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REPAIRS AND MODIFICATIONS TO VARIOUS ELECTRONIC EQUIPMENT performed By Unitech Electronics Pty. Ltd.

Phone: +61 2 9820 - 3555 sales@unitechelectronics.comFAX: +61 2 9603 - 8685
Updated March 19th 2013
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CIRCUIT REPAIRS____Another of our fine list of services

repair pic 2a

Above is a video box with 50 outputs, seen here monitoring signals on the CRO
(CRO = Cathode Ray Oscilloscope)

repair pic 1a____repair pic 3a

Signals and wave forms being monitored on the CRO (Cathode Ray Oscilloscope)


repair pic 4a


  Above is a " reverse engineered " rough layout of a circuit board by which we had to "trace out" and  derive a working 
  electronic circuit layout to effectively service and repair a 30 output  video amplifier / distribution box for our client 
  to use and work from.
 
  Someone had attempted (though very poorly) some 10 + years ago, to build a video duplication box with 30 outputs with 
  using a now obsolete hex transistor array, which normally under digital or logic switching would function as per the 
  data sheet, however it was very much a different output when deployed as a video amplifier, with odd stray parasitics 
  due to the use of the same chip "die" within the LM3086N. Bad choice of video amplification components by the previous 
  designer of the 30 way video distribution amplifier.
 
  Despite these problems, the owner "struggled-on" for years with a poor resolution output for his Tape Duplication business. 
  As there was no circuit available, we contacted the owner and explained that in order to repair the unit, we would need to 
  devise some form of workable schematic diagram, this was before we discovered the stray parasitics and other inherent  
  "noises" within each LM3086N chip. The LM3086N is basically a six NPN transistor array in a 14 pin DIL package.

  This all takes time to carefully check for 100% accuracy and correct component orientation as well as the correct data
  sheets and identification of each part. The circuit above took 2 hours to trace out and a further 2.5 hours to  carefully 
  draw the relevant 100% accurate working electronic circuit.
   
  Note: The circuit  (above) was "reasonable", however the "LM3086N chip transistor array" exhibited thermally induced 
  parasitics and a basic lack of performance, inherent picture instability, features not conducive to a  client's projected long 
  term usage in a business where quality matters, in fact it is an absolute requirement.

  This more than likely resulted from aging stock and manufactured in circa 1994 and no longer  made by NS,  So, after an 
  in depth consultation with our client, it was resolved that the unstable circuit boards were to be removed from the Video
  box and returned to our client, we set to and designed a   fresh "new circuit" approach was to adopted thus providing our
  client with 50 good solid video outputs from one video input source. Our client was highly delighted with our efforts and
  paid us accordingly.

  The scrapped circuitry was fully removed and using the fresh new idea and approach, a viable circuit design was skillfully 
  produced, prototyped and tested by us at Unitech and field tested at the clients premises with all benefits measured in
  terms of reproduced picture quality on a series of video tapes and the final test of a copy from a copy, this is the 
  "acid test " on how well a copy is being made, the results were delightful, however, more importantly,  our client was
  very happy with our efforts and especially with the results.  As a bonus from prototype testing, we were able to include
  such benefits as 10 stage video signal attenuation to cater for various video input strengths. Not all video tape signals
  are weak and not all are strong either.

  Research and development on a project such as this takes time and money, more time and more money usually, however, 
  the end result is what counts, a very satisfied client, delighted with the extra efforts and attention to detail we took to make 
  sure each video output was fully stabilised  and that all 50 video outputs functioned correctly,  thus providing an excellent 
  amplified video signal Video to all 50 outputs simultaneously to each and every VCR (VTR), with no distortion or color 
  fade or drop out, even with the annoying Macrovision.


OUR REPAIR SERVICE AND VARIOUS " OTHER SERVICES " LABOUR RATES


  Please note:   For repair work , it is advisable to acquire a correct circuit diagram prior to delivery of your goods 
  or equipment to be serviced and repaired. If one is not supplied, then we will need to do " reverse engineering " 
  of the circuit and tracing it out fully, thus establishing a correct operational circuit schematic diagram to work  
  with for fault finding. Without a circuit diagram is like trying to travel to Canberra blindfolded. It simply costs time 
  We do not do quotes for electronic equipment work as no-one can make asumptions without fully finding the faults 
  as there are so many variables in service work and no-one is nostradamas and can make a certain prediction ever.  
  Having an accurate circuit diagram will typically make service work a whole lot simpler and more precisely better.  
  This will cut down wasted time in trying to establish how the circuit works and what faults stop it.  There is no  
  guess-work here.      We do not own a "crystal ball"     and no-one here is called Nostradamus.


P R O T O T Y P I N G


   Labour rates design work  Prototyping ......... AUD$ 150.00 per hour ( $2.50 / Min )..... Plus GST. 
 ( time taken calculated in months, weeks, days, hours and /or minutes depending on complexity ) 


 Please Note : Labour rates do not include any materials or components nor do they include GST.
 All parts and materials used are in addition to time spent on the client's behalf to get a project to fruition.


NOTICE - REPAIRS - BE VERY AWARE - SERVICE - NOTICE


 Please be aware, we are not a " results only company ", that is to state as in " only "
 being paid " only " if the result is goods or equipment works.  We accept  " your goods "  for 
 repair or service in good faith, however if it is found at some stage during the repair(s) that 
 the said item(s) for repair or service are not going result in a  positive working outcome, 
 either due to the age of item(s) or component(s) that are " still now " available in stock, we 
 will advise you of the costs so far in arriving at this conclusion. There are no "Free lunches". 
 All company time is accountable for. This is only fair as where you work, you would not like  
 be NOT PAID as a result of a project or job not working out right and your boss telling you, 
 " tough luck mate...it did not work so no pay for the hours wasted on trying to get it going".


 We require payment for company time spent on your behalf working on your goods or equipment  
 irrespective of the final results that the item(s) in question are working. We strive for perfection  
 in servicing and repairs, however there are times where component tolerances change over the   
 years, thus often resulting in undesirable "hard to diagnose" faults along with stray capacitances   
 and weird parasitics etcetera, plating "growths and spurs" that creep into circuits boards over time.  

This rule (above) does not apply to goods or products manufactured by us, here at Unitech Electronics Pty. Ltd.

We support our manufactured goods and equipment with quality original backup service parts for up to 5 years.

There are Circuit Rules


What is involved in a simple idea or design, taking that idea or concept through to a completed prototype.

Flow chart on Ciruits

above is what is involved in a simple idea or design, taking that idea or concept through to a completed prototype.


Unitech Electronics Pty Ltd is your one stop "global shop" for all your "computer" and "Electronic"
Hardware solutions , we design and manufacture for you.         We make it happen for you!

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