9 Nov
2005
9 Nov
'05
7:20 p.m.
Subject: RE: Discharging a VT100 CRT
From: "Julian Wolfe" <fireflyst at earthlink.net>
Date: Wed, 09 Nov 2005 12:43:29 -0600
To: "'General Discussion: On-Topic and Off-Topic Posts'" <cctalk
at classiccmp.org>
Well, you were right. Something did blow on the VT100 video board, and in a
bad way. It looks very much like it was that diode you speak of, cause
there's a huge burnmark on the board at the contact points of the diode. If
that's not an "I died" indicator, I don't know what is.
Can anyone tell me what diode to buy to replace it? I'm thinking of getting
a replacement video board, and then replacing the diode on that, just in
case it took something else with it. The whole "y" trace has a brownmark
around it that the diode was connected to, and that has a big cap next to
it.
Check the diode first as often they survive. If it didn't it may be
the 1A 1000V device (1n4007 will work) at CR102. The cap is correct value
(22uf) but about half the required working voltage so it shorts after a
long time. I forget if it was C102 or c103 and the working voltage should
be at least 100V but not more than 160V. or so memory says.
Allison
9 Nov
9 Nov
10:51 p.m.
Yep, you know your stuff Allison. C102 and 103 are both 50v caps according
to the schematic. Should I replace them with equivalent electrolytic 100v
caps? I'm not an electrician, but I've built working stuff with a soldering
iron when given the right parts.
If I can build this into a better VT100 and not have to open it again for a
good long time, it'll be worth my time and trouble now.
-----Original Message-----
From: cctalk-bounces at classiccmp.org [mailto:cctalk-bounces at classiccmp.org]
On Behalf Of Allison
Sent: Wednesday, November 09, 2005 1:21 PM
To: cctalk at classiccmp.org
Subject: RE: Discharging a VT100 CRT
Subject: RE: Discharging a VT100 CRT
From: "Julian Wolfe" <fireflyst at earthlink.net>
Date: Wed, 09 Nov 2005 12:43:29 -0600
To: "'General Discussion: On-Topic and Off-Topic Posts'"
<cctalk at classiccmp.org>
Well, you were right. Something did blow on the VT100 video board, and in
a
bad way. It looks very much like it was that diode you
speak of, cause
there's a huge burnmark on the board at the contact points of the diode.
If
that's not an "I died" indicator, I
don't know what is.
Can anyone tell me what diode to buy to replace it? I'm thinking of
getting
a replacement video board, and then replacing the diode
on that, just in
case it took something else with it. The whole "y" trace has a brownmark
around it that the diode was connected to, and that has a big cap next to
it.
Check the diode first as often they survive. If it didn't it may be
the 1A 1000V device (1n4007 will work) at CR102. The cap is correct value
(22uf) but about half the required working voltage so it shorts after a
long time. I forget if it was C102 or c103 and the working voltage should
be at least 100V but not more than 160V. or so memory says.
Allison
10 Nov
10 Nov
1:16 a.m.
New subject: VT100 video board repair.
I believe that you can get by with a fairly wide range of diodes and
caps if you just readjust the video after throwing the cap and diode in.
If I remember correctly the diode was 50v -- and should be at least 100
as you say.
I think I used a 47uf once since I had the right voltage on the shelf at
Radio Shack.
The good news is I think the thing's still working.
Bill
Allison wrote:
Subject: RE:
Discharging a VT100 CRT
From: "Julian Wolfe" <fireflyst at earthlink.net>
Date: Wed, 09 Nov 2005 12:43:29 -0600
To: "'General Discussion: On-Topic and Off-Topic Posts'" <cctalk
at classiccmp.org>
Well, you were right. Something did blow on the VT100 video board, and in a
bad way. It looks very much like it was that diode you speak of, cause
there's a huge burnmark on the board at the contact points of the diode. If
that's not an "I died" indicator, I don't know what is.
Can anyone tell me what diode to buy to replace it? I'm thinking of getting
a replacement video board, and then replacing the diode on that, just in
case it took something else with it. The whole "y" trace has a brownmark
around it that the diode was connected to, and that has a big cap next to
it.
Check the diode first as often they survive. If it didn't it may be
the 1A 1000V device (1n4007 will work) at CR102. The cap is correct value
(22uf) but about half the required working voltage so it shorts after a
long time. I forget if it was C102 or c103 and the working voltage should
be at least 100V but not more than 160V. or so memory says.
Allison
6997
days inactive
6998
days old
2 comments
3 participants
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