Singing Digi-dash
Thread Starter
Pro
Joined: Oct 2000
Posts: 564
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From: Riverview Florida
Singing Digi-dash
There is a high pitched (about 17,000 Hz) tone coming from somewhere inside the dash on my '88. It isn't loud but definately audible even with the car running.
The symptoms I have noticed are;
Tone varies slightly in frequency but not in a specific pattern.
Volume changes under various conditions (battery charge level, engine running, etc.)
Tone is more noticable when battery is not fully charged.
This began around the same time as the volt gauge started acting strangely. When I start the car the gauge shows between 17 and 19 volts and a red bar appears next to the voltage readout. The voltage display slowly drops to normal levels (13.4-13.9) after about 5 minutes of engine running. The tone isn't audible when the gauge is showing the high readings but becomes audible after the readings drop into the "normal" range.
I have checked the alternator output and the reading at the battery with a voltmeter. Both show right at 14.2 V no matter what the volt gauge display in the car shows.
Anybody have similar experiences?
The symptoms I have noticed are;
Tone varies slightly in frequency but not in a specific pattern.
Volume changes under various conditions (battery charge level, engine running, etc.)
Tone is more noticable when battery is not fully charged.
This began around the same time as the volt gauge started acting strangely. When I start the car the gauge shows between 17 and 19 volts and a red bar appears next to the voltage readout. The voltage display slowly drops to normal levels (13.4-13.9) after about 5 minutes of engine running. The tone isn't audible when the gauge is showing the high readings but becomes audible after the readings drop into the "normal" range.
I have checked the alternator output and the reading at the battery with a voltmeter. Both show right at 14.2 V no matter what the volt gauge display in the car shows.
Anybody have similar experiences?
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
Engine idling, dash singing, unplug the alternator. If the high pitch goes away, then you have a voltage regulator inside the alternator that is oscillating. Replace the regulator. If not, then the power supply board in the cluster is singing. It supplies about 100 v to the LCD panes in the cluster. The step up transformer on the board might be singing, but I don't know where you could get a replacement. If you can hear 17 KHz, you have good ears.
Race Director
Joined: Dec 2004
Posts: 15,025
Likes: 2
Might check with the dash rebuilders like these guys to see if they would sell you the PS. They have a new power supply design they install when they rebuild them. I'm sure the other rebuilders have something similar.
17khz is going to be more of a discomfort than actually identifying that frequency audibly. I know of very few people that can hear that high.
If you can hear 17 KHz, you have good ears.
Le Mans Master
Joined: Jul 2007
Posts: 5,043
Likes: 8
From: Tampa Florida
There is a high pitched (about 17,000 Hz) tone coming from somewhere inside the dash on my '88. It isn't loud but definately audible even with the car running.
The symptoms I have noticed are;
Tone varies slightly in frequency but not in a specific pattern.
Volume changes under various conditions (battery charge level, engine running, etc.)
Tone is more noticable when battery is not fully charged.
This began around the same time as the volt gauge started acting strangely. When I start the car the gauge shows between 17 and 19 volts and a red bar appears next to the voltage readout. The voltage display slowly drops to normal levels (13.4-13.9) after about 5 minutes of engine running. The tone isn't audible when the gauge is showing the high readings but becomes audible after the readings drop into the "normal" range.
I have checked the alternator output and the reading at the battery with a voltmeter. Both show right at 14.2 V no matter what the volt gauge display in the car shows.
Anybody have similar experiences?
The symptoms I have noticed are;
Tone varies slightly in frequency but not in a specific pattern.
Volume changes under various conditions (battery charge level, engine running, etc.)
Tone is more noticable when battery is not fully charged.
This began around the same time as the volt gauge started acting strangely. When I start the car the gauge shows between 17 and 19 volts and a red bar appears next to the voltage readout. The voltage display slowly drops to normal levels (13.4-13.9) after about 5 minutes of engine running. The tone isn't audible when the gauge is showing the high readings but becomes audible after the readings drop into the "normal" range.
I have checked the alternator output and the reading at the battery with a voltmeter. Both show right at 14.2 V no matter what the volt gauge display in the car shows.
Anybody have similar experiences?
Thread Starter
Pro
Joined: Oct 2000
Posts: 564
Likes: 0
From: Riverview Florida
In the past, I've offered you to pull the cluster on your own and bring it by and I'll hook it up to my cluster bench tester for "free" to see if it is the cluster or something else in the car causing the problem. The cluster test takes about 5 min. The offer still stands.
This weekend another problem cropped up that has to take precedence over the dash. After driving a few miles the brakes start to drag and heat up then drag more. Don't know if it is the master cylinder or the ABS unit but I have to fix that first.
Thanks for your generous offer.
Thread Starter
Pro
Joined: Oct 2000
Posts: 564
Likes: 0
From: Riverview Florida
Might check with the dash rebuilders like these guys to see if they would sell you the PS. They have a new power supply design they install when they rebuild them. I'm sure the other rebuilders have something similar.
17khz is going to be more of a discomfort than actually identifying that frequency audibly. I know of very few people that can hear that high.
17khz is going to be more of a discomfort than actually identifying that frequency audibly. I know of very few people that can hear that high.
