[Amps] ALPHAs and momentary power outages

[jeremy-ca]

Well, enterprising hackers have figured out how to improve engine 
performance and defeat CATV cable boxes.
All you need is to find an enterprising teenager to tackle the Alpha and 
come up with a virtual reset switch.

Carl
KM1H


----- Original Message ----- 
From: "Dick Green WC1M" <wc1m at msn.com>
To: "'jeremy-ca'" <km1h at jeremy.mv.com>; "'Tom W8JI'" <w8ji at w8ji.com>; "'Jim 
Brown'" <jim at audiosystemsgroup.com>; <amps at contesting.com>
Sent: Wednesday, July 18, 2007 1:52 PM
Subject: RE: [Amps] ALPHAs and momentary power outages


> Yes, the 87A uses simple analog op-amp sensors to monitor the supply
> voltages. The sensors can be hacked to fool the CPU into thinking all the
> supply voltages are at nominal values, but there are quite a few of them 
> and
> it would take some major surgery. More problematic, you would be defeating 
> a
> significant part of the amp's self-protection capability. I wouldn't do 
> that
> with such an expensive amp. I guess you could add a circuit or
> microprocessor to turn on the hacked sensor circuitry only if the main AC
> voltage falls below a predetermined value, but that's even more 
> complicated.
>
> 73, Dick WC1M
>
>> -----Original Message-----
>> From: jeremy-ca [mailto:km1h at jeremy.mv.com]
>> Sent: Wednesday, July 18, 2007 1:30 PM
>> To: Tom W8JI; wc1m at msn.com; 'Jim Brown'; amps at contesting.com
>> Subject: Re: [Amps] ALPHAs and momentary power outages
>>
>> I would think that the Alpha microcessor is pretty basic and looking
>> for
>> simple analog inputs.
>>
>> Much like an automotive processor. I had a built up LT1/4L60E Corvette
>> combo
>> in a 38 Chevy coupe and the tranny began slipping. A rebuild was $1800.
>> A
>> little bit of monitoring with a DVM ascertained what voltages the
>> processor
>> was looking for to cause the shift solenoids to actuate.  Then it was
>> simply
>> a trip to the junkyard for a good non electronic 700R4 tranny and a
>> couple
>> of resistors across the old harness connector to fake out the processor
>> and
>> I was back in business for $250 with sharper shifting to boot.
>>
>> Sometimes it pays to think out of the box.
>>
>> Carl
>> KM1H
>>
>>
>>
>> ----- Original Message -----
>> From: "Tom W8JI" <w8ji at w8ji.com>
>> To: <wc1m at msn.com>; "'Jim Brown'" <jim at audiosystemsgroup.com>;
>> <amps at contesting.com>
>> Sent: Wednesday, July 18, 2007 1:02 PM
>> Subject: Re: [Amps] ALPHAs and momentary power outages
>>
>>
>> >> I'm glad someone was paying attention. It would be hard to
>> >> reprogram the
>> >> microprocessor, but it would be easy to patch the timer
>> >> value on the fly, as
>> >> needed. You just have to get the address(s) and meaning of
>> >> the value(s) from
>> >> Alpha.
>> >
>> > My bet is the timer has a reset line or line that monitors
>> > power down. It may even just be when the power to the
>> > microprocessor is removed, the CPU restarts.
>> >
>> > The simplest approach would be to fool the system into not
>> > knowing the power ever went down. You could do that with a
>> > battery and R/C timer, a large electrolytic and a few
>> > diodes, or any other number of ways.
>> >
>> > Maintaining the entire power line and HV supply is probably
>> > not even necessary. I would however restrict the hang time
>> > to several seconds and no longer, and make sure the step
>> > start recycled.
>> >
>> > 73 Tom
>> >
>> >
>> >
>> > _______________________________________________
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>> > Amps at contesting.com
>> > http://lists.contesting.com/mailman/listinfo/amps
>> >
>
>
>