Sales, Author at Management Services and Solutions

Operational Technology (OT) vs Information Technology (IT)

OT and IT: What’s the Difference?

Information Technology (IT) is a familiar concept to most modern office workplaces encompassing the products and networks providing data-centric computing, supporting various business functions such as finance, personnel, management and administration. This has grown to being fundamental to corporations large and small, and continues to rapidly develop in scale and capability.

By contrast, Operational Technology (OT) is understood by utilities, transport, manufacturing and other industrial sectors, as encompassing an array of systems engineering, event monitoring and process control to facilitate operations. Historically, the technologies and products used to implement the required infrastructure have been bespoke and separate from other corporate systems.

The growth of standardisation

With the explosion of computing devices, the internet and communications generally, the underlying IT hardware and software have become ubiquitous and standardised. The majority of businesses now deploy products and networks which are interchangeable with most other global corporations, bringing overall costs down, increasing ease-of-use and enabling global inter-operations.

In recent years, there has been a trend to capitalise on these developments by seeking to replace old OT bespoke systems with widely available and deployed IT products.

The problem with convergence

Despite the advantages brought by a move to using IT technologies to fulfil Operational infrastructure needs, there are some draw-backs.

Although no-one wants systems to fail, and high performance is often a key requirement, in traditional OT systems, there is an emphasis on availability, reliability and ‘mission-critical’ operations, dictating deterministic technologies which standard IT products are not designed to provide. The packet-oriented ‘best-efforts’ nature of TCP/IP networking solutions is not sufficient to provide the performance required. Some operational systems have specific timing requirements, utilising PDH and SDH TDM-based technologies to deliver signalling and tele-protection information.

For years, ‘security’ against ‘remote attacks’ was not an issue, because most OT systems were regionally based and not connected to the wider world. And even those with remote monitoring and control tended to use bespoke equipment which was not widely understood or utilised by non-specialists. With a move to going ‘on-line’, and utilising ‘standard’ IT equipment to fulfil OT requirements, this is no longer necessarily the case. Which brings the possibility of outages due to system or denial of service attacks. ‘Cyber-security’ in recent years has needed to become part of the considerations for OT infrastructure, learning from the experiences of threats to IT systems and ‘denial-of-service’ attacks.

And whilst modern IT communications bring gigabit data bandwidths, OT data needs have remained modest, often to fulfil the unchanged monitoring requirements for an enormous existing deployed network of slow-speed kilobit data devices, such as pumps, valves and actuators.

In short, the needs and desires of businesses for computing devices, networking systems and global communications to provide ever-increasing bandwidth and application support continues to diverge from the requirements of industrial operations, requiring availability, compatibility and mission-critical performance.

Future trends

Whilst vendors of networks, computing and communications continue to develop advanced technologies to meet the growing needs of IT for businesses, the desired ‘convergence’ to replace OT systems continues to be a work-in-progress.

OT systems tend to be built with longevity as a priority over cost of ownership, due to the challenges of replacement once in continuous operation. Whereas IT products are often ‘written down’ and replaced over a much shorter timescale, with a view to taking advantage of continuous developments to provide higher performance and productivity.

Consequently, technologies that are considered ‘legacy’ by IT professionals continue to be maintained and even further deployed as trusted and proven OT systems to fulfil operational needs.

Your operational systems requirements

@YellowsBestLtd would like to know your infrastructure goals, deployment experiences and maintenance challenges and how we may assist you to fulfil your OT and IT requirements, for both new and existing operational systems. We look forward to understanding your needs for technical support, solutions sourcing, repair services and equipment spares.

Optical Teleprotection Signalling (TPSO) Equipment (C37.94)

Electrical power systems protection

Teleprotection for power systems protection has been deployed by utility companies for many years. It’s purpose is to monitor the condition of the Electricity Grid, isolate faults, disconnecting faulty parts from the rest of the network and thereby prevent damage to critical parts of the power infrastructure.

Teleprotection is a physical interface between the telecommunications equipment and the electrical grid protection relays. When a fault occurs, the protection system switches on circuit breakers or reclosers to avoid a fault rippling through the network. Also, in the event of an outage, teleprotection helps restart power to a part of the grid.

Early teleprotection systems used voice-frequency signalling technologies. These were replaced by digital electrical Tele-Protection Signalling (TPS) equipment using 4 or 8 command channels encoded into a 64kbit/s standard digital data channel, in accordance with the ITU-T G.703 recommendations. This brought dependability and interoperability of systems, meaning that dedicated channels were no longer required as any standard digital transmission network could be used, separate from the power system.

This was later enhanced by the development of Tele-Protection Systems with Optical (TPSO) interfaces, which allowed the direct fibre connection between the teleprotection device and the primary multiplexer.

The IEEE C37.94 standard for TPSO interfaces

The IEEE C37.94 standard defines an optical fibre interface for use between teleprotection systems and digital multiplexer equipment, operating at a data rate of nx64kbit/s.

This allows the interconnection of different vendors teleprotection equipment with different vendors multiplexer equipment, without any restriction on the content of the nx64kbps data, using up to 2km of 50μm or 62.5μm multimode (or up to 20 km of 9μm single-mode) optical fibre.

Critical Systems deployment

Teleprotection systems are typically installed in high-voltage transmission grids where distances are usually greater than in distribution grids and play a critical role in preventing instability in the grid and damage to expensive substation equipment.

Teleprotection systems monitor conditions on transmission lines and coordinate tripping of the transmission lines to quickly isolate faults.

A teleprotection system usually has two components: a protection relay, which executes the actual switching; and the teleprotection equipment itself, which is the interface to the mission-critical communications network.

To ensure that the power systems are properly protected, real-time exchange of status information messages and commands between teleprotection equipment must be reliably transferred with tightly-controlled latency over a deterministic mission-critical communications network, traditionally composed of TDM multiplexers and optical PDH or SDH equipment.

Nokia ‘Dynanet’ TPSO 24204

An example of a vendor’s multiplexer is the Nokia ‘Dynanet’ equipment family. This utilises the TPSO 24204 interface unit for connecting the teleprotection devices directly to the primary multiplexer. This provides four IEEE C37.94 standard interfaces, with nx64kbit/s optical data channels (where n is 1 to 12).

Because of the direct connection, there is no need for a separate converter to change the optical connection to electrical. This eliminates electrical interference and data corruption caused by disturbances from the high voltage power line.

Your operational systems requirements

Let us know how we can assist you to keep your new and legacy systems operational with technical support, repair services and equipment spares. We look forward to hearing from you.

New and Legacy communication issues

Challenges with maintaining Legacy systems

It can make perfect sense to continue to run existing reliable and proven systems, especially if operational requirements have not changed. Alas, the developing nature of technology means that from time-to-time, issues arise.

Changes to email encyption protocols

Modern computer communication services support the Transport Layer Security (TLS) encryption protocol. This aims to protect the information sent and received over a standard Simple Mail Transfer Protocol (SMTP) connection between two computers while ensuring that they both agree and understand the method of data transfer.

However, the earlier versions of TLS 1.0 and 1.1 have been deemed by the industry to be not secure enough and have been superseded by versions 1.2 and 1.3. You and/or your service provider may have already transitioned to the latest protocols. However, if you have old hardware running legacy software, as support from service providers is withdrawn, you may find your email stops working.

How you can tell if it’s an issue

If you’re using an Apple Mac then the Safari Browser has supported TLS 1.2 for web traffic protection since version 7 in 2013. However, if you’re still running ‘El Capitan’ OSX 10.11 with Apple Mail 9.3, it won’t support TLS 1.2 for email. Other computer hardware and software combinations may also run into problems.

Most browsers including Safari ended support for TLS 1.0 and 1.1 in March 2020, and various service providers have either already dropped or soon will withdraw operation of the older TLS protocols.

For instance, one.com will stop support of TLS 1.0 and 1.1 on 17^th August 2021. Other service providers may have different end of life dates. If you’re using the one.com service then there’s an easy way to check:

send an email to:

protocol@tls-check.one.com.

This will provide an automated reply telling you what protocol you’re using (works with iPhones and iPads too), like this:

{
            “started”: true,
            “protocol”: “TLSv1.2”,
            “cipher”: “ECDHE-RSA-AES256-GCM-SHA384”,
            “keysize”: 256
}

Other service providers may have similar methods of verifying the protocols, so it’s worth checking with them. Failing that, you may be able to examine the headers of your emails, to look for something like this:

version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128

Solutions if you’re affected

To ensuring your email continues to function, the options include:

Updating your operating system. In the case of Apple Mail on Mac computers, this means moving to ‘Sierra’ OSX 10.12 as Mail cannot be separately upgraded.
Using a different email client with TLS 1.2 support, e.g. Mozilla Thunderbird.
Using a browser based solution for your email
Changing your settings to send and receive email without encryption (not recommended)

Balancing New Requirements and Legacy Support

If you want to stick with your current hardware and software choices, this does present a problem, particularly if you’re otherwise happy with your setup and are unable to upgrade.

Alas if you want full compatibility (and security) with the latest industry supported functionality, whilst retaining operation of other legacy applications, consideration has to be made to invest in new hardware to run in parallel with older systems, which continue to be maintained to perform dedicated compatibility functions.

YellowsBest: Keeping Customers Operational

If you have similar or other new requirements and legacy maintenance needs, please get in touch to discuss how we may be of assistance to keep you operational.

International Trading (Post Brexit)

New rules for Business

It’s been an uncertain period leading up to the United Kingdom (UK) leaving the European Union (EU). Now that that ‘Brexit’ has happened, as of 1^st January 2021, businesses are having to work out the practical changes having an impact on international trading.

The reality of the situation is that it will take time to fully understand the new rules and what effect they have on imports and exports. Due to this uncertainty, some companies are choosing to curtail international activities, which is having an effect on availability of supply.

So this is a subject that will need to be revisited as experience is gained. What seems likely is that there will be more administration and higher costs.

@YellowsBestLtd has a 5-year history of trading not just within the EU, but globally, and it’s this experience which is helpful in understanding the adjustments needed. Put simply, all import and export business within and beyond the EU is now ‘similar’ in principle in terms of customs and tax, with or without government ‘trade deals’ being agreed.

VAT charging and reclaim in the UK

It’s helpful to first understand how VAT works on a national level. In the UK, it’s charged on the sale of many goods where ‘value has been added’ at a rate of 20% of the selling price. To consumers, that’s just a tax they pay within the total purchase price. For businesses, that element of the sale is ‘collected’ on behalf of the government, totaled and paid quarterly via their tax return. However, VAT-registered businesses are able to ‘claim back’ the taxed paid on their own purchases. The logic being, that when you’re ‘trading’ i.e. buying and selling, the amount of tax due on goods is that relating to the ‘value add’ – so the difference between the tax charged on the cost price and that charged on the selling price. Which of course should be more, if you’re making any kind of profit.

How VAT previously applied for UK businesses trading within the EU

To avoid the complications of how to ‘settle’ the collection and claiming back of taxes on purchases made between EU member states, an arrangement is in place such that each country is responsible for their own VAT affairs. Here’s how charging for VAT works for businesses when trading within the EU:

The goods are zero-rated for VAT, from suppliers that are VAT-registered. This means that the export invoice, stating “intra-community supply”, charges VAT at 0%.
The VAT-registered buyer (importing company) then declares the ‘acquisition’ on their VAT return (in “Box 2”)
The buyer simultaneously also ‘reclaims’ the VAT (included in “Box 4”) on the same VAT return
The logic behind these transactions is that the purchaser acts as both the “seller and the buyer”, for VAT purposes, Hence the transaction is accounted for entirely within one member state, and no funds need to be transferred to or from the tax authorities.

When these arrangements applied to UK businesses selling goods to buyers in EU member states, a ‘VAT EC Sales List” also needed to be completed and sent to the HMRC.

VAT and trading globally

Now the UK is ‘outside’ the EU, the ‘intra-community’ arrangement for VAT no longer applies from 1^st January 2021. Instead, all international trading follows the same process, for all countries both within and beyond the EU.

UK businesses making global purchases receive an invoice from their international supplier which has no VAT added. But the UK government will separately charge VAT at 20%; this amount needs sending directly to HMRC. Typically, this amount will be collected by the courier physically transporting the goods, and normally an administration fee will be additionally charged for this transaction. If an agreement hasn’t been made with the seller, it is often the case the buyers find they need to pay these additional costs before the imported goods will be released from customs and delivered. Reclaiming of import VAT will then be made via the VAT return as an input tax, following the normal rules for UK-paid VAT.

Alternatively, import VAT can be accounted for using “postponed VAT accounting” on the VAT-return, which essentially is a similar scheme to the EU “intra-community” arrangement. This requires ensuring that the courier is advised how import VAT will be accounted, so they can complete the customs declaration appropriately.

Similarly, UK businesses selling goods internationally don’t add VAT to their invoices, but are likely to have import taxes added by the authorities in the receiving country. If the buyer has not agreed to include these additional costs within their purchase order, this can mean that the seller needs to settle these charges as part of their cost of supply, typically being charged by the courier used to deliver the goods. The difficulty is knowing in advance what is likely to be charged.

Customs Duty and Commodity Codes

In addition to VAT, businesses trading internationally need to take into account Customs Duty (and for certain products, Excise Duty as well) that may be charged on imports.

For UK businesses, this means checking with the HMRC and specifying the correct ‘Commodity Code’ for the goods, which will determine how much is charged. Unfortunately, there are thousands of such codes, covering all manner of products, so identifying the right code can take some searching.

@YellowsBestLtd typically imports a range of telecommunications spare parts, and can therefore advise that for similar requirements the following is applicable: Commodity Code: 8517620000

According to the HMRC website, sales of these goods should have no Duty to pay on imports. It’s less clear what may need to be paid on exports since this will vary by country. The ongoing concern is trying to anticipate these costs in advance, but by making an excessive allowance for them can mean an uncompetitive offer, causing a loss of business.

Your Experiences and Questions

We’d like to hear about your concerns or practical experiences of international trading, both before and after Brexit, within and beyond the EU. Please get in touch, and let us know how we can help with your continuing business requirements. We look forward to hearing from you.

New Year, New Stock! ‘Dynanet’ Spares

Nokia ‘Dynanet’ PDH Transmission products

For many years, the ‘Dynanet’ family of PDH Transmission telecoms products have well served Public Operator and Private Network Customers across the Telecoms, Utilities, Transport and Public Safety markets with high availability mission critical infrastructure, and indeed some networks are continuing to provide good operational service.

They were first introduced by Nokia over 20 years ago, and were continued in recent years by DNWP. Production of the majority of the product range was ceased in 2019.

Spare parts for continued operational service

@YellowsBestLtd satisfies world-wide customer product sourcing requirements for current and ‘legacy’ equipment technologies from a wide range of Original Equipment Manufacturers (O.E.M.s).

For the ‘Dynanet’ range, we have recently obtained of a number of additional refurbished and surplus equipment items. Hence, for those customers continuing to maintain their networks, there now exists the opportunity to increase stocks of spare parts to take advantage of the current availability.

Stocklist of items for immediate supply

Here is a list of the main items currently in stock, though there may be a few additional parts that can be supplied. Hence, please check and if you do have any requirements, please let us know. We look forward to hearing from you.

Part Number	Description
CC 24002	DB2 2×2 Mb/s Branching Unit (B2), 75ohm

Part Number	Description
CC 24011	DB2 2 Mb/s Switching Unit (X2), 75ohm

Part Number	Description
CC 24101	DN2 2×2 Mb/s Interface Unit (IU2), 75ohm

Part Number	Description
CC 24111	DN2 Control Unit (CU), 75 ohm
CG 24170	DN2 Bus Power Unit (BPU)
CG 24171	DN2 Extended Bus Power Unit (EBPU)
CU 24013	Data Interface Unit (DIU) 2M, nx64k: G.703/704, 75ohm

Part Number	Description
D-21470	Euro Connector, 3×7

Part Number	Description
D-24204	Optical Teleprotection Interface Unit, C37.94

Part Number	Description
T31094.01	DCN Adapter C4.0

Part Number	Description
T37870.01	NDM 19in 17-slot Subrack

Part Number	Description
T37871.01	NDM DN2 19in 17-Slot Subrack
T37882.02	NDM DC Unit (NDUe)

Part Number	Description
T37885.01	NDM Ring Generator

Part Number	Description
T37885.02	NDM Ring Generator + DC/DC converter

Part Number	Description
T37889.01	NDM Backup Unit (NBU)

Part Number	Description
T65580.01	ACL2i PF GEN Line Terminal Card

Part Number	Description
TA 21513	Optical Line Terminal Repeater (DF2-8), 1300 nm LED MM/SM
TA 21516	Optical Line Terminal Repeater (DF2-8), 1300 nm LASER SM
TA 21518	Optical Line Terminal Repeater (DF2-8), 1300 nm LASER LP

Part Number	Description
TC 21101	DM2 Multiplexing Unit, 75ohm

Part Number	Description
TC 21301	DM8 Multiplex Equipment, 75ohm
TC 21705	Supervisory Substation
TC 21710.01	TMS Adapter
TU 21122.5	Data Interface Unit (DIU) 48..64k, V.11, 10ch
TU 21124	Data Interface Unit (DIU) nx64k, V.11/V.35/X.21, 2ch
TU 21124.05	Data Interface Unit (DIU) nx64k, V.11/V.35/X.21, sync
TU 21125	Data Interface Unit (DIU) 48..64k with sync, X.21

Part Number	Description
TU 21205	Channel Unit SUB/SUB
TU 21206	Channel Unit SUB/SUB

Channel Unit Subscriber / Subscriber – TU 21206

Part Number	Description
TU 21215	Channel Unit SUB/EXCH
TU 21216	Channel Unit SUB/EXCH

Channel Unit Subscriber / Exchange – TU 21216

Part Number	Description
TU 21234.20	Channel Unit E&M/VF-P, 10 ch, 20 E&M ch
TU 21236.10	Channel Unit 8ch E&M/uP: 1xUKe&m/VF

Part Number	Description
TU 21255.01	Channel Switch, 4 port

Repair Services – is it B.E.R.?

Equipment repair decisions – the Customer’s right!

Customers with critical infrastructure networks have elements that fail from time-to-time. These can usually be swapped out with items from a spare parts stock, to return the system to operational service with the minimum of disruption to overall system availability.

The question then arises of whether the failed item can be repaired. In most circumstances, it is possible to restore parts to working condition, but sometimes they are classified as ‘Beyond Economic Repair’ (B.E.R.). This can be a somewhat contentious issue.

In theory, the term should be only applied to items where the repair cost would exceed the price of the purchase of a new or refurbished replacement. However, on the one hand the term can be used to label something that physically cannot be restored e.g. due to fire or water damage. On the other, it’s often applied to items where no repair facilities exist or it’s not possible to easily source the required components to complete the remedial work. So in other words, the term is used instead of the negative-sounding ‘repair not possible’.

The reason why this can become a source of frustration is because some customers rightly insist that they should be the “one who decides” if the item is ‘B.E.R.’. Maybe for reliability statistical reasons or version compatibility, it is sometimes desired to retain the original part even if repair costs are high. Sometimes, legacy replacement spare parts are in very short supply, and so it makes sense to retain and refurbish items rather than scraping and losing them forever. Even if the short-term associated costs are greater, for products that are no longer being manufactured, the available ‘spares pool’ is finite and diminishing over time and so the decision to repair may avoid longer-term supply issues in the future.

Reduce – Reuse – Recycle

@YellowsBestLtd helps Customers with their operational needs, and one aspect is to #Reduce the demand for avoidable whole-scale replacements through a combination of #Reuse of refurbished spares and repair of system elements. When removal and disposal of no-longer serviceable infrastructure parts is necessary, we can also assist with the resale and #Recycle for ‘value recovery’ of valuable materials.

We can assist by supplying critical and hard-to-find spare parts and hardware repair services, even when the systems have been declared ‘obsolete’ (i.e. no longer in production) by the O.E.M. And we will endeavour to ensure that repair options are always available and the question of B.E.R. is up to the Customer to decide. Please let us know how we can help; we look forward to hearing from you.

Maintenance of Legacy networks – Spares, Connectors and Cables

Continued use of Legacy Telecoms – Nokia PDH ‘Dynanet’

Public Operator and Private Network Customers across the Telecoms, Utilities, Transport and Public Safety markets maintain ‘legacy’ infrastructure for mission critical applications, which continue to deliver good operational service with high availability.

Typical products utilised are those from the ‘Dynanet’ family of PDH Transmission telecoms products, which were first introduced by Nokia over 20 years ago, and were continued in recent years by DNWP. Production of the majority of the product range was ceased in 2019.

In order to maintain these systems and networks, it’s still possible to supply spares from surplus stocks and refurbished items to keep networks operational.

Don’t forget the Connectors and Cables!

One challenge for the continued use of existing infrastructure, particularly when installing replacement parts, is sourcing the appropriate specialised and often propriety connectors for cabling of interfaces and management connections.

Regarding ‘Dynanet’, fortunately some products can still be produced, notably the Euro / SMB connectors, along with the DCN Adapter C4.0, related management software products and other items such as the TPS64 and NDUE. Listed here are a few of those currently available new:

Part Number	Description
21475	SMB Connector for RD179 cable
21472	Euro Connector 3×32
21470	Euro Connector 3×7

Part Number	Description
24201	TPS Control Unit
24202	TPS Channel Unit
T37882.02	NDM DC Unit, enhanced (NDUE)
T31094.01	DCN Adapter C4.0

We are able additionally produce a wide range of cable products to suit most connection requirements, utilising our UK-based manufacturing partner. Bespoke cable assemblies, control boxes, harnesses, wiring looms, panels, fibre optic products are some of the network solutions available.

@YellowsBestLtd satisfies world-wide customer product sourcing requirements for current and ‘legacy’ equipment technologies from a wide range of Original Equipment Manufacturers (O.E.M.s), surplus stocks and refurbished items.

Hence, please check and if you do have any requirements, please let us know. We look forward to hearing from you.

Remaining stocks of Nokia ‘Dynanet’ spares – Update

Surplus and Refurbished Items for continued operational service

Many Customers have ‘legacy’ telecommunications networks which are continuing to provide good operational service. Particularly where functional requirements have not changed, it makes sense to avoid or delay costly and time-consuming change-out replacement projects, by obtaining spare parts.

@YellowsBestLtd satisfies world-wide customer product sourcing requirements for current and ‘legacy’ equipment technologies from a wide range of Original Equipment Manufacturers (O.E.M.s).

Stocklist of Nokia ‘Dynanet’ Spare Parts – Available for immediate supply

For the ‘Dynanet’ family of PDH Transmission telecoms products, which has provided 20+ years of service, we still have a few spare units are in stock and available for immediate supply. These items have been mostly retrieved from operational service during Customers’ decommissioning projects, and have been refurbished, tested and are warranted for working operation.

Given that production of the majority of the product range was ceased in 2019 or before, it is recommended to consider purchasing spare parts whilst there is still availability.

Part Number	Description
CC 24002	DB2 2×2 Mb/s Branching Unit (B2), 75ohm
CC 24011	DB2 2 Mb/s Switching Unit (X2), 75ohm
CC 24101	DN2 2×2 Mb/s Interface Unit (IU2), 75ohm
CC 24111	DN2 Control Unit (CU), 75 ohm
CF 24186	DN2 19in Subrack
CF 24186.09	DN2 19in Subrack, grey-L91 EMC
CG 24170	DN2 Bus Power Unit (BPU)
CG 24171	DN2 Extended Bus Power Unit (EBPU)
CU 24013	Data Interface Unit (DIU) 2M, nx64k: G.703/704, 75ohm
D-21470	Euro Connector, 3×7
D-24204	Optical Teleprotection Interface Unit, C37.94
T30506.09	17-slot DYNANET Subrack
T30851.02	Subrack Power Adapter (SPA)
T31094.01	DCN Adapter C4.0

Part Number	Description
T37870.01	NDM 19in 17-slot Subrack
T37871.01	NDM DN2 19in 17-Slot Subrack
T37882.01	NDM DC Unit (NDU)
T37882.02	NDM DC Unit (NDUe)
T37885.01	NDM Ring Generator

Part Number	Description
T37885.02	NDM Ring Generator + DC/DC converter

Part Number	Description
T37889.01	NDM Backup Unit (NBU)

Part Number	Description
T65520.01	ACL2 RM DC Power Gen
T65580.01	ACL2i PF GEN Line Terminal Card

Part Number	Description
TA 21513	Optical Line Terminal Repeater (DF2-8), 1300 nm LED MM/SM
TA 21516	Optical Line Terminal Repeater (DF2-8), 1300 nm LASER SM
TA 21518	Optical Line Terminal Repeater (DF2-8), 1300 nm LASER LP

Part Number	Description
TC 21101	DM2 Multiplexing Unit, 75ohm
TC 21301	DM8 Multiplex Equipment, 75ohm
TC 21705	Supervisory Substation
TC 21710.01	TMS Adapter
TG 21261	Ring Generator 25HZ 15W
TU 21122.5	Data Interface Unit (DIU) 48..64k, V.11, 10ch
TU 21124	Data Interface Unit (DIU) nx64k, V.11/V.35/X.21, 2ch
TU 21124.05	Data Interface Unit (DIU) nx64k, V.11/V.35/X.21, sync
TU 21125	Data Interface Unit (DIU) 48..64k with sync, X.21

Part Number	Description
TU 21205	Channel Unit SUB/SUB
TU 21206	Channel Unit SUB/SUB

Part Number	Description
TU 21215	Channel Unit SUB/EXCH
TU 21216	Channel Unit SUB/EXCH

Part Number	Description
TU 21234.20	Channel Unit E&M/VF-P, 10 ch, 20 E&M ch
TU 21236.10	Channel Unit 8ch E&M/uP: 2xe&m/vf
TU 21255.01	Channel Switch, 4 port
TV 21640.08	Power Interface Adapter DC

Legacy Telecoms Spares – Nokia ‘Dynanet’ Update

Nokia DCN Adapter – Management & Other products

The ‘Dynanet’ family of PDH Transmission telecoms products were first introduced by Nokia over 20 years ago, and were continued in recent years by DNWP. These have well served Public Operator and Private Network Customers across the Telecoms, Utilities, Transport and Public Safety markets with high availability mission critical infrastructure, and indeed some networks are continuing to provide good operational service.

Production of the majority of the product range was ceased in 2019. However, some products remain available to order, notably the DCN Adapter C4.0, related management software products and other items such as the TPS64, NDUE and Euro / SMB connectors.

Continued Supply of Spare Parts – Surplus and Refurbished Items

@YellowsBestLtd satisfies world-wide customer product sourcing requirements for current and ‘legacy’ equipment technologies from a wide range of Original Equipment Manufacturers (O.E.M.s).

For the ‘Dynanet’ range, we should be able to continue to supply refurbished and surplus equipment for as long as required, but the effect of the discontinuation of production is squeezing the availability of remaining stocks, with a consequential impact on pricing.

Hence, for those customers continuing to maintain their networks, it is recommended to consider purchasing spare parts whilst there is still availability. Please get in touch to advise what you need!

Repair Services

Maintenance Services for Systems Equipment

From time-to-time, hardware elements within infrastructure systems fail, and repair services are required for a diverse range of parts procured over a considerable period of time, from a multitude of Original Equipment Manufacturers (O.E.M.s), some of which no longer exist.

YellowsBest is able to provide a comprehensive repairs management service for both new and old equipment items, all to a standard equivalent to the original working condition and with warranted operation.

Component Level Repairs Example: SES Displayboards

An example of the type of equipment that we are often asked to assist with is the MS1 Matrix LED ‘displayboards’ produced by SES and used for professional signage applications.

Typical issues to deal with are Faulty LEDs, damaged capacitors and broken sockets, which have occurred in operational use over time. Adding to this are problems stemming from heat gun damage and resoldering caused by previous ‘user fixes’. But these issues are addressable and the boards restored to full working condition.

Other types of equipment for repair services include Telecommunications products, power supplies and CCTV cameras.

Reduce – Reuse – Recycle

Most customers have implemented their private network infrastructure systems over a number of years, and for many their operational requirements have not changed. Consequently, it makes more sense both financially and environmentally to maintain these systems rather than embark on complete change-outs. We can assist by supplying critical and hard-to-find spare parts and hardware repair services, even when the systems have been declared ‘obsolete’ (i.e. no longer in production) by the O.E.M. We look forward to hearing from you.