Re: 5103 Mainframe HV PS help

Paul Amaranth
 

Now that's a good question. Chokes don't usually fail spontaneously.
I'll replace that one too while I have it apart. More proof that
schematics make more sense after coffee than after a long day.

I'm getting tempted to replace every part in that section. There's
not much left.

Paul

On Thu, Dec 30, 2010 at 12:25:44AM -0500, Tom Miller wrote:
So how did L259 get smoked unless DC got through C259? That is the choke you refer to, correct?

You have a good one. Good luck.

Tom




----- Original Message -----
From: Paul Amaranth
To: TekScopes@...
Sent: Wednesday, December 29, 2010 11:44 PM
Subject: Re: [TekScopes] 5103 Mainframe HV PS help



That one was easy to check. C259 is actually 0.22 uf and, in my case,
measures out at .19 uf, so that's close enough. Yeah, that Q was toast
(that's the NTE-94). I thought the 10uf/100V cap (C251) might have
been shorted, but that was OK too. So far it looks like mostly
semiconductors, plus some collateral damage.

Paul

On Wed, Dec 29, 2010 at 10:27:27PM -0500, Tom Miller wrote:
> Be sure to check C-259. If the choke failed, I would think the cap shorted. It's a 2.2 uF. If it shorted, the Q will be toast.
> I also could not find the VR reference in the parts list but would agree with you as it being a 9.1 volt 1 watt zener.
>
> Tom
>
>
> ----- Original Message -----
> From: Paul Amaranth
> To: TekScopes@...
> Sent: Wednesday, December 29, 2010 9:56 PM
> Subject: [TekScopes] 5103 Mainframe HV PS help
>
>
>
> I'm trying to repair the HV section on my 5103n and I've run
> into a bit of a problem.
>
> The power transistor had shorted out and took out a few other
> components. I crossed the 151-0256-00 to an NTE-94 which
> seems to be an identical match from the data sheets.
>
> However, I also have a couple of shorted diodes. One, a
> 152-0141-02 crosses to a 1n4152, so that's fine. The
> other one is a bit of a puzzle. From the schematic it
> looks like a 9.1V zener and is called out as VR258.
>
> In the scan of the manual I have, I do not have any
> listings for VR numbers. After all of the transistors,
> there are a few resistors and that's it.
>
> There's no readable marking on the part.
>
> Anyone have a clue what the part number is?
>
> This is for sn <= SN119999 from a 5110 manual.
>
> Failing any other leads, I'll just try a 1w 9.1v zener.
>
> Also, anyone have a source for a 74uH axial choke? The one
> in the PS failed open.
>
> thanks
> --
> Paul Amaranth, GCIH | Rochester MI, USA
> Aurora Group, Inc. | Security, Systems & Software
> paul@... | Unix & Windows
>
>
>
>
> ----------------------------------------------------------
>
> No virus found in this message.
> Checked by AVG - www.avg.com
> Version: 10.0.1191 / Virus Database: 1435/3346 - Release Date: 12/29/10

--
Paul Amaranth, GCIH | Rochester MI, USA
Aurora Group, Inc. | Security, Systems & Software
paul@... | Unix & Windows




------------------------------------------------------------------------------

No virus found in this message.
Checked by AVG - www.avg.com
Version: 10.0.1191 / Virus Database: 1435/3346 - Release Date: 12/29/10
--
Paul Amaranth, GCIH | Rochester MI, USA
Aurora Group, Inc. | Security, Systems & Software
paul@... | Unix & Windows

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