[Amps] Help ! Hard Fault 99

James C. Hall, MD nwtcc at earthlink.net
Mon Feb 3 09:11:27 EST 2003

Thanks Dick for your information !  I had previosly measured the AC line
voltage with an old RS Archer voltmeter from my novice days and got about
240 volts.  I then measured with my Fluke DMM and got 247.3 volts. The 240
volt tap should be correct.  I checked out the HF and SF logs after 3
attempts to turn the amp on. Interestingly, all 0's. When I attempt to turn
the amp on, the led's barely begin to glow when it shuts off - < 0.5 sec.
Most bizzare.  Got to head to work now, but will get over here during lunch
and give Glenn a call. I'll let you know how it goes.

Jamie WB4YDL

-----Original Message-----
From: Dick Green [mailto:dick.green at valley.net]
Sent: Monday, February 03, 2003 12:48 AM
To: W0UN--John Brosnahan; James C. Hall, MD
Cc: amps at contesting.com
Subject: RE: [Amps] Help ! Hard Fault 99


When you say the amp immediately shutdown, do you mean before or after the
three minute warm-up period? Many of the faults are detected only when the
amp finishes the warm-up period. If it shutdown immediately after you hit
the ON switch, then some sort of voltage problem is likely. I've seen the
87A do this when I had a defective leaky tube that was arcing internally.
The arc pulled the AC down so fast that the amp hard faulted with various
bad voltage codes. I'm not saying you have a bad tube, although that is
possible. In my case, the arc was so bad that it sometimes blew the main
fuses or the small fuse in the step-start circuit. I think John's theory
that the AC tap is set incorrectly is more likely and is more consistent
with the amp operating normally earlier in the day.

Note that if the fuses are intact, in all likelihood the microprocessor is
functioning. Are you aware that you can hook a PC to the 87A while the power
is off and still perform diagnostic commands? That's because the
microprocessor runs at all times when the amp is plugged into the AC -- even
if the amp is powered down or has been shutdown by a hard fault. Among other
reasons, this is necessary to be able to enter the unlock code! You should
hook up your PC with a straight cable (not a null modem cable), run a
terminal program, set the baud rate to 4800, and issue the following


The 87A will list the last eight hard faults. Unless you cycled the amp
through the hard fault 14 times, you should see one or more fault codes
other than the fault 99. I would hope the 87A wouldn't overwrite the hard
fault buffer with useless fault 99 codes (only one is necessary) but
wouldn't be surprised if it did. Anyway, if you see anything other than
eight 99s, then you are seeing the hard fault codes that caused the

Let us know what happens.

73, Dick WC1M

> -----Original Message-----
> From: W0UN--John Brosnahan [mailto:shr at medinaec.com]
> Sent: Sunday, February 02, 2003 11:34 PM
> To: James C. Hall, MD
> Cc: amps at contesting.com
> Subject: Re: [Amps] Help ! Hard Fault 99
> Hi, Jamie--
> I didn't mean to send the copy of the Glenn note to the reflector!    ;-)
> But now that I have I guess I will continue.  Without the error code
> I don't know what to tell you.  The AC mains issue is only one
> scenario that comes to mind.  And I copied the reply to the reflector
> for the education of other readers--not to embarrass anyone!    ;-)
> I am especially bad about not reading manuals--computer manuals
> specifically!
> Basically Eimac specs filament voltage at +/- 5%.   And 5% of
> 240 volts (the tap you set) is 12 volts.  240 volts minus 12 volts
> is 228 volts as a lower limit.  You say your line voltage is 230 volts
> +/- 5 volts.   Or 225 to 235 volts.   If it drops to 225 then it
> is outside
> the range of the 240 volt tap and its +/- 5% range.   So I think a line
> voltage issue is a distinct possibility--maybe even a probability.
> You need to set your line voltage tap to the proper one for your
> line voltage and also contact CrossLink about resetting the fault 99.
> I have three Alpha 87As--although that does not make me an
> expert on faults.    I have had very, very few over the 10+ years
> that I have owned 87As.
> Good luck--John   W0UN
> At 10:18 PM 2/2/2003 -0600, James C. Hall, MD wrote:
> >Thanks John for your very good information.  I indeed missed the part
> >about the fault 99 and the 6 tries, your out deal.  But I did read the
> >rest of the manual.  Checking the AC main prior to hookup, I
> measured 230
> >volts +/- 5 volts.  I left the tap at 240 volts.  Was this an error
> >?  Should I have moved the tap to 220 volts ???  After resetting the
> >microprocessor, I tried again, this time looking directly at the segment
> >lights and with the terminal on.  It again failed and shut off
> immediately
> >- no indication on the segment lights was given and the terminal program
> >returned no useful information.
> >
> >I, like you, think I might have erred on the tap setting.  I will
> >re-evaluate and discuss with Glenn tomorrow.
> >
> >Thanks again,
> >
> >Jamie  WB4YDL

More information about the Amps mailing list