DIY: OEM Alpine Head Unit Capacitor Replacement

[crxguy52]

I'm late to the party here, but I actually have some experience interfacing with low-level hardware like this. In order to retrofit an existing head unit with a RPi or similar, I see the following steps occuring:

1. Map out the ribbon cable to the front panel. I would imagine the pins are for power, ground, front panel buttons, and data and clock for the display drivers. Not sure if each display driver is individually driven or they are daisy chained together. At the very least, use the datasheet for the display driver IC to figure out which pin on the ribbon is the data and clock so we can start messing with it

2. Start toggling bits through the shift register. Based on the datasheet, this should be fairly straightforward. My initial thought was to use the SPI port on an Arduino, but I think there is a simpler way, since I would imagine you can only transmit 8 bits at a time with the Arduino. It probably doesn't matter since we're transmitting into a shift register, but that's besides the point. I think you could write a "slow" program and just bit-bang two GPIO's for clock and data, since the datasheet doesn't specify a maximum time between clocks. This would be fairly simple to code up and test out. It would also make driving the STB pin easy, since everything is in software.

A note, it would be good to figure out which driver IC is hooked up to what, so we know what to drive state of the LED\FIP pin to.

Hope this helps, and keep us posted!

 

[drew]

Ah, I was hoping crxguy52 was going to weigh in. I emailed you as I will need some hand holding.

If anybody would like to donate their dead OEM parts (display daughter- and mother- boards) for the project, it would be appreciated.

 

[Logprod]

Looking for someone skilled in fixing my 1991 NSX stereo. I've read some threads to contact Daryle at http://www.willmanselectronics.com/default.htm however I have sent them emails without any response. .so looking for plan B.

 

[SWFL_NSX]

Looking for someone skilled in fixing my 1991 NSX stereo. I've read some threads to contact Daryle at http://www.willmanselectronics.com/default.htm however I have sent them emails without any response. .so looking for plan B.

I think Daryle isn't very intersted in repairing the old units. I've heard that [MENTION=13572]cmc140[/MENTION] here on the forums "has a guy."

http://www.nsxprime.com/forum/showt...40-s-OEM-Stereo-amp-Amp-Uprade-Repair-Service

Let us know how it turns out!

 

[betthemortgage]

Pics from 2004 NSX Alpine head unit

My audio started making "popping/crackles" when the volume knob was turned up/down. Usually, this would take care of itself after a few minutes and/or exercising the volume knob up/down. I've got some time on my hands, and knowing that the radio and amps are problematic with older capacitors, I decided to take out my amps and radio head to inspect. Much to my surprise, all items - on all three amps and the radio boards - looked good.

Reading through these threads regarding Bose amps and Alpine head unit, I realized that the pictures posted are NOT representative of what is contained in my 2004 NSX. Mind you, the pics are close, but my boards/units appear to have undergone factory changes meant to resolve the transistor & capacitor issues from earlier NSX's. So, I snapped a few pics from the Alpine head unit and have included them with this post. Also, I was able to see model (?) numbers on my boards and have included those also. However, a quick search on Google did not reveal any matches with anything Alpine or otherwise.

I'll take some photos of my Bose amps and post those too.

Back to my problem with the "popping/crackles" ... I did some in-system troubleshooting and from what I can tell, the issue is not with my amps. In my earlier days working with electronics, I'd describe my problem as a "dirty pot" or potentiometer - at least that's what it sounds like. Looking at the volume board, caps E401 and E402 look ok, but I might replace those and try spraying some contact cleaner into the visible portions of the volume potentiometer stack. I've ordered other replacement caps for the 3 Bose amps, but only want to replace those after more iterative troubleshooting.

I'll post updates when parts come in.

 

[Old Guy]

If the problem really is surface contamination on the volume potentiometer, try squirting some Caig Deoxit into the pot. Purchase the F100L with the needle applicator (the green stuff) which is meant for faders / carbon based non linear potentiometers.

F100L-L25C CAIG Laboratories, Inc. | Tools | DigiKey

I like the long needle applicator because you can stick it into any small holes to get it onto the wiper and carbon surface. The Caig stuff is pricey but definitely works better than simple surface cleaners. I have an older Fender Mustang IV guitar amp. The design of the final gain circuit is very sensitive to any kind of dirt / contamination on the master volume control pot which appears as really loud scratching when doing small volume changes. I replaced the pots; but, the noise reappeared after about 1-2 years. I did that twice, now I just squirt a little Deoxit into the pot when it gets scratchy. So far, the Caig treated pot has gone longer without noise than the replacement pots.

 

[tucsonsx]

Since I am loath to take anything apart unless absolutely necessary I just pulled the knob off and shot a small amount CRC QD electronic cleaner down the shaft of the volume knob, replaced the knob, turned it a few times, and have had no further problem. If it happens again I'll try the Caig stuff instead but since then I try to use stereo more with the thought that it might last a little longer that way than using it very rarely. I hoping someone that knows more than me can weigh in on whether that is a valid idea or just wishful thing ( Drew and Old Guy I'm looking at you ).

 

[SWFL_NSX]

Nice work-always great to see people working on these stereos. We seem to learn something every time somebody opens them up.

Reading through these threads regarding Bose amps and Alpine head unit, I realized that the pictures posted are NOT representative of what is contained in my 2004 NSX. Mind you, the pics are close, but my boards/units appear to have undergone factory changes meant to resolve the transistor & capacitor issues from earlier NSX's.

The boards definitely went through changes over the years, and there may also be regional differences for different markets (different frequencies in US/EU/Japan, etc). Some of the boards also have "fly-wire" repair work done, apparently straight from the manufacturer.

That said, I don't think any of the changes eliminate the issues with the electrolytic caps. AFAIK these components simply have a service life and will begin to leak at some point. Additionally, the leaking electrolyte remains hidden under the caps for a while, so may not be visible unless you remove the cap.

 

[drew]

> I just pulled the knob off and shot a small amount CRC QD electronic cleaner down the shaft of the volume knob, replaced the knob, turned it a few times, and have had no further problem.

I would presume Placebo Effect is in full play here. If it sounds better to you: then that is the only test that matters.

Look at the lower left photo with the knob (post #80 PCB marking E401 and IC402) that is the On/Off/Tone...the volume knob is very similar. Your cleaning fluid has to get past the panel nuts, the chassis, and into the internals. It is possible, but unlikely, that your application of fluid did much good.

**

I have radio boards from a few different year NSX's (I'm looking for more if anybody has any to give/sell). It appears Alpine made small batches of the radio and then threw away the layout after production. I presume Alpine makes a lot of boards and it is easier to recreate than to keep track of. So each time a new batch was required, (and just like programming: it is easier to write new code that read old code), EoL proprietary chips, and so a new PCB layout using the old one as a guide. The big change was the integration of the VFD power supply unit into the board as the early boards (YM: 1990-1993) had an external VFD PSU.

Now I understand why later, analog interface, radios have a larger reception range and increment by the smallest common multiplier....just build one radio and be done with the world. And there are so many different variations of FM and AM band that they hard-coded the differences instead of using jumpers and built to the required spec only...the future changes so fast, so why bother?

And 30 years later they are correct.

 

[betthemortgage]

I'll take some photos of my Bose amps and post those too.

As promised ... two of my Bose amps - one from the doors and one from the sub/center:

 

[tucsonsx]

> I just pulled the knob off and shot a small amount CRC QD electronic cleaner down the shaft of the volume knob, replaced the knob, turned it a few times, and have had no further problem.

I would presume Placebo Effect is in full play here. If it sounds better to you: then that is the only test that matters.

Look at the lower left photo with the knob (post #80 PCB marking E401 and IC402) that is the On/Off/Tone...the volume knob is very similar. Your cleaning fluid has to get past the panel nuts, the chassis, and into the internals. It is possible, but unlikely, that your application of fluid did much good.

**

I have radio boards from a few different year NSX's (I'm looking for more if anybody has any to give/sell). It appears Alpine made small batches of the radio and then threw away the layout after production. I presume Alpine makes a lot of boards and it is easier to recreate than to keep track of. So each time a new batch was required, (and just like programming: it is easier to write new code that read old code), EoL proprietary chips, and so a new PCB layout using the old one as a guide. The big change was the integration of the VFD power supply unit into the board as the early boards (YM: 1990-1993) had an external VFD PSU.

Now I understand why later, analog interface, radios have a larger reception range and increment by the smallest common multiplier....just build one radio and be done with the world. And there are so many different variations of FM and AM band that they hard-coded the differences instead of using jumpers and built to the required spec only...the future changes so fast, so why bother?

And 30 years later they are correct.

When I removed the volume knob and gave the shaft a blast of QD the snap, crackle, and pop when changing the volume went away - maybe just a coincidence but looking at the pictures it looks like the shaft of the knob goes directly to the potentiometer so it would seem that, since the QD is an aerosol spray with a fair amount of pressure, that shooting it between the volume control shaft and the sleeve that surrounds it would have a good chance of reaching the potentiometer. In any event the answer to the question that I am looking for is that does using an electronic component like a stereo increase it's service life compared to never using it. I really just prefer to listen to the engine when driving the car, but being OCD also like to have everything on the car operational so should I use the stereo or not?

 

[drew]

so should I use the stereo or not?

Capacitors degrade and leak with age. Using the stereo will add heat and accelerate the process...sure, a little. It should be noted that the heat from amps is offloaded to the speakers, so not a lot heat will be created by using the stereo.

However, the heat generated from the stereo is a distant second compared to AZ climate, where a car starts baking with the morning 110-degrees at 0700 and easily hits 175-degrees (80c) inside the car during the day.

So use your stereo as it will fail regardless, it matters not if it is being used.

This is why we are creating a new PCB to give an OEM style alternative and give it another few decades.

 

[Heineken]

Like @drew stated, leakage is one of multiple failure cases for capacitors and unfortunately very common in the the NSX. Elevated temperatures (especially storage temperature) speeds up the process but it's not the key factor, that would be age.

You can safely use the radio, until it starts to show typical issues related to capacitor leakage (like a warm-up-time, too low volume, increased noise, etc., especially if these changes over time) - after that, there's no time to waste. If you want to be particularly safe, just get them replaced while there are no issues yet. Should be the safest and cheapest option unless you plan to sell the car soon.

PS: Crackle and pop when turning the volume knob is a known issue and related to corrosion of the resistor wipers - to be fixed by applying de-oxi spray but it needs to reach the affected areas. Not sure whether the bottom PCB needs to be removed for that which is a little delicate task.

 

[betthemortgage]

If the problem really is surface contamination on the volume potentiometer, try squirting some Caig Deoxit into the pot. Purchase the F100L with the needle applicator (the green stuff) which is meant for faders / carbon based non linear potentiometers.

F100L-L25C CAIG Laboratories, Inc. | Tools | DigiKey

I like the long needle applicator because you can stick it into any small holes to get it onto the wiper and carbon surface. The Caig stuff is pricey but definitely works better than simple surface cleaners. I have an older Fender Mustang IV guitar amp. The design of the final gain circuit is very sensitive to any kind of dirt / contamination on the master volume control pot which appears as really loud scratching when doing small volume changes. I replaced the pots; but, the noise reappeared after about 1-2 years. I did that twice, now I just squirt a little Deoxit into the pot when it gets scratchy. So far, the Caig treated pot has gone longer without noise than the replacement pots.

So, I ordered/received the CAIG F100L and placed some drops in the volume potentiometer stack (see arrows in picture). Worked the volume knob CW/CCW a bit to ensure a good coat on the wiper. While I had everything apart, I did check about 50% of the capacitors on all boards in the Alpine Radio Head and the Bose amplifiers with an ESR meter. All caps checked good. I reassembled the radio and placed in the car - ops checked GOOD! No pops of any kind when knob is used.

Thanks to Old Guy for the CAIG F100L tip - worked like a charm. Here's the pic of the volume knob pot stack and where I used the F100L drops ...

 

[Old Guy]

While I had everything apart, I did check about 50% of the capacitors on all boards in the Alpine Radio Head and the Bose amplifiers with an ESR meter. All caps checked good.

If you have a good ESR tester and the results indicate that the ESR remains below the spec values in the data sheets then that is a good indication of the health of the capacitors. Did you remove the capacitors to test them? In-circuit testing results can be distorted by the presence of other circuit elements which may provide parallel resistance paths which lower the measurement value.

 

[SWFL_NSX]

Finally re-opened my radio to replace the rest of the caps (yes, after almost 4 years =)

-I upgraded my de-soldering gun from the Chinese version posted earlier in this thread to a Hakko FR-301 and found it much easier to use.
-Also found the FFC ribbons on digikey. The replacements I ordered were longer and it made re-installation much easier.
-Volume knob now works correctly. Sound quality is better on FM radio than it is from the "USA spec" RCA auxiliary input-no clue why.

Next up is to work on the front control panel. Some of the buttons aren't working and I want to see if they can be replaced.

 

[Heineken]

Having better audio from FM than the CD changer input strikes me a little odd.
On all the NSX radios I've been using so far, the CD changer input was the input providing the best quality (compared to radio and tape).

Did you observer capacitor leakage before exchanging the caps? The acid often damages the CD changer input OP amp which could cause sound detoriation.

 

[SWFL_NSX]

Yes, I had some leakage in the large capacitors (E508, E504, etc. as well as E317 on the bottom processor board, and a couple on the power board) but the area near what I believe is the op-amp didn't appear to be affected. The traces that had acid damage were scraped, cleaned and then covered with acrylic conformal coating and none seemed to require a solder bridge. That was somewhat surprising because one of my FFC was absolutely destroyed!

Regarding sound quality, the FM radio has some static from poor reception, but the bass, mid and treble are all present and clear. When I use the RCA aux input there is no static but the bass is lacking and the sound is less clear. Hope that makes sense =)

Also, when I say, "RCA auxiliary input" I mean using a 3.5mm-to-RCA jack cable that is plugged into my iPhone on one end and the USA Spec adapter on the other. I don't have a CD player but plan on trying the iPod cable with a 3rd gen iPod I have laying around.

 

[SWFL_NSX]

Kicking this up again.

I was able to connect the USA Spec adapter to an old iPod and the sound was really pretty good-better than on my old Miata or current Prius.

Unfortunately, I can't navigate the iPod because the top row of buttons (1,2,3,4) on the head unit don't work!

After disassembly it appears that the buttons on the faceplate simply isn't reaching the corresponding buttons on the circuit board. The lower row (5,6,7,8) are fine.

Pics below-does anybody know if I'm missing a piece, or have an idea what the issue might be?

 

[SWFL_NSX]

Update: Issue appears to be that the clear plastic screen on the faceplate has warped over time. It's now slightly concave (or convex) and is making contact and scratches on the red LCD screen that is soldered to the circuit board. Removing the clear faceplate allows the upper buttons to work again but leaves the radio slightly more unprotected. Not sure how to fix the issue properly, perhaps heating the clear screen till it gets soft and flattens out?

 

[Heineken]

Good that you identified the issue, that would have been hard to tell from the pictures.

The risk in heating it up is that it may shrink in all dimensions .. I would probably try to extend the buttons pins by adding a few drops of glue before messing with the clear plastic.
Alternatively you could cut-out a new piece of clear plastic from a more thin and flexible material as a replacement?

 

[acuhon]

Is this gone to far ?

 

[SWFL_NSX]

Smarter people will jump in shortly, and keep in mind I'm speaking as a hobbyist.

As far as I can tell the only thing that actually kills these boards is if an alpine-specific chip bites the dust. We don't know whats on them, and so can't manufacture new chips. The other thing is that we don't have schematics, which makes troubleshooting issues very difficult.

Beyond that the repairs are just removing/replacing all the caps, scraping the acid off and repairing any of the copper traces that was completely eaten away. You'll need maybe 500$ of tools (desoldering iron, soldering iron, conformal coating, etc) and a lot of time.

A better question is, how many hours do you want to dedicate to this vs. starting with one that is in better shape?

Whatever you do, don't throw it away! Somebody in the community will eventually want it, even just for parts.

 

[Heineken]

That's indeed a very severe case but you could be lucky after all. Critical (like @SWFL_NSX said) are the Alpine proprietary chips but the layout of the non-RDS radios is a little more forgiving in this regard - critical chips are not that close to the capacitors as on the RDS radios in EUDM cars.
Another important factor is also whether the radio was powered - since the acid is conductive, having power on the board will cause even more trouble and rapidly eats away traces (especially power supply lines) as well as damage components much easier. Note that parts of the radio are constantly powered even when off (RAM, CPU, etc.)

To find out you'll have to clean up the mess (down to bare metal), repair the traces, check all affected VIAs (note that the acid sometimes even dissolves VIAs under SMD chips ..) install new capacitors and hope for the best. If it does switch on than there might be further trouble with the audio path that needs to be addressed, requiring more parts to be replaced.

Before I forget, the capacitors on the small power board are leaking too and the acid can drip on the middle board potentially killing parts there as well.

I would certainly give it a try with the proper tools and experience (SMD soldering, etc.).

 

[oneplustwo]

I'm going through a recap proactively for my head unit. Thankfully, everything looks ok so far so hopefully the recap goes smoothly. I had to make some edits to the digikey cart with some bits that were obsolete (or not in stock.) Hope this helps those folks who might be looking to give this a go.