Re: K6100 T901

I've thought about this some more, and it seems to me this would not
be that hard to rewind yourself. You can easily measure the turns ratio
of a working transformer with a signal generator set to the right frequency
and a volt meter to read the output. Or just probe the input and output
terminals of the transformer in a working circuit, though the load on the
transformer could affect the readings.

Then you could estimate the number of turns on the primary by measuring the
resistance of the wire and it's gauge, and using a chart that lists the
resistance/foot of the standard wire gauges.

Winding transformers is not fun, but not hard to do. Just time consuming.
If there is enough demand, it might be worth while to get a batch of them
custom made.

I know someone who sold a Scope Clock kit, and he had the special transformer
he needed for his design custom made. I could ask him where he got them made
if there is enough interest to investigate this further.

Is there a pent up demand for this transformer?

___
Ken

> --- k_lists@scrapheap.net wrote:
>
> From: Ken Sumrall<k_lists@scrapheap.net>
> To: vectorlist@vectorlist.org
> Subject: Re: VECTOR: K6100 T901
> Date: Sun, 28 Aug 2011 19:33:27 -0700
>
> I searched my local archives of the vector list, and found this post
> from July 8, 2007 from Hans O:
>
> > AH, now I remember. They're found in old B& W raster chassis.
> > Track down an old 19V1001 or 1003 chassis. Should be a bunch of
> > dead ones out there.
> >
> > Hans O
>
> Good luck!
>
> ___
> Ken
>
> akswanson@ntelos.net wrote:
>
>> lol..no worries.. I guessed maybe I had the wrong part ##. I will
>> DEFINATLEY check that out!!
>>
>>
>>
>> > Oops, I just realized you're not talking about the flyback, but the
>> > smaller transformer on the HV board.
>> >
>> > Sorry, I don't know where to get a new one of those. However, I do
>> > recommend you read the installation manual for the replacement flyback
>> > which you can find at the first link below. It includes instructions on
>> > how to add 3 fuses to the HV circuit to protect components (including
>> > T901) in the event of another failure like the one you have.
>> >
>> > ___
>> > Ken
>> >
>> >
>> > Ken Sumrall wrote:
>> >
>> >> You can get one here:
>> >>
>> >> http://www.cinelabs.com/wg6100/
>> >>
>> >> which has link to here:
>> >>
>> >> http://arcadeshop.com/wgxy-fb/wgxy-fb.htm
>> >>
>> >> $79, and comes with extra protection components and a new focus
>> >> assembly.
>> >>
>> >> Note, I've never ordered or used one of these flybacks, I just
> remmeber
>> >> seeing it recently while searching for other parts to bring a 6100
> back
>> >> to life.
>> >>
>> >> ___
>> >> Ken
>> >>
>> >>
>> >> akswanson@ntelos.net wrote:
>> >>
>> >>> I had suspected the triple nickel (555), and indeed it was fried.
>> >>> It also took out Q905, AND T901.. I verified this by trying T901 in a
>> >>> known good HV unit. I got smoke, and another blown Q905.. So if
>> >>> anybody knows where I can get a replacement T901 thatd be swell!
>> >>>
>> >>>
>> >>>
>> >>> > I'm not saying that you don't have a bad T901, but can you verify
>> >>> that
>> >>> > IC901 (555 timer as a simple oscillator) is running. A scope would
>> >>> show a
>> >>> > nice square wave coming out at pin 3. If it is stuck in the high
>> >>> state,
>> >>> > it would keep Q904 and Q905 turned on constantly and that would
>> >>> certainly
>> >>> > cause your problem. Of course in this state, there would be no HV
>> >>> output
>> >>> > at all. Check ZD900 for 13V across it. ZD900 is the voltage
>> >>> regulator
>> >>> > for the 555 chip. If the zener is partially shorted and there isn't
>> >>> > enough voltage across the 555 chip, then the 555 chip output might
>> >>> be
>> >>> > stuck even if there's nothing wrong with it. If the zener is
>> >>> > open-circuit, the 555 chip will likely have blown.
>> >>> >
>> >>> > You should remove R917 and leave it out until you can verify that
>> >>> IC901 is
>> >>> > running okay and that the transistors Q904/905 are both switching.
>> >>> To
>> >>> > functionally test Q905, you can add a temporary 10k (to 47k)
>> >>> resistor
>> >>> > (1/2W to 1W) from +Vsupply (+28V) to Q905 collector. If scope shows
>> >>> a
>> >>> > good square wave, remove the temporary resistor and return your
>> >>> focus to
>> >>> > T901.
>> >>> > If you do not have a scope but you have a voltmeter, connect your
>> >>> meter
>> >>> > (-) to ZD900 anode or IC901 pin 1. Use the meter(+) to measure
>> >>> voltage at
>> >>> > ZD900 cathode and IC901 pin 8. Both should be about 13V. Measure
>> >>> IC901
>> >>> > pin 3. If it is running, it should be around 6.5V plus/minus around
>> >>> 0.5V
>> >>> > roughly. The point here is that pin 3 should be outputting a square
>> >>> wave
>> >>> > having roughly a 50% duty cycle so the voltmeter should show
>> >>> approximately
>> >>> > one half the chip supply voltage.
>> >>> >
>> >>> >
>> >>> > William Boucher
>> >>> > http://www.biltronix.com
>> >>> > ----- Original Message -----
>> >>> >
>> >>>
>> From: akswanson@ntelos.net
>> >>> > To: vectorlist@vectorlist.org
>> >>> > Sent: Sunday, August 28, 2011 9:20 AM
>> >>> > Subject: VECTOR: K6100 T901
>> >>> >
>> >>> >
>> >>> > One of my 6100s had a fire on the HV board, took out R917 and Q905.
>> >>> I
>> >>> > replaced those, and got smoke again.. Comparing the resistance of
>> >>> the
>> >>> > primary of T901 to a known working T901 I get 9.5 Ohms on the
>> >>> suspected
>> >>> > bad one and 17 ohms on the known good one. I get the feeling I
>> >>> melted
>> >>> > the varnish on the wiring and shorted them together.. Does anyone
>> >>> know
>> >>> > where (or have) and extra T901? Also, Is there a secondary cause,
>> >>> such
>> >>> > as a flyback failure that would cause this kind of failure? I dont
>> >>> > want to blow the dang thing again..
>> >>> >
>> >>> >
>> >>> >
>> >>> > Andrew
>> >>> >
>> >>>
>> >>
>>
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>> >> chris@westnet.com
>> >>
>> >>
>> >
>>
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>> >
>>
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Received on Fri Sep 2 16:59:37 2011