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I have a TG501 with Option #1 and I need Y50 5Mhz Oscillator which is TEKTRONIX p/n 119-0262-00 or 119-0503-00. These are also used in 7xxx series plugins and other TM5xx plug ins as well. I have looked at the usual sources, including Sphere's online catalog and E-Bay as well, no luck so far. Does anyone have an extra unused part that they would be willing to sell? I would be more than happy to pay a reasonable price and shipping to anyone who might have one. I would prefer an item located in the USA, but would consider anything that is offered. I can pay through PayPal.
I have also read a couple of posts regarding this part and discussion about using some very common 10Mhz OCXO part to replace it. I am not 100% clear on how this is done, ISTR this involved using a 5V regulator to step down the 15V to 5V and rewiring the U50 divider to divide the 10Mhz down to 1 Mhz. Dennis Tillman touched on this in a post, I believe regarding a TM5xx series counter which he improved the performance of, using this method. I am not as experienced as Dennis, so what seems obvious and simple to most is somewhat more daunting to me. I would also consider this route, if I could get some more details, possibly a schematic, pictures and a BOM?

Thanks to All!
--
Michael Lynch
Dardanelle, AR

Here's some info on repairing 620's. It had a crt dot but it might help you.
Leonard

Hi group,

I'm refurbishing a 602 with no spot visible (with Z input driven at ~
1V). All LV voltages are good. Waiting for a high voltage probe in order
to do more checks.

I want to keep a spare CRT on hand just in case, and I'd prefer it to
have P7 or P45 phosphor.

I also have 634 and 604 here. Does anyone know the CRT compatibility for
the various 6xx family models? Ebay hasn't turned up a 154-0562-01 or
154-0572-01 yet, but if there is wider compatibility it would be
interesting to know.

Thanks for any guidance on 602 troubleshooting or CRTs.

--Toby

On 13/12/19 02:54, ehsjr via Groups.Io wrote:

On 12/12/2019 3:59 PM, Mark Pilant wrote:

So, here is a list of what I tried and whether or not it "worked":
??? 1)?? Used the TekWiki cap/resistor replacement for the battery.? Did not work.

Two things come to mind on that.
First, do not attempt to power on the 1502 immediately after plugging
in the AC cord or wall wart supply.? Give it a few seconds to charge
the cap, then turn the 1502 on.

Second, the cap may be too small.? I used 4700uF which works
fine for me - I think the wiki recommends 2200.

The problem is that if the capacitor is too large it takes too long to charge up. The PSU interprets the low voltage as a failed cell, and shuts down.

The required C (and R) seems to be select-on-test, varying from one 1502 to another. Even if suitable values are found, it makes me wonder if it will switch on /next/ time :(

On 12/12/2019 3:59 PM, Mark Pilant wrote:

Success.
After using the bench supply, and giving the unit a couple of minutes to warm up,
I started rotating the intensity control. As I swept to the upper end, I could see
evidence of a trace, although off the CRT. By adjusting the vertical position, I
was able to finally see the trace on the CRT.
I decided to check a couple of RG-58 test cables I had laying around, and the TDR
got them right.
So, here is a list of what I tried and whether or not it "worked":
1) Used the TekWiki cap/resistor replacement for the battery. Did not work.

Two things come to mind on that.
First, do not attempt to power on the 1502 immediately after plugging
in the AC cord or wall wart supply. Give it a few seconds to charge
the cap, then turn the 1502 on.

Second, the cap may be too small. I used 4700uF which works
fine for me - I think the wiki recommends 2200.

Finally, if using an external supply (wall wart or otherwise),
put a diode in series between the supply and the cap/resistor
combo. The diode is to protect the 1502 against plugging in a
wall wart or supply with the opposite polarity, and protect "backfeeding" the wall wart or supply. The TDR tries to put
about 17 volts across the bananna jacks to charge the battery.

Ed

<snip>

On Thu, Dec 12, 2019 at 10:41 PM, John Griessen wrote:

must mean it is for eindhoven Netherlands. Tek had a factory at Heerenveen,
so maybe the customer was in eindhoven?

Dutch Philips' main offices were in Eindhoven.

Raymond

On the HV board, find Pin G, disconnect the wire and put your ammeter in-line. You should get a baseline reading when you first turn it on. As the unit warms up you should see the current draw slowly increase (if the HV transformer is shorted). This is the 100V Supply, but it affects the entire system when it overloads the main transformer.
--
Michael Lynch
Dardanelle, AR

Eric,

I’m not saying that I am 100% correct about this, it just sounds exactly like what my unit did as well.

--
Michael Lynch
Dardanelle, AR

That is my guess as to the problem. Mine did exactly the same thing. I have a very old one and a very late model one as well. The old one had the Brown transformer, the new unit has the Black one. I found the power in wire to the HV transformer and put an ammeter in-line to read the current draw. I will look at the schematic and tell you which wire I used. What mine did was started out at a low current draw , the unit worked fine, and as it heated up, the draw slowly increased until the power supply finally tripped. I don’t remember the exact current draw numbers. BTW, I have a prototype transformer in the works to replace the brown transformers. I will put you down on my list as potentially needing a replacement for yours.

--
Michael Lynch
Dardanelle, AR

Ignacio,

Oops! Fumble fingers here. The correction has been made.

Thanks!!

Greg

<<<<<

Ignatio EB4APL mentioned:

Greg,

After searching for your album, I realized that there is typing error in the name, "Tex" instead of "Tek"

Regards,

Ignacio

This one does for sure the brown potted one. The serial number is 22XXX. I would have never guessed that one would have spent the night banging my head agents the power supply. Is there a test I can do to confirm the transformer?

On 12/12/19 3:24 PM, John Williams wrote:

would appreciate it if someone out there could shed any light on purpose, origin, etc.

That mostly black film is a tooling film for making
photosensitive prints by contact probably. It's what patterned
the resist for an aluminum anodized front panel.

FOR HOVEN MOD MONTEK

must mean it is for eindhoven Netherlands. Tek had a factory at Heerenveen,
so maybe the customer was in eindhoven?

HV transformer is going out. Look to see if it has the brown encapsulated HV transformer.
--
Michael Lynch
Dardanelle, AR

I purchased these Tektronix photos on Mylar from eBay. I would appreciate it if someone out there could shed any light on purpose, origin, etc. The listing has good photos so I won’t try to post any more. Thanks. John

Working in the low voltage section of the 576. This is an older low voltage board all gold traces. The power supply keeps resetting itself. I was monitoring the -75 volt rail yesterday and it was rock solid for about 20 minutes. Then the power supply starts to rise to 0. Then it totally collapses and starts oscillating. And as it is doing that all the relays in the unit start to chatter and stutter. Any one have any ideas what might cause this or am I in for a hunt?

Don't be surprised if this turns out to be Tek-made - you may be able to tell by the boards, parts, and construction techniques. Tek did work with LCDs in the late 1980s to early 1990s. The well known ones are the color-shutter, used with CRTs in various products, and the plasma-addressed liquid crystal (PALC) technology. So, it's possible that this setup was used for in-house R&D.

The color-shutter is what gives many of the TDS scopes their multi-color display capability. For those who never heard of PALC, here's a very succinct description:


Ed

When I was putting mine back together a while ago after fixing a HV
issue, I had the IEC extender that's screwed into the cabinet just fall
apart on me. I was able to use the terminal pieces to fabricate a
replacement using a urethane rubber casting compound, but some recent
experience leads me to think that you could also use hot melt glue as a
thermal casting material to mold the item.

It's probably not waterproof anymore, but I don't plan on dunking it anyway.

Be careful putting it back together - that extender is NOT available anywhere that
I could find.

That is one neat little box.

Paul

--
Paul Amaranth, GCIH | Manchester MI, USA
Aurora Group of Michigan, LLC | Security, Systems & Software
paul@... | Unix & Windows

Success.

After using the bench supply, and giving the unit a couple of minutes to warm up,
I started rotating the intensity control. As I swept to the upper end, I could see
evidence of a trace, although off the CRT. By adjusting the vertical position, I
was able to finally see the trace on the CRT.

I decided to check a couple of RG-58 test cables I had laying around, and the TDR
got them right.

So, here is a list of what I tried and whether or not it "worked":
1) Used the TekWiki cap/resistor replacement for the battery. Did not work.
2) Checked all the 470uf caps on the underside of the power supply board. Two
checked fine on my ESR/cap meter and one checked open. I replaced the
"open" cap with a new one. Not certain it "worked".
3) Power supply still not functioning, so I hooked the 1502 to a bench supply.
Success, all voltages correct.
4) I checked the supposed "open" cap out of circuit it checked fine. So I put it
back. Non-problem.
5) Left the 1502 powered up for a bit while I checked the power supply voltages.
After a bit (a minute or two) on a whim I tried rotating the intensity control and
saw evidence of a CRT trace.
6) Using the vertical position, intensity, and focus controls I was able to get a nice
clean trace on the CRT.

So now to figure out what I want to do about the battery pack and then put everything
back together (mostly put the case on).

Thanks for all the suggestions.

- Mark N1VQW

Greg,

After searching for your album, I realized that there is typing error in the name, "Tex" instead of "Tek"

Regards,

Ignacio

On 12/12/2019 11:59 AM, Mark Pilant wrote:

Hi Tom.
Got around to testing the 1502 using a bench supply.? As you suggested,
when hooked up, the 1502 power supply started operating as expected.? All
the voltages appeared to be to spec.? Although still no trace on the CRT.
I guess there may be some issues with the TekWiki suggested modification
of a 2200uf cap in parallel with a 270 10W resistor.
So now I need to figure out what to do.? I'm thinking of possibly using
a 12V 2A "wall wart" supply connected to the banana plugs instead of the
nor mal AC power cord.? The main problem is how to actually connect it
all up.
There is room on the rear panel for one of the ubiquitous coaxial power
connectors, but I'm a little reluctant to drill a hole for it.? I could
terminate the power card in the supply in a female banana jack attached
to some sort of "paddle" to make it easier to connect / disconnect; but
it would be "a bit" ugly :-)
Any other ideas out there?

Yes. First see Paul's reply. It's good for building a
battery pack AND for the cap/resistor mod AND for
mounting a jack for a 12V supply. NO internal mods
to the 1502.

Another way (but Paul's is better in my opinion) is
what I did years ago with a method a little different
than Paul's: two plates, connected by a threaded
rod and held apart by nuts on the rod. The distance between
the plates is adjusted so they exactly fit the depth of
of the battery compartment, then the nuts are tightened.
The inner plate has the dual banana plug and the outer
plate has the jack for the wall wart supply. There's
tons of room between the plates for the cap and resistor.

Inside Outside
Plate Plate
|............|
|==========={|}=
|............|

The = signs are the threaded rod, the {} are the nuts.
Ignore the periods - they are there to make the spacing
appear correctly for those with different font settings.

Ed

- Mark? N1VQW