1. Repair Solutions for a Legacy Network

2. The Failure Model with Repair Data
Solder Issues
Engineering Changes
Component Manufacturing Issues
Component Aging
Electrolytic capacitors/
Electrolyte leakage
Electro-mechanical devices
Plastic, rubber components
Static Memory
Batteries
Transient Voltages / Electrical over stress
Poor Environmental Conditions
Foreign Material

3. 2 Primary Challenges When Repairing Legacy Products
Understanding Component Aging
Dealing with Component Obsolescence
Availability of parts is the main reason repair service providers are not able to repair legacy equipment.
Often time a creative, cost effective and even more robust solution can be developed.
What components are susceptible to aging?
What are the signs that a components is nearing the end of its life?
How do you truly extend the life of legacy equipment?

4. Types Of Components Used in Legacy Repair

5. Electrolytic Capacitors
Corrosive electrolyte leakage is spread over a wide area of the circuit board impacting many components and trace wiring.
Badly discolored components are a sure sign of failing capacitor and electrolytic fluid leakage
Electrolyte must be cleaned completely. With components removed the problem becomes easy to see
After cleaning, trace repair must be performed for the circuit board to become operational.
Electrolyte gets into barrels affecting solderability and conductivity.

6. Electro-Mechanical Components
DC brushless motor in a fan will theoretically last forever but the mechanical components of a fan will fail over time and can be repaired.
Mechanical components will wear out over time
High end fan and blower assemblies are rated for 50,000 – 60,000 operational hours, or approximately 7 years.
Environmental conditions can adversely (or positively) affect the lifespan.
SCSI Drives are more robust but it is important to check the mechanical health of any drive approaching 10 years old.
Impeller
Shaft
Bearings

7. Environmental Factors Leading to Failure
Excessive ambient heat accelerates the effects of aging
Dust, Dirt, and debris (such as insect infestation) can also contribute to early failure.
IC’s operating at the upper threshold of their temperature rating F
100 -
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8. Fight (component) Obsolescence
Parts availability is primary reason many OEMs/ Repair Vendors can’t repair legacy products.
With creativity and ingenuity a cost effective, and often times more robust, solution can be developed.
When product reaches the critical stage in the lifecycle where support is ended and all the spares are gone these creative solutions are the only option for carriers to keep the network operating.

9. Obsolescence Solution #1 Obsolete SRAM
Original design contains 16 obsolete 64k x 1 SRAM IC’s
Retro-fit PCB houses 1 readily available 64K x 8 SRAM IC

10. Obsolescence Solution # 2 Obsolete Optical Module
Original design optical module has on board clock recovery circuit and is no longer available for purchase
Retro-fit PCB design uses commercially available optical module with separate clock recovery circuit

11. Solution # 3 Trimm Power Supply PCB Re-design
Original design had 2 problem areas related to heat dissipation.
Reverse engineered entire PCB.
Took advantage of extra space to allow for a small cooling fan.
Added ventilation holes to further assist heat dissipation.
Increased trace width for better conductivity and heat dissipation.