Test Equipment Anonymous (TEA) group therapy thread

[Andrew_Debbie]

In Soviet Russia, PROM programs you!

LOL.

[tggzzz]

TE incomming,
Just won my cheapest ever Fluke on ebay. A 5.5 digit DMM for 99p 
www.ebay.co.uk/itm/Fluke-NetDAQ-2645a-46a-Networked-Data-Acquisition-Unit-/363608963162
OK it's not exactly a DMM, the local display is only 4.5 digits and it's a little beaten up but what do you expect for 99p?
It's misdescribed, it is the higher resolution 2640A not a 2645A. Importantly it comes with the input module and even a bunch of J type thermocouples with connectors.
I think nobody else bid as it's tatty and "Collection Only". But the description says "will post for £12"  So total delivered price £12.99. These typically sell for >10x that.
There is the small issue of software. The current version is not cheap but the demo gives you 40 hours of logging time. I cna use that to configure it and it will then be mostly used as a 20 ch thermometer in local monitior mode.
I might be able to find the older software and run it on an old XP laptop.....

I too found a Fluke for 99p. The vendor said the previous owner (a ham, naturally) had bought it as a desk DMM. Oops. Teardown, showing that it has an internal dim bulb protector at https://www.eevblog.com/forum/testgear/fluke-8125a-military-dmm-teardown/msg2542050/#msg2542050

Since yours it is a networked device, it should be sufficient to run XP inside a VM.

[Andrew_Debbie]

I keep finding the strangest 'unstruments' on the web.

Here one from India:
https://www.japson.com/conversion-of-galvanometer-into-a-voltmeter-ammeter.html
Just the title is a hoot!

And what the world needed - another talking multimeter:
http://www.microseveninc.com/vm10brochure.htm
The one from Voltcraft was bad enough while it kept to one language.

Note to self: Shake it off! Look at something functional and precise and forget that it exists!

The first one looks like it might be for school electronics labs on a budget.    Even so,  a couple of Aneng DMMs might work just as well and cost less.


The second one looks like it could be for blind technicians.   Another niche market, but I could see a use for it. 

I'm not sure what this is for:

Telephone interface option is available to obtain measurement data over telephone line. Measurement data is obtained by entering a unique command after entering your PIN. Measurement mode and range are also selected by entering unique codes.

Maybe someone who can't use a computer?        The internet is just about everywhere now    The VM10 is $300, so maybe if you can't afford Starlink? 

Ahh - VM10 has been around since 2007.  Telephone interface is just an old feature...


   

[McBryce]

I keep finding the strangest 'unstruments' on the web.

Here one from India:
https://www.japson.com/conversion-of-galvanometer-into-a-voltmeter-ammeter.html
Just the title is a hoot!

And what the world needed - another talking multimeter:
http://www.microseveninc.com/vm10brochure.htm
The one from Voltcraft was bad enough while it kept to one language.

Note to self: Shake it off! Look at something functional and precise and forget that it exists!

My Fluke meter talks to me too! It keeps saying "Please clean my yellow bumper" and "Buy me some decent test leads"

McBryce.

[med6753]

I have 2 of these little scopes... one in it's original carry pouch.  Been following your progress on this one.  On one of mine, besides the battery packs, the vertical attenuator switches fell apart and I had to get creative in repairing them.  Fragile after so many years.  It's the most un-usable scope I have, but I sort of adore the little bugger!

I have the carry pouch for this one too but it's all moldy on the inside so I won't be using it. I have no issues with the vertical attenuators including any fuzzy traces as terra operative mentioned with his. Both are stable throughout their ranges.

I did check the other resistors in the HV section and they are within tolerance so I left them. After careful adjustment of the CRT grid bias I now have a stable trace throughout the intensity range with no pulsing or flashing of the trace. So all trace issues are now fixed. The scope has been running most of the night and all intermittent problems are now fixed. But I will be putting it through multiple burn-in cycles before declaring total victory.

The biggest hurdle remaining is getting it all back together although I'm getting much better and quicker. There's a reason Tek field technicians hated working on these mini scopes. So many times after reassembly the damn thing doesn't work because something came loose or was pinched in the covers. Not one of Tek's better designs.   

[med6753]

So now that I have all the gremlins out of the mini 212 I find myself without a follow on project. That's dangerous because then I'll wander the streets and get myself in trouble.  I've been cruising Ebay but other than that RCA VTVM I've mentioned previously nothing really pipes my interest. And since that clown seller won't respond to my request for internal pictures after stating he would then he can go fuck himself. I'll bet it has been under water.

So, what to do? Well, I really should consider doing the HV solid state mod on the Type 547. It has that failure prone epoxy potted HV transformer. The solid state mod removes the 5642 HV rectifier tubes and installs NTE517 HV rectifiers. The point of this mod is to eliminate the tubes filament voltage which in turn lightens the load on the HV oscillator and transformer thus extending their life.

Pictures from Tekwiki with the original 5642 tubes and the SS mod.

https://w140.com/tekwiki/wiki/547#/media/File:Tek_547_HVSection-NoCover.jpg

https://w140.com/tekwiki/wiki/547#/media/File:Tek_547_HV_Diodes.jpg   

Those NTE517 HV rectifiers are not cheap. About $7.50 USD a pop. And I need 5 and at least one or two spares. But considering that the HV transformer is nearly unobtainium it's worth it. Nearly every Tek scope in the 1950's and early 1960's uses these 5642 HV rectifiers in the HV but most of those HV transformers are wax potted and not subject to moisture ingress which causes the failure.   

[McBryce]

So now that I have all the gremlins out of the mini 212 I find myself without a follow on project. That's dangerous because then I'll wander the streets and get myself in trouble.  I've been cruising Ebay but other than that RCA VTVM I've mentioned previously nothing really pipes my interest. And since that clown seller won't respond to my request for internal pictures after stating he would then he can go fuck himself. I'll bet it has been under water.

So, what to do? Well, I really should consider doing the HV solid state mod on the Type 547. It has that failure prone epoxy potted HV transformer. The solid state mod removes the 5642 HV rectifier tubes and installs NTE517 HV rectifiers. The point of this mod is to eliminate the tubes filament voltage which in turn lightens the load on the HV oscillator and transformer thus extending their life.

Pictures from Tekwiki with the original 5642 tubes and the SS mod.

https://w140.com/tekwiki/wiki/547#/media/File:Tek_547_HVSection-NoCover.jpg

https://w140.com/tekwiki/wiki/547#/media/File:Tek_547_HV_Diodes.jpg   

Those NTE517 HV rectifiers are not cheap. About $7.50 USD a pop. And I need 5 and at least one or two spares. But considering that the HV transformer is nearly unobtainium it's worth it. Nearly every Tek scope in the 1950's and early 1960's uses these 5642 HV rectifiers in the HV but most of those HV transformers are wax potted and not subject to moisture ingress which causes the failure.   

Here's a steam-punk boat anchor for you to fix up. That should keep you off the streets for a couple of days: https://www.ebay.de/itm/193700185615

McBryce.

[med6753]

So now that I have all the gremlins out of the mini 212 I find myself without a follow on project. That's dangerous because then I'll wander the streets and get myself in trouble.  I've been cruising Ebay but other than that RCA VTVM I've mentioned previously nothing really pipes my interest. And since that clown seller won't respond to my request for internal pictures after stating he would then he can go fuck himself. I'll bet it has been under water.

So, what to do? Well, I really should consider doing the HV solid state mod on the Type 547. It has that failure prone epoxy potted HV transformer. The solid state mod removes the 5642 HV rectifier tubes and installs NTE517 HV rectifiers. The point of this mod is to eliminate the tubes filament voltage which in turn lightens the load on the HV oscillator and transformer thus extending their life.

Pictures from Tekwiki with the original 5642 tubes and the SS mod.

https://w140.com/tekwiki/wiki/547#/media/File:Tek_547_HVSection-NoCover.jpg

https://w140.com/tekwiki/wiki/547#/media/File:Tek_547_HV_Diodes.jpg   

Those NTE517 HV rectifiers are not cheap. About $7.50 USD a pop. And I need 5 and at least one or two spares. But considering that the HV transformer is nearly unobtainium it's worth it. Nearly every Tek scope in the 1950's and early 1960's uses these 5642 HV rectifiers in the HV but most of those HV transformers are wax potted and not subject to moisture ingress which causes the failure.   

Here's a steam-punk boat anchor for you to fix up. That should keep you off the streets for a couple of days: https://www.ebay.de/itm/193700185615

McBryce.

No thanks. And Hickok was one of the companies that cloned Type 535/545 for the .gov and ignored multiple Tek patents.

[Robert763]

So now that I have all the gremlins out of the mini 212 I find myself without a follow on project. That's dangerous because then I'll wander the streets and get myself in trouble.  I've been cruising Ebay but other than that RCA VTVM I've mentioned previously nothing really pipes my interest. And since that clown seller won't respond to my request for internal pictures after stating he would then he can go fuck himself. I'll bet it has been under water.

So, what to do? Well, I really should consider doing the HV solid state mod on the Type 547. It has that failure prone epoxy potted HV transformer. The solid state mod removes the 5642 HV rectifier tubes and installs NTE517 HV rectifiers. The point of this mod is to eliminate the tubes filament voltage which in turn lightens the load on the HV oscillator and transformer thus extending their life.

Pictures from Tekwiki with the original 5642 tubes and the SS mod.

https://w140.com/tekwiki/wiki/547#/media/File:Tek_547_HVSection-NoCover.jpg

https://w140.com/tekwiki/wiki/547#/media/File:Tek_547_HV_Diodes.jpg   

Those NTE517 HV rectifiers are not cheap. About $7.50 USD a pop. And I need 5 and at least one or two spares. But considering that the HV transformer is nearly unobtainium it's worth it. Nearly every Tek scope in the 1950's and early 1960's uses these 5642 HV rectifiers in the HV but most of those HV transformers are wax potted and not subject to moisture ingress which causes the failure.   

That NTE 517 is grossly over specificed for the application. The 5642 is only  rated at 10kV PRV (3.6kV RMS typical) at 250uA (1.5mA peak) and about 3-10k impedance. 
10 1N4007s and a 4k7 in series would be a good subsitute.

Edit: I just checked the 547 schematic and at 8.5kV HT and 5 stage multiplier, five 1N4007s and a 4k7 in series per 5642 would be more than adequate.

[Cerebus]

Hmmm Cerebus's SWMBO is potty which may explain why he is like he is. 

No, it doesn't explain why I am like I am, but it possibly explains why I still have a SWMBO.

[Cerebus]

TE incomming,
Just won my cheapest ever Fluke on ebay. A 5.5 digit DMM for 99p 
www.ebay.co.uk/itm/Fluke-NetDAQ-2645a-46a-Networked-Data-Acquisition-Unit-/363608963162
OK it's not exactly a DMM, the local display is only 4.5 digits and it's a little beaten up but what do you expect for 99p?
It's misdescribed, it is the higher resolution 2640A not a 2645A. Importantly it comes with the input module and even a bunch of J type thermocouples with connectors.
I think nobody else bid as it's tatty and "Collection Only". But the description says "will post for £12"  So total delivered price £12.99. These typically sell for >10x that.
There is the small issue of software. The current version is not cheap but the demo gives you 40 hours of logging time. I cna use that to configure it and it will then be mostly used as a 20 ch thermometer in local monitior mode.
I might be able to find the older software and run it on an old XP laptop.....

Ooooh, nice. Wish I'd spotted that.

[med6753]

So now that I have all the gremlins out of the mini 212 I find myself without a follow on project. That's dangerous because then I'll wander the streets and get myself in trouble.  I've been cruising Ebay but other than that RCA VTVM I've mentioned previously nothing really pipes my interest. And since that clown seller won't respond to my request for internal pictures after stating he would then he can go fuck himself. I'll bet it has been under water.

So, what to do? Well, I really should consider doing the HV solid state mod on the Type 547. It has that failure prone epoxy potted HV transformer. The solid state mod removes the 5642 HV rectifier tubes and installs NTE517 HV rectifiers. The point of this mod is to eliminate the tubes filament voltage which in turn lightens the load on the HV oscillator and transformer thus extending their life.

Pictures from Tekwiki with the original 5642 tubes and the SS mod.

https://w140.com/tekwiki/wiki/547#/media/File:Tek_547_HVSection-NoCover.jpg

https://w140.com/tekwiki/wiki/547#/media/File:Tek_547_HV_Diodes.jpg   

Those NTE517 HV rectifiers are not cheap. About $7.50 USD a pop. And I need 5 and at least one or two spares. But considering that the HV transformer is nearly unobtainium it's worth it. Nearly every Tek scope in the 1950's and early 1960's uses these 5642 HV rectifiers in the HV but most of those HV transformers are wax potted and not subject to moisture ingress which causes the failure.   

That NTE 517 is grossly over specificed for the application. The 5642 is only  rated at 10kV PRV (3.6kV RMS typical) at 250uA (1.5mA peak) and about 3-10k impedance. 
10 1N4007s and a 4k7 in series would be a good subsitute.

I don't disagree. But when you start stacking rectifiers in series you should also have balancing capacitors which just makes the design messier and more prone to flash over and all kinds of nastiness.   

[BU508A]

So now that I have all the gremlins out of the mini 212 I find myself without a follow on project. That's dangerous because then I'll wander the streets and get myself in trouble.  I've been cruising Ebay but other than that RCA VTVM I've mentioned previously nothing really pipes my interest. And since that clown seller won't respond to my request for internal pictures after stating he would then he can go fuck himself. I'll bet it has been under water.

So, what to do? Well, I really should consider doing the HV solid state mod on the Type 547. It has that failure prone epoxy potted HV transformer. The solid state mod removes the 5642 HV rectifier tubes and installs NTE517 HV rectifiers. The point of this mod is to eliminate the tubes filament voltage which in turn lightens the load on the HV oscillator and transformer thus extending their life.

Pictures from Tekwiki with the original 5642 tubes and the SS mod.

https://w140.com/tekwiki/wiki/547#/media/File:Tek_547_HVSection-NoCover.jpg

https://w140.com/tekwiki/wiki/547#/media/File:Tek_547_HV_Diodes.jpg   

Those NTE517 HV rectifiers are not cheap. About $7.50 USD a pop. And I need 5 and at least one or two spares. But considering that the HV transformer is nearly unobtainium it's worth it. Nearly every Tek scope in the 1950's and early 1960's uses these 5642 HV rectifiers in the HV but most of those HV transformers are wax potted and not subject to moisture ingress which causes the failure.   

That NTE 517 is grossly over specificed for the application. The 5642 is only  rated at 10kV PRV (3.6kV RMS typical) at 250uA (1.5mA peak) and about 3-10k impedance. 
10 1N4007s and a 4k7 in series would be a good subsitute.

I thought the same, but I would probably use the 2CL75

ebay, int. shipping, NAWTS:
https://www.ebay.com/itm/254505796198

datasheet attached

Edit:
The datasheet for the 5642 can be found here:
http://www.r-type.org/pdfs/5642.pdf

[Robert763]

So now that I have all the gremlins out of the mini 212 I find myself without a follow on project. That's dangerous because then I'll wander the streets and get myself in trouble.  I've been cruising Ebay but other than that RCA VTVM I've mentioned previously nothing really pipes my interest. And since that clown seller won't respond to my request for internal pictures after stating he would then he can go fuck himself. I'll bet it has been under water.

So, what to do? Well, I really should consider doing the HV solid state mod on the Type 547. It has that failure prone epoxy potted HV transformer. The solid state mod removes the 5642 HV rectifier tubes and installs NTE517 HV rectifiers. The point of this mod is to eliminate the tubes filament voltage which in turn lightens the load on the HV oscillator and transformer thus extending their life.

Pictures from Tekwiki with the original 5642 tubes and the SS mod.

https://w140.com/tekwiki/wiki/547#/media/File:Tek_547_HVSection-NoCover.jpg

https://w140.com/tekwiki/wiki/547#/media/File:Tek_547_HV_Diodes.jpg   

Those NTE517 HV rectifiers are not cheap. About $7.50 USD a pop. And I need 5 and at least one or two spares. But considering that the HV transformer is nearly unobtainium it's worth it. Nearly every Tek scope in the 1950's and early 1960's uses these 5642 HV rectifiers in the HV but most of those HV transformers are wax potted and not subject to moisture ingress which causes the failure.   

That NTE 517 is grossly over specificed for the application. The 5642 is only  rated at 10kV PRV (3.6kV RMS typical) at 250uA (1.5mA peak) and about 3-10k impedance. 
10 1N4007s and a 4k7 in series would be a good subsitute.

I don't disagree. But when you start stacking rectifiers in series you should also have balancing capacitors which just makes the design messier and more prone to flash over and all kinds of nastiness.   

The NTE is just  stack od chips with no capacitors. With such a margin on current rating I see no issue with 5 1N4007's in series.  Just make sure thy are all off the same reel.

[GreyWoolfe]

I didn't realize until I tried these NOS probes how much I hate the feel of Pliovic leads anymore; even my cheap Chinese probes are all silicone now. The probes that come with the 27  are shrouded, but the sockets are just a bit smaller and most of my extra probes don't fit; I may actually have to splurge on some Fluke or Pomonas in silicone.

That is interesting.  Some years ago I bought a Fluke 27 F/M packaged like yours, big probulator, crappy leads, hard case but no manuals.  Pitched the crappy leads and I have been using the Brymen leads that Frankie was selling on his website.  If fact, I have 5 sets of the leads and they fit fine in my Fluke.  I would have thought that they would use the same jacks for ease of inventory and lower BOM cost for more profit.

[med6753]

So now that I have all the gremlins out of the mini 212 I find myself without a follow on project. That's dangerous because then I'll wander the streets and get myself in trouble.  I've been cruising Ebay but other than that RCA VTVM I've mentioned previously nothing really pipes my interest. And since that clown seller won't respond to my request for internal pictures after stating he would then he can go fuck himself. I'll bet it has been under water.

So, what to do? Well, I really should consider doing the HV solid state mod on the Type 547. It has that failure prone epoxy potted HV transformer. The solid state mod removes the 5642 HV rectifier tubes and installs NTE517 HV rectifiers. The point of this mod is to eliminate the tubes filament voltage which in turn lightens the load on the HV oscillator and transformer thus extending their life.

Pictures from Tekwiki with the original 5642 tubes and the SS mod.

https://w140.com/tekwiki/wiki/547#/media/File:Tek_547_HVSection-NoCover.jpg

https://w140.com/tekwiki/wiki/547#/media/File:Tek_547_HV_Diodes.jpg   

Those NTE517 HV rectifiers are not cheap. About $7.50 USD a pop. And I need 5 and at least one or two spares. But considering that the HV transformer is nearly unobtainium it's worth it. Nearly every Tek scope in the 1950's and early 1960's uses these 5642 HV rectifiers in the HV but most of those HV transformers are wax potted and not subject to moisture ingress which causes the failure.   

That NTE 517 is grossly over specificed for the application. The 5642 is only  rated at 10kV PRV (3.6kV RMS typical) at 250uA (1.5mA peak) and about 3-10k impedance. 
10 1N4007s and a 4k7 in series would be a good subsitute.

I don't disagree. But when you start stacking rectifiers in series you should also have balancing capacitors which just makes the design messier and more prone to flash over and all kinds of nastiness.   

The NTE is just  stack od chips with no capacitors. With such a margin on current rating I see no issue with 5 1N4007's in series.  Just make sure thy are all off the same reel.

Again, don't disagree. But those stack of chips inside the NTE should be of the same die and are hermetically sealed. A much neater and simpler solution despite the additional expense. KISS applies here especially with HV circuits which I dislike working on.   

[0culus]

So now that I have all the gremlins out of the mini 212 I find myself without a follow on project. That's dangerous because then I'll wander the streets and get myself in trouble.  I've been cruising Ebay but other than that RCA VTVM I've mentioned previously nothing really pipes my interest. And since that clown seller won't respond to my request for internal pictures after stating he would then he can go fuck himself. I'll bet it has been under water.

So, what to do? Well, I really should consider doing the HV solid state mod on the Type 547. It has that failure prone epoxy potted HV transformer. The solid state mod removes the 5642 HV rectifier tubes and installs NTE517 HV rectifiers. The point of this mod is to eliminate the tubes filament voltage which in turn lightens the load on the HV oscillator and transformer thus extending their life.

Pictures from Tekwiki with the original 5642 tubes and the SS mod.

https://w140.com/tekwiki/wiki/547#/media/File:Tek_547_HVSection-NoCover.jpg

https://w140.com/tekwiki/wiki/547#/media/File:Tek_547_HV_Diodes.jpg   

Those NTE517 HV rectifiers are not cheap. About $7.50 USD a pop. And I need 5 and at least one or two spares. But considering that the HV transformer is nearly unobtainium it's worth it. Nearly every Tek scope in the 1950's and early 1960's uses these 5642 HV rectifiers in the HV but most of those HV transformers are wax potted and not subject to moisture ingress which causes the failure.   

I want to do this mod as well, but my top concern is getting the replacements soldered in as cleanly as the factory did. That's going to be particularly important in this EHT area, to avoid creating opportunities for corona and/or arcing. 

[ch_scr]

So now that I have all the gremlins out of the mini 212 I find myself without a follow on project. That's dangerous because then I'll wander the streets and get myself in trouble.  I've been cruising Ebay but other than that RCA VTVM I've mentioned previously nothing really pipes my interest. And since that clown seller won't respond to my request for internal pictures after stating he would then he can go fuck himself. I'll bet it has been under water.

So, what to do? Well, I really should consider doing the HV solid state mod on the Type 547. It has that failure prone epoxy potted HV transformer. The solid state mod removes the 5642 HV rectifier tubes and installs NTE517 HV rectifiers. The point of this mod is to eliminate the tubes filament voltage which in turn lightens the load on the HV oscillator and transformer thus extending their life.

Pictures from Tekwiki with the original 5642 tubes and the SS mod.

https://w140.com/tekwiki/wiki/547#/media/File:Tek_547_HVSection-NoCover.jpg

https://w140.com/tekwiki/wiki/547#/media/File:Tek_547_HV_Diodes.jpg   

Those NTE517 HV rectifiers are not cheap. About $7.50 USD a pop. And I need 5 and at least one or two spares. But considering that the HV transformer is nearly unobtainium it's worth it. Nearly every Tek scope in the 1950's and early 1960's uses these 5642 HV rectifiers in the HV but most of those HV transformers are wax potted and not subject to moisture ingress which causes the failure.   

That NTE 517 is grossly over specificed for the application. The 5642 is only  rated at 10kV PRV (3.6kV RMS typical) at 250uA (1.5mA peak) and about 3-10k impedance. 
10 1N4007s and a 4k7 in series would be a good subsitute.

I thought the same, but I would probably use the 2CL75

ebay, int. shipping, NAWTS:
https://www.ebay.com/itm/254505796198

datasheet attached

I'm on team different diodes as well, but I'd pick these
https://www.ebay.com/itm/224214028051
NAWTS as usual: cheap, shipped from the us and overspecced

[Neomys Sapiens]

I keep finding the strangest 'unstruments' on the web.

Here one from India:
https://www.japson.com/conversion-of-galvanometer-into-a-voltmeter-ammeter.html
Just the title is a hoot!

And what the world needed - another talking multimeter:
http://www.microseveninc.com/vm10brochure.htm
The one from Voltcraft was bad enough while it kept to one language.

Note to self: Shake it off! Look at something functional and precise and forget that it exists!

The second one looks like it could be for blind technicians.   Another niche market, but I could see a use for it.   

I would have expected Braille labeling for the keys on the topside then, but you could be right anyway.

[med6753]

So now that I have all the gremlins out of the mini 212 I find myself without a follow on project. That's dangerous because then I'll wander the streets and get myself in trouble.  I've been cruising Ebay but other than that RCA VTVM I've mentioned previously nothing really pipes my interest. And since that clown seller won't respond to my request for internal pictures after stating he would then he can go fuck himself. I'll bet it has been under water.

So, what to do? Well, I really should consider doing the HV solid state mod on the Type 547. It has that failure prone epoxy potted HV transformer. The solid state mod removes the 5642 HV rectifier tubes and installs NTE517 HV rectifiers. The point of this mod is to eliminate the tubes filament voltage which in turn lightens the load on the HV oscillator and transformer thus extending their life.

Pictures from Tekwiki with the original 5642 tubes and the SS mod.

https://w140.com/tekwiki/wiki/547#/media/File:Tek_547_HVSection-NoCover.jpg

https://w140.com/tekwiki/wiki/547#/media/File:Tek_547_HV_Diodes.jpg   

Those NTE517 HV rectifiers are not cheap. About $7.50 USD a pop. And I need 5 and at least one or two spares. But considering that the HV transformer is nearly unobtainium it's worth it. Nearly every Tek scope in the 1950's and early 1960's uses these 5642 HV rectifiers in the HV but most of those HV transformers are wax potted and not subject to moisture ingress which causes the failure.   

That NTE 517 is grossly over specificed for the application. The 5642 is only  rated at 10kV PRV (3.6kV RMS typical) at 250uA (1.5mA peak) and about 3-10k impedance. 
10 1N4007s and a 4k7 in series would be a good subsitute.

I thought the same, but I would probably use the 2CL75

ebay, int. shipping, NAWTS:
https://www.ebay.com/itm/254505796198

datasheet attached

I'm on team different diodes as well, but I'd pick these
https://www.ebay.com/itm/224214028051
NAWTS as usual: cheap, shipped from the us and overspecced

Cheap? At $11.99 USD each plus $4.60 shipping. I don't think so. 

[BU508A]

So now that I have all the gremlins out of the mini 212 I find myself without a follow on project. That's dangerous because then I'll wander the streets and get myself in trouble.  I've been cruising Ebay but other than that RCA VTVM I've mentioned previously nothing really pipes my interest. And since that clown seller won't respond to my request for internal pictures after stating he would then he can go fuck himself. I'll bet it has been under water.

So, what to do? Well, I really should consider doing the HV solid state mod on the Type 547. It has that failure prone epoxy potted HV transformer. The solid state mod removes the 5642 HV rectifier tubes and installs NTE517 HV rectifiers. The point of this mod is to eliminate the tubes filament voltage which in turn lightens the load on the HV oscillator and transformer thus extending their life.

Pictures from Tekwiki with the original 5642 tubes and the SS mod.

https://w140.com/tekwiki/wiki/547#/media/File:Tek_547_HVSection-NoCover.jpg

https://w140.com/tekwiki/wiki/547#/media/File:Tek_547_HV_Diodes.jpg   

Those NTE517 HV rectifiers are not cheap. About $7.50 USD a pop. And I need 5 and at least one or two spares. But considering that the HV transformer is nearly unobtainium it's worth it. Nearly every Tek scope in the 1950's and early 1960's uses these 5642 HV rectifiers in the HV but most of those HV transformers are wax potted and not subject to moisture ingress which causes the failure.   

That NTE 517 is grossly over specificed for the application. The 5642 is only  rated at 10kV PRV (3.6kV RMS typical) at 250uA (1.5mA peak) and about 3-10k impedance. 
10 1N4007s and a 4k7 in series would be a good subsitute.

I thought the same, but I would probably use the 2CL75

ebay, int. shipping, NAWTS:
https://www.ebay.com/itm/254505796198

datasheet attached

I'm on team different diodes as well, but I'd pick these
https://www.ebay.com/itm/224214028051
NAWTS as usual: cheap, shipped from the us and overspecced

Cheap? At $11.99 USD each plus $4.60 shipping. I don't think so. 

"12 PCS Brand New 2CL106 12KV 450mA Rectifier Diode"

This would be 1 Dollar per piece. And you have some spares... 

[med6753]

So now that I have all the gremlins out of the mini 212 I find myself without a follow on project. That's dangerous because then I'll wander the streets and get myself in trouble.  I've been cruising Ebay but other than that RCA VTVM I've mentioned previously nothing really pipes my interest. And since that clown seller won't respond to my request for internal pictures after stating he would then he can go fuck himself. I'll bet it has been under water.

So, what to do? Well, I really should consider doing the HV solid state mod on the Type 547. It has that failure prone epoxy potted HV transformer. The solid state mod removes the 5642 HV rectifier tubes and installs NTE517 HV rectifiers. The point of this mod is to eliminate the tubes filament voltage which in turn lightens the load on the HV oscillator and transformer thus extending their life.

Pictures from Tekwiki with the original 5642 tubes and the SS mod.

https://w140.com/tekwiki/wiki/547#/media/File:Tek_547_HVSection-NoCover.jpg

https://w140.com/tekwiki/wiki/547#/media/File:Tek_547_HV_Diodes.jpg   

Those NTE517 HV rectifiers are not cheap. About $7.50 USD a pop. And I need 5 and at least one or two spares. But considering that the HV transformer is nearly unobtainium it's worth it. Nearly every Tek scope in the 1950's and early 1960's uses these 5642 HV rectifiers in the HV but most of those HV transformers are wax potted and not subject to moisture ingress which causes the failure.   

That NTE 517 is grossly over specificed for the application. The 5642 is only  rated at 10kV PRV (3.6kV RMS typical) at 250uA (1.5mA peak) and about 3-10k impedance. 
10 1N4007s and a 4k7 in series would be a good subsitute.

I thought the same, but I would probably use the 2CL75

ebay, int. shipping, NAWTS:
https://www.ebay.com/itm/254505796198

datasheet attached

I'm on team different diodes as well, but I'd pick these
https://www.ebay.com/itm/224214028051
NAWTS as usual: cheap, shipped from the us and overspecced

Cheap? At $11.99 USD each plus $4.60 shipping. I don't think so. 

"12 PCS Brand New 2CL106 12KV 450mA Rectifier Diode"

This would be 1 Dollar per piece. And you have some spares... 

Oh crap, you're right. Read that too quick. I'll go back in my hole. 

[med6753]

This showed up today from the Land of the Rising Sun. A modification kit for the AC input battery charge circuit for the mini 212. Thanks TERRA operative. 



Trouble is....I already reassembled the scope and it's currently in a burn-in cycle. Once it passes I'll consider doing the mod.

If I ever meet the Mechanical Engineer who designed the packaging for this scope I'm going to punch him in the nose. 

[BU508A]

This showed up today from the Land of the Rising Sun. A modification kit for the AC input battery charge circuit for the mini 212. Thanks TERRA operative. 

Cool! There you have your next project after the HV mod. 

Trouble is....I already reassembled the scope and it's currently in a burn-in cycle. Once it passes I'll consider doing the mod.

If I ever meet the Mechanical Engineer who designed the packaging for this scope I'm going to punch him in the nose. 

The CRT does not align ...     

[Martin.M]

I have never seen a replacement kit in one of them.

211, 212, 214 and 221 use 2x 5pcs pack AA NiCd.
213 use 2pcs D, NiCd

211,212,213 and 214 must b3e solded to the right AC voltage, 120V uncle Sam or 220V Europe.
221 likes any AC voltage between 90 and 230V