I did similar to my 500ZC with simple resistor choices. Since I always use
headphones a bit of remaining noise is no bother.
Carl
KM1H
----- Original Message -----
From: "Dick Green WC1M" <wc1m73@gmail.com>
To: "'Carl'" <km1h@jeremy.mv.com>; "Dick Green WC1M" <wc1m73@gmail.com>;
"'Paul Kraemer'" <elespe@lisco.com>; "AMPS" <amps@contesting.com>
Sent: Saturday, March 17, 2012 1:16 AM
Subject: RE: [Amps] LK 550-ZC
> Guess I have a real late one: it has the fan speed temperature sensor. The
> stock fan speed is too slow in low-speed mode, so the fan cycles low-high
> constantly. And it's like a freight train at high-speed. I increased the
> RPM
> at low-speed so it goes to high speed much less often. That didn't raise
> the
> noise level very much. I also decreased the RPM in high-speed mode, which
> reduced the sound considerably, but didn't appreciably affect the
> cool-down
> time to low speed. I used a temperature probe to make sure the tube
> temperatures stayed well within spec.
>
> 73, Dick WC1M
>
>> -----Original Message-----
>> From: Carl [mailto:km1h@jeremy.mv.com]
>> Sent: Thursday, March 15, 2012 6:36 PM
>> To: Dick Green WC1M; 'Paul Kraemer'; AMPS
>> Subject: Re: [Amps] LK 550-ZC
>>
>> Amp International was the last name, Denny was selling into the
>> commercial market.
>>
>> The ZC included the day to day updates to the ZB, and finalized the ALO
>> circuit, QSK, and the step-start and fan speed. Real late ones had a fan
>> speed temperature sensor.
>>
>> Carl
>> KM1H
>>
>>
>> ----- Original Message -----
>> From: "Dick Green WC1M" <wc1m73@gmail.com>
>> To: "'Paul Kraemer'" <elespe@lisco.com>; "AMPS" <amps@contesting.com>
>> Sent: Thursday, March 15, 2012 5:12 PM
>> Subject: Re: [Amps] LK 550-ZC
>>
>>
>> > As far as I know, there was no individual manual for the ZC. I think
>> the
>> > "400/500 Series" manual was intended to cover all the variations in
>> both
>> > series. I don't recall exactly what set the ZC apart from other models
>> in
>> > the 550 series, but I think it was QSK. The BAMA manual has the
>> schematic
>> > and some instructions for the QSK Board. Is there some part of the
>> manual
>> > you specifically need?
>> >
>> > I happen to have a working LK-500ZC sitting unused in the basement. It
>> has
>> > QSK, but I'm pretty sure it lacks the No-Tune option (it's been a long
>> > time
>> > since I used that amp.) I don't recall if it has the "new" step-start
>> > circuit discussed in the BAMA manual, but I think so. It carries the
>> Amp
>> > International label, which I believe indicates that it was one of the
>> last
>> > amps made by Denny before the enterprise went under. The manual that I
>> got
>> > from the previous owner is almost identical to the BAMA version, but
>> > appears
>> > to be an earlier edition. Perhaps that means I have it backwards, and
>> that
>> > the original company was Amp International and the last-gasp company
>> was
>> > Amp
>> > Supply, and that my amp is an earlier model instead of late one. My
>> manual
>> > does have the pages missing from the BAMA manual (3, 15, 21-24), but
>> those
>> > pages don't contain any critical information. The BAMA manual has more
>> > complete schematics and bills of material.
>> >
>> > I did a lot of repair work on the amp when I got it. The previous
>> owner's
>> > wife had thrown something at him during a fight (a chair, I think),
>> and
>> > the
>> > amp got knocked off the desk. All three tube seals were compromised,
>> and
>> > when the previous owner turned it on, the resulting arc fried the
>> plate
>> > choke and a number of other components. I also replaced a 40m output
>> cap
>> > that was actually broken by the blow to the amp. The meter bezels were
>> > damaged, too. I fixed all that stuff, added a glitch resistor to
>> protect
>> > the
>> > plate choke from future mishaps, replaced all of the meter calibration
>> > resistors (which had either deteriorated or were replaced by a
>> previous
>> > owner with the wrong values in order to fool the ALO circuit, throwing
>> off
>> > the meter readings), slightly increased the fan speed at the low
>> setting
>> > to
>> > prevent it cycling into high speed mode so often, and lowered the fan
>> > speed
>> > in high speed mode so it wouldn't sound like a freight train.
>> >
>> > 73, Dick WC1M
>> >
>> >
>> >
>> >> -----Original Message-----
>> >> From: Paul Kraemer [mailto:elespe@lisco.com]
>> >> Sent: Thursday, March 15, 2012 2:29 PM
>> >> To: AMPS
>> >> Subject: [Amps] LK 550-ZC
>> >>
>> >> Can someone help me find a copy of manual for Amp Supply LK-550 ZC.
>> >>
>> >> I have the download from BAMA which covers the 550 but not the ZC
>> >>
>> >> Thanks
>> >>
>> >> Paul K0UYA
>> >
>> >
>> > _______________________________________________
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>> > Amps@contesting.com
>> > http://lists.contesting.com/mailman/listinfo/amps
>> >
>> >
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>>
>
>
>
>
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