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--- In TekScopes@..., Michael Dunn <mdunn@c...> wrote:

Does anyone know the difference between the 1A5 and 1A7
differential plug ins?

thx

-----------------------------------------------------------------
Michael Dunn | Surround Sound Decoder & Stereo Enhancement
Cantares | Self-Amplified Speakers, Test Equipment
74 George St. | Ambisonic Surround Sound CDs and Recording
Waterloo, Ont. | (519) 744-9395 (fax: 744-7129)
N2J 1K7 | mdunn@c...
Canada |
----------------------------------------------

1A5 is an amplifier with differential inputs and up to 50 Mhz
bandpass, depending on sensitivity. It has an input for a special
differential probe P6046 and also has a comparison power supply built
in which may be connected to one of the differential inputs and
subtracted from the signal connected to the other differential input.
1A7 is an extremely high gain differential amplifier. It has a
bandpass of 500 Khz and a maximun sensitivity of of 10 uv/ division.

Regards, Bernard Lee

I was going to suggest that maybe, with questions like that, you could use a
copy of my book (OSCILLOSCOPES--Selecting and Restoring a Classic) that is
full of such descriptions and includes both the 1A5 and 1A7. However, I see
that Bernard Lee has written you a response that is almost an exact copy of
what I wrote so I can say that you can rely on his answer.

Stan
w7ni@...

Michael Dunn wrote:

I am looking for the 'lock down assembly' for a TEK MOD-3 scope mobile cart.

I am using a TEK R217 rack cart and would like to mount a lock down for my
7904.

Anyone have a spare or any idea where I might find one.

Thanks,
Don

My Tek model 570 vacuum tube curve tracer seems to have
lost the ability to keep the high voltage running. When
it is first powered on, I get a nice trace, but the HV
oscillator tube (6AQ5) looks like it's really unhappy
about it. In a minute or so, the high voltage goes
away with the usual dim expanding trace.

I've replaced the tubes, and don't see anywhere the
supply is overloaded, so I'm guessing a failed
capacitor or shorted turn in the transformer. Anyone
know where to get small quantities of the 1,2,3, and 4
kilovolt capacitors? I've found about half of them,
a couple apiece at five different vendors (I'd end up
spending 10 times more in shipping than in parts).
Are some capacitors more likely to fail than others?
I don't have a high voltage capacitor tester, though
I plan to go through it with the one I do have if I
can't just replace 'em all. And if I'm really unlucky,
anyone know where I can obtain a replacement HV transformer?

Failing all the above, can anyone recommend a place to have
classic Tek gear repaired?

-- Thanks,
John Rehwinkel
spam@...

spam@... wrote:

My Tek model 570 vacuum tube curve tracer seems to have
lost the ability to keep the high voltage running. When
it is first powered on, I get a nice trace, but the HV
oscillator tube (6AQ5) looks like it's really unhappy
about it. In a minute or so, the high voltage goes
away with the usual dim expanding trace.

I've replaced the tubes, and don't see anywhere the
supply is overloaded, so I'm guessing a failed
capacitor or shorted turn in the transformer.

If this unit uses those little oil-filled caps in the HV supply,
try hitting them with some freeze spray. My RM545B did this
(as well as smoking the 6AU5 cathode resistor) due to electrical
leakage in the .001 uF 1KV oscillator tank cap. Chilling this
cap made the problem go away temporarily. I replaced it with
a ceramic disc with the same value and rating.

--
Dan Kerl
dlkerl@...

PS- looking for a 577

At 5:07 PM +0000 2000/12/07, spam@... wrote:

know where to get small quantities of the 1,2,3, and 4
kilovolt capacitors? I've found about half of them,

Digikey has a limited number of HV caps. You can always make series/parallel combinations too... You'd probably want equalizing resistors in the case of series strings.

p.s., I've probably asked before, but does anyone have an 8608 tube to spare?

-----------------------------------------------------------------
Michael Dunn | Surround Sound Decoder & Stereo Enhancer
Cantares | Self-Amplified Speakers, Test Equipment
74 George St. | Ambisonic Surround Sound CDs and Recording
Waterloo, Ont. | (519) 744-9395 (fax: 744-7129)
N2J 1K7 | mdunn@...
Canada |
-----------------------------------------------------------------

spam@... wrote:

My Tek model 570 vacuum tube curve tracer seems to have
lost the ability to keep the high voltage running. When
it is first powered on, I get a nice trace, but the HV
oscillator tube (6AQ5) looks like it's really unhappy
about it. In a minute or so, the high voltage goes
away with the usual dim expanding trace.

I've replaced the tubes, and don't see anywhere the
supply is overloaded, so I'm guessing a failed
capacitor or shorted turn in the transformer. Anyone
know where to get small quantities of the 1,2,3, and 4
kilovolt capacitors? I've found about half of them,
a couple apiece at five different vendors (I'd end up
spending 10 times more in shipping than in parts).
Are some capacitors more likely to fail than others?
I don't have a high voltage capacitor tester, though
I plan to go through it with the one I do have if I
can't just replace 'em all. And if I'm really unlucky,
anyone know where I can obtain a replacement HV transformer?

Failing all the above, can anyone recommend a place to have
classic Tek gear repaired?

-- Thanks,
John Rehwinkel
spam@...


To unsubscribe from this group, send an email to:
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Hi John,

You can use just about any scope as a high voltage capacitor checker. You
just set the vertical input to DC coupling and some fairly sensitive range
like 0.1 volts/division. You then (carefully) connect some low ripple DC
(like the +500 volts from an older Tek scope) to one end of the cap and
touch the other end to the scope input. A very good cap will not leak DC
and the scope trace will return to the screen when the cap is charged. A
leaky cap will cause the trace to remain off screen. You can actually
measure the amount of leakage by realizing the scope is putting 1 megohm on
the end of the cap to ground and forming a DC divider with it. By measuring
the amount of DC deflection on the scope and knowing how much DC you are
applying to the cap, you can actually make a pretty good calculation of the
internal DC leakage resistance of the cap. It should be very very high in a
good cap . . . To get familiar with this testing technique, try some known
good mylar caps (very low leakage) and then try some older "black beauty"
type caps (usually quite high leakage). Make sure you don't apply more DC
than the cap is rated for. Less is OK but won't give you as good a test as
testing it near its rated voltage. The 500 volt supply in an older Tek
scope is DEADLY. BE CAREFUL.

I know of no source of good 570 High Voltage transformers although I know
one guy who rebuilds certain old Tek HV transformers. I am not sure he does
570 transformers, though. He is: Bill Schell, 10102 Winder Trail, Orlando,
FL 32817 Phone: (407) 282-4289.

I had a HV transformer failure in my early 570 and found that I could
substitute a HV transformer from an RM15. It provides a slightly different
CRT cathode voltage than the original but it was close and I think I can
make it work OK if I adjust it to keep the total CRT accellerating voltage
the same as it was originally. I have only partially restored my 570 so I
don't really know if this is a good solution or not.

Stan
w7ni@...

Hi All,

What will be the replacement part for 151-0487-00 ( a transistor) from
the power supply of Tek scope 7603? Many thanks.

Regards,

feng

--- In TekScopes@..., Hong F Du <feng@s...> wrote:

Hi All,

What will be the replacement part for 151-0487-00 ( a transistor)

from

the power supply of Tek scope 7603? Many thanks.

Regards,

feng

December 14, 2000.

The transister is Silicon...NPN.......2N3773...151-0487-00

Regards,
Bernard Lee

Looking for a source for the Sprague 68D series caps used on the
rectifier board of the 7633. Apparently Mallory made a cross at one
time.
I need the 9600uf for sure. I suspect there will be others one I get
the board out.

Thanks,
Rick

Hi,

I just bought a 7704A which works, but poorly. It only has a
bandwidth of 170MHz and the tube blooms badly at a low intensity. It
looks like it needs a new tube but does anyone know whether a weak
tube affects the bandwidth, or do I have other problems?

My other 7704A was tested at the same time and had a 240MHz bandwidth.

Is there a source for replacement tubes?

Can someone give me a few hints.

Just a small thing. I have a number of TM500 modules with broken
plastic edges which look ugly. I have started to fix them by cutting
a section from the hood of a DB25 connector with a matching color.
Glue it in place with cyanoacrylate plastic cement and the device
looks good again.

John Stanton

Anyone have or know where I might be able to get one or both frame adapters
to adapt to my C30 camera:

A 016-0269-02 for a TEK 475A to C30 and/or a 016-0248-00 for 7000 series to
C30.

Thanks in advance!!
Don

Hi Rick,

I might have some of the caps you need but I will need Tek Part Numbers to
do a good search of my stock.

Stan
w7ni@...

Rick Davis wrote:

I need a Fixed film resistor for a TEK 464 scope. Part no 307-0431-01

Thanks in advance
Rob

I'm trying to locate a CRT to repair my Sony/Tek scope. The Part No.
is 154-0866-00. I'm willing to pay a reasonable price for one.

I would also consider purchasing a dead or near dead 336 scope to
salvage the CRT for my unit.

Regards
Rob.

I have just joined your group and reading through the posts show you
have a lot of knowledgeable and helpfull folks here.

I don't want to be a brain picker, but are newbie's allowed to start
with a plee for diagnostic help on the resurection of a dead 321?

If you could put up with some dumb questions and poor spelling I
would appreciate it.

sorry i can't help.

I would be glad to read your questions about fixing your 321 and try to
help.

Stan
w7ni@...

music_lover@... wrote:

Yoohoo. I got a pair of NOS, Tek-boxed 8608 tubes for the vertical of my 556! They work great. Has anyone else had an 8608 fail on them. My bad one had a grid short. I noticed it because the vertical position knob acted like a light dimmer, making the tube glow incandescent white depending on the setting!!!

Michael

-----------------------------------------------------------------
Michael Dunn | Surround Sound Decoder & Stereo Enhancer
Cantares | Self-Amplified Speakers, Test Equipment
74 George St. | Ambisonic Surround Sound CDs and Recording
Waterloo, Ont. | (519) 744-9395 (fax: 744-7129)
N2J 1K7 | mdunn@...
Canada |
-----------------------------------------------------------------

We finally organized and posted all our Tek semiconductors,
along with cross ref data, and they are now on line
here:



we will keep adding more parts categories, like controls, knobs, etc.
as time permits. hope this is helpful to everybody. we will keep
adding more cross-ref data for those who just need to know what is
what, and can get the parts locally.

all the best,
walter