have the first one of these crowns that's performance matches its look! Its expensive and ambitious plan but it'll be worth it, good on you for giving it a go

hehe yeah you are right, but i hope that the fiber glass and acrylic reinforcement will do well enough for making that piece of plastic sound right

Couldnt sleep this night so i made a little picture as a theme to my project

Today i started sculpting the broken parts of the rear part of the crown.

i took a quick reminder photo to remember where the cables were attached to.

front part waiting for speaker installation and glas fiber reinforcement.

almost the whole side part of the rear broke into pieces on both sides

started with the first layer of special compound. will have to wait till tomorrow and then sand it down, and apply second layer.

speakers should be here by friday

will post as soon as there is news

Greets

Patrick

Good luck to the project.

Do not forget to reinforce the speaker screw posts, to take up the heavy load of new speakers!

Great project and so far so good !

I d like to see a video of how it will sound in the end.

Hey.. of course, thats the main part that needs reinforcement ! I will mold the whole inside with glass fibre and special compound, hope that does the trick

@deech

thanks, will post a video as soon as finished

Today i installed the new Speakers and Tweeters and thought i would check out the Performance of the standard BA 5408 AMP IC's on a quick test.

The Power Supply puts out a voltage of 15.9 Volts at about 2.5-3.0 Amps.

I was able to drive one speaker for a quick test run, the Voltage instanstly dropped to about 14.8 Volts with just one speaker connected on Mid Volume.

The Frequency response of the AMP IC's also is pretty bad, so i will install a new Amplifier for sure now.

The Original AMP got around 2x 3 Watts at a THD of 0,3 %

The New AMP i will install has around 2x 26 Watts at a lowest THD of 0,02 %.

http://www.st.com/web/en/resou...sheet/CD00293186.pdf

I will have to make the crossover network and speakers work at 4 Ohm so i will have the highest power output, which should be pretty nice (around 10 times the power the old amp has).

After reflowing all of the solder points on the PCB's i got rid of the Popping Noise that occured whenever switching the unit on/off. Also the humming sound that was there at the beginning vanished now

Here are some pics of the current status, i used some Acrylic Anti Vibration Compound around the Speakers and will continue soon with the Fiber Glass Layers the next days.

Greets, Patrick

Just finished the VU Meter modification with some bright new CYAN Coloured LEDs (i love cyan, reminds me of the flash 80's)

http://www.youtube.com/watch?v...amp;feature=youtu.be

Watch in 1080p for better Quality..

the Crown after a normal mod:

and after RyuX's 

Can't wait to see this in action!

hahah guys

Well i hope it will be as cool as i imagine it in the end, but i think i can do it and make it an interesting unit in the end

Greets

good work a very interesting post ,  good on you for turning a turkey into a box with some quality sound  

Finished 2 Layers of Glass Fibre reinforcement today.

After that i will finish the Rear Cover of the Boombox with special acrylic compound and sand it down, prime and paint it so that it will look like it never broke

I'm assuming you're laying the glass fibre sheet over the inside then pushing into all the nooks and crannies...when it sets that'll be super strong! Does this box not have air vents that'll be cover up now tho? What's this compound you mention?

Hey!

This Box has air vents on the back and on the side. I covered those on the back and will also fill them up with compound on the outside so it looks clean. The Acrylic compound is something they use to repair bumpers in the car industry. It has a hardener component and after it hardened it will have the same strenght and flexibility like plastic.

The Air ventilation on the side will be enough, because the speakers themselves will also push alot more air and it will flow in and out of the sides nicely  

Finished the Glass Fibre reinforcement today. its really massive now, also did some work on the broken sides, already looking pretty good, only needs a little more detailed work in the next days. Sorry for the bad picture quality, only had my mobile phone cam around

Hey !

Well yeah its a pretty effective way to reinforce a box.

Today i got myself some high grade anti vibration mat. It is the same they use on the inside of higher/midclass cars like BMW and Mercedes.

You can cut them with a scissor and stick them on the inside of the box. I started to do so, and will finish the inside tomorrow.

Also the electrical parts were in the mail today (capacitors, etc.) Alot of work in the next days/weeks

this is the size of one anti vibration mat from Teroson

this is the front with the new speakers...

started to stick the mat on the inside.

Also the crossover networks and cables etc. are here now, so i have all parts ready.

The voltage converter for the Bluetooth Adapter and the new Amplifier will be the last thing i will install when everything else works.

Greets

Patrick

Ok i tried fitting the crossover networks, amp, and battery in today. The room inside the Box starts to run short

I am glad that i did the glass fibre reinforcement, the old plastic would not have been able to carry all that stuff.

Greets

IT LIVES!!!

excellent work this box is going to sound amazing   

Today i started replacing the capacitors. I am already half way through, but will continue tomorrow to finish the capacitor part, now i need some rest

Coffee ready.. capacitors ready.. set... go !!

enough for today

Great project; I've really enyoyed watching this unfold!  

Ryux maybe you need to reinforce the handle too.

just a thought of mine .

Hey!

Reinforcing the handle wont really help, if it will break i will have to work out something completely new, so i will just leave it as it is and see what happens

Today i finished replacing all of the capacitors.

Later on i will start the wiring of the internals and give it a first test spin to see if the replacement of the capacitors worked out well (there is always a risk that with newer grade capacitors the unit will act strange in some ways)

Over and out

I replaced about 50-60 capacitors and put the old ones in a bag (in case i need some of them later)

this Crown project of yours reminds me of the infamous soup of stones. here's the recipe: take a pot, fill it with water, put in a stone. add three or four pebbles. separately, dice celery, carrots, zucchinis, two small onions, a potato. slice cabbage and broccoli. cut in two some pitted olives and two to four capers. add all diced vegetables, olives, capers and, to taste, a pinch of pepper. remove stone and pebbles. simmer for half an hour and serve hot.

Sometimes Sal I haven't got the faintest clue what you're on about lol

more often than not, neither am i Si 

here however the idea is that the "soup of stones", if you read carefully, has nothing to do with stones, as you simply put them in the pot, then remove them before you turn on the store. you think it should be very poor (just water, stones and pebbles), in fact is very rich; and so on. in other words, "stones" are so to speak the... (LOL) red herring of the situation 

now for some reason all this reminds me of RyuX modded Crown: what will be left of the original box, when he completes his project? 

OK I get ya...I think

I'm looking forward to seeing how this turns out...the crown does need beefing up as it looks the biz but doesn't cut it sound wise...so this, I reckon, could turn out well...still don't think putting carrots and cabbage in it will help tho...(kidding! )

a nice green crown box 

Lol...i think this Crown might actually be as packed and as heavy ...hopefully it'll sound better tho

Hey!

It seems samovar doesnt like that project much

I can understand that, if you are a purist, but you got to know that the Crowns are no good when it comes to sound.

So i had to take the cool looks and put something into it i can work with.

It would have also been my wish to keep almost everything thats good from the box, and i did, so the only thing left is the Box itself.

The Speakers, and the Amp are a real mess, dont get me wrong, if i had a JVC RC-M70 or M90, the modifications would only have been to fix some broken capacitors and clean the case...

But on this crown it needs far more modifications to make it a good Box.

But i keep the Filter/EQ of the original crown, also the radio and cassette unit will be original, so its just the AMP and Speakers that is not original, all the other stuff just gets tuned a little.

Also the reinforcement is needed, the Crown breaks when you look at it

So hopefully when finishing it i will not have too many enemies at the purist's party.

I just need a reliable good sounding ghettoblaster, thats all

Nothing wrong with making improvemnts mate!  I think you have done a sympathetic and good job on this; more to the point it has made me think about this hobby in a different way; a good looking boombox dosn't need to be ousted to the back row through poor performance, it can be modded. This has been an inspiration to me! Keep up the good work, hope it turns out ok!

Small Update: 

Reinstalled the Stock electronics and did a quick test run if the capacitor replacements went ok - seems everything is fine so far.

Maybe can hook up the Speakers and the new Amp in the next days so i can do a first soundcheck on Sunday

The sticker is way too big, i will remove it when i am finished i think, i was looking for a little sticker to put somewhere on the box, seems i ordered the size wrong

on the contrary. i was just poking a little fun on your slightly maximalist project. but not only i find it great: i wish i had 1/1000th of your abilities to get some of my units back to work -- to mod some myself, even

i am not, of course

wrong again! i know that your model looks great but has a very unsatisfactory sound output. but ask radio raheem what does he think of such outstanding units as the CSC 850, 980 and, above all, the 970

True Samovar; all Crown's are poorly built but some of them make some great sounds. I always wondered if this was more by luck than judgement though!

This is a great project though. It will show what can be done, and how. 

I have some boxes that in spite of looking great and even being very rare are past their best and need new parts that just will not be found in the future. If by bypassing old stuff that does not work properly and introducing discreet new items like amplifiers or even wireless or bluetooth devices; they can live again and gain a new relevance in today's world while looking much as they used to and keeping the nostalgia alive.

I can't wait to have a go at one or two of my own boxes. No time at the moment but soon.....

agree 100%. this is indeed a great project and the updates showing its progress are among the most interesting reads these days

Ryux just a thought again and sorry for my mix up but i d suggest

this dust caps for your speakers !!

Those would look way nicer imo in your machine !!

Check them out here

http://www.ebay.de/itm/Staubsc...;hash=item19b42cb25e

Hey guys, thanks for the replys.

Sorry i got you all wrong samovar, i thought you dont like that i "destroy" this old 80's Gem.. also i know that not all crowns have poor sound, this was only meant for the Model SZ-5100 (at least that was what i was speaking of)

@deech: i think the dust caps would have been a cool touch, but i also like the new all black speaker front of my crown now..

I hope that the standard power supply can handle all of my mods, also i hope that the Lithium Polymer Battery will last at least 2-3 hrs of playing time (i cannot say if it will be 30 minutes or 10 hours play time right now, no idea how much power it will actually eat).

But even if the power supply etc. doesnt work, i have enough time to fix it, also found some nice regulated power supply which i could use.

So tomorrow after work, i will hook up the new Amplifier for the first time!

I hope my passive cooling system will work out OK, you saw the amp facing towards the speakers in an open case. This is because i want to have the Air that is moved by the speakers to run through the Amps Case to cool down the IC without having to install a fan.

So i will just use the Air that is moved by the speakers (which are moved by the amp) to cool the Amp itself. Pretty easy but yet effective way of passive cooling.

Greets

Thank you sir.....the 970 is indeed a  cracker  of a box

I did some more rear panel wiring today, i have to work an extra shift tomorrow at my job, so i wont be able to hook up the amp till mid of next week

Here are some current status pics

That frame is just going to blow apart lol

Atually i should have quoted you sal lol apologies my friend.....the 970 is indeed in a different leque to this plastic crown lol