Another radio question

[Spottwd]

Set the scene. A stock 1991 MT with door speakers already replaced. When I turn the radio on, everything lights up and the radio functions such as Seek etc work. The antenna goes up and down like a charm. But, and there is always a but, No Sound, at all. The volume knob elicits nothing.

Last Fall, before storage, after turning the radio on, it sometimes took awhile before I got sound.

Any ideas about what might be the problem?

 

[Honcho]

@Kaz-kzukNA1 @Heineken

They will know,

 

[Streaky09]

Take out radio and speakers, put Bluetooth speaker in. Problem solved

 

[vf2ss]

Set the scene. A stock 1991 MT with door speakers already replaced. When I turn the radio on, everything lights up and the radio functions such as Seek etc work. The antenna goes up and down like a charm. But, and there is always a but, No Sound, at all. The volume knob elicits nothing.

Last Fall, before storage, after turning the radio on, it sometimes took awhile before I got sound.

Any ideas about what might be the problem?

Sounds like the infamous failing/leaking capacitors ... here's one post that might provide a solution and keep it stock [LINK] and here's the company that did the repair 8 years ago and it still works flawlessly every time.

Acura Radio Navigation CD Changer Repair - Hi-Tech Electronic Services

We repair all models of ACURA GPS Touch Panel Stereo. If you do not see the model of your unit here please call. 818-785-8085, Acura Radio Navigation repair

hitechserv.com

 

[Old Guy]

Set the scene. A stock 1991 MT with door speakers already replaced. When I turn the radio on, everything lights up and the radio functions such as Seek etc work. The antenna goes up and down like a charm. But, and there is always a but, No Sound, at all. The volume knob elicits nothing.

When you say 'seek' works, does that mean that you can press seek and it will find known AM and FM stations, or just that when you press seek it will scroll through the frequencies; but, doesn't find anything? If seek scrolls through the frequencies for both AM and FM and finds and stops at known stations then that likely means that the AM and FM tuners are functioning and that the problem may be in the audio output portion of the head unit. If you can scrounge a cassette and do a test with the cassette function that would assist in confirming where the problem is. No audio from the cassette would support a problem in the audio signal path.

It would be good to toggle the AM / FM / CD function just to make sure that the failure is not in the input switching function.

The volume control rheostats can sometimes take a dump and develop dead spots; but, if you turned the volume knob back and forth and nothing happened that is not the problem.

If the audio path has failed it could be a capacitor problem - either a failed capacitor and / or damage to a circuit board trace caused by a leaking capacitor. I seem to recall that there have also been some Op Amp failures reported. Either way, that requires removal, disassembly and inspection to determine the problem - soldering skills required!

 

[Heineken]

I think @Old Guy already described it - if the door speakers show a slight hiss when the radio is switched-on they can be considered OK. Since there is an amplifier in each door, it's unlikely for them to fail all at once.

My number one suspect is failing capacitors in the radio - better get it fixed while it still turns on ..

 

[Spottwd]

Seek operates correctly. It stops at stations. I haven't yet dug out a cassette to try and I'll do that tomorrow. Down in the bowels of the basement. No CD player on this one.

I do have soldering skills leftover from my Heath-Kit days, but I don't have the instruments needed to test individual components. So I guess that is is off to find a radio repair place that has the necessary stuff and skills. Not sure if there is one in town. And I don't think that my Acura dealer, with the mechanic who has cared for this car since 1991 and the original sale, has the electronic skills. Does anyone have any suggestions if I can't find one here?

Thanks to everyone for their info and advice.

 

[Old Guy]

Send a message to Brian at

NSXE-REPAIR.com

nsxe-repair.com

 

[Slikna1]

Brian does not repair the head units,only place I'm aware of is hitech in southern California and it's not 100% that it can be repaired depends on what is actually damaged, i had mine "fixed" and it still doesn't work right and sits in a box now after putting $1k into refurbishing it

 

[Honcho]

Brian does not repair the head units,only place I'm aware of is hitech in southern California and it's not 100% that it can be repaired depends on what is actually damaged, i had mine "fixed" and it still doesn't work right and sits in a box now after putting $1k into refurbishing it

@Kaz-kzukNA1 in the UK and @Heineken in Germany can do them.

 

[Old Guy]

If the seek function seems to be working correctly, the problem would appear to be in the audio path. A test with a cassette would reenforce that conclusion.

If Brian K does not work on the head units and you have some soldering skills, you do have the option of pulling it apart yourself. @Heineken has done a number of posts on repairing the head unit which can provide some guidance. Capacitors that have failed to the point of non operation will usually be obvious and with a little care are fairly easy to replace. Damage to the traces on the circuit board caused by leakage from the capacitors can be a little more challenging. Solid state components have a very low failure rate except where that failure is precipitated by a short caused by electrolyte leakage.

If you don't feel confident about your diagnostic and repair skills, bundling it up and sending it to Heineken or Kaz may be an option. The only problem is that they can't test the radio function because the North American FM function doesn't work in Europe and digitally tuned AM can get screwed up by the different tuning step size. They will be able to confirm the audio path.

 

[Spottwd]

I dug out an old Dillards cassette, stuck it in, and got a momentary (very momentary) blast of sound. After that, no go. Tried it again and couldn't get even the momentary sound. However, the cassette did forward/reverse etc.

No Dillards. So sad.

 

[Heineken]

If the seek function seems to be working correctly, the problem would appear to be in the audio path. A test with a cassette would reenforce that conclusion.

If Brian K does not work on the head units and you have some soldering skills, you do have the option of pulling it apart yourself. @Heineken has done a number of posts on repairing the head unit which can provide some guidance. Capacitors that have failed to the point of non operation will usually be obvious and with a little care are fairly easy to replace. Damage to the traces on the circuit board caused by leakage from the capacitors can be a little more challenging. Solid state components have a very low failure rate except where that failure is precipitated by a short caused by electrolyte leakage.

If you don't feel confident about your diagnostic and repair skills, bundling it up and sending it to Heineken or Kaz may be an option. The only problem is that they can't test the radio function because the North American FM function doesn't work in Europe and digitally tuned AM can get screwed up by the different tuning step size. They will be able to confirm the audio path.

Almost correct except that receiving FM with a US radio in Europe is fine - we even have an AFN radio station (with US de-emphasis) here in Stuttgart Haven't heard or experienced any tuner issues yet, it's rather safe to assume that it's OK.

 

[Old Guy]

Almost correct except that receiving FM with a US radio in Europe is fine - we even have an AFN radio station (with US de-emphasis) here in Stuttgart Haven't heard or experienced any tuner issues yet, it's rather safe to assume that it's OK.

I thought that the Euro zone used different FM channel - channel spacing and used even numbers for the center frequencies (i.e. 92.2 versus 92.1) versus North American odd. This could screw up some digitally tuned FM radios if the tuner's synthesized frequency was set to increment to tune to only odd numbers. Analog tuning works fine. Clearly I must be thinking of some other place if your experience says they work. I know that the Japanese FM band is offset compared to North America with a small overlap at the respective top and bottom parts fo the band.

 

[Old Guy]

I dug out an old Dillards cassette, stuck it in, and got a momentary (very momentary) blast of sound. After that, no go. Tried it again and couldn't get even the momentary sound. However, the cassette did forward/reverse etc.

No Dillards. So sad.

Sound - as in music or just noise? If you got some music the problem might be in the source selection function which may or may not be easier to fix. However, if you are not inclined to break out the soldering iron Heineken is probably your best bet.

 

[docnsx]

I was driving ,my car radio was popping and cracking then it went like bang bang bang and now no sound .. so I am assuming it is the radio since unlikely all speakers would go at same time.. I have a Williams radio that I purchased for this time In need and was looking for printable I use to have instructions to remove radio vs a video .. does anyone have the printable instructions wit photos to remove radio steps.. thanks in advance

 

[Heineken]

I guess you are referring to this YouTube video?

Note that while remove of the center vent, the clips holding it in place are at the bottom so there's no need to work around the top.

 

[Heineken]

I thought that the Euro zone used different FM channel - channel spacing and used even numbers for the center frequencies (i.e. 92.2 versus 92.1) versus North American odd. This could screw up some digitally tuned FM radios if the tuner's synthesized frequency was set to increment to tune to only odd numbers. Analog tuning works fine. Clearly I must be thinking of some other place if your experience says they work. I know that the Japanese FM band is offset compared to North America with a small overlap at the respective top and bottom parts fo the band.

We do have 1 MHz increments with channels at odd and even numbers (eg. 92.2 and 107.7). The pre-emphasis is different causing US radios to have more noise and less high frequencies when tuning to German stations but nothing serious.

Japan uses the same Pre-emphasis as Europe but with a narrower band (76-90 MHz) until 2011, now extended to 95 MHz.

 

[docnsx]

I guess you are referring to this YouTube video?

Note that while remove of the center vent, the clips holding it in place are at the bottom so there's no need to work around the top.

I actually spoke to daryl at Willman electronics and he remembered I bought his first second generation retrofit.. he had some confidence that my symptoms are most likely the head unit .. so im gonna install his unit I had sitting in my garage for this day since 2017 and will send him this unit to retrofit from to have as backup in the future for myself or my brother who has oem radio in his 1991. Will attempt to remove orig radio later in week time permitting any written instructions would be helpful

 

[Old Guy]

The original set of printed instructions complete with diagrams is the Service Manual. You will need to consult the Body Section which covers removal of the interior pieces to access the head unit. Here is an archived version of the 1991 manual.

Acura NSX 1991 Service Manual : Honda Motor Co : Free Download, Borrow, and Streaming : Internet Archive

Service manual for the 1991 model year Acura NSX

archive.org

The service manual is what I used when I needed to remove my head unit.

 

[Heineken]

Meanwhile the radio arrived safely. On a first test there was no sound coming out even though the tuner works fine and locks to stations. After a few minutes it suddenly came alive. This won't be easy, I'm afraid ..

 

[Old Guy]

It is just taunting you .

Intermittent failures of any kind have to be the worst to diagnose. In this case it sounds like you have 2 or 3 minutes after turn on to diagnose the failure and then have to start all over again once it starts working.

 

[Heineken]

Very certainly .. today I've managed to improve the state of a radio that needs warmup to run distortion free but can't find the last missing piece that makes it work correctly from the start. After investing a two-digit numbers of hours I'm close to giving up since I can't replace every part on the PCB neither map out the full schematics.

Before capacitor replacement it wasn't usable at all with massive crackling noise and a broken CD port. The port was fixed and supplied with a new OP amp which made it come alive again.

Now there was a ticking sound, independent from the volume level and even audible when the volume and sound PCB was disconnected. After replacing one more OP, two transistors, one Zener diode and two more capacitors the issue was unchanged.

Using a large amount of freeze spray I could locate an area that reacted very sensitive and introduced the ticking noise when cooled down. Interestingly, no replacement of the components in that area (a transistor and six capacitors) changed anything. What did change the situation was replacement of the ribbon belt connector which gave me the idea of a potential PCB issue.
After re-soldering all VIAs in that area, the ticking noise was gone and couldn't be brought back even using freeze spray.

So far so good but the distortions on all inputs (when cold) that came together with the ticking noise was still there and unimpressed. It goes away after a few minutes but that's not an proper repair, I'm afraid.

You can't fix everything it seems but I'm afraid the issue might become worse over time, the same way it improved while working on it - but maybe that's the only remaining option - wait till it gets worse to be able to find it.

 

[Heineken]

It's been a tough fight.

The issue was related to a too high DC level on the muting control line mixed with stray signals. That caused the muting circuit to half-mute and distort the audio signal. After more parts replacements and another acid contaminated flex cable connector exchange the issue became better but still not acceptable. At this point were at more than 40 replacements and counting.

With the help of a 1 kΩ pull-down resistor on the muting line it's no longer audible and sounds fine right from the start. Not a perfect repair but a patch that works fine. Since the muting line is rarely activated, the extra load from the resistor shouldn't be a problem - man these radios do get old ..

 

[docnsx]

Set the scene. A stock 1991 MT with door speakers already replaced. When I turn the radio on, everything lights up and the radio functions such as Seek etc work. The antenna goes up and down like a charm. But, and there is always a but, No Sound, at all. The volume knob elicits nothing.

Last Fall, before storage, after turning the radio on, it sometimes took awhile before I got sound.

Any ideas about what might be the problem?

No expert but it may be due to capacitor leakage over time which is inevitable more rapidly in Warner climates the experts have told me.
Mine started out like warming up over time then snap and crackles then nothing . Sorry to inform u and hopefully I am wrong . I just replaced with Williams radio which is oem shell retrofitted with all new update kenwood components