$$$$$ Chris, the schematic is correct, the actual wiring is wrong. All units
have one or both problems. ALL units need some level of re wiring for them to
conform to the schematic.
I read the original post as these were home assembled from kits, and
the original build manual / schematic showed an incorrect way to wire
the interlock? Or are they all commercially assembled units?
--
Best Regards,
Chris Wilson.
-----Original Message-----
From: Chris Wilson <chris@chriswilson.tv>
To: amps <amps@contesting.com>
Sent: Mon, Oct 14, 2013 6:02 am
Subject: Re: [Amps] Ameritron AL-82/1200/1500 amps mis-wired!
Jim Thomson> Date: Sat, 12 Oct 2013 07:04:48 -0400 (EDT)
Jim Thomson> From: Louis Parascondola <gudguyham@aol.com>
Jim Thomson> To: amps@contesting.com
Jim Thomson> Subject: [Amps] Ameritron AL-82/1200/1500 amps mis-wired!
Jim Thomson> For those of you who might have any of these amps, they
Jim Thomson> are mis wired. Seems that pretty much all of them going
Jim Thomson> back quite some time. They are not wired according to
Jim Thomson> the schematic and therefore a possible shock hazard is
Jim Thomson> possible. One might assume that when interlock switch S5
Jim Thomson> is open (cover removed) that there is ZERO high voltage
Jim Thomson> in the amp. But due to the mis wiring there is about
Jim Thomson> 400vdc which is in the power supply and on the tube
Jim Thomson> anodes. I suggest you "CAREFULLY" make the test to your
Jim Thomson> amp to see if the problem exists. Simply remove the
Jim Thomson> cover and turn the amp on and look at the HV meter. If
Jim Thomson> you get any reading other than zero, your amp is
Jim Thomson> mis-wired and you should consider wiring it properly.
Jim Thomson> The fix is simple. There is a blue/white wire coming from
Jim Thomson> the contactor relay going over to the step start relay at
Jim Thomson> junction with R3. There is a wire on S5 (on left contact
Jim Thomson> as viewed from front). These 2 wires need to be switched
Jim Thomson> to conform to the schematic. In doing so, th
Jim Thomson> e 400vdc with S5 open goes away. Although the manual
Jim Thomson> states never to plug the amp in with the lid off, I know
Jim Thomson> many of us do troubleshooting and we may wrongly assume
Jim Thomson> that no HV is present when S5 is open. If you are not
Jim Thomson> qualified to make the repair, ask someone that is to do
Jim Thomson> it for you. I believe this is a repair that should be
Jim Thomson> made to all these amps that exhibit this problem. Please
Jim Thomson> be careful in making the test or doing the repair. Lou
Jim Thomson> ## I have NOT looked at the schematic. Does the
Jim Thomson> Interlock short the B+ to the chassis..or does it open
Jim Thomson> off the 240vac to the plate xfmr....or both....or what ??
Jim Thomson> Is the problem on older amps... or newer vintage
Jim Thomson> versions?? IE: how widespread is the issue ?
Jim Thomson> Surprised somebody hasn’t fried themselves already.
Jim Thomson> Either way, the correct procedure would be.... to also
Jim Thomson> chassis ground the B+ with an alligator clip. Then
Jim Thomson> you know its at zero volts. Clip goes on 1st....and comes off
dead last.
Jim Thomson> Then if something else goes wrong...... you are
Jim Thomson> covered. If you want to be super safe, use 2-3
Jim Thomson> clips..and grnd the B+ in two different places...like
Jim Thomson> the anodes, and the B+ end of the
Jim Thomson> string of HV filter caps. Another good place is
Jim Thomson> directly between the B+ and B- of the string of filter caps.
Jim Thomson> ## Ameritron of course, should be notified. Its not
Jim Thomson> a design issue, its an assembly issue. IF you have the
Jim Thomson> SNs, they may be able to track it down to a specific employee or
Jim Thomson> group of employees. If they cant, they truly are idiots.
Jim Thomson> ## So much for any kind of testing of the finished
Jim Thomson> product. IE: step 1, check interlock, does Vdc and or
Jim Thomson> ACv drop to zero ? If not, check wiring XXX.
Jim Thomson> Damned good thing they are not building medical or
Jim Thomson> military or aircraft equipment.
Jim Thomson> Jim VE7RF
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14/10/2013 11:00
I read the original post as these were home assembled from kits, and
the original build manual / schematic showed an incorrect way to wire
the interlock? Or are they all commercially assembled units?
--
Best Regards,
Chris Wilson.
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