[Hammarlund] HX-500 power supply service bulletin

[Richard Knoppow]

    A couple of things occur to me that may be completely off the wall.
    First, what kind of meter does Hammarlund specify using specifically 
what input resistance? Secondly is this with the load connected? The 
reason I ask about the meter is that the voltage chart for the SP-600-JX 
specifies a 1000 ohm/volt meter except for bias voltages. If you use a 
20K ohm/V meter the readings at most points will be quite high. Maybe 
not here but worth checking.
    BTW what are the voltages supposed to be?

On 4/13/2016 8:02 PM, jeff wrote:
> Thanks Al!
> Finally got the chance to get the rig on the bench. The power supply was completely hacked up.
> Somebody was in there and had put all kinds of power resistors in series and in parallel, some values were greater than, and some less than, the schematic indicated.
> I've got the supply back to where the addendum says it should be. Here's where the problem is- I have very high vtages across the board. I am feeding it a line voltage of 115. My HV is over 1000 volts (with the 5R4 tube in place), the LV coming off of the 6CA4 is over 400 volts, and the 15 ohm resistor at the LV choke input is still above 400. I'm seeing about 270 volts at the junction of R122 and R119.
> I've disconnected the 15 ohm resistor and I see about 330 volts; still high, but where it would be more reasonable. LV choke resistance is 260 ohms, and all new electrolytic of course.
> Bias supply is right on:-90 volts.
> Any thoughts?
>
>
>
> -------- Original message --------
> From: Al Parker <anchor at ec.rr.com>
> Date: 03/20/2016  3:56 PM  (GMT-05:00)
> To: hammarlund at mailman.qth.net
> Subject: Re: [Hammarlund] HX-500 power supply service bulletin
>
> Hi Jeff,
>       Here's the info on the p.s. mods, which incl. what you wanted, on
> the rectifiers, plus the change to an improved pwr xfmr.  I can't
> remember if my HX-500 has the better xfmr or not, but it does have the
> rectifier mods.
>       The .pdf att won't get thru to the reflector, but if anyone else
> wants it, send me a note.
>       I hope it helps.
> 73,
>
> Al, W8UT
> www.boatanchors.org
> www.hammarlund.info
>
> "There is nothing -- absolutely nothing -- half so much
> worth doing as simply messing about in boats"
> Ratty, to Mole
>
> On 3/20/2016 1:32 PM, Jeff wrote:
>   > Does anyone have a copy of the service bulletin that shows what
> modifications were done to the supply? This would be the change between
> the 12 AX 4S and the 5R4, along with a semiconductor device for the bias
> supply.
>   >
>   > Thanks!
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-- 
Richard Knoppow
1oldlens1 at ix.netcom.com
WB6KBL