Stereo/DVD: SC-xxx AUX INPUT HACK

[JH4music]

Same thing here, bobbych's pictures are gone. Where do you get 2 volts from on the circuit board?

I'm assuming the symptom of this being incorrectly connected is the "Tape 1/Tape 2" Mode constantly switching back and forth.

[JH4music]

I found a spot on the circuit board that measured 2 volts, but when I connected it to RUN_DET the radio refused to power up (SC-811). I ended up just rigging the cassette mechanism into the play position, and then breaking the plastic stem off the eject button so that it can't accidentally be taken out of this mode. I am not getting any interference from the cassette motor, I ran my headphone cord out the bottom of the radio so it's not likely to pick anything up. Sound quality is pretty good for a car stereo, it's definitely a huge improvement over the cassette adaptor and I think it sounds better than any aftermarket car CD player I have ever owned.

[MrC70]

It's good you found a solution. I want to put an aux-in on my SC-901. Seems nobody has managed to do the cassette hack for these or am I just not looking hard enough?

[JH4music]

It seems like it's been done before:

http://forums.swedespeed.com/showthr...x-Hack-Problem

Sounds like he had it working for a few days before having problems, not sure if the problems were a result of the hack or a problem with the tape module itself.

If you know where to solder on the wires, I think you will be fine, if you can't figure out RUN_DET trick, the method I used will work as well. Basically what I did:
1. Look at the back of the cassette loader, you will see a small black switch that is activated by a spring loaded metal arm. With no cassette loaded, the switch will be depressed.
2. Remove the spring from the arm, and tape the arm down so that it is not pushing on the switch.
3. Power up the radio with the top cover off, and use your finger or a pencil to press the switch. The tape mechanism will "load" even though there is not a tape inserted. Your aux input should work fine as long as you don't push the eject button. Since I know my kid will eventually push the eject button, I disabled it by cutting the plastic pin off the back of it.

This way you don't need to have a tape loaded in the tray, so it makes less noise. The only thing you hear is the capstan roller spinning, which I can't hear unless the music is turned off and the car is not running.

[MrC70]

Thanks for that info. I'll try to find out what he did.
I'm not sure whether to go the cassette hack route or just add an aux socket to the cd changer input din socket. Apparently then I can play a 'silent' cd to convince the head unit that the changer is present and inject my aux input over the top. Seems simpler if it works.

[JH4music]

If you have a working CD changer, you're right... a CD with one track of flatline audio playing would probably do the same as the tape hack. A blank, unformatted CD might also work, not sure if the changer will ignore it and/or spit it out or if it will be enough to work.

[pakabassplaya]

Originally Posted by bobbych

ok, bringing up this old thread, as I was hacking another SC801 for ANDYSR. anyway, it was bugging me on these units, why i could not remove the tape deck. I needed to fool the unit into thinking that a tape was installed, so it allows you to select TAPE on the front.

Well, in the past, i had drew a blank, and on these units you needed to insert a blank cassette.
But, today, i did some more invest, and at last found a solution. Basically, there is a line which uses a voltage to tell the unit that a tape is inserted. This uses a 2V supply which is active when the motor is running. So, i dug around the circuit board, and found a donor 2v supply.

So, you can now hack this 801, using the same method as described earlier for the Sc802. it involves soledering to the bottom circuit board for the sound lines, plus one extra line.

look at the pic, and you will see the second top connection on the bank is labelled RUN DET. this is the RUN DETECTION line. when no tape is inserted there is Zero volts. When a tape goes in, a live 2v feed is here. So, follow my RED LINE on the pic, and you will see the circled pin. This is another live 2V feed. Simply solder a direct connection between the two. This now allows you to remove the full tape deck, and glue shut the tape door!! you can now select TAPE on the front and you get no noise from the tape motor etc.

Happy Days

Hi to everyone who is struggling to find more info about the above method.

I'm working on the aux hack in the SC-801 and I figured out how to feed RUN DET.

Actually the RUN DET is fed by a variable DC signal. The average of this voltage is about 2.6VDC. I found a place which meets similar conditions and can feed the RUN DET.

To avoid further problems with disappearing pics: when facing front of the unit, find the DISP BUSY, DISP SCK and DISP DATA pins. The DISP DATA is connected to a slightly bigger solder joint right on the left. Then look exactly 2.5cm above it. You should be looking at a beige-gray SMD part. There are no other components very near to it. Solder the lead to the side you are facing (whey you look at the front of the unit).

Cheers,
Bart

[JH4music]

Thanks for the pics. Unfortunately I still can't get the RUN_DET thing to work with my SC-811. My circuit board is slightly different than your SC-801 picture. I did find a few places in that general area that read 2.0 to 2.5volts, but connecting them to RUN_DET either stops the radio from powering up or does nothing.

My cassette unit broke now, so I'm back to having the unit keep switching between TAPE1 and TAPE2... Really need to figure out a fix for this.

[960kg]

When i did this hack when the cassette is pushed in don`t wait for it to accept it or give it a chance to eject you just press play straightaway and it accepts and runs back & forth. You know where the tape is as it comes up on the screen as B or A running. As you say don`t eject at all just press for CD or Radio and when you want the hack again press Tape. When the ignition is turned off or if you turn off the radio by button it all still remains as is when turned on again, just don`t press eject!

See my hack somewhere in Search.

[JH4music]

I got that far, and it worked great for a few months until the tape mechanism broke. There is a rubber belt that broke, and apparently it used to turn a gear or move something that keeps the tape from auto reversing. I really don't want to bother fixing the cassette mechanism, I'd rather just hack it electrically like bobbych did. but maybe that isn't possible on an SC-811?