475B intermittent horizontal


Ondrej Pavelka
 

Hi,

I have a 475 here with what I thought is just a dirty switch. It's intermittently loosing the horizontal signal, it's triggering fine but the display does not stretch properly or not at all. When I press x10 switch it basically works most of a time in the x10 setting but when I let the button go the display disappears. I initially thought the x10 is a switch is ON-ON type and it's stuck in the intermediate position as if it was ON-OFF-ON. After consulting the schematics I'm a little confused (see attached) because it suggests the switch is one pole and it's just bypassing the R1012.


Anyone can shed some light here?


https://photos.app.goo.gl/bNpXe4CdxoPdWiyM8


Michael W. Lynch
 

On Fri, Mar 12, 2021 at 04:15 PM, Ondrej Pavelka wrote:


I have a 475 here with what I thought is just a dirty switch. It's
intermittently loosing the horizontal signal, it's triggering fine but the
display does not stretch properly or not at all. When I press x10 switch it
basically works most of a time in the x10 setting but when I let the button go
the display disappears. I initially thought the x10 is a switch is ON-ON type
and it's stuck in the intermediate position as if it was ON-OFF-ON. After
consulting the schematics I'm a little confused (see attached) because it
suggests the switch is one pole and it's just bypassing the R1012.
The 10X Mag switch is a multi-contact switch. Look at the Horizontal Amp Schematic in the area of Q1124. It is also possible that the Beam finder switch is intermittent. Both switches can cause horizontal issues if ALL the internal contacts are not opening and closing correctly when the switch is operated. Try cleaning and exercising both switches. Also check that each switch is making the appropriate connections by testing the various contact positions while operating the switches. These switches are very prone to getting dirty or failing to open or close properly. These schematics split these switches onto multiple pages of the schematics. The 10X is shown partially on Schematic #8 and #10 and the Beam Finder is found partially on #4, #10 and #12 I have repaired many of these units and these switches cause trouble from time to time. Switch cleaning is a first order of business.

Anyone can shed some light here?

--
Michael Lynch
Dardanelle, AR


Ondrej Pavelka
 

Thanks Michael,
That would explain a lot, I will clean them both thoroughly and I will have a look if I don't have the same configuration brand new ones. I have massive crate full of various configurations, 6 12 18 24 and even some 96 pin.
From my experience these can be cleaned most of a time, but sometimes they are simply worn out too much.


 

Interesting model!

Raymond


Ondrej Pavelka
 

It's a brain fart, I have also 2445B 2467B so when I typed 475 I automatically put B there as well. It's regular 475, not even A. I also have 485 to fix and 561A but that's for another day.


Michael W. Lynch
 

Ondrej,

Hopefully cleaning and exercise will correct the problem. These switches don't get used that much. I suppose they could wear out, but these are some of the least used switches on the scope. I have never had to replace one as of today. But I am a relative newcomer to this hobby. I am sure others may have had a different experience. Best of luck, let us know how this works out for you.

--
Michael Lynch
Dardanelle, AR


 

On Sat, Mar 13, 2021 at 12:17 AM, Ondrej Pavelka wrote:


It's a brain fart
Hi Ondrej,
Just couldn't help myself...
As we're all aware, errors in subject titles, especially wrong model numbers, can be annoying, often negatively affecting future searching. Not applicable in this case of course.

Raymond


Wayne
 

Perhaps it's just me, but I'm not understanding what you mean by the display not stretching properly--is the trace physically too short on the screen, or are you talking about "stretching" the pulse width of the displayed signal when you speed up the time base? I assume you are saying the "triggered" light is staying on when this happens, correct?


Ondrej Pavelka
 

It's not easiest for me to describe in non native language,
Basically what happens is the trigger light is on but I see no trace. It
behaves as if I lost the horizontal all together. It only works when I keep
the button pressed. It's most likely dirty contacts I'll get to it on
Monday.

On Sat, 13 Mar 2021, 19:58 Wayne via groups.io, <WAYNECL=AOL.COM@groups.io>
wrote:

Perhaps it's just me, but I'm not understanding what you mean by the
display not stretching properly--is the trace physically too short on the
screen, or are you talking about "stretching" the pulse width of the
displayed signal when you speed up the time base? I assume you are saying
the "triggered" light is staying on when this happens, correct?






 

Ondrej,
As Michael said, these switches aren't used a lot, so they are likely to become dirty but won't wear out.

As suggested, clean with contact cleaner like Kontakt 60. Use it sparingly and flush with IPA or a contact washing/lubrication liquid like Kontakt 61.
I suspect that maybe you're in the Czech Republic, correct? In that case, you should be able to get these (originally from Germany) or something alike.
Many people leave contact cleaner on but that's usually not a good idea.

Also, you seem to be wondering what kind of switches they are:
The Beam Finder key is a momentary switch: Press - ON, take finger away - OFF.
The 10X key is a toggle: Press - ON, take finger away - stays on, press again - OFF.

Hope this is clear. Any other physical behavior means physically sticking key.

Raymond


Michael W. Lynch
 

On Sat, Mar 13, 2021 at 03:36 PM, Raymond Domp Frank wrote:


The Beam Finder key is a momentary switch: Press - ON, take finger away - OFF.
The 10X key is a toggle: Press - ON, take finger away - stays on, press again
- OFF.

Hope this is clear. Any other physical behavior means physically sticking key.
Raymond is correct to point this out. One may also "feel" the action of the switch as it operates and the switch may not be returning fully to the "out" position. I have seen beam finders that would not "pop out" fully when the button was released, in other words, switch stuck or stopped in some intermediate position. The 10X Mag can also fail to "toggle" fully, even though the button may at first appear to pop out.

--
Michael Lynch
Dardanelle, AR


Michael W. Lynch
 

On Sat, Mar 13, 2021 at 03:36 PM, Raymond Domp Frank wrote:


clean with contact cleaner like Kontakt 60. Use it sparingly and flush with
IPA or a contact washing/lubrication liquid like Kontakt 61.
Raymond,

Do you feel that these are some of the best products available? I would like to try another product as I have been using DEOXIT and other similar chemicals. Never have tried this brand.

--
Michael Lynch
Dardanelle, AR


 

On Sat, Mar 13, 2021 at 11:32 PM, Michael W. Lynch wrote:


Do you feel that these are some of the best products available? I would like
to try another product as I have been using DEOXIT and other similar
chemicals. Never have tried this brand.
Hi Michael,
I'm in continental Europe and the Kontakt brand has traditionally been a standard for electricals over here. The American products were virtually unknown, to hobbyists at least. Some UK products existed but were not as popular as Kontakt by far.

Personally, I consider Kontakt 60, the contact cleaner, to be very good and/but perhaps a bit stronger than some others. In fine electronics (for which it's recommended), it's really best flushed away after it's done its work. Kontakt 61 is used for rinsing (sometimes after using IPA first) and leaves a non-sticky, non-teflon, non-silicon etc. and very importantly, "never" drying-out very thin layer of lubrication behind.

Raymond


Mlynch001
 

On Sat, Mar 13, 2021 at 05:04 PM, Raymond Domp Frank wrote:


Hi Michael,
I'm in continental Europe and the Kontakt brand has traditionally been a
standard for electricals over here. The American products were virtually
unknown, to hobbyists at least. Some UK products existed but were not as
popular as Kontakt by far.
Raymond,

I did some research and it appears that KONTAKT is somehow affiliated with CRC in the US. I will see if CRC has an equivalent product to KONTAKT 60 and 61. I have used DeOxit products, for some applications but the cost seems very high. If I can find something that works well, even as a partial substitute, that would be nice.
--
Michael Lynch
Dardanelle, AR


 

On Sun, Mar 14, 2021 at 12:45 AM, Mlynch001 wrote:


I did some research and it appears that KONTAKT is somehow affiliated with CRC
in the US.
Yes, I remember having seen CRC on the cans for a few years now. Have a look at kontaktchemie.com under the "About" heading.

Raymond


greenboxmaven
 

De-Oxit and De-Oxide have oxalic acid as a constituent to remove metal oxides.  Another product is Cramolin, also reportedly based on oxalic acid. Forty years ago, there were many products sold here as "TV tuner cleaners" . They were too often over applied and made a real mess to clean up later.  They were all moderately effective for rotary switch tuners, but excellent in turret coil tuners when used wisely. The voltage and current going through contacts has a great deal of influence over cleaning. High voltages and currents will "fry" dust and dirt between contacts, chemically bonding them into the contact surface. That is the most difficult to remove.  Contacts that carry tiny currents are very vulnerable to dirt being worked in between the contacts, it spreads them apart and prevents contact.  I have had great results spraying these contacts with a solvent cleaner that contains both hydrocarbons and isopropyl alcohol, then running a small piece of clean paper soaked with the solvent between them a few times. It has worked very well on Tektronix "Cam pushes the bridging contact down onto the gold plated spot on the circuit board"  switches.

        Bruce Gentry, KA2IVY

On 3/13/21 18:04, Raymond Domp Frank wrote:
On Sat, Mar 13, 2021 at 11:32 PM, Michael W. Lynch wrote:

Do you feel that these are some of the best products available? I would like
to try another product as I have been using DEOXIT and other similar
chemicals. Never have tried this brand.
Hi Michael,
I'm in continental Europe and the Kontakt brand has traditionally been a standard for electricals over here. The American products were virtually unknown, to hobbyists at least. Some UK products existed but were not as popular as Kontakt by far.

Personally, I consider Kontakt 60, the contact cleaner, to be very good and/but perhaps a bit stronger than some others. In fine electronics (for which it's recommended), it's really best flushed away after it's done its work. Kontakt 61 is used for rinsing (sometimes after using IPA first) and leaves a non-sticky, non-teflon, non-silicon etc. and very importantly, "never" drying-out very thin layer of lubrication behind.

Raymond




 

On Sun, Mar 14, 2021 at 12:49 AM, Raymond Domp Frank wrote:


Yes, I remember having seen CRC on the cans for a few years now. Have a look
at kontaktchemie.com under the "About" heading.
Just remembered that Kontakt WL is their preferred rinsing fluid. I use IPA instead, in larger containers.
Raymond


Ondrej Pavelka
 

Hi Raymond,

I have their complete set of chemicals and I am very familiar with damage
unwashed contact sprays can do.
WL is good but all 3 requires really good ventilation it stinks and gives
headache pretty much instantly.

On Sun, 14 Mar 2021, 00:57 Raymond Domp Frank, <hewpatek@gmail.com> wrote:

On Sun, Mar 14, 2021 at 12:49 AM, Raymond Domp Frank wrote:


Yes, I remember having seen CRC on the cans for a few years now. Have a
look
at kontaktchemie.com under the "About" heading.
Just remembered that Kontakt WL is their preferred rinsing fluid. I use
IPA instead, in larger containers.
Raymond






Ondrej Pavelka
 

I have cleaned all the switches and viola, all nice and dandy!!
Thank you guys!

The only problem remains the faulty 100x divider module in the attenuator of the 2nd channel. I bought new one some time ago, but it fell apart as soon as i touched it despite being new, it wasn't cheap including postage so i wonder if i should just try again, it originally put me off ordering again.


Michael W. Lynch
 

On Mon, Mar 15, 2021 at 06:14 PM, Ondrej Pavelka wrote:


I have cleaned all the switches and viola, all nice and dandy!!
Thank you guys!
Great News! Glad it was a simple fix. Those are the best.

--
Michael Lynch
Dardanelle, AR