Date   
Re: Type G plugin versions

Dave Wise
 

Chris's manual is for the 53G (12AU6x2, 12AT7x2, 12AT7), while his plugin is the later, faster G (6AK5x2, 12AU6x2, 12AU6x2, 12AT7). I edited the wiki page to mention that 53G has five tubes while G has seven.

Regards,
Dave Wise
________________________________________
From: TekScopes@groups.io <TekScopes@groups.io> on behalf of Jerry Ingordo <gjingordo@...>
Sent: Wednesday, October 24, 2018 3:59 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Type G plugin versions

Hi Chris.
You have an early G plugin. Here is a link to the early manual.

http://ebaman.com/index.php/remository/func-startdown/22331/

You have to log in to download the manual. Log in is simple, create a screen name and password and your in. There may be a waiting period for new users to download. If you have a problem getting the manual contact me and I'll get a copy to you.

Jerry
W2JI

Re: Type G plugin versions

Dave Seiter
 

My G (serial number just under 10K) has holes in the front panel for the original connectors, but is loaded with BNCs which look factory installed.  Anyone know when this transition took place?
-Dave

From: Dave Wise <david_wise@...>
To: "TekScopes@groups.io" <TekScopes@groups.io>
Sent: Wednesday, October 24, 2018 7:32 AM
Subject: Re: [TekScopes] Type G plugin versions

Chris's manual is for the 53G (12AU6x2, 12AT7x2, 12AT7), while his plugin is the later, faster G (6AK5x2, 12AU6x2, 12AU6x2, 12AT7).  I edited the wiki page to mention that 53G has five tubes while G has seven.

Regards,
Dave Wise
________________________________________
From: TekScopes@groups.io <TekScopes@groups.io> on behalf of Jerry Ingordo <gjingordo@...>
Sent: Wednesday, October 24, 2018 3:59 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Type G plugin versions

Hi Chris.
You have an early G plugin.  Here is a link to the early manual.

http://ebaman.com/index.php/remository/func-startdown/22331/

You have to log in to download the manual.  Log in is simple, create a screen name and password and your in.  There may be a waiting period for new users to download.  If you have a problem getting the manual contact me and I'll get a copy to you.

Jerry
W2JI

Re: 475 Probe Calibration problem with x10 probes

n2msqrp
 

Thanks. Has anyone tried Caig Labs Deoxit?

Mike N2MS


On October 24, 2018 at 9:44 AM "Colin Herbert via Groups.Io" < colingherbert=blueyonder.co.uk@groups.io
wrote:

This might indeed help, but be cautious when doing it. There are posts on
this forum where the correct technique is laid out - it is very easy to
damage the cam-operated contacts. Also, note that the material of the
attenuator board is a bit special and is easily damaged by heat and
various solvents. Briefly, the technique is to put a little IPA (isopropyl
alcohol) onto a sliver of ordinary paper and use that to clean the
contacts. Check that the contacts are open, slide the ipa-wetted paper
between them, close the contacts and then carefully pull the paper out
level with the board, as far as possible. This can be done a few times to
get all the contaminants off. You can probably ascertain which of the
attenuator contacts need cleaning by checking in the service manual as to
which attenuators are in circuit when the poor bandwidth is seen.
Good Luck, Colin.

-----Original Message-----
From: TekScopes@groups.io [mailto: TekScopes@groups.io ] On Behalf Of
ef804s tubes
Sent: 24 October 2018 14:27
To: TekScopes@groups.io
Subject: Re: [TekScopes] 475 Probe Calibration problem with x10 probes

I have two 475 scopes. Both have developed a similar probe calibration
problem on one channel. I am using the scope calibration signal. I have
verified results with multiple probes

First scope - Channel 1 probe calibration tests fine with x1 and x10
probles. Channel 2 calibration tests fine with a x1 probe but the waveform
has a sloped rise and fall time when testing with a x10 probe on a
vertical sensitivity setting of .5v/div and above.

Second scope - Channel 1 probe calibration tests fine with x1 probes but
the waveform is a spike when testing with a x10 probe with vertical
sensitivity setting of .5v/div and above. Channel 2 probe calibration
works fine with x1 and x10 probes.

Has anyone seen this problem?

Mike N2MS

Hi,

please clean the attenuator contacts ans the pins of the attenuator blocks
as well.

Fred





Re: 475 Probe Calibration problem with x10 probes

 

n2msqrp
Oct 23 #151898

I have two 475 scopes. Both have developed a similar probe calibration problem on >one channel. I am using the scope calibration signal. I have verified results with >multiple probes

First scope - Channel 1 probe calibration tests fine with x1 and x10 probles. Channel 2 >calibration tests fine with a x1 probe but the waveform has a sloped rise and fall time >when testing with a x10 probe on a vertical sensitivity setting of .5v/div and above.
Second scope - Channel 1 probe calibration tests fine with x1 probes but the >waveform is a spike when testing with a x10 probe with vertical sensitivity setting of >.5v/div and above. Channel 2 probe calibration works fine with x1 and x10 probes.

Has anyone seen this problem?

Mike N2MS
(quote doesn't seem to work so I put the little arrows in like Usenet, hope it is clear enough)

Unless those switches are dirty at many ranges or something it is not really likely they need to be cleaned and that is it. Therefore, troubleshooting is in order.

A look at the front end on the print tells that in .5V/div and up the X100 attenuator is switched in the circuit. It is bypassed at the more sensitive rages. I assume here that when you wrote "and up" you meant higher in V/div. because "sensitivity" could be expressed the other way, more sensitive being <V/div.

Also note that the X100 is the first in line so is most prone to damage by ridiculously high voltages. (that can happen when they DO NOT LISTEN ! - KEEP IT IN 10X AT ALL TIMES UNLESS YOU REALLY NEED THE GAIN. Better to fry the 9 meg or whatever resistance in the probe than the front end of the scope.

The print does not give details on the internal of the attenuators, and with further examination I find that they are a unit, encapsulated and everything. I'm sure you'll find plenty in the hen's teeth department.

As such, I say most likely there is a resistor in there that is blown open. I also say that most likely it simply goes from the input to the output. Its value should be calculable using the resistance of the output of the attenuator to common. (ground) Maybe 99X that measured value ?

What it is not saying is if all these attenuators are in one package. All but the X10 show no connection to common. (ground) This is more than unlikely so I suspect there is simply an attenuation "block" of sorts. You'll have to determine which pins need the resistor.

Either that or replace it/them. If there are separate ones for each channel at least you can make one good scope out of the pair. If there is only one for both channels you are up the creek.

Actually it occurs to me now that you HAVE a good channel, a precision ohmmeter will tell you the value of resistor you would need to jump it out in the bad channel. You'll have to build that no doubt, unless you know where to buy like a 9.04256 megohm or whatever it is. Be mindful of RF/EMI, keep the leads short and straight as possible.

Re: Type G plugin versions

cmjones01
 

On Wed, Oct 24, 2018 at 06:16 AM, cmjones01 wrote:
Thank you very much for the pointer. That manual matches what I've got. A
replacement 12AU6 (most of the vacuum has escaped from one of the ones in the
plugin) has just arrived so I'll see if I can get it working.
Replacement 12AU6 installed in addition to a substitute for the missing 6AK5, adjustments to gain, DC balance and vertical position range as expected, plugin now seems to work perfectly. That wasn't too hard!

Chris

Re: Type G plugin versions

cmjones01
 

On Wed, Oct 24, 2018 at 10:21 AM, Dave Seiter wrote:
My G (serial number just under 10K) has holes in the front panel for the
original connectors, but is loaded with BNCs which look factory installed. 
Anyone know when this transition took place?
My G also has BNC connectors. If it's anything like the other 500 series equipment, I think the transition was in the mid-to-late 1960s. My 535A has factory-fitted BNCs as well.

Chris

Anyone have a 5.5 to 18PF variable ceramic trimmer they would like to sell

Brendan
 

I ordered a 4 to 34PF from jameco but I would like another option. I just tapped it and I lost the trace on the 468 I'm working on. Good news is I found a dead transistor on the timing board. Now I have to wait on a trimmer to see if it fixes my issue.

Re: Anyone have a 5.5 to 18PF variable ceramic trimmer they would like to sell

Bill Riches
 

Can you send me a pic of the trimmer you need and how much room is there to mount it?

73

Bill, WA2DVU

-----Original Message-----
From: TekScopes@groups.io <TekScopes@groups.io> On Behalf Of lop pol via Groups.Io
Sent: Wednesday, October 24, 2018 7:23 PM
To: TekScopes@groups.io
Subject: [TekScopes] Anyone have a 5.5 to 18PF variable ceramic trimmer they would like to sell

I ordered a 4 to 34PF from jameco but I would like another option. I just tapped it and I lost the trace on the 468 I'm working on. Good news is I found a dead transistor on the timing board. Now I have to wait on a trimmer to see if it fixes my issue.

Re: 2247A PSU Troubleshooting

tekscopegroup@...
 

Hi Nick, can't really give you other troubleshooting tips for a dead 2247A power supply, as I fortunately never had this problem with my own scope, but I hope in the end its something easy to fix. Maybe one of the 22xx series experts here would have some useful tips for you. You mention that you have the schematic, not sure if you actually have the complete service manual as well. If not I would strongly suggest to download a copy which just in case is available on the right hand column on this page:

http://w140.com/tekwiki/wiki/2247

Good luck with the troubleshooting, and don't forget to (hopefully) keep it fun. Also, please report back any progress so the information might possibly be useful for the next person having to go through the same scenario as you are now.

Alex

Re: TEK 475 Q1478 2n5859

 

It is not critical.

Re: Anyone have a 5.5 to 18PF variable ceramic trimmer they would like to sell

Brendan
 

On Wed, Oct 24, 2018 at 05:57 PM, Bill Riches wrote:


Can you send me a pic of the trimmer you need and how much room is there to
mount it?

73

Bill, WA2DVU

-----Original Message-----
From: TekScopes@groups.io <TekScopes@groups.io> On Behalf Of lop pol via
Groups.Io
Sent: Wednesday, October 24, 2018 7:23 PM
To: TekScopes@groups.io
Subject: [TekScopes] Anyone have a 5.5 to 18PF variable ceramic trimmer they
would like to sell

I ordered a 4 to 34PF from jameco but I would like another option. I just
tapped it and I lost the trace on the 468 I'm working on. Good news is I found
a dead transistor on the timing board. Now I have to wait on a trimmer to see
if it fixes my issue.


I added a photo of the capacitor. Just in case.

https://groups.io/g/TekScopes/photo/76822/0?p=Name,,,20,1,0,0

Re: Anyone have a 5.5 to 18PF variable ceramic trimmer they would like to sell

 

I run into the same problem many times when restoring radios.

The original trimmers are simply not available

So, I order new modern SMD trimmers from Mouser, and simply solder legs onto them.

Works just fine.

Menahem

Re: 2247A PSU Troubleshooting

nielsentelecom@sbcglobal.net
 

Nick,

I have a 2246A that I had to overhaul, which most likely has the identical power supply for your 2247A. I would do a search for the 2246A power supply also here. So I will refer to the component number in your schematic if there is a difference. I wouldn't be concerned with the diodes and caps mentioned in Alex's post until you verify the following.

I also blew up U2201 when I accidentally shorted my scope probe shield against a heatsink while probing. That caused a no power on the main 44VDC bus measured at C2203. even if that is good, I would get a spare replacement. they are not expensive and still available as of a couple years ago.

Get the service manual, refer to page 97, or 3-59, the power supply block diagram, and verify the voltage indicated prior to the preregulator and startup circuit at c2202. that is the main DC bus that feeds the Switching power supply pre-regulator. If you are plugged into 120VAC, it should be at about 160-170VDC. then switch meter to AC, and see if there is any ripple there. That's 120 hz so any meter will work. If that is good then check the previous paragraph for the 44VDC check.

I also was able to test my power supply out of the cabinet. It was risky, but necessary. I used a 10KV AC rated linemans glove and placed the CRT lead inside of it. I also have the resistor values that were close loads for the power supply to operate at a typical load.

NielsenTelecom

Re: Type G plugin versions

Dave Wise
 

I don't know the G serial number at which Tek switched from UHF to BNC*, but the 1962 catalog shows UHF while 1963 is BNC**. I think I have a newer manual at home, I'll try to remember to look.

There was a mod kit for converting instruments in the field. I have at least one modded scope and plugin. Yours too, most likely, as Tek would not have sold instruments with such an obvious bodge.

Dave Wise

* For what it's worth, the 535A mainframe switched at 31260.
** Some old models were not updated.
________________________________________
From: TekScopes@groups.io <TekScopes@groups.io> on behalf of cmjones01 <chris@...>
Sent: Wednesday, October 24, 2018 11:59 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Type G plugin versions

On Wed, Oct 24, 2018 at 10:21 AM, Dave Seiter wrote:
My G (serial number just under 10K) has holes in the front panel for the
original connectors, but is loaded with BNCs which look factory installed.
Anyone know when this transition took place?
My G also has BNC connectors. If it's anything like the other 500 series equipment, I think the transition was in the mid-to-late 1960s. My 535A has factory-fitted BNCs as well.

Chris

Re: Type G plugin versions

Albert Otten
 

According to the later manual Type G switched from UHF (131-012) to BNC (131-277) at S/N 9480. No idea in which year that was.
Albert

On Thu, Oct 25, 2018 at 08:17 PM, Dave Wise wrote:


I don't know the G serial number at which Tek switched from UHF to BNC*, but
the 1962 catalog shows UHF while 1963 is BNC**. I think I have a newer manual
at home, I'll try to remember to look.

There was a mod kit for converting instruments in the field. I have at least
one modded scope and plugin. Yours too, most likely, as Tek would not have
sold instruments with such an obvious bodge.

Dave Wise

* For what it's worth, the 535A mainframe switched at 31260.
** Some old models were not updated.

Re: Anyone have a 5.5 to 18PF variable ceramic trimmer they would like to sell

 

On Thu, Oct 25, 2018 at 03:14 AM, lop pol wrote:
Hi Lop Pol,

Re: Anyone have a 5.5 to 18PF variable ceramic trimmer they would like to sell



I added a photo of the capacitor. Just in case.

https://groups.io/g/TekScopes/photo/76822/0?p=Name,,,20,1,0,0
Quite likely I have one NOS, possibly original. Cost is shipping from Netherlands. To be certain, please tell me which cap (C...) on which board.

Raymond

Re: Anyone have a 5.5 to 18PF variable ceramic trimmer they would like to sell

Brendan
 

On Thu, Oct 25, 2018 at 12:59 PM, Raymond Domp Frank wrote:


On Thu, Oct 25, 2018 at 03:14 AM, lop pol wrote:
Hi Lop Pol,

Re: Anyone have a 5.5 to 18PF variable ceramic trimmer they would like to
sell



I added a photo of the capacitor. Just in case.

https://groups.io/g/TekScopes/photo/76822/0?p=Name,,,20,1,0,0
Quite likely I have one NOS, possibly original. Cost is shipping from
Netherlands. To be certain, please tell me which cap (C...) on which board.

Raymond
The cap is C120 on the A13 board so its A13C120. Thanks for looking.

Re: Anyone have a 5.5 to 18PF variable ceramic trimmer they would like to sell

 

On Thu, Oct 25, 2018 at 10:05 PM, lop pol wrote:


The cap is C120 on the A13 board so its A13C120. Thanks for looking.
Just realized yours is a 468. It's probably the same as the equivalent cap in a 465(B). I'll be in the lab coming Tuesday and have a look, possibly take a few pictures. I can't imagine the "rotated-by-90 degrees same-function cap" in both models being different. The physical location definitely is but they both are the lying-down variety.
Please send me a PM on Tuesday as a reminder and we'll take our communication off-group.

Raymond

Re: Type G plugin versions

cmjones01
 

On Thu, Oct 25, 2018 at 12:44 PM, Albert Otten wrote:
According to the later manual Type G switched from UHF (131-012) to BNC
(131-277) at S/N 9480. No idea in which year that was.
My 535A and G are Guernsey-built. The 535A is s/n 101936, and the G is s/n 101127. They both have BNCs which look like they were factory-fitted, though they are of the special Tek type with enlarged flanges to fit the UHF connector hole.

Chris

Re: Type G plugin versions

Dave Wise
 

I was partly wrong. Tek retooled the front panel for BNC, but not until 1967. From 1963 through 1966, they used the UHF front panel with a square-flange BNC jack and plastic trim covering the annular gap. The letter-series plugins built this way are CA, D, G, and L. Others like the K were retooled immediately, if the catalogs are right.

I have plugins of each construction. One of my scopes, a 545, was definitely field-modded, since it was built in the 1950's. It doesn't have the trim and it looks a bit awkward without it.

Beaverton 535A switched to BNC at 31260, but that doesn't tell us anything about Guernsey.

Dave Wise
________________________________________
From: TekScopes@groups.io <TekScopes@groups.io> on behalf of cmjones01 <chris@...>
Sent: Thursday, October 25, 2018 1:27 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Type G plugin versions

On Thu, Oct 25, 2018 at 12:44 PM, Albert Otten wrote:
According to the later manual Type G switched from UHF (131-012) to BNC
(131-277) at S/N 9480. No idea in which year that was.
My 535A and G are Guernsey-built. The 535A is s/n 101936, and the G is s/n 101127. They both have BNCs which look like they were factory-fitted, though they are of the special Tek type with enlarged flanges to fit the UHF connector hole.

Chris