Audacity shows no input signal when I record from the system or from the built in mics.

Make sure you have the Sigmatel driver installed, and that  Microphone Array is the default device on the Recording tab of the Sound properties. Here is a screen shot, but what you will see on your laptop can vary a lot, depending on the operating system, and which version of the driver is installed.

from the system

I'm not sure what you mean by "the system". Internal sounds can only be recorded if "stereo mix" is selected as the recording source, rather than a microphone. If I recall correctly, stereo mix was only available with the XP version of the Sigmatel driver.

Scratch the part in my last post about Microphone Array. The E1705 did not have an internal microphone.

Hello. You don't mention which operating system so I'll try to cover different OS scenarios here.

I can not get sound to an external speaker from the headphone port.

Test with more than one device -- if you have some headphones or earbuds lying around, try those. If you hear audio through any of them, then the jack is okay.

The headphone jack would normally work with any operating system, and whether or not you have the Sigmatel audio driver installed, unless you are using XP, in which case you have to install the Sigmatel driver and its prerequites, in the correct order (Notebook System Software, Intel Mobile Chipset driver, Sigmatel driver).

I can not record from a device using a cable to the mic port.

If possible, try more than one microphone. Make sure levels are up in the Sound properties. This is a screen shot from a laptop with IDT audio, showing the path to the levels. Yours should show Sigmatel in place of IDT, and "Microphone/Line In" in place of Internal Mic.

The mic port will not work with the Windows native audio driver, so you do have to have a Sigmatel driver installed for it to work. The  only supported operating systems are Win 2000, XP, and Vista, so if you have a newer OS you would have to install the Vista version of the driver, but do it using compatibility mode. See section 8 of the Audio Driver FAQ for instructions for Win7, but should also work with the newer OSes..

Inspiron E1705 Are the 1/4" mini mic and headphone ports integral to the mobo, or are they on a replaceable card?

Not replaceable. See section 4 of the Headphone Jack FAQ. An easy workaround Is to get a cheap usb audio jack, and use that instead of the laptop's integrated jacks.

How can I trouble shhot this problem?

See section 2 of the Audio Diagnostics FAQ for an explanation of how to use the Dell 32-bit Diagnostics to diagnose audio. The diagnostic tool eliminates Windows and Windows-based driver from the tests, so if the jacks don't work during the tests then it is because of hardware failure. If the jacks do work during the diagnostics, then the problem is in the software.

The laptop probably no longer has the diagnostics on the hard drive, but you can run them from the original Dell utilities cd if you have it, or if not, you can download it and install on a cd or flash drive. 

I got a USB audio device.. I tried it on my other laptop, an Inspiron 1520 running Linuxmint 18 Cinnamon 64bit. The USB device outputs sound and inputs sound from a mic. I am running Linuxmint Cinnamon 32bit on the Inspiron E1705. I get output but not input from the USB device.

I am thinking the recording hardware on the E1705 is bad, or not being driven.

When I had XP installed, the device manager would indicate the Sigmatel drivers were not installed. I reinstalled the Sigmatel drivers, but the DM still indicated they were not installed. I am thinking the Sigmatel hardware is bad and therefore will not accept a driver.

When I had XP installed, the device manager would indicate the Sigmatel drivers were not installed. I reinstalled the Sigmatel drivers, but the DM still indicated they were not installed. I am thinking the Sigmatel hardware is bad and therefore will not accept a driver.

In XP, the Sigmatel driver will not install unless it is done in the "correct order" (Notebook System Software, Intel Mobile Chipset driver, Sigmatel driver). If the Sigmatel driver did not install, then the Windows native audio driver, called "High Definition Audio Device", was installed. The Sigmatel hardware could not have produced audio without some sort of audio driver being installed.

I got a USB audio device.. I tried it on my other laptop, an Inspiron 1520 running Linuxmint 18 Cinnamon 64bit. The USB device outputs sound and inputs sound from a mic. I am running Linuxmint Cinnamon 32bit on the Inspiron E1705. I get output but not input from the USB device. I am thinking the recording hardware on the E1705 is bad, or not being driven.

When you use a usb audio device, it has its own audio hardware (the DAC for audio output, and the ADC for input), so it would not matter if the Sigmatel recording hardware is bad. The Sigmatel's DAC and ADC are not used when a usb audio device is the default device.

As far as drivers, if you were still using XP, the usb audio device would run off the Windows native usb audio driver, not a Sigmatel driver. I don't know what driver is used when the operating system is Linux.

You might be able to get better advice on a Linux discussion forum, but the problem is not the Sigmatel hardware if you are using usb audio hardware. If you want to test the Sigmatel hardware, see section 2 of the Audio Diagnostics FAQ for an explanation of how to use the Dell 32-bit Diagnostics to diagnose audio. The diagnostic runs in its own operating system, so it doesn't matter whether you have Linux running on the laptop. The diagnostic has its own drivers. If the laptop no longer has the diagnostics on the hard drive, you can run it from the original Dell utilities cd if you have it, or if not, you can download it and install on a cd or flash drive

I used the cdd_1298.iso

Audio:

Mono Output Sound Playback Test failed - Error 1863.111B

Side Mic Record and Playback Test failed - Error 1863.1818

All other Audio tests passed.

I ran both of those tests again using the USB Port Replicator

Mono Output Sound Playback Test passed

Side Mic Record and Playback Test failed    (know good mic.)

I also ran the System Board tests. They all passed.

How can I determine if the Sigmatel hardware is indeed on my mobo. It has been suggested that it may not be since Intel bought Sigmatel.

In Linux I ran hwinfo and hardinfo. I saw no reference to Sigmatel. What would be the windows command  to find hardware?

Dell had the motherboards for the E1705/9400 made with Sigmatel HD audio chips -- it was the first Dell laptop model to have the new HD audio codecs. Although the IDT company later bought Sigmatel, I can't think of how an IDT chip could have gotten into your laptop, unless the MB has been replaced with one from a later model.

It has been suggested that it may not be

There was some cross-over. When IDT first took over, the company made some  products that were just slight variations on the Sigmatel products, so it happened that some IDT drivers would install and work on some Dell laptops with Sigmatel hardware. It was a matter of experimentation --people used to experiment a lotwith different audio drivers, and would stumble on combinations that worked. Maybe someone got hold of one of those laptops and formed the mistaken idea that IDT chips were placed on motherboards that were supposed to have Sigmatel.

How can I determine if the Sigmatel hardware is indeed on my mobo.

What would be the windows command  to find hardware?

I don't know of a command. In XP, if you open the Sounds & Audio Devices Properties (right click on the audio icon on the taskbar), there is a Hardware tab that shows the hardware.

You could check the Device I.D. In XP, open Device Manager, right click on the audio device, then Properties. On the Details tab, click the drop down arrow and select Hardware ID. Google to find out how to use the number if necessary.

[In XP, installing the Notebook System software and Intel Chipset driver are essential for the OS to identify the audio hardware.]

It is possible the mobo was replaced. Is the Sigmatel chip on the top or bottom side of the mobo? I have the palmrest off but do not see it. Is it under something else on the mobo. The mobo is supposed to have both an Intel and a sigmatel audio chip - right ? What does the Intel chip look like?

I didn't seriously think the MB would have been replaced by one from a different model --it would be unlikely to fit in the case or match the port openings.

I don't know about the location of the audio chip -- would have to open one of my laptops  to check. Here are pics of both sides of the E1705 motherboard. They aren't very sharp and don't have the processor or cooling assembly..

This a an Intel Core Duo processor of the type that was used in the E1705:

Here is where it would go on the motherboard, underneath the cooling assembly.

lifted