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ACC Introductory Information Compiled and Maintained by Mike Morris WA6ILQ I have very little knowledge or hands-on with this equipment! Comments, corrections, critiques, suggestions and updates (even anonymous) for this page are requested and appreciated.

Apparently Link Communications no longer deals with ACC equipment; RLC Communications has taken control of that product. You can find RLC information on their site by clicking here. And RLC was purchased by Audio Test Solutions, Inc. Are you confused yet?

Last we heard (updates welcome), Link / RLC / ATSI also had the following:

• The older ACC Manuals - $20 for the RC-85 or RC-96 manual, $40 for RC-850 (two binders).
• RC-85 and RC-96 Firmware Updates - Complete upgrade kit to the last ACC version (5.2) $125. Includes 27C011 emulator board, DS1216E clock module, 28C64A EEPROM and manual. Parts are available separately as well.
• 27C011 Emulator Board - This makes a 27C010 EPROM (included) work like a 27C011 (which is no longer available). $65.
• DS1216E Clock Module - $36.50. This must be enabled after installation by entering "9213528835". This "secret" code sets the tens year inside the clock chip to 5. The controller should respond to the code by saying "OK". If the DS1216E is not initialized properly, the following features in Version 5 will not work: female vocabulary, time, date, HF remote base. These are side effects of an effort to prevent software (firmware) piracy. See the "Y2K" article below.
• 28C64A EEPROM - $15. Needed for later software versions. This is a common chip, you may be able to do better locally, or by checking your compatriot's junk boxes. Jameco occasionally has them in stock.
• RC-96 PAL - $15.
• TMS5220 Speech Synthesizer - $15. This part has been discontinued, and there is no drop-in substitute, but Link / RLC / ATSI still had a few. You may want one for a spare.
• RC-850 Firmware Upgrades - A complete upgrade kit is NOT available. If you do not have the Computer Interface Board (CIB), you will not be able to upgrade past Version 3.42. Every version after that (V3.5, 3.6, 3.7 and 3.8) all require the presence of the CIB which is no longer available. ACC used a weird (and now very, very scarce) EPROM chip - the 27C011s - to minimize the parts count. The rare 27C011s have an internal address latch register that the common PROMs do not have.
  If you already have 27C011s, they can be erased and reprogrammed. If you do not have them but have everything else you need for Version 3.8, then two of the 27C011 EPROM emulator boards can be used. If you have Version 3.7 and are running links or remote bases, you should probably not upgrade to 3.8 as it is rumored that it has a bug that mutes link/remote audio when a voice ID runs on the repeater channel and the CW ID does not work if the link/remote COS becomes active. Someone may have patched the code, if so, please send us the patches for publication.
• Version 6.0 for the RC-85 or RC-96 was developed, demonstrated but never formally released before ACc went under. If anyone ever turns up a unit with that version please let the page maintainer know!

Shipping on any of the above is additional. Prices listed and parts availability are as of the time of this writing (2001) and at that time were approximate. An update would be appreciated.

Aged Capacitors:
To continue the list of problems with old equipment, all of the ACCs are 30+ years old. Electrolytics dry out with age and cause problems... As the capacitors age the µF values go down, the audio levels change. the audio gets intermittent, raspy, hummy and you can hear an increased incidence of buss and clock noise characterized by low frequency fluttering.

Many repeater site buildings are't ventillated and elevated summer temperatures age the capacitors faster. As the DC power bypass or filtering caps age and the values lower the reduced filtering can really affect things. One problem that has bit several people badly is that the audio processing op-amps in all the ACCs run on + and - (bipolar) voltages, and the negative supply is an interesting design: the CPU crystal is divided down to 1 pulse per second (for the various timers and the time-of-day clock), and midstream on that divider chain you find a 15 KHz frequency... that is tapped and feeds a common LM386 speaker driver IC. That amplified 15 KHz is AC coupled to a rectifier and regulator that creates the negative DC voltage for the entire audio chain. As the filter caps dry out and the values go down the negative supply develops a bad ripple at 15 KHz. This can cause your repeater transmitter exciter to develop spurs every 15 kHz up and down the band. Yes, your author saw it happen in person on a local 2 meter club repeater! It looked like a comb on the spectrum analyzer!

Another issue is that dried out capacitors cause is the +5 volt DC voltage regulator gets squirrley and you get random and repeated resets of the microprocessor. That's one more reason to change EVERY electrolytic in the box!

So if your controller has never had the filter caps changed, and you have some strange problems please consider a mass replacement of all the electrolytic filter caps, power buss bypass caps (this process is sometimes referred as shotgunning the circuit board). Please use higher quality / higher temperature capacitors for the replacements... And lease use metalized plastic film electrolytics as the audio coupling capacitors as they have the lowest distortion.

Note that tantalums make great filter and bypass caps but please don't use them as audio coupling caps as they change µF value with the voltage across them.

Back up your PROMs !!!!
The RC-850 started production in the 1982 / 1983 time frame, which makes the oldest units out there way over 35 years old. Have you ever backed up your PROM chips ??? Or the EEPROM ???
If you don't have backups of the EPROMs in your ACCs, and of the EEPROM in those that have them you need to do it ASAP - they do start to drop bits eventually (the common term is "bit rot"). The EPROM has the operational program (the firmware), and the EEPROM contains all of your IDs, Timers, Constants, Autodial numbers, etc.
I am willing to bet that most repeater tech folks DO NOT have a complete and current list of the contents or value of every Courtesy Beep, ID string, Timer and Autodial location...
So one day pull the EPROMs and read each one individually using a PROM burner connected to a desktop or laptop then reinsert them. Just save the chip image with the chip number (for example U31) and the date... i.e. "RC850-U31-1990-11-04.bin". If you don't have a Computer Interface Board on your RC-850 ypu will have to do the same thing to the EEPROM chip. If you do have a Computer Interface Board then you can skip the EEPROM chip and just log in and download an e2prom.hex file. If needed Paul Kindell WB8ZVL, The ACC Repair Guy can create a replacement EEPROM chip from the e2prom.hex file.

Courtesy Tones / Beeps:
While not ACC-specific, there is separate tech info web page at this web site that is a collection of manufacturer default and user-created courtesy beeps (trust me - the "Nextel Beep" is cute, but becomes very annoying after a while).

Firmware Bugs and Patches:
No firmware is perfect, and ACC certainly had a number of bugs in theirs. ACC is no more, and Link/RLC/ATSI owns the remains, and provides NO support, and probably doesn't care. Undoubtedly there are repeater groups or even individuals that have reverse engineered or disassembled the firmware in the various ACC boxes to fix bugs or to add features. If anyone would like to write up their PROM patches (with credit or anonymous), please send it the page maintainer.

System Interfacing:
ACC was the first really successful commercial controller, and the companies that followed them had the opportunity to resolve some of the ACC design problems and "gotchas". One was that the ACC required active-high signals on several of the incoming signals (like CTCSS decode). Many of the later controllers offered inversion on each signal, either by software or hardware jumpers.

Contact Information:

The author can be contacted at: his-callsign // at // repeater-builder // dot // com.

This page split from the main index page 16-Nov-2011.

This web page, this web site, the information presented in and on its pages and in these modifications and conversions is © Copyrighted 1995 and (date of last update) by Kevin Custer W3KKC and multiple originating authors. All Rights Reserved, including that of paper and web publication elsewhere.