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Will do.? Thanks for the offer, I plan to take you up on it.

On Mon, Apr 8, 2024 at 4:43?PM Peter Gottlieb <hpnpilot@...> wrote:

Try starting with a 60 Watt incandescent.?

If you need help troubleshooting the supply I would be happy to assist.?

Peter

On Apr 8, 2024, at 7:33?PM, Michael Yellin <michaelhq54@...> wrote:

?

Peter,

This idea "You could wire an incandescent bulb in place of the fuse so you don't keep blowing them.? Find a wattage that will allow the supply to boot, but then light

up when the short occurs" is very interesting.? How can I choose the appropriate wattage of light???

Thanks,

Michael

On Sat, Apr 6, 2024 at 7:05?PM Peter Gottlieb <hpnpilot@...> wrote:

Could be a lot of things.? The manual is available on the web.? At quick glance
it seems when the supply is "on" before being enabled, the main transformer and
rectifiers are live.? You can verify by measuring at the main electrolytics.

My guess is something is wrong with the pass elements and the supply crowbars
but doesn't limit current and the fuse takes over.? You may be able to max out
the crowbar OVP limit and not blow the fuse but that won't solve the problem.

You could wire an incandescent bulb in place of the fuse so you don't keep
blowing them.? Find a wattage that will allow the supply to boot, but then light
up when the short occurs.

Peter



On 4/6/2024 9:48 PM, Harvey White wrote:
> if the fuse blows when activated, then something downstream of the fuse, (once
> activated) is likely a short.? Assuming that the high amperage fuse blows
> roughly as fast as the low amperage fuse (don't try to measure it......) then
> you're likely looking at a dead short downstream of the fuse.
>
> Harvey
>
> On 4/6/2024 7:18 PM, Michael Yellin wrote:
>> Mates,
>>
>> Recently acquired an HP 6643A.? When the unit is plugged in and turned on, it
>> boots, and seems fine.? However, as soon as the unit is "activated" to
>> generate voltage and amperage, the glass fuse blows.? I don't have an endless
>> supply of fuses, but I have tried some very low and very high voltage and
>> amperage settings, but that made no difference (I didn't think it would, but
>> well, it made me feel better to try)? Opened her up, looked around, and
>> everything appears fine, no burnt parts, no bulging caps, no melted wires,
>> and nothing obviously shorted.? Anyone have any ideas what could be wrong, or
>> can send me down a path to try and resurrect the thing.
>>
>> TIA
>> Michael
>>
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