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300zx Bose Restoration: Center Speaker April 8th, 2010 by Dane

 

The 1990 300zx 2+2 is one of the few cars in the world ever to have a center channel (they changed the DIN to a crap-holder in 1991). From an acoustics standpoint… it’s probably a bad idea.  But, it’s novel and I’ve decided to keep it.  To restore the amplifier for the central channel , you’ll have to remove the unit. This can be done by following directions for removing the head unit. There are plenty of guides out there for doing this, so I won’t re-write those guides.

Once the head unit is exposed, you will see the classic Bose speaker cloth covering the DIN below the cassette player. Remove the 2 screws on each side of the center speaker channel, and unplug the connector from the back. This black box contains a small speaker and an amplifier.

Using a 5mm socket, remove the screws on the top of the unit. At this point you can crack open the unit to see the small speaker and amplifier. The amplifier is unlike other amplifiers found in Bose-equipped vehicles. It only has one IC chip compared to the two found on most of  their automotive amplifiers. There are a few quirks that I can’t really place reason behind on the unit. The enclosure is unsealed, nor ported; it has vents for the heatsinks. I’m not sure how great a downward-firing speaker in an unsealed enclosure can be tuned.  I’m not going to question it, I’m just going to refurbish it.

Upon inspecting the amp, 8 electrolytic capacitors can be seen. There are 4 shiny green small cylindrical capacitors, and 4 larger blue cylindrical capacitors. I used Parts Express to order my parts. Its easier to use than Digikey. Here is what is needed to replace the electrolytic capacitors:

  • 4.7uF  x1
  • 47uF  x3
  • 100uF x2
  • 220uF x1
  • 1000uF x1

For all of these, I’ve opted for 50v and 105*c tolerances. You can look on the sides of the caps to find what Bose installed, but keep in mind what I said earlier about the 16v caps they used. Using 50v for all of them made the ordering process easier. It did cost about 10 cents more, though.

Remove the goop by heating it with a heat gun or space heater. I used a combo of a pocket knife, needle nose pliers, and snips. Heat the solder and suck it up with a solder sucker. Be sure to note the polarity of the caps as they are removed.

300zx Bose Restoration April 7th, 2010 by Dane

 

While Bose may have a reputation for innovation in the audio world, they also have a reputation for failure in the automotive world.  I will be documenting my experiences in restoring a Bose system in a 1990 Nissan 300zx 2+2. Much of this information will be applicable to other Bose automotive systems in Nissans, Infiniti’s, and other makes. I have gleaned information from sources relating to Corvettes and Infiniti Q’s. This has provided me a start in the restoration.

Background:

This website provides a good detail of Bose systems found in the 300zx family of cars.

Z Max Stystems Bose Page

Here are the high points:

  • Bose automotive systems use individual amplifiers for each speaker.
  • The amplfier/driver/enclosure are all tuned to each other (as they should be) http://en.wikipedia.org/wiki/Thiele/Small
  • The amplifier gain, equalization and compression are all changed based on what car the speaker is located in, where the speaker is located in the car, and it is rumored that even cloth/leather trims are considered.

Root of the problem:

That being said, it is common for these complex systems to fail.  The most common problem is capacitor failure. Much of the blame can be put on Bose for attempting to save a couple cents, opting for capacitors with a 16v tolerance. Now, a typical car circuit works on 12v (12v battery up front, right?). However, when the car is on, the alternator typically brings the voltage up into the 14-15v range. Getting awful close to that 16v break down voltage, huh? There are additional stresses that can be caused by jump-starting as well. While a higher break down tolerance may have helped most problems, the truth about electrolytic capacitors is that they can deteriorate in time, lowering the breakdown voltage. Let’s not forget the stress that all the bumping around can cause. Also moisture in the air, hot and cold… It’s really a miracle that more car stereos aren’t broken.

Solutions to the problem :

  • Buying New/Used Bose

Its still possible to purchase speaker/amp modules from Bose. They charge $140 a pop for a new unit. For a lot of people, this may be a solid option if convenience outweighs cost. You know for sure you’ll get a working unit that is up to factory spec. There are also amps that come up on ebay that have been used or are refurbished. One must be careful they are getting the EXACT replacement for their make/model/year/trim/speaker position.  Other amps may work, but they won’t be matched as they were from the factory.

  • Repair

For those who want to spend the least amount of money, this is the option. 20 bucks, one can purchase replacement capacitors for all of the amps in their car. However, some mechanical know-how, soldering skills, and time are the trade off. Some sources also claim that the performance will not be as good as new amps, however, I contest that IC’s, inductors, and ceramic capacitors don’t deteriorate like electrolytic caps, so upon replacement, the unit should work like new.

  • Aftermarket Replacement

This option has the advantage that sound quality can be improved (ie louder), modern equipment can be used (cd/dvd/nav systems) and other personal touches can be added. However, this means a non-stock headunit, which leads to two things: thieves like stereos and new headunits won’t match your interior. Also, all speakers must be replaced. Bose uses speakers whose DCR is <2 ohms. Most amps (and no head units I’ve ever seen) cannot run these speakers.

Personally, repair is what avenue I have chosen. For an heirloom car like a 1990 300zx in great condition, having the stock system is a definite plus. I’ve had a loud bumping system before, but the cleanness of a stock system is nice, especially in a small car like a 300zx. Not to mention, there are some weight savings to be had over a large system!  The notes below should help anyone trying to restore their 300zx or any early 90’s car equipped with a Bose system.

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Fix HDHomerun blocky video in Vista & 7 Media Center March 31st, 2010 by Justin

 

For quite a while I thought my cable signal in my apartment was weak, resulting in the signal falloff artifacts — e.g. stuttering, blocks, etc — but as it turns out I tested the video stream from the HDHomerun on a Mac one day and the video was clear and smooth. I then started prying about the Silicon Dust forums and my own Win7 HTPC.

The solution was either one of two variables, but I suggest you address both if you can.

  1. Turn off Vista and 7’s network throttling. This doesn’t have a toggle in the control panel or device settings, so you have to RegEdit it of course. Type regedit in the search bar in Windows 7 and right click and click ‘run as administrator.’ Regedit might not show up in the Vista search, in which case you can find it in your C:\Windows\system32\ directory from explorer. Make sure you open it as Administrator though.
  2. Click on through to this folder of the registry HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Multimedia\SystemProfile (sorry, regedit is about as intuitive as using a garden rake to comb your hair)
  3. There will be a registry key called “NetworkThrottlingIndex” — click this and type in FFFFFFFF in the “value data” box (8 F’s). Hexadecimal should remain checked.  Click okay and the key’s data value should show up as “0xffffffff (4294967295)”. In MS-lingo, this apparently means “OFF” so yay!

The second variable depends on your network card drivers. I had Realtek, so I went to realtek’s website, downloaded the latest ethernet drivers, installed them, rebooted, and changed another type of network throttling, called “Interrupt Modulation,” to disabled in the advanced properties of the device’s configuration window in device manager.

After one final reboot, I had perfect video on my HTPC. Wunderbar!

We’re back with higher dB’s March 12th, 2010 by Justin

 

Headline pretty much wraps up the result of Comcast’s transition to all-digital transport which exposed some weak wiring in the hosting household of our server. Rocking out a straight path from the pole to the modem now.

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