Restoration Difficulty Level

[andyburns]

A bit off pure 113 discussion but I thought I would throw this one in for the audio buffs amongst us.

The car audio project has been fraught with problems that have taken me what seems like an eternity to overcome.  I really love my music so its been an important aspect of the project should I be lucky enough to keep the car long term. 

Today I tackled a niggling issue which only surfaced after I had installed the gear in the car.  Whenever I turned off the ignition, which disconnected the power to the remote power source controlling all the equipment, the amplifier was popping the speakers out with some crazy signal sent to it from either the line level mixer or the Bluetooth unit.

I festered around with the suspects for a good couple of hours before I determined that the popping was being caused by both units.   I did a little research on the internet and discovered its a very common problem and that its normally overcome with turn off delays of one description or another. 

So my solution was to use the biggest dirtiest capacitor I had floating around  and wire it to main 12v remote line so it charged and stored around 10-30 seconds worth of capacity to hold up both the bluetooth and line level mixer after the amp turned off.  In practice I simulated it manually to make sure it would solve my issues.  Worked perfectly.

I measured the current draw off the remote line for all devices to be around 150ma so decided to go for a 8000uF capacitor, after a few rough calcs, to give me plenty of wriggle room.  Wired the cap with a IN4001 diode upstream of the devices I wanted to control.  Its capable of sourcing 1A of current so again plenty of headroom.

Wired it all up and it worked perfectly first time.  Was a little surprised that only held up the gear for 10 seconds after the power was removed.  Thought it would have been closer to 30 seconds but good enough.  No more nasty banging and popping from the speakers.  Perfectly quite start up and shut down.

I was also running all the gear through the ignition.  So the car had to be turned on to operate the radio.  I thought about this long and hard over the past couple of days.  I am sure I will from time to time want to sit in the car parked up and listen to some tunes. 

When I put the gear in I metered all the fuses and discovered that none of them were connected to the accessory position on the ignition.  All were either permanently live or switched to the run position on the ignition.  I am picking that if I had access to the ignition barrel I would possibly find a spare terminal I could make work but its just too hard to access.

An you categorically do not want to sit with the engine off and the ignition on listening to the radio.  You would end up with burnt out coils I should imagine.

So a new plan was hatched.  Wire the old Becker to 12v permanent and use the electric aerial  12v feed to power the remote for all the new gear under the seat.   I was a bit worried that the electric Ariel feed might not be capable of supplying enough current but after metering that a about 400ma I quickly concluded that another 100ma wouldn't hurt.   I was going to use a solid state relay if it was going to be an issue.

Net effect is at anytime, independent of ignition position,  I can turn on the becker which in turn immediately raises the electric ariel and turns on the amp, bluetooth unit and line level driver.   

Works beautifully.  The only issue it raises is the radio being left on and flattening the battery.  I figure by nature its going to be obvious if its left on.  Also I have the benefit of knowing if the aerial is extended then the battery is being flattened.  Good little visual reminder.  I could go a step further and wire a buzzer that would sound if the door opened and the radio was on but I think I have taken the system far enough.  My weird OCD has already cost me too much time on this little project.

I also solved another separate but related issue on top of this.  I have an android phone which I intend to use as the source for my audio system.  I connects via bluetooth which is fairly clunky out of the box.  You have to dive into sub menus and turn on bluetooth and then select manually the device you want to connect to.  Not something you want to do on the run or even stationary when you get in your car each time.

I found a freeware bluetooth auto connect application in the android store and its solved all my issues in a spectacular manner.  Not only can you tell it to auto connect to a prioritized list of bluetooth devices but you can also specify an application on your andriod device to run when a new connection has been established.  Obviously you configure your music player.

Net effect I turn on my becker and now magically the phone bursts to life connects to the bluetooth and the music player automatically starts.  Very very slick.  If anyone is interested I can make another video of it all.

Just ironing out all these little glitches has cost me another 8 hours today.  Just goes to show the last 10 percent of the job often takes 90 percent of the time!

[hands_aus]

Hey Andy,
The ignition switches for the 230SL and early 250SLs did not have accessory positions.
For you to have the audio working in the Ignition switch OFF position you will need a separate fused power supply from the battery.

[andyburns]

Hi Hands,

I think I have the fusing situation sorted with all the gear being adequately protected.  I have gone to great lengths to make the becker look original including sourcing an original Mercedes/Becker fuse holder which usually was positioned in the engine bay.  When I got my car it had a bracket just forward of the brake booster with nothing on it.  I believe that was where the original fuse holder was.  I have tapped into fuse number 1 which is the only fuse which is always live irrespective of ignition position.

The electric aerial has its own inline fuse which is also connected back to terminal one on the fuse box.

All the rest of the new gear has very carefully been fused to a 100amp circuit breaker.  Pretty standard for high end amps to have this sort of protection.  I ensure I ran the shortest possible run of 8 gauge unfused wire to the battery.  Also used some very heavy heat shrink as additional mechanical protection on this link which is exactly what mercedes did with its unfused heavy wiring all the way back to the alternator and starter motor.

The ignition accessory position is a bit of a mystery to me.  My barrel definitely has provision for it.  See attached photo.  Perhaps at some point my barrel was replaced with a 280sl version?

[Paul & Dolly]

Hi Andy,
Good to see you progressing the Pagoda again.
My early 250SL has similar switching, so I have added a relay to power the Radio & Bluetooth with the ignition off, for similar reasons to you.

I can power just the Radio system up with an illuminated rocker switch ( so I know it is on) when parked.
I also have a silver push button switch to isolate the power to the electric aerial, so I can run non radio music with the aerial retracted.

Always enjoy reading your updates

Keep well

Paul

[andyburns]

Thank Paul,

I came very close to slamming a solid state relay in.  They are getting so cheap now.  I resisted the urge to 'play' and after metering everything out decided the existing wiring was well up to the task. 

I do like your idea of being able to retract the aerial when your not using it.  I had contemplated it but decided that I love the way that the becker on off button now controls everything in one place so just left it at that.   At the moment I am loving the novelty but I may well change my mind.

I love your wiring diagram.  Obvious to me that you have taken a few electronics lessons in your day!  Would love to see some pics and more of a description of exactly what your running.

[Paul & Dolly]

Hi Andy,

I am a retired petrochemical Engineer, so cannot help but fiddle...... the aerial still works automatically with the radio, dependant on switch position.

I have  gone modern with a Retrosound Model 2, it plays USB and is Bluetooth connected for a smart phone,  so I have now removed the Parrot CarKit I had previously installed. I have 4 speakers - nothing sophisticated.

All my mods are reversible and housed on an additional small centre panel, that hides the wireing.
I have added a "hazard" flasher.
I  have a switched live, permanent live and earth running along the transmission tunnel to the boot, and “cigarette lighter” sockets to charge my phone, and to connect a “fridge” situated on the back seat., and a rechargeable torch in the boot.
I have also connected the boot light switch to the permanent live, as it only used to work with the lights on.

I  have a socket (similar to the underbonnet one) fitted to a centre arm rest to easily connect a smart charger for the winter, or the so called optional  "Trouble" light if needed.

Keep well
Paul

[hands_aus]

Hey Andy,

#1 is called the Garage position.
It is there to allow you to take the key out without having the locking mechanism engaging.

The correct ignition switch for your 230sl will not have contacts for an Accessory position.
see the attached pic so you can check your wiring diagram against the visible contact #s
The referenced #s in the pic titles relate to 250sls.

cheers

[andyburns]

Hey Hands,

Thanks for that.  Wow, so its purpose is to be able to unlock the steering lock on the car and allow it to be pushed around manually.  I will try it out tomorrow.  I guess it would come in really useful for when the car is towed but cant imagine it would be that useful in the garage.  Can you think of any other useful applications for it?  Perhaps it was called garage mode because the day head mechanics didn't trust their underlings to drive the cars around cramped workshops under power and made them push them carefully around instead

My barrel looks exactly the same as the one you have shown so am assuming it correct. 

[andyburns]

I have been working over the past couple of days on the dash wood and finishing up my speaker install.  I have a bit of a query on the wooden speaker grill.  It slots in at the front of the dash under the two wood bows.  Then at the front it has two pins which mate up with two pillars which are welded onto the dash.  These pillars have a single hole drilled into the top which the pin goes into.  The fit is very loose.  I suspect that there is meant to be some sort of clip which create a bit of interference with the pin.   I have looked back through all my dash photos taken during the dissasembly process and none of them show any clips.  Can anyone help me out on this.  The wood grill sits down ok but I would be much happier if it was secured along the front lip.

[tel76]

Andy,
In the speaker install kit that you got from George there are two clips that you fitted to hold the rear of the speaker, two clips like those fit in the small towers that the grille attaches to, two long screws go through the wood grille into the clips .

[andyburns]

Thanks Eric,  still a little confused.  Perhaps the early grills were a bit different.  mine definitely isn't fixed with screws to the turret.  Take a look at this photo.  Its got two inbuilt pins that home in on the turret holes.   Definitely no screw used to hold the wood down with by the looks. 

[tel76]

Andy,
The set up that I have been referring to is much later than the set up that you have, your's does not look a secure location for the wood grille.
I will be interested in what other members have, I thought all grilles were held down with two long screws at the rear with the front located under the front wood.

[mmizesko]

Andy and Eric,

My 1970 grille simply slides under the front bow wood and secures into the pillars with the two screws.  When putting the bows back in, you have to make sure the spacer blocks are put in on both sides of the bow to make sure you have clearance and that the blue knurled nuts don't pull the bows too far down to the dash.

I hope I am explaining this right.  Andy if you are worried about rattling, I'm sure you can add a little felt to the back of the grille which slides under the bow.

Mike Mizesko

PS  Andy, I'd love to see a final demonstration of your audio system when you're done.

[Jonny B]

My early 250 SL has the wood grill secured with two screws. My 280 SL grille also is set in place with the two screws. Will be most curious to see what others type.

[andyburns]

Thanks for the feedback guys.  Guess the early 230 has a different system altogether.  Looking at it I wouldn't be surprised if Mercedes changed it.  The pins I have dont look that effective but are definitely factory. 

I did know about the packing spacers for the under the bow.  I should have taken some photos.  Ended up using very dense 15mm closed cell foam.  Compressed down it holds beautifully and will prevent any vibration.  Using closed cell foam you can sand it down to exactly the thickness you want.

I dont have the two little blue thumb screws.  When I got my car the wood had been painted black so had obviously been out of the car before.  Whoever painted it also sanded through the veneer in places.  I stripped the wood last week with chemicals and blew yet another couple of coats of varnish on it to see if I could get it looking better.   From certain angles it looks great but if your looking hard the 'sand through' is not a good look.    Putting it all back they had used nuts and had obviously lost the thumbscrews. 

I think at some point I will replace the wood so have only gone to the trouble of securing int behind the speaker.  I actually holds really well with the other end jammed under the A pillar molding and rubber.  To get the remaining three bows screws done you have to pull out the vents to get access.  There is also one up behind the speedo which will probably need to be taken out as well.



Mike will try and put together a short video of the system all up and running. 

[paults1]

Andy, I had the same problem with my early 230SL speaker pins.  From a suggestion from this forum way back, I used small plastic wall anchors pushed into the hole in the bracket. I think they are the small blue ones. The pins pushed into them & too this day they are very secure.  Just in case my memory is incorrect, I would buy several of the anchors of different colors (sizes). Hope they are available in NZ.
Regards, Paul

[andyburns]

Thanks Paul.  I kind of know what you mean.  Cant think of where to get them but will look at the hardware store next time I am down.  Are they designed to push through the plaster board and then take a screw? 

[paults1]

Andy, Yes that is type I used.  Regards, Paul

[andyburns]

Decided to improvise on Pauls suggestion and create some interference with two small section on heat shrink on the pins.  Worked magnificently creating just enough tension to hold the speaker grill snugly against the dash leather.  One small win!   

[paults1]

WOW, The heat shrink appears to be a better idea!!

[andyburns]

Paul, sometimes less is more   

[georgem]

Andy,

My 230 has pins - the main problem I have is keeping them attached to the wooden grill - super glue doesn`t do it. Epoxy is next

[andyburns]

George, there are plenty of glues out there that would hold it.  I think your spot on with starting with epoxy though.   Good luck.  Post some pictures.

[114015]

Hello Andy,

I have looked back through all my dash photos taken during the dissasembly process and none of them show any clips.  Can anyone help me out on this.

Yes,
there are (should be) clips in place to hold down the pins of the speaker grill.

Just don't have a picture on hand to show you.
They're short and yellow cad colored.
Should be this one: A 001 988 5378 (2 x)

Best,
Achim

[andyburns]

Thanks Acim.  I think I will run with my solution for the mean time and search out those clips.  They are easy to get at so can do it at any time.  I have started a list of stuff I am not happy with and want to revisit.    The wood is on it so I can do the clips at the same time.  To be honest I am just really getting desperate to drive it.  Even a few feet in and out of the garage would be immensely satisfying.  I am starting to waver on the quality assurance department since the the back operation. 

Today I picked up the injection pipes from the acid stripper.  They managed to completely unblock all but two.   The two are partially unblocked.  Importantly the pipe which supplies the cold start valve with fuel is 100% sorted!  Dodged a big bullet!

Lesson learnt.  Never never never never electroplate these lines if you havn't spent the time cleaning them out. 

The second set I stripped came up really well.  One thing I have learn t is that these pipes naturally block themselves over time.  Other than the pipes I blocked I have tested all the other pipes by blowing through them.  The resistance through them varies with some teetering on being blocked.

One of you guys mentioned earlier that these are a serviceable item.  I am interested in how they serviced them.  I am thinking that if these pipes start to block then it may effect the pressure at the injector nozzle.  If you get uneven pressures across all the injectors I can imagine it would result in the car not running smoothly.  Quite a hard problem to diagnose.

In any event I am now spoilt for choice and will be able to put together a really good free flowing set.