Date   

Re: DM502 with problems

Roger Evans
 

Correction, I don't think the cam switches improve with use, if they are dirty they need cleaning with IPA and strips of paper.

Roger


Re: DM502 with problems

Roger Evans
 

Colin,

Some of the TM500 plugins had notoriously unreliable IC sockets. I would certainly remove the socketed ICs, clean pins and see if anything improves. Several people have commented that the long term solution is to replace with decent IC sockets, I expect someone will know how to identify the unreliable originals. Have you checked for ripple on the +/-12V and 5V lines? Also it is worth exercising the range switch a few dozen times! Is the DM502 a new acquisition or one that was working OK but has now failed?

Regards,

Roger


DM502 with problems

Colin Herbert
 

I have a DM502 which isn't working correctly. I have checked the power supply voltages at +5V, and +/- 12V and they are within spec. I have also adjusted the clock frequency to 20.48 kHz and that is fine. On initial switch-on and warming-up, the display "jumps about" rather than staying stable as one would expect, even with only a battery connected to the test-terminals and a suitable DC voltage range selected or with a resistor across the test terminals and a suitable ohms range selected. After being powered on for a while, the display just shows a constant sequence of digits, whatever the position of the range switch, only the position of the decimal point changing. I haven't got around to checking anything else, yet, but after the plug-in has been on for a while,the transformer T410 is rather hot to the touch, so much so that I can't keep a finger-tip in contact with it. Is this correct behaviour, or should I check other components (don't forget that the voltages out of the transformer are within spec.)?
TIA, Colin.


MCM68766 and MCM68764

 

Looking at the datasheets these devices appear the be the same, am I missing
something, or was it just a case of the MCM68766 superseding the MCM68764?

Thanks
David


Success with Tek 602 XY's

toby@...
 

Hi group

Just a success story with a very minor repair and hint to others later:
Today fixed two 602's with SAME fault (no spot, no HV) - fuse F217 had
blown.

Reason for blown fuse was C216 and/or C217 electrolytics had failed short.

The Bussman fuse MDL-1 is still available from Mouser.

Hope this saves someone some time or saves a 602 unit. They are
beautiful when running.

--Toby


Tek 545A w/2 plug-ins $39 Boston

David Berlind
 

Showed up on the local Craigslist. I'm not the seller. I'd take it myself but I already have too many old Tek scopes.

https://boston.craigslist.org/gbs/ele/d/arlington-tek-545a-vintage-oscilloscope/7135498444.html


Re: Tek 475A transformer replacement

Daveolla
 

Greetings, on pin removal tools, I have a box full of old telescopic TV and radio antennas collected over the years and another box of ones that have been taken apart and cut into various lengths over the years. Perhaps you might have one in just the right diameter to use as a pin remover.

I often use some of these short length ones as punches. If you run the pointed end of an exacto blade (duh, the other end would be the handle) or even the kitchen steak knives into the end of the tubing and scrape, or a deburring action on the edge, it will sharpen up near razor sharp, it should take less than 10 seconds. It will punch great holes in rubber, card, paper etc. Sometimes with thick rubber a bit of lube (spit is usually available) and spin in a drill chuck for better holes without the squishing from punching effect on the holes. You can easily spin and do lovely binder holes in a phone book. Sometimes a small triangular needle file can put some saw teeth on the end of the tube if need be. Ive even used them for banana jacks on occasion, a taper end of a punch or ball bearing easily with a bit of hammering will flare the end, or flare and then flatten for a nice flush end if pushed into a panel hole

The telescopic pins in old watch straps are another source for some handy tubing

You find you will want them right near your bench so you don't have to go far to utilize their handyness.

Dave

At 08:49 AM 6/04/2020, you wrote:
Hi Jim, I have some pin removal tools that work on various Molex style
connectors. They amount to a thin tube that slides over the pin which
disengages the exterior spurs plus, a piston plunger to eject the pin.
The pin diameter needs to be near the tools size.
I shall send a photo in a few minutes. They require more muscle than you
expect however, they work neatly with a bit of persistence. Wish you
success with the project, Gary

On Thu, Jun 4, 2020, 5:55 AM <jim.hall@...> wrote:

Hello. I am new to this group, but am very interested in the discussions.
As a hobby, I have restored some Tek 465 and 475 scopes. My latest 475A has
a bad low voltage transformer. It plows the main fuse even when all of the
secondary windings are disconnected. To replace it, I need a pin removal
tool (Tek 003-0707-00), but have been unable to locate one. I would
appreciate any suggestions where I can acquire one. Thanks.




Re: Tek 475A transformer replacement

WB6GHK
 

Hi,

Here's a possible pin removal tool solution:

https://www.amazon.com/s?k=pin+removal+tool&ref=nb_sb_noss_1

You're most welcome!


Re: Slight;y OT CRT question

 

the (F) suffix for CRTs always indicates a Flat Face. a 5UP1 has a
spherical face, but a 5UP1(F) is flat (these tubes only come from Japan, the US makers did not offer this variation). I have never seen an (S) suffix in real life, maybe someone has added that to distinguish between the flat and spherical versions of the same tube.

the 5DEP1(F) was a very popular CRT for low end scopes, it has very high brightness with low anode voltages, and good deflection sensitivity, coupled with a flat face, and you have the makings of a very nice lower frequency (10-20Mhz) scope.

we do have some if you need one (although not so cheap), see:
https://www.sphere.bc.ca/test/crts.html
they also show up on ebay regularly, as they were used in many 5" low end scopes and kits.
often new tubes from un-built kits show up at a good price.

all the best,
walter

--
Walter Shawlee 2
Sphere Research Corp. 3394 Sunnyside Rd.
West Kelowna, BC, V1Z 2V4 CANADA
Phone: +1 (250-769-1834 -:- http://www.sphere.bc.ca
+We're all in one boat, no matter how it looks to you. (WS2)
+All you need is love. (John Lennon)
+But, that doesn't mean other things don't come in handy. (WS2)
+Nature is trying very hard to make us succeed, but nature does not depend on us.
We are not the only experiment. (R. Buckminster Fuller)


Re: Tek 4041 GPIB Controller

Dave Brown
 

A public thank you for all the work you have put into this, Monty.
Will contact you directly to progress things.
DaveB, NZ

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Monty McGraw
Sent: Friday, June 05, 2020 04:08
To: TekScopes@groups.io
Subject: Re: [TekScopes] Tek 4041 GPIB Controller

Gary Robert Bosworth and Dave Brown and anyone else interested in a copy of the 4041 System Verification tape,

send me an email: mmcgraw74@...

Monty McGraw


Re: 7854 POST fail, stuck at Step 2

Martin Whybrow
 

The behaviour is decidedly odd, when it does POST correctly, the digital section works for a time then crashes so none of the mode controls work and the OSD disappears. Whilst researching, I found mention of the TI P25 sockets, so I checked and found mine uses them; should I bite the bullet and swap them all for a better type? What's the consensus as to which is the best alternative?


Re: 7854 ROM replacement issues

Martin Whybrow
 

It does appear not to be the ROMs after all, they all read and verify correctly for rthe -01 revision.


Re: Slight;y OT CRT question

Greg Muir
 

Thanks Michael, Albert.

Michael, the data sheets for this tube do indicate that there are different phosphor options available for different writing speeds so I think that the speed is defined by the phosphor given that standard theory.

Albert, I believe that your observation of the suffix is true. As to why they offered both features is beyond me. As for a 5UP1 being interchangeable with the 5DEP1, I first thought that I could go ahead and pick a 5UP1 up but later found that it has a much lower deflection sensitivity. Otherwise it would be a fit.

There is one (F) tube on the auction site that I wanted to get and looks to be in good condition but the seller never responded to any of my offers nor emails. I think there might be a possibility that they may have fallen prey to the virus. Anyone else have this problem with purchasing things recently?

Greg


Re: Slight;y OT CRT question

Albert Otten
 

At the CRT page Sphere often mentions flat face for 5xxx(F) tubes. In one case, 5UP1(F), the description explicitly states "Electrostatic CRT with flat face (F)".
Albert

On Thu, Jun 4, 2020 at 08:44 PM, Michael W. Lynch wrote:


Greg wrote:
This particular scope uses a 5DEP1(F) CRT. I my search for a replacement I
learned that the are a few used CRTs available which also sport a (S) suffix
on their part number. The few data sheets that were found do not allude to
the >differences between the (F) and (S) suffix tubes. I am making a basic
assumption that this refers to the face of the tube being either flat or
spherical shape respectively

I think that I read somewhere that this indicates the write speed of the
phosphor. S for slow and F for fast. This may not be accurate.

--
Michael Lynch
Dardanelle, Arkansas


Re: SC502 Old Enough to Smoke?

 

Please don't use a Philips screwdriver on any Tektronix equipment - they are all Pozidriv head screws. There's a massive difference: the geometry of the heads and a Philips screwdriver will cam out and wreck a Pozidriv screw.

The same comments apply to a lesser extent to using Philips screwdrivers on screws with JIS cross heads - similar to Philips, but *not* the same.

David

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of DaveH52
Sent: 04 June 2020 20:46
To: TekScopes@groups.io
Subject: Re: [TekScopes] SC502 Old Enough to Smoke?

I was hoping I'd be able to remove the Main board without removing the CRT, but the only destructions start with "CRT Replacement" My efforts are currently thwarted by the rear screw holding the Horizontal Deflection board that was apparently installed by a 500 pound gorilla. I can't seem to find a Phillips screwdriver that will remove it. I've got it soaking in penetrating oil.


Re: SC502 Old Enough to Smoke?

DaveH52
 

I was hoping I'd be able to remove the Main board without removing the CRT, but the only destructions start with "CRT Replacement" My efforts are currently thwarted by the rear screw holding the Horizontal Deflection board that was apparently installed by a 500 pound gorilla. I can't seem to find a Phillips screwdriver that will remove it. I've got it soaking in penetrating oil.


Re: Slight;y OT CRT question

Michael W. Lynch
 

Greg wrote:
This particular scope uses a 5DEP1(F) CRT. I my search for a replacement I learned that the are a few used CRTs available which also sport a (S) suffix on their part number. The few data sheets that were found do not allude to the >differences between the (F) and (S) suffix tubes. I am making a basic assumption that this refers to the face of the tube being either flat or spherical shape respectively
I think that I read somewhere that this indicates the write speed of the phosphor. S for slow and F for fast. This may not be accurate.

--
Michael Lynch
Dardanelle, Arkansas


Re: TLA711 Benchtop controller schematic needed

Jim Ford
 

Or a ham-fisted Jim Ford with some oversized wire cutters hacking around. Just sayin'.

Jim

------ Original Message ------
From: "Roy Thistle" <roy.thistle@...>
To: TekScopes@groups.io
Sent: 6/4/2020 7:19:06 AM
Subject: Re: [TekScopes] TLA711 Benchtop controller schematic needed

On Thu, Jun 4, 2020 at 12:53 AM, Egge Siert wrote:


In my experience it is nearly impossible to damage through-hole connections in
Multi-Layer Boards.
Hi Egge, Hi All:
Trust me, with a Mr. Carlson Weller soldering gun special, and a Hexagon 100Wer... people do it to Tek stuff, all the time.
Best regards and wishes.
Roy



Re: TLA711 Benchtop controller schematic needed

Jim Ford
 

Thanks, Egge.

It's been over 3 years since I messed with the benchtop controller, so I don't recall the P/N I used to replace the original module. I'm not a fan of Dallas Semiconductor or Maxim Integrated who bought them, so I probably put in an STMicroelectronics part instead. I do recall that the original module had the battery and crystal included but the modern equivalent just had the memory only.

I will take a look on my board shortly. I'm more motivated these days because a buddy is moving and is giving me a PCMCIA to GPIB adaptor, which would allow me to connect the TLA to GPIB. I'm just getting started connecting my other test gear to my garage lab PC through GPIB, so it would be handy to have the TLA on the bus as well. Probably this weekend I'll look into it.

Jim

------ Original Message ------
From: "Egge Siert" <eggeja2@...>
To: TekScopes@groups.io
Sent: 6/4/2020 12:53:18 AM
Subject: Re: [TekScopes] TLA711 Benchtop controller schematic needed

Hi Jim.

Some months ago I bought (out of curiosity) a "working" TLA704 with an overdue DS12887 (OS not found). Mouser still has this device and after replacing the old one new settings can be saved and the TLA704 is now working flawlessly. Based on its (DS12887) Diagram and Pin-Out it seems not a hard one to reconstruct the missing traces. In my experience it is nearly impossible to damage through-hole connections in Multi-Layer Boards. I suggest to put back a new DS12887 (this time with DIL-Socket).

https://www.youtube.com/watch?v=daoxD-SS3ZU (for another solution)

Succes,

Egge Siert



Slight;y OT CRT question

Greg Muir
 

Although a slightly off topic subject nothing better to ask a scope group this question.

In the process of mentoring a young individual with regards to basic electronics I dug out an old Heathkit oscilloscope form my junk pile and decided to fix up for him so that he would begin to learn a little more about analog signals. But After firing it up I discovered that the CRT emission is weak and that the scope traces take a little concentration to see.

This particular scope uses a 5DEP1(F) CRT. I my search for a replacement I learned that the are a few used CRTs available which also sport a (S) suffix on their part number. The few data sheets that were found do not allude to the differences between the (F) and (S) suffix tubes. I am making a basic assumption that this refers to the face of the tube being either flat or spherical shape respectively.

Any ideas?

Thanks,

Greg