[Amps] Ameritron AL-82/1200/1500 amps mis-wired!

[Jim W7RY]

That is incorrect Bill.

The schematic of the SB-1000 (an looking at the one currently on my 
bench) clearly shows the open interlock controls the one and only AC 
power relay to the rest of the amplifier. No filament or high voltage is 
present with the interlock switch open.

Unless you count the voltage not yet bled down from the filter capacitors.
73
Jim W7RY


On 10/12/2013 9:30 AM, Bill Turner wrote:
> ORIGINAL MESSAGE:          (may be snipped)
>
> On Sat, 12 Oct 2013 07:04:48 -0400 (EDT), Louis wrote:
>
>> For those of you who might have any of these amps, they are mis wired.  Seems that pretty much all of them going back quite some time.  They are not wired according to the schematic and therefore a possible shock hazard is possible.  One might assume that when interlock switch S5 is open (cover removed) that there is ZERO high voltage in the amp.  But due to the mis wiring there is about 400vdc which is in the power supply and on the tube anodes.  I suggest you "CAREFULLY" make the test to your amp to see if the problem exists.  Simply remove the cover and turn the amp on and look at the HV meter.  If you get any reading other than zero, your amp is mis-wired and you should consider wiring it properly.  The fix is simple. There is a blue/white wire coming from the contactor relay going over to the step start relay at junction with R3.  There is a wire on S5 (on left contact as viewed from front).  These 2 wires need to be switched to conform to the schematic.  In doing so, t
>   h
>> e 400vdc with S5 open goes away.  Although the manual states never to plug the amp in with the lid off, I know many of us do troubleshooting and we may wrongly assume that no HV is present when S5 is open.   If you are not qualified to make the repair, ask someone that is to do it for you.  I believe this is a repair that should be made to all these amps that exhibit this problem.  Please be careful in making the test or doing the repair. Lou
> REPLY:
>
> There was a very similar issue with the Heath SB-1000 many years ago. I
> reported it to Heath but never heard back from them.
>
> If you are an SB-1000 owner you should make the same check as above.
>
> In fact, many of the Heath/Ameritron amps share some circuitry so it might
> be wise to check yours just to be sure.
>
> 73, Bill W6WRT
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