[TechAssist] Re: Tektronix 485 Oscilliscope - Power Supply Cycling ON/OFF - FIXED
- From: "majorthom@xxxxxxxxxxxxx" <majorthom@xxxxxxxxxxxxx>
- To: techassist@xxxxxxxxxxxxx
- Date: Wed, 23 Feb 2005 21:25:27 -0800 (PST)
www.sphere.bc.ca/test/tekparts.html I believe
Pete
David Lessard <mr_fixit@xxxxxxxxxxxx> wrote:
Pete, Do you know who they are? Send me the information please.
David Lessard
Alexandria, Ontario, Canada
mr_fixit@xxxxxxxxxxxx
----- Original Message -----
From:
To:
Sent: Wednesday, February 23, 2005 10:44 PM
Subject: [TechAssist] Re: Tektronix 485 Oscilliscope - Power Supply Cycling
ON/OFF - FIXED
> David,Theres a Canadian source that supplies all kinds of TEK parts.right
on down to the snap-in parts on Vert In attenuator.
> Later,Pete
>
> David Lessard wrote:
> They sure are, I couldn't have traced this short without one. The (- 5V)
> power distributes everywhere. This was a great experience for me, now I'll
> be able to service this thing forever...oh yeah...most of the parts are
> obsolete now...forgot this thing is 30+ years old. You couldn't tell by
the
> way it works.
>
> David Lessard
> Alexandria, Ontario, Canada
> mr_fixit@xxxxxxxxxxxx
>
> ----- Original Message -----
> From:
> To:
> Sent: Wednesday, February 23, 2005 10:05 PM
> Subject: [TechAssist] Re: Tektronix 485 Oscilliscope - Power Supply
Cycling
> ON/OFF - FIXED
>
>
> > Aren't schematics great
> > Pete
> > David Lessard wrote:
> > FIXED
> >
> > These things are built like brick sh*! houses. After acquiring a
schematic
> I
> > discovered a shorted C852 (.47uf) on the attenuator board - PS
decoupling
> > capacitor shorting (-5V) to ground. All power supply current is
monitored,
> > shorts or excessive loads cause the power supply to shutdown. In this
case
> > the power supply was restarting, over and over again, about 3 times a
> > second. While I had it opened I cleaned all the switches and
> > potientiometers. Signals look better then ever.
> >
> > David Lessard
> > Alexandria, Ontario, Canada
> > mr_fixit@xxxxxxxxxxxx
> >
> > ----- Original Message -----
> > From:
> > To:
> > Sent: Tuesday, February 22, 2005 1:23 AM
> > Subject: [TechAssist] Re: Tektronix 485 Oscilliscope - Power Supply
> Cycling
> > ON/OFF
> >
> >
> > > I love these old TEK's
> > > On and on
> > > I'm replying because I have the complete S/M [1" thick]Maybe I send
you
> a
> > schema of a cktif you like
> > > Regards,
> > > Pete I mennt the 475A:they are very similar,Pete
> > > Wally Heise wrote:
> > > David,
> > >
> > > I don't know if the 485 is similar to the 465 scope, but my 465 died
> last
> > > year. I traced the problem to the sealed high voltage module which is
no
> > > longer available from Tektronix. My scope would power up when I
removed
> > > this module, except no high voltage of course. I still have service
> manual
> > > but gave the scope to a friend. Hope that helps in troubleshooting it.
> > >
> > > Wally Heise
> > > South Isle Repair
> > > Isle, Mn.
> > > sirepair@xxxxxxxxxx
> > >
> > >
> > >
> > > ----- Original Message -----
> > > From: "David Lessard"
> > > To:
> > > Sent: February 21, 2005 7:31 PM
> > > Subject: [TechAssist] Tektronix 485 Oscilliscope - Power Supply
Cycling
> > > ON/OFF
> > >
> > >
> > > > Hello All, My week just got tougher, my scope failed today. I may
need
> a
> > > scope to fix my scope. When powered "ON" I can hear the power supply
> > > cycling - on/off/on, etc. The rear fan starts to spin and panel lights
> > start
> > > to light up but only when the power supply is on for that brief 1/2
> > second.
> > > Would anyone have a schematic of the power supply or tips.
> > > > Thank you,
> > > > David Lessard
> > > > mr_fixit@xxxxxxxxxxxx
> > > >
> > >
> >
>
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> > >
> > > Peter Neal
> > > Neal Electronics
> > > 1905 E. Wm.Cannon
> > > Austin,TX 78756
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
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> > Peter Neal
> > Neal Electronics
> > 1905 E. Wm.Cannon
> > Austin,TX 78756
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> Peter Neal
> Neal Electronics
> 1905 E. Wm.Cannon
> Austin,TX 78756
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Peter Neal
Neal Electronics
1905 E. Wm.Cannon
Austin,TX 78756
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