1. TekScopes@groups.io
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Re: Mystery TM 504 screws.

Colin Herbert
 

A typo on the diagram could just be the answer. The problem is that while I can credit that 212-0040-00 is the correct screw for where "9" is labelled on the diagram, there are only nine called out in the list, when twice this number is actually required. Perhaps whoever compiled that part of the manual had a "liquid lunch" on a Friday - it's a typo upon a typo.

It still leaves the puzzle of what the little plastic screws are meant for....
Colin.

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of teamlarryohio
Sent: 05 August 2020 14:35
To: TekScopes@groups.io
Subject: Re: [TekScopes] Mystery TM 504 screws.

My manual (same) shows 212-0040-00 are used in many places. I'd bet on a typo.
-ls-
OT Thank You

Stephen
 

I am quite new to this higher level of electronics (for me), and also new here.
My knowledge is therefore very limited compared to that of most people here.

Thus, following some posts I’ve been seeing, I just wanted to thank all the nice people that have, and continue to help me.
I have learned more here, and continue to learn, every day. Even though I don’t always yet understand everything.

So again THANK YOU for being there, and for kindly share your knowledge, time and experience with noobs/beginners like me.

I hope that someday I’ll be able to help others the way you are helping me.

Stephen
Re: Mystery TM 504 screws.

teamlarryohio
 

My manual (same) shows 212-0040-00 are used in many places. I'd bet on a typo.
-ls-
Re: Message to satbeginner and Saroj Pradhan re: Tektronix 2230

ArtekManuals <manuals@...>
 

I highly recommend a nap and a couple of fig newtons

Curmudgeon in Training
Dave
manuals@artekmanuals.com

On 8/5/2020 9:21 AM, Roy Thistle wrote:
On Tue, Aug 4, 2020 at 08:13 PM, Chuck Harris wrote:

our group has a few grumpy old men
... well... some of might be grumpy; but, not old men.... and some of us may be "grumpy old men"... and some of might be other things too!

In my opinion... and this is exactly, and only, my opinion...and exactly and only what I am claiming (so please don't try to insert clandestine personal interpretations and attribute them to me)...
(1) Plainly, the whole point of having a Manager/Moderator is to arbitrate.
(2) The logical consequence of (1)

Groups.io has information pertaining to how (in their expert view) a Groups.io group ought to be managed/moderated.
Groups.io Managers Forum is where the ought is worked out in the wash.

--
Dave
Manuals@ArtekManuals.com
www.ArtekManuals.com
--
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus
Re: Message to satbeginner and Saroj Pradhan re: Tektronix 2230

Roy Thistle
 

On Tue, Aug 4, 2020 at 08:13 PM, Chuck Harris wrote:


our group has a few grumpy old men
... well... some of might be grumpy; but, not old men.... and some of us may be "grumpy old men"... and some of might be other things too!

In my opinion... and this is exactly, and only, my opinion...and exactly and only what I am claiming (so please don't try to insert clandestine personal interpretations and attribute them to me)...
(1) Plainly, the whole point of having a Manager/Moderator is to arbitrate.
(2) The logical consequence of (1)

Groups.io has information pertaining to how (in their expert view) a Groups.io group ought to be managed/moderated.
Groups.io Managers Forum is where the ought is worked out in the wash.
Mystery TM 504 screws.

Colin Herbert
 

Can anyone shed some light on this mystery? I was carrying out some repairs to my TM 504 mainframe, I noticed that there was a particular screw missing. I further noticed that an eBay seller (from who I had purchased before and was sure of their honesty) was selling these screws. On checking in my TM 504 Service Manual (ID# 070-1716-00) I ascertained that the description of the screws in the manual and on the seller's listing were substantially identical. The eBay listing was:

211-0040-00 TM 504 Plastic Screws 4-40 x .25"

The Manual has:

211-0040-00 SCREW, MACHINE: 4-40 x .25", BDCH PLSTC

The manual also shows in Fig. 2 Exploded that these screws are attaching a frame section and that nine are required.

This is where the mystery starts. The screws actually in place on my TM 504 are steel, countersunk head and of a much greater diameter than the plastic ones (which is what you might expect). Does anyone have any idea of what these plastic screws are for and how did such an anomaly happen in the TM 504 Service Manual?
TIA, Colin.
Re: eBay / PayPal Changes and our alternatives

Precaud
 

They require bank data reom sellers, not buyers.
Re: 155-0035-00

Colin Herbert
 

FYI, although there are no 155-0035 ICs there, someone on eBay is selling Tek 155 ICs. You just have to travel to Camberley, UK to pick them up:

https://www.ebay.co.uk/itm/Tektronix-Custom-IC-155-XXXX-XX-New-Old-Stock/333676532016?var=542767266724&;hash=item4db0abd130:g:HjYAAOSwL1VfKoiU

I might point out that Camberley isn't far from London and that I have bought stuff from this seller happily. He usually posts stuff, so why he is only offering pick up on things that would go in a static-sensitive bag in a Jiffy-Bag I don't understand.

Colin.

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Dave Casey
Sent: 05 August 2020 01:50
To: TekScopes@groups.io
Subject: Re: [TekScopes] 155-0035-00

Page 3-6 of the 1982 Semiconductor common design parts catalog lists the
Tek made (155) ICs.

Dave Casey



On Tue, Aug 4, 2020 at 7:09 PM Dennis Tillman W7pF <dennis@ridesoft.com>
wrote:

Hi pitti_pu,
I am puzzled by this part number. The 7L5 service manual confirms it is
correct but there are no 155-0035 ICs. In fact there are no ICs starting
with 155 in any of the Tek Semiconductor or IC parts catalogs I have.

Can someone point me to a list of Tek ICs that does have the 155-xxxx IC
in it?

Dennis Tillman W7pF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of
pitti_pu@hotmail.com
Sent: Tuesday, August 04, 2020 11:27 AM
To: TekScopes@groups.io
Subject: [TekScopes] 155-0035-00

The spectrum analyzer 7L5 contains two 155-0035-00 quad op amps. One of
the four was faulty. No direct replacement was available. Therefore, I
disconnected the three affected pins, then piggy-backed a LM324 in place
with ±15V lines attached to the 115-0035 and added three wires for the
socket. The remaining three op amps in the LM324 are not used.
Works nicely. The gain/bandwidth product of the LM324 is much smaller, but
that does not affect the performance.





--
Dennis Tillman W7pF
TekScopes Moderator
Re: eBay / PayPal Changes and our alternatives

Heinz Breuer
 

Well I was already forced to pay via Adyen by dealing with another company. No problem at all, I could chose PayPal as method of payment. They also offered credit card payment. No bank data required.

regards
Heinz DH2FA, KM5VT

Von meinem iPhone gesendet
Re: FG 502 Adjustment and Possible New Issue

Stephen
 

On Tue, Aug 4, 2020 at 11:04 PM, Roger Evans wrote:


R170 actually controls the slope of one half of the triangle wave by adjusting
the strength of one half of the constant current source into the timing
capacitor. You want to make the positive and negative currents equal so that
the positive and negative slopes are equal and the positive peak is half way
between the two negative peaks. The square wave switches when the triangle
generator switches between the charge / discharge cycles so that makes the
square wave 1:1 as well. It is easier to adjust the way you did it!

Roger
What I actually did, is set the switch to 10(-6), the frequency to .1, and triangle waves. Scope to 1us. That way I have quite a very clear view of the symmetry of the shape. And, as far as I can tell, it works. I find it much easier, and it allows for a more precise, and finer adjustment than what the manual says.
Re: FG 502 Adjustment and Possible New Issue

Roger Evans
 

R170 actually controls the slope of one half of the triangle wave by adjusting the strength of one half of the constant current source into the timing capacitor. You want to make the positive and negative currents equal so that the positive and negative slopes are equal and the positive peak is half way between the two negative peaks. The square wave switches when the triangle generator switches between the charge / discharge cycles so that makes the square wave 1:1 as well. It is easier to adjust the way you did it!

Roger
Re: FG 502 Adjustment and Possible New Issue

Stephen
 

On Tue, Aug 4, 2020 at 10:14 PM, Roger Evans wrote:

Interleaved answers.
My FG502 also has a small DC offset when the offset control is switched out,
looks like R250 should adjust that, I will try it later on.
I will definitely check that out. Thank you Roger!


C287 (0.25 - 1.5pF) is only going to affect the very highest frequency
components, ie the shape of the tip of the triangle at the switching point.
Hummm, interesting... Will check that out too. The interaction is not very obvious with you touch it

Make sure the cable to the scope is terminated in 50ohm for best high
frequency response.
It always is (Albeit with my homemade through terminators).

Thanks again, Roger.
Re: FG 502 Adjustment and Possible New Issue

Stephen
 

On Tue, Aug 4, 2020 at 10:14 PM, Roger Evans wrote:


According to the manual R170 compensates for small offsets in the op-amps that
control the positive and negative constant current sources that control the
timing. The offsets are most noticeable for small voltages into the op-amps
(ie the 0.1 end of the frequency dial. So R170 should compensate for item 4.
in your list but have very little effect when the frequency dial is set to the
upper half of its range.

My FG502 also has a small DC offset when the offset control is switched out,
looks like R250 should adjust that, I will try it later on.

C287 (0.25 - 1.5pF) is only going to affect the very highest frequency
components, ie the shape of the tip of the triangle at the switching point.
Make sure the cable to the scope is terminated in 50ohm for best high
frequency response.

Roger

I actually figured out (I think) what R170 was doing. It adjustS the horizontal symmetry of a square wave signal. You adjust for the same length (pos and neg sides). And that also affects the triangle shapes as well... Hence my weird looking triangles when I messed with it.
Re: FG 502 Adjustment and Possible New Issue

Stephen
 

Rectifications:

1-R170 has much effect. I wasn’t looking for the right thing.
2- C287 has still no visible effect.
3- -25db bleed is still present
4- The picture above is because I messed with R170 without understanding they meant horizontal “Symmetry”. Much better now.

Addendum:

5- More often than not, for a brief moment, the trace gets taller as if more voltage was input...
That happens pretty often, (too often if you ask me), and the signal doesn’t seem to be extremely stable. Flickering vertically just a tiny bit too. It’s hard to explain, but my overall impression is that it’s not very healthy.

On a side note, all pots were cleaned several times over, both with IPA and a good, non lubricating, contact cleaner that doesn’t leave any residual stuff anywhere.


(OFF TOPIC) PS: I bought this contact cleaner once at an all-purpose hardware store to test It, because it was dirt cheap.
I never went back to the much more expensive stuff. It’s from the U.K., so some of you may have seen it or even used it. Here it’s part of the “3-EN-UN” TECHNIQUE (“3-IN-ONE“ TECHNIC), line of products.
Re: FG 502 Adjustment and Possible New Issue

Roger Evans
 

According to the manual R170 compensates for small offsets in the op-amps that control the positive and negative constant current sources that control the timing. The offsets are most noticeable for small voltages into the op-amps (ie the 0.1 end of the frequency dial. So R170 should compensate for item 4. in your list but have very little effect when the frequency dial is set to the upper half of its range.

My FG502 also has a small DC offset when the offset control is switched out, looks like R250 should adjust that, I will try it later on.

C287 (0.25 - 1.5pF) is only going to affect the very highest frequency components, ie the shape of the tip of the triangle at the switching point. Make sure the cable to the scope is terminated in 50ohm for best high frequency response.

Roger
Re: DC503 Not Working

Stephen
 

On Tue, Aug 4, 2020 at 02:03 PM, Harvey White wrote:


Vocabulary thingie......

A pulse, likely sequential, is (at least at on time) called a strobe.

Take a display with a common anode for all the segments.  It needs to be
connected to VCC (power) to light.  However, there's a limit where the
display continuous power per segment is exceeded. This is not a good
design.  However, if you pulse the LED (segment) with more current than
the continuous rating, but for less time, then the display survives. 
Due to a quirk with human vision, it appears brighter.  So what you do
is connect the source of each digit to a signal (strobe) which in
sequence selects each digit.

The segments drivers themselves are selected so that the current through
each segment (assuming common anode with digit strobe to +vcc, and
segment driver (through resistor) to ground) is the nominal peak current
that they want.

So if all displays were driven in parallel, there'd be one driver chip
per display, no pullup transistor to VCC, and  a lot of chips.  If you
multiplex the displays (please look this up), then you have a sequential
pullup to VCC (called a strobe), a pulldown to ground (called the
segment driver, which determines which segments on which digit are on
when....) and a current which is more than needed for a single digit
(perhaps # digits times current per segment, because you don't know if a
segment is on or off, so you do it per segment).

So:

a scanned display turns on each digit sequentially, with more current
per segment than permitted (steady state but less than pulsed) and with
less chips, but more complex than a few digits. However, as the digit
count goes up, the circuit is simpler. Microprocessors love this kind of
thing.

Harvey
Ok, so you suggest I sweep each digit for a signal at its input? At the ribbon cable connections then...
Re: eBay / PayPal Changes and our alternatives

Jay Walling
 

Oh, yes, I can still buy, but again, ONLY if I agree to give Adyen ( some company in the Netherlands) my banking >info. No thanks.
cmdrdick
I don't think that's true. You can still buy using a credit card.
Re: 7834 Missing Trace

Roger Evans
 

My best guess is that there is a mechanical problem eg a switch or a plug/socket connection rather than a failed component. Switches may improve with use, plugs and sockets may benefit from removing and reseating or light cleaning with IPA or Deoxit. There is a thin coaxial cable from J2208 on the Zaxis board that goes to J4408 on the A6 Logic Board via the main interface board that the plugins mate with. If you can identify any of the plug/sockets on this signal and reach them easily, just pull the plug out and (carefully, it is easy to bend the centre connector) reinsert it.

If at any time the trace goes back to its original intensity then return R2135 to its original position (the exact setting is not critical, you should not be able to see the trace at minimum brightness setting on the front panel controls).

Can you now see the retrace (flyback) line where the spot returns from the right side of the CRT to the left side?

Do the A and B front panel brightness controls both work?

The advice I have seen here is that the safest way to use a storage mode CRT for everyday purposes is to use variable persistence mode with the persistence set to minimum. If you use normal non-store mode don't let the brightness increase to the point where the trace increases in width but not in brightness.

Regards,

Roger
Re: Message to satbeginner and Saroj Pradhan re: Tektronix 2230

DaveC <davec2468@...>
 

I concur Chuck.

I was enrolled here a decade ago when I was fixing a Tek 2465 (since retired to a hobbyist). I am now selling my last Tek, a 2430A. I would like to stay a member but have no equipment challenges (although still soldering up circuits and might like to tap this deep group brain once in a while).

I enjoy reading the back-and-forth between the owner and any number of helpers on a repair project. Photos of waveforms help me visualize being there, doing the probing and troubleshooting. That experience might even stir an idea for the owner that I could post to the group.

In all, I think this format works well.

Cheers,
Dave

On Aug 4, 2020, at 8:13 PM, Chuck Harris <cfharris@erols.com> wrote:

Hi Dennis,

I didn't mean to make trouble, but I thought we were trying
to encourage newbies, and helping them often requires a lot
of one-on-one hand holding. I have done this myself many times,
as have others. Satbeginner is anything but a beginner, and
does a very nice job of helping others get their footing.

If they were diverging off to talk about trucks, or honey badgers,
I could see your point, but in my scan through the thread, they
didn't. It was tightly focused.

Because of the experience level, satbeginner obviously thought
it better to only introduce one task at a time... which lead
to a lot of one and two sentence posts.

15-20 years ago, Tekscopes was set so that replies went to the
individual, rather than the group. We collectively voted to stop
that practice because it hid the "sausage making" from the group,
and only the one engaged in the private banter learned anything.

I think we made a wise decision when we encouraged the replies to
be on the group.

Also, although I really hate it, our group has a few grumpy old men
that start spouting off whenever the groups topics don't exactly match
their interests.

If you want to start moderating, ... well, there's a challenge.

-Chuck Harris

Dennis Tillman W7pF wrote:
Hi Chuck,
The first thing I can say is I always appreciate you input.

I did receive a complaint about it so I took a closer look. What I saw was an awful lot of messages with only two individuals involved. I was concerned that others might find it annoying.

It was a judgement call. But since many others indicate they are benefitting from it please accept my apology.

Dennis W7pF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Chuck Harris
Sent: Monday, August 03, 2020 6:55 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Message to satbeginner and Saroj Pradhan re: Tektronix 2230

Dennis,

Are you serious? Why is the 2230 not worthy of long threads, but every damn thing else is?

Yes, it is bit of a chit/chat fest, but the messages all seem to me on topic. Bandwidth (ha ha!) is minimal, perhaps less than 40K for the entire thread.

I admit that I care nothing for the 2230, but others do.

So, why?

-Chuck Harris



Dennis Tillman W7pF wrote:
Gentlemen:
You are creating an excessive amount of unnecessary message traffic, consuming significant bandwidth, and taking up precious storage on TekScopes.
I believe the best way for you to explore your mutual interests regarding the 2230 is to communicate directly to each other rather than through TekScopes.
If you need further assistance please contact me directly.
Thank you,
Dennis Tillman W7pF
Re: Message to satbeginner and Saroj Pradhan re: Tektronix 2230

Chuck Harris
 

Hi Dennis,

I didn't mean to make trouble, but I thought we were trying
to encourage newbies, and helping them often requires a lot
of one-on-one hand holding. I have done this myself many times,
as have others. Satbeginner is anything but a beginner, and
does a very nice job of helping others get their footing.

If they were diverging off to talk about trucks, or honey badgers,
I could see your point, but in my scan through the thread, they
didn't. It was tightly focused.

Because of the experience level, satbeginner obviously thought
it better to only introduce one task at a time... which lead
to a lot of one and two sentence posts.

15-20 years ago, Tekscopes was set so that replies went to the
individual, rather than the group. We collectively voted to stop
that practice because it hid the "sausage making" from the group,
and only the one engaged in the private banter learned anything.

I think we made a wise decision when we encouraged the replies to
be on the group.

Also, although I really hate it, our group has a few grumpy old men
that start spouting off whenever the groups topics don't exactly match
their interests.

If you want to start moderating, ... well, there's a challenge.

-Chuck Harris

Dennis Tillman W7pF wrote:

Hi Chuck,
The first thing I can say is I always appreciate you input.

I did receive a complaint about it so I took a closer look. What I saw was an awful lot of messages with only two individuals involved. I was concerned that others might find it annoying.

It was a judgement call. But since many others indicate they are benefitting from it please accept my apology.

Dennis W7pF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Chuck Harris
Sent: Monday, August 03, 2020 6:55 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Message to satbeginner and Saroj Pradhan re: Tektronix 2230

Dennis,

Are you serious? Why is the 2230 not worthy of long threads, but every damn thing else is?

Yes, it is bit of a chit/chat fest, but the messages all seem to me on topic. Bandwidth (ha ha!) is minimal, perhaps less than 40K for the entire thread.

I admit that I care nothing for the 2230, but others do.

So, why?

-Chuck Harris



Dennis Tillman W7pF wrote:
Gentlemen:
You are creating an excessive amount of unnecessary message traffic, consuming significant bandwidth, and taking up precious storage on TekScopes.
I believe the best way for you to explore your mutual interests regarding the 2230 is to communicate directly to each other rather than through TekScopes.
If you need further assistance please contact me directly.
Thank you,
Dennis Tillman W7pF
9261 - 9280 of 179223