Refurbishing a Digital Storage Oscilloscope (DSO) with high quality components

[Kiriakos GR]

This article will not help you to repair your scope with an offering of practical tips.
 
This article will help experts, them to perform a wider search when it comes down to Component Level Repair.
Component Level Repair this by 99%, leads to component replacement by a new and of a better quality if possible.

This article will mainly focus, at components, which these accept highest level of wear and tear.
Encoders / Contacting Encoders


Intro: I have spot several traces over the internet, of young people trying to replace Contacting Encoders, with low-quality parts from Aliexpress and eBay (No-Name Chinese production of goods).
Long story in sort, the oscilloscope due the wrong selection of parts, it will lost it functionality.
Even if functionality this is perfectly restored, the newly replaced Encoder it will fail again in a sort time.

Reputable brands at making oscilloscopes, they have two paths to follow at acquiring acceptable quality of encoders for their products.
Path A =  Getting branded components from international sources. 
Path B =  Getting their parts from Asian B2B sources, by the delivery of their own specifications and quality standards.
In this example the Asian factory, will deliver a large quantity of grade A components, and the quality control inspection (QC), this is happening two times.
At production stage and at the company this receiving the goods.

Any rejected products due the quality control, they will end at Aliexpress and eBay, as unbranded goods.
In our perfect world, at the year 2026, they are not unbranded goods, they are goods that a factory does not feel pride for their quality. 
 

Encoders / Contacting Encoders and branded sources
I am mostly an maintenance electrician, and I also perform repairs of electronics, but about contacting encoders, I do not know much.
ALPS Japan, this is or was the most known factory (first choice of parts used by the Japanese industry).

This period of time, I discovered and a second one, this is Bourns company base in the USA, production facility in Mexico.
https://bourns.com/products/encoders/contacting-encoders

The reading alone of ALPS and Bourns, product documentation this is a great school, so us to gain deeper awareness of generic and specific per component properties.
IP40 or not (dust proof)
Maximum aloud rotations per minute rate ...  100 rpm
And much more details.

 
Refurbishing a Digital Storage Oscilloscope (DSO)
From a personal example, and by demonstrating trust at GW Instek, at getting a medium priced oscilloscope with three years warranty, I will say today after 13 years, that I did a good choice.
The slogan simply reliable, this is true in my case.
But eventually even the rotary decoders of my scope they will need to be replaced.

GDS-2000A and another two more economical series after it, they rely on for a perfect operation, at rotary encoder Knob this named as VARIABLE.
VARIABLE/Knob in a way this is the hart of the system.
And at my scope, this rotary encoder it just started to lose accuracy under rotation, and or it just began shown signs of imperfection. 

Another interesting find, at GDS-2000A they are two types of rotary encoder, of two different stepping.
And this translates, that I will need to discover two part codes, and then I will asses the needed quantity.

Taking apart a Digital Storage Oscilloscope (DSO), this is not fun.
Its a work this requiring 100% focus and detail for its step.
The last that you need this is using wrong components, and or damaging the scope by not having serious performing soldering tools.
Soldering temperature for rotary encoders this is specific, an calibrated soldering iron, this is a must have so to even start thinking of such a repair.
     
Not all oscilloscope owners, have an identical age, if you are too young or too old, then using repair services due an authorized distributor, this is the most secure path.
Because the entire responsibility for appropriate spare parts selection, and of repair process workflow, this is at expert hands.

The ideally refurbished DSO.
The term Ideally refurbished, this includes at least three targets of having new parts in place.
a) All rotary encoders.
b) All BNC connectors.
c) Inspection of the DC cooling fan.
e) Power supply inspection
f) Mechanical Power ON switch this be replaced by a new.

Such an  ideally refurbished DSO, this will remind you of the day which your scope came as NEW from the factory.
Medium priced DSO these manufactured at 2013 and later, they will not stop be useful in the years to come.
I do see old electronic applications these facing away and any related to these DSO features, this not be that useful any more, but the oscilloscope it self, this retain it usefulness as a pack.
An similar example this is modern DMM, they come loaded with features, not every one will use then all.

An Digital Storage Oscilloscope, this has a greater number of inputs and of dedicated controls.
The ideally refurbished DSO decision, this comes under a price tag.
Before even making such a decision, you need to be aware, that retail price of spare parts alone, this is not possible to be lower than 150 Euro / Dollars
And if the job this is made from another repair man, neither labor costs this can be lower than 250 Euro / Dollars
 
Getting help from oscilloscope manufacturer.
The only assistance that you might get, this is getting for a price, an assembled PCB with all rotary encoders in place.
This is not possible, from all Asian brands, but it worth to try, as assistance at lower down the sum of the bill.   
   
Throwing away the scope / getting a new.
This is not a reasonable option.
Since 2013 and up to date, there is a race at the segment of Low End DSO, at the segment of medium priced DSO, the pricing this has increase by 35~40%.
You must be crazy if you do think, that build quality of latest 12bit toys, this is equal with a scope this surviving for more than 10 years, in a serious lab.

The recent (10 years or more) Chinese government directive, this is the Chinese manufacturing this to be made exclusively due Made in China components.
The western world he should forget the reliability offered due Nichicon capacitor and ALPS encoders, and or of American design micro processors, and or made in Israel high precision resistors.

In conclusion, an well build modern DSO, this is not disposable trash.
Disposable trash, this is every new model of a mobile phone.
The ideally refurbished DSO concept, this is a reality, this is reasonable way of thinking.
The exact cost per scope model this is not known.
If you follow the path at shopping parts of your own, then get double quantity of all parts plus two as extra.   
Such an investment it will extend the life cycle of your scope, for fifteen years ahead as a minimum. 
       
I do remember since 2005, the offering of computer motherboards, these build with new generation of low profile capacitors, with lifecycle specification of 50 years or more.
This was the standard for all top dollar PC motherboards, from ASUS and GIGABYTE or MSI.
An DSO motherboard this is not different, if this is working for 13 years problem free = successful product design.
It is sad, that they are out there several high priced oscilloscopes, theses coming with unsuccessful product design. 

Either way, if you own an successful product design, now you are informed of a full pack of options, so to decided of which is more suitable for you.