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2246 Horizontal Drive problem.

 

G'day to all.
First time posting, long time reading and enjoying the amazing talent here.
This could be a long shot... but here goes anyway. I now need to repair
my 2246. Horizontal drive to the CRT is asymmetrical with only beam present
on the RHS of the display. I seems the mosfets for the neg horizontal output
have failed. ( Q801, Q802 ). Can anyone assist me in locating a pair ??
Have made inquiries to the usual suppliers here in Oz with no success.
And, would an original factory service manual be available in hard copy ?
S
 

The 2245A and 2247A also used the same horizontal amplifier so their
service manuals are just as good for this.

There was also an alternative horizontal amplifier using bipolar
transistors. As a matter of fact, I just checked the schematics for
both and they look identical except for the output transistors which
makes a weird sort of sense because of the design. So that gives you
another set of replacement options.

On Sun, 3 Apr 2016 15:48:36 +1000, you wrote:


G'day to all.
First time posting, long time reading and enjoying the amazing talent here.
This could be a long shot... but here goes anyway. I now need to repair
my 2246. Horizontal drive to the CRT is asymmetrical with only beam present
on the RHS of the display. I seems the mosfets for the neg horizontal output
have failed. ( Q801, Q802 ). Can anyone assist me in locating a pair ??
Have made inquiries to the usual suppliers here in Oz with no success.
And, would an original factory service manual be available in hard copy ?
S
 

Tektronix P/N to Generic Transistor Type Cross Reference


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Tektronix P/N to Generic Transistor Type Cross Reference
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On Sunday, April 3, 2016 7:49 AM, "Simon Tregear soulamp@... [TekScopes]" <TekScopes@...> wrote:


?
G'day to all.
First time posting, long time reading and enjoying the amazing talent here.
This could be a long shot... but here goes anyway. I now need to repair
my 2246. Horizontal drive to the CRT is asymmetrical with only beam present
on the RHS of the display. I seems the mosfets for the neg horizontal output
have failed. ( Q801, Q802 ). Can anyone assist me in locating a pair ??
Have made inquiries to the usual suppliers here in Oz with no success.
And, would an original factory service manual be available in hard copy ?
S
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[Non-text portions of this message have been removed]
 

try 2N3495
 

and 2N3501S
 

Many thanks for the reply and advice.
s
 

I am not sure what I was looking at when I posted that the two
horizontal amplifier designs were the same except for the transistors.
Whatever it was, I cannot find it now that I am looking for details to
suggest modern replacements for the MOSFET transistors.

There are no modern replacements for the original VP0116 and VN1316
MOSFETs that Tektronix used. The closest I was able to find are the
readily available ZVP2120G and ZVN2120G and they should work just
fine; they have a little more capacitance and a little more gain.

They use the surface mount SOT223 case which is large enough to work
with. A metal heat sink needs to be soldered to the large drain tab
and the gate, source, and drain leads on the other side can be
extended using small lengths of wire so they can be mounted in the
original locations.

On Mon, 4 Apr 2016 14:27:50 +1000, you wrote:

Many thanks for the reply and advice.
s

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