This post is aimed mainly at those who are into telephony (both POTS and digital) and other telecommunications modes, such as T1/T3, though it will also cover some of the network-testing capabilities of the HST3K. JDSU, according to the unit's data sheet, described it as a "Triple-Play Network Access Tester" and it certainly seems to live up to that. Even its product name contains a hint (HST = Handheld Services Tester).
It's my hope the info offered here will help keep the instruments useful (at least to hobbyists) far beyond its 2018 discontinuance.
SO WHAT IS IT?In short: This is a multifunction test set designed to handle, depending on which module's plugged in and which software options are enabled, just about any kind of standard testing for copper POTS lines, SIP-based VoIP, T1/T3 circuits, DSL/ADSL/VDSL, Ethernet (fiber and copper), BERT (Bit Error Rate Testing) and TIMS (Transmission Impairment Measuring Set).
THE GUTS AND THE OPTIONSViavi does still support these units as of the date of this post, at least for calibration and best-effort repairs, but they never published any publicly-available data on what goes on in the guts of the thing. So, after having been (somewhat rudely) told, "Oh, we don't allow our end users command-line access" I decided to do a little digging of my own.
The unit (at least for the only hardware revision worth messing with, the ACE-II) runs on an Intel PXA270 series CPU clocked at around 500MHz. It uses a Spansion 29GL01GP13 FLASH memory chip to hold its firmware, and a Dallas/AD DS2433 One-Wire EEPROM (8-pin SOIC) to hold version and option info (which is preserved across firmware updates).
It's OS is a shrunken-down Linux core, using Busybox to conserve memory space. All HST-3000's come with a base unit Ethernet port which shares duties between circuit testing and remote access. See page 14 in the Base Unit User's Guide (attached).
The Linux CLI in the unit can be easily accessed by:
- Assigning an IP address to the base unit's Ethernet port, either manually or through DHCP.
- Establish a standard Telnet connection to whatever IP the unit got assigned on your network.
- At the login prompt, give it the user name root and the password is phantom4
- Explore to your heart's content, but, if you value your unit, be bloody careful about changing anything! I have no idea what will happen if you damage the base OS, nor do I have any idea how to recover it -- outside of unsoldering the BGA FLASH chip from a known-working unit, reading it, copying that load into another chip and re-soldering it to the target unit's board!
As far as digging into the hardware goes, have a look at the photos SplitView and 1-wire. In SplitView, you can see there are six machine screws which need to be removed (from the back) to get the thing open. You may have to do some gentle prying, along the perimeter, since the units are weatherproofed with silicone sealant at the factory, but they separate pretty easily once the stuff gives.
SplitView shows the front cover and display assembly on the left, CPU and mezzanine boards in the base unit on the right. Note the unused socket on the backside of the keypad PCB. I'm told this was to accommodate an optional 802.11 WiFi card, though darned if I've ever seen one in that form factor. There's also another version of the front assembly (see the photo bt) which has Bluetooth hardware. Note that it was either one or the other with these sets. I've never heard of, or seen, one with both WiFi and Bluetooth.
Take a closer look at the base unit on the right. Specifically, the photo 1-wire zooms in on the Dallas 2433 chip. To enable all available options, it's best to desolder this one from the board and manipulate its contents with a device programmer (I made use of the Reveltronics Revelprog IS).
Here's the best news: To enable everything, you only have to change ONE byte in the EEPROM. Specifically, at address 0x2C, you'll usually find the hex byte 0D. Change this to anything you want, from 00 to FF (I prefer 42, just to be silly), reprogram the chip and solder it back in. You're good to go!
There is, however, a caveat: Enabling all the software options does not magically make the test set do things it doesn't have the hardware to do. As one example, they don't all come with copper testing capability. While you can certainly turn on options like 'Copper Expert' in software, it won't change a thing if the proper mezzanine board (to actually execute those tests) isn't installed.
Another example is the 802.11 WiFi. I've yet to see a unit which is equipped with the radio module to handle that. It won't hurt anything if the option's enabled in the software, but neither will it start trying to use the nearest WiFi access point if the radio's missing.
I welcome questions or comments. I have a lot more information on these units than I had room to post here.
Happy tweaking.
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