Cryptnotic

Well, I finished my aux in adaptation on my W203 radio. I killed the tape playing functionality.

Here are the steps involved for those interested:

0. Insert tape into W203 radio while power is available to the radio.
1. Remove W203 radio.
2. Remove screws from top panel.
3. Remove screws from cassette mechanism.
4. Remove cassette mechanism.
5. Cut or desolder ground wires going to the motors on the cassette mechanism (there are two motors).
6. There is a trace to cut on the tape mechanism board and a surface mount resistor to remove in order to get pins 1 and 3 on the ribbon connector to be disconnected from the tape mechanism board.
7. Cut one end off of an RCA cable, preferably the type with twisted pairs of wires inside a somewhat hollow sheath.
8. Figure out a way to run that cable in through the back of the radio.
9. Solder the left channel wire to pin 1 on the tape mech ribbon cable.
10. Solder the right channel to pin 3 on the tape mech ribbon cable.
11. Close everything up and reinstall with the end of the RCA cable sticking out somewhere useful like into the glovebox or ashtray. You could maybe run it under the center console past the shifter to the center storage area or the cup holder spot.

Anyway, that's the mod. Here's how it works. You just switch to tape mode and the tape doesn't spin (because there's no power to the motors) and you don't hear anything from the tape (because the tape mech board is disconnected from the output going to the radio's main board). Instead your input goes through the RCA's into the radio in place of the tape audio. The radio doesn't even notice that the tape is essentially "stuck".

I haven't had any problems yet. If you try this, it is at your own risk. This post should not be taken as any kind of guarantee of the feasibility or practicality of this modification.

All I can say is, "works for me".


(of course, an optical AUX-in adapter would still be better).

jules

You mention one RCA cable and spliting off the right and left chanels from the one cable. This makes me think that you actually have a digital coax. Is this so? If it is not digital, what kind of sound quality do you get as compared to using a cassette adaptor?

Cryptnotic

I used a stereo RCA cable (two RCA connectors on each end). Cut one end off and strip the wires so you get 4 wires: left, left-ground, right, and right-ground.

The quality is better than what you would get through a cassette adaptor since you skip the tape adapter transducer stage as well as the tape pickup and amplification stage. The signal goes straight from the new aux-in cable to the main board of the receiver.

I didn't mention this, but I also cut out the amplifier circuit and wired the outputs to be line-level outputs instead. I looked up the specs on that amplifier (ST TDA7454, if I recall), and it is a "high-efficiency" amplifier, which usually also means "high distortion". Anyway, I now have line-outs going to an external amplifier and the external amplifier driving some decent speakers.

ice777

Cryptnotic,

could you supply some details on how you bypass the amplifier circuit to get line-outs from the HU? thanks in advance!

Cryptnotic

I used a desoldering tool to remove the amplifier chip from the board. I looked up the data sheet for the chip (It is an STMicro TDA series part) and found what the input and output pins were. If I recall, I had to remove some filtering capacitors.

Anyway, after that, I just traced the signals on the board and jumped the preamp signals out to the traces that go to the 8-pin

oktane

Cryptnotic,

Nice work. Do you have any pictures of this available?

Is there any way to retain the tape player functionality without using a switch and without risking damage to the preamp stage of the radio?

Thanks.

ice777

yes, could you please provide a picture or give some details of exactly which pin goes into the amplifier chip? i want to get a cleaner signal for my sub.
thanks :p

Cryptnotic

I should have taken pictures as I went along... oh well... maybe next time I take apart the head unit I'll try to document it.

Here's the ST web site document for the amplifier chip...

http://eu.st.com/stonline/books/pdf/docs/1775.pdf

The part number is TDA7454. That document should give you all you need on the inputs and outputs of the chip.

AMGrider

yea this is my "HOT" custom sound system...
JL 12W6 x2
Xtant 600W x2
performance technique 1200W x1
eclipse AV8022 7" motorized LCD screen
also i dynomated my car to prevent raddling....
and some people wanna know if dynomat worth it.....and i say...dynomat is crazy....its so nice....the car doesnt raddles at all!
but one bad thing is that you can here anything out side of your car....like if u have crazy sound system and u cant show off..you cant here ur system bumping at out side of ur car.~~~but is good^^

Mercedes

English please. Thanks

hercules

Hello Cryptonic

I have today desmantle my audio10 cassette radio and noticed that the IC amp is a TDA8568Q wich is alower specifcation of the one that you mentionned in the forum.
Do you know if the cassette or the CD version use a different IC amp?:rolleyes

AMGrider

yo MERCEDS what u mean by "English please"?
what the F*ck are u trying to say?

Kal Rubinson

I, too, find this text strange and uncommunicative.

AMGrider

u know what
i wasnt here......i came here like 4yrs ago...wht u call F.O.B
okay? when u see somebody who doesnt speak english very well...stop ******* disparage them

awiner

CHILL on all the potty language AMGrider. This is your first and last warning.

Kal Rubinson

Not trying to disparage you, just to understand. The spelling aside, I cannot determine what you mean. Do you want to hear the sound of your car's system outside the car or not?

lockuplever

Could you supply more information on item #6. I have the tape mechanism out.

6. There is a trace to cut on the tape mechanism board and a surface mount resistor to remove in order to get pins 1 and 3 on the ribbon connector to be disconnected from the tape mechanism board.

What trace and which ribbon connector are you reffering to.
BTW, thanks in advance. This is exactly what I have wanted to do for over a year now.

mmgrad

Alright, ya'll just gotta chill. AMGrider, they are just playing with you about the english. All others, I'm sure you know what he/she means with the statement about dynomat.

Simply put, it eliminates rattling from his ICE system. However, if you want to show off your sound system, dynomat will make it hard for others to hear the music outside the car (when the windows are all closed).

But back to tread at hand, Cryptonic, nice job. You must have lots of electrical knowledge to comfortably take apart your stereo like that. Congrats on the mod.

20FHK02

Cryptnotic:

Where should the Ground on the RCA cable be connected to?

lovin_my_C230K

Cryptnotic. Thanks a million for the information. I couldn't have done it without you.

Make sure to checkout the web page with the pics...

Here's the info.

Thread with the info.

-Eric

C230 Sport Coup

The question was asked,
can the tape functionality be left intact?

The pics are great!
I'll have to consider doing this.

First need to go back find those instructions for R&R of radio.

BUT despite the wunerful pics, it's still not clear to me where the trace is to be cut. Hard to tell. And thats the part where, you better hope you don't screw up.
(and what does cutting the trace accomplish?)

Also where did you put your 1/8 " jack?
Do you just have a wire hanging somewhere or did you make it nice, put a female plug somewhere?

Also there was mention by Crypto of replacing caps and such.
Did you do that?

I'd really like to have tape too!

What keeps it from making that annoying beep?

Ya know, if it wasn't for that annoying beep it could be possible to use a audio to phoney tape convertor.

Anybody have a shematic for this radio?

C230 Sport Coup

Oh wait, last pic is clearer, show cut traces, but my other questions remain.....

lovin_my_C230K

Cutting the traces stop any signal from the small Sony Integrated Circuit's line out channels from reaching the radio. When the traces are cut another intput can be sent through the same trace.

"1/8th inch jack"

I bought the pretty Monter iPod cable for $35 from Best Buy. When I got home I could not pull myself to cutting it. If the job didn't work I would be out a stereo and a $35 cable. eech. Luckily I found a good sony RCA to 1/8 male adapter that was long enough. I figured it was worth sacrificing. A key point... Another reason I didn't use the monster cable is that it was so large. The soldering points were so small. The Sony cable worked great.

About Crypto's caps..

He recommended removing a cap just south of pin 1. I went ahead and cut the trace right before it. I had a good high quality soldering iron but I didn't have any surface mount desolderers and I thought I could fill my cut trace and get the system working again if need be.

Annoying Beep....

I keep the tape door shut.

Scematic...

I don't have one for the radio. I did find one for the Sony IC that controlled the tape system. I checked Crypto's pins and he was right.



-Good Luck

Steve C

I'm interested in the mod to the tape player. You mentioned pin 1 and 3 on the tqpe cable. I understand that you must join the RCA wires for each channel to those piins but what do I do with the ground part of the RCA wire? Also when you mention the pins on the tape ribbon are they numbered or are they as viewed from the top with radio face pointing towards me? Should I count left to right up to down?

Regards,
Steve.

chuni959

so is your tape stuck in your deck now? What was the point of putting a tape in the deck before doing the solder work?