[Boatanchors] Johnson Invader 2000 Help Needed
Al Parker
anchor at ec.rr.com
Mon May 16 09:33:36 EDT 2005
HI Mark,
Sorry to hear that you let the smoke out.
I first looked at the skem, as that was the easiest, and see one path
to gnd thru R88, an 82k res. at the relay amp tube, V-5B. So that's half
of what you're seeing. I then finally got into mine & I measure 38.9k
from V-7 pin 5 to gnd, ~same as you do.
So, it looks like you don't have a problem in the exciter chassis, at
least not there.
Let me know when you get yours on the air, maybe we can get 2 talking
to each other. I haven't used mine for several months, and was initially
startled when I opened the lid and it was warm in the 0A2 area - the
heater resistor on the VFO chassis had been keeping things warm thru the
Winter, I still had the 240vac plugged in. The Invader 2000 shares a
240vac outlet with the URT-23B, so I guess that's been idle longer than
the INV2000.
73,
Al, W8UT
New Bern, NC
BoatAnchors appreciated here
http://www.thecompendium.net/radio/
http://www.hammarlund.info
----- Original Message -----
From: "Mark Bell" <bell at blazenet.net>
To: "Boatanchors List" <boatanchors at mailman.qth.net>
Sent: Monday, May 16, 2005 12:15 AM
Subject: [Boatanchors] Johnson Invader 2000 Help Needed
> Gang --
>
> Bad news -- Initial smoke test of my Invader produced.....smoke!
>
> I popped the fuse on the LV Power Chassis and had some smoke coming from
the
> compartment housing R61 on the Invader. R61 look cracked, but not
burned,
> and I replaced it. The sniff test indicated this was not the culprit,
but
> it ohmed out at 33 ohms, not the 1K it was supposed to be.
>
> The 300V line on the LV supply was blown, and I tracked it down to the
> 5U4 -- it tested dead on both sides. I performed voltage check on the
LV
> supply before installing another tube, and all was OK. After the new
5u4
> was installed, all voltages from the LV chassis was good (high, but I
didn't
> have a load on it).
>
> I then proceeded to do the resistance checks as per the manual. Every
> measurement associated with the 300 / 150V circuit was really high. By
> removing the 0A2, I was able to check the 150V circuit and the dropping
> resistors associated with it are good.
>
> My problem is the 300V circuit. With the 0A2 out of the circuit, and
all
> cables removed from the Invader chassis, I should see essentially
infinite
> resistance between the 300V supply of the LV cable connector (J3 pin 5)
and
> ground. I'm measuring about 33K ohms. I get about 39K from 0A2 pin 5
> (with the OA2 removed); again, I expect to see almost an open.
>
> I need some help in understanding what could be causing this in order to
> know what to look for.
>
> I think there are a few Invader 2K owners on the group; if so, can you
do a
> check on the 0A2 pin 5 and let me know what you getting?
>
> Thanks
>
> Mark K3MSB
>
>
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