Caring for your studio
Contents
1. Given that the most expeditious method of repair is on a board leva we must be conscientious in our methods High speed digital electron ics coupled with a proliferation of CMOS has elevated static control to a required science used to think that it was sufficient to grab a grounded chassis before handling boards Not so One of the most important tools used by aspiring repair techs should be the static strap and ground lead When you pull out a PCB you need a grounded surface to lay it on so carry a con ductive mat The preferred method ology is to wear a conductive wrist band that is physically hard wired to a conductive mat which in turn is tied to technical ground In addition to static control always shut off the equipment before swap ping modules Hot plugging is about as close aS you can come to Russian roulette with your electronics Power ing up equipment in the wrong se quence can introduce soft errors that corrupt the system s integrity Another way to prevent premature failure is to turn off equipment before plugging and unplugging other equipment You never know when you ll get the power and data lines terminated just a few microseconds before the system ground and electrostatic shields are made creating potentials of much greater level than the system was de signed to handle I ve zorked systems by unplugging the 422 data line with the power on The equipment was unusable until we perform2. echnology is great Except when the blasted things break and the question of whom to call becomes the crux of the matter In the past studios had personnel on hand to care for the equipment However even with an adequate tech staff the philosophy of dealing with equipment servicing and or failure is different today For one thing personnel qualified to perform component level repair are becoming more and more expensive even manufacturers have difficulty re taining people of this caliber To the end user repairs are more difficult and the equipment s reliability becomes an important factor Many manufacturers have responded to this situation by engineering more careful designs Televisions don t break every six months and the PC clone with the cheap motherboard seems to last for ever The average commercial studio today has invested significantly in so phisticated signal processing gear While a studio operator may have a common sense understanding of the technology in order for the facility to function smoothly there has to be at least one person on staff who can operate each piece of equipment in the place Without complete equipment understanding the studio cannot ef fectively recognize and deal with equipment malfunctions A Builder s Perspective Most manufacturers place a lot of weight in customer service Since the end user is not usually fully literate in technical matters suppliers need to have
3. pots connectors motors drums guides and the like are most prone to an inopportune vacation from full and proper function For instance tape recorder electronics fail far less often than the transports Here in New York City the trou bleshooting process goes something like this 1 Trouble is noted 2 Determine that an actual failure Py GEG HANKS eS has occurred and call the manufacturer 3 The factory rep walks through some of the system di agnostics and or failure symptoms with the operator and gets an idea of what could possibly be wrong 4 Some elementary tests are performed by the operator with factory urging and either the trouble is isolated and gotten around or a field service rep is dispatched with the appropriate modules 5 The offending subassembly is replaced and the stu dio is back online At least that s how it works in theory It usually gets a little messier in reality The financial powers in most successful companies feel that unless the service personnel are over worked then they must be overstaffed This means you might not get the immediate attention you may require In less populated areas a growing number of suppliers have initiated 24 hour tech support hotlines This makes it possible to at least talk to a human being at 2 a m who un derstands how the bloody piece is supposed to be working Tools of the Digital Repair Trade Servicing digital elec
4. you nuts Because of the relative immunity of most bit based gear to field radiation was surprised to discover that a client s hard disk problem was traced to a tape de gausser placed on top of the disk drive cabinet Spare Partson Hand The level of financial risk you face in case of failure will detennine the spare parts requirements of your facility If you cannot afford to be down at all then look at having full redundancy in all your equipment However you don t need to worry about this if you can live with the schedule and parts e Burlington Audio Video Tapes Inc 106 Mott Street Oceanside New York 11572 FOR HARD TO GET ACCESSORY ITEMS Reels Boxes Custom Cassettes Leaders and Splicing Tape DigitalAudio Tape Available In Stock and Priced Right Immediate Delivery Call for Free Catalog USA amp Canada 1 800 331 3191 NYC Area 516 678 4414 FAX 516 678 8959 Circle 204 on Reader Service Card AUDIOFORCE Your Digital Source NY rental exclusives Mitsubishi X 86HS Harmonia Mundi Sample Rate Converter Plus Sony 3324 amp 3348 Lexicon AMS Yamaha With The Best Of Analog Call we ve got what you need PACKAGE RENTAL RATES 24 HOUR SERVICE WORLDWIDE DELIVERY TECHNICAL SUPPORT Call 800 847 4123 toll free in USA 212 741 0919 in NY State DIGITAL ASSOCIATES d b a AUDIOFORR ys Somes creel See SOUND RENTAL rot 37 West 20th Street NY
5. NY 10011 Circle 205 on Reader Service Card 142 MIX OCTOBER 1990 availability Of your technical service vendor Most facilities find themselves somewhere between these two ex tremes It s no longer practical to maintain a complete collection of spare parts for all critical functions Most of these new toys have an amortized life of two or three years and they use far too many critical boards to keep spares in stock When a piece is no longer being manufactured then it s time to buy re placements for any boards that have a history of failure What you should have on hand is determined by many things not the least of which is how well the manufacturer stocks replace ment assemblies Another consider ation may be what redundant features are designed into the unit to allow partial modular replacenent with lim ited functionality You no longer can carry the generic semis and passive components more often than not it just ain t feasible The spares you should concentrate on are spare sources of supply Maintain a relationship with the factory reps on both coasts Your Rolodex is one of your best tools Routine Maintenance No generic routine service tasks exist for digital equipment other than keeping the cooling vents clear and the insides clean Each equipment will have its own recommendations from the manufacturer These things should be explained in the owner s manual Read it usually learn something when do
6. a multilevel support system in place This is true for things analog as 138 MIX OCTORER 1000 Mantang DIGITAL EQUIPMENT KNOW USER SERVICEABLE PARTS well as digital Support from the manufacturer includes training re gional spare parts and or repair field service warranty replacement module replacement exchange service con tracts uptime insurance telephone advice loaner units and modules etc An educated consumer is the supplier s best customer Just under standing how audio commonly works is no longer sufficient to cope with today s advanced technology To per form any troubleshooting to reduce the problem area to a subsystem we need to know what the subsystems are and how they interact To this end many manufacturers supply technical train ing and product specific information This sometimes takes the form of in depth classroom education for either the owner or the technical staff from independent schools With a funda mental understanding of what goes on inside the gear you can operate as the eyes and ears of the factory personnel for troubleshooting purposes Service contracts are not very popular since they are little more than an extended warranty but this doesn t have to be the case Equipment reli ability expectations of a unit can be measured via the availability price and quality of a manufacturer s service contract The company that is willing to back up its product without
7. addi tional expense is confident in its product s reliability When the Stuff Hits the Fan The help you get from the manufac turer depends on a number of factors not the least of which is the price of the unit and your geographic location You will find help in New York L A Nashville and Chicago in the form of spare units replacement PC boards and field service personnel for most of the industry players if not from the factory then from their dealers and reps In the secondary markets and beyond help can get a little spottier What this means to you as an owner is significant differences in what is re quired from you in way of prepared ness Here in New York at least when the unit is still under warranty you can usually get a factory rep to comein and swap the defective subassembly From the supplier s position it is always far wiser to replace a defective assembly than to attempt a component level re pair The offending module is then re turned to the shop and either repaired there or at the factory Component level restoration with modern high speed digital electronics is very difficult or impossible without specialized tools and test equipment At least while the unit is under warranty this work is best left to the factory Expeditious service is the goal and assembly level replacement is usually the fastest route to relief The most common failures involve moving parts Disk drives switches
8. chips Don t attempt repairs on surface mount technology un less you have the right tools Workstations integrating sol dering vacuum materials handling with static protection and desoldering are available from Viking or SMD tools but can cost over 2 000 In most cases when the unit employs VLSI attached via surfacemount technology replace the board It is really only feasible to work on SSI and MS1 74XXX 46XX 80XX and discrete technology An Ounce of Prevention With a preventative philosophy the first order of business is to assure that the environment is not hostile To ascertain the most efficient methods of preventing future difficulty it s a good idea to figure out what types of failures are most common or most financially serious and attack the cause rather than the symptoms This may include optimizing the environment where the equipment is situated performing routine service as recommended by the manufacturer and OCTOBER 1990 MIX 139 Al ne ve Music library Call for our Compact Disc Demo 800 227 1954 212 333 5766 FAX 212 262 0814 MANDAT TAN PRODUCTION MUSIC o Box 1268 RadioCityStation ew York New York 10101 Circle 198 on Reader Service Card R amp M PRO AUDIO SPECIAL Buy 9 of the industry s finest PRO DAT cassettes and receive one 3M PRO DAT 120 minute cassette FREE with this limited time AES promo tional special Offer is limited to two cases per
9. customer starting Sept 21 thru Oct 31 1990 Cassettes are available in 46 60 90 and 120 minute lengths CALL R amp M PRO AUDIO 1080 Pacheco Street San Francisco CA 94116 1318 415 665 8480 Circle 199 on Reader Service Card 140 MIX OCTOBER 1990 ensuring that all service performed uses reliable methods Some factors that affect the long term reliability of equipment are eec trical service and ground integrity temperature humidity and the pos sible presence of electromagnetic or electrostatic fields The electrical service is common to all equipment Urban environments traditionally require some form of power protection Line sags overvolt age conditions spikes and line noise all contribute to reliability problems In the past most computer companies required power conditioning in order to honor the warranty Nowadays most equipment is manufactured with MOV and inductor protection as an integral part of the IEC power socket You really need power conditioning when your computers begin latching up because of dirty power Line sags lead to premature failure in motors and transformers due to increased heat loads and in extreme cases the power rails can drop out of regulation lead ing to all sorts of interesting phenomena Grounding is as important in digital circuitry as it is in analog and it is necessary to keep signal common and electrostatic shield separate Compo nent interconnect lines may r
10. e Mitsubishi A former chief engineer at Wally HeiderRecording L A and San Fran cisco Greg Hanks now beads New York Technical Support providing in stallation service and consulting to the audio industry
11. ed a full hard reset Once you ve corrupted the operation of a logic device it is best to power everything down and start everything from ground zero Good work habits should carry over from your analog discipline such as examining all traces on the PC board after a solder job to ensure that no spooge remains to short out adjacent traces Use flux remover and clean the board after any repairs as flux residue can provide a capacitive path between conductors making for strange op eration Note Don t install sockets when you replace a chip unless you are going to use gas tight ones There are more reliability problems with sockets in digital electronics than in the logic devices themselves Conscien tious work methods will provide for more satisfactory results Thanks to the increased reliability of today s systems we can realistically own operate and service the techno logical wonders that fill our studios Becoming educated to the topography of the individual systems meeting and becoming friendly with the factory service personnel keeping the neces sary tools and parts on hand and maintaining impeccable work habits all contribute to the long term success of your facility Acknowledgment I would like to thank the following persons for their assistance in getting this article together Ron Rimshell and Bob Manilla from Sony Corp Neal Karsh and Griff McCree of New En gland Digital and Robby Hidalgo Nev
12. eful new PC based tool Its primary function is to burn EPROMs PALs GALS and such Since programming modern devices re quires using a set of A D and D A converters this tool can exercise and test logic devices However it only works with 24 pin and smaller devices The primary equipment tested are 74 series and with an extended IC clip hooked to a 7 header it operates with in circuit chips Don t attempt repairs on surface mount technology un less you have the right tools Workstations integrating sol dering vacuum materials handling with static protection and desoldering are available from Viking or SMD tools but can cost over 2 000 In most cases when the unit employs VLSI attached via surfacemount technology replace the board It is really only feasible to work on SSI and MS1 74XXX 46XX 80XX and discrete technology An Ounce of Prevention With a preventative philosophy the first order of business is to assure that the environment is not hostile To ascertain the most efficient methods of preventing future difficulty it s a good idea to figure out what types of failures are most common or most financially serious and attack the cause rather than the symptoms This may include optimizing the environment where the equipment is situated performing routine service as recommended by the manufacturer and OCTOBER 1990 MIX 139 has occurred and call the manufacturer 3 The factory reo wa
13. ing SCSI devices fail to initialize monitors will look fuzzy and other nasty things may happen We routinely recommend power conditioning throughout an entire fa cility to alleviate such concerns Re member that a low source impedance is necessary to attenuate noise gener ated on the conditioned side of the line Power conditioning is an effective form of insurance One lightning strike to your power line can destroy every piece of equipment in your facility and while that is exceedingly rare it does happen Temperature affects the operation of electronics in many ways The safe operating area of any semiconductor is a function of junction temperature Bipolar devices have a positive tem perature coefficient meaning that when the temperature goes up so does the current gain which increases the current flow which increases the junction temperature FETs and CMOS devices have a negative temperature coefficient When they get hot the in put capacitance goes up and the circuit slows down This latter condition is also true of bipolar devices although to a lesser degree The junction temperature of the devices enployed must fall within the device rating It is controlled through conduction to the surrounding air either directly or through heat sinks When the ambient tenperature of the environment becomes elevated the heat sink s ability to function de creases Linear increases in the ambi ent temperature become loga
14. lks through some of the system di agnostics and or failure symptoms with the operator and gets an idea of what could possibly be wrong 4 Some elementary tests are performed by the operator with factory urging and either the trouble is isolated and gotten around or a field service rep is dispatched with the appropriate modules 5 The offending subassembly is replaced and the stu dio is back online At least that s how it works in theory It usually gets a little messier in reality The financial powers in most successful companies feel that unless the service personnel are over worked then they must be overstaffed This means you might not get the immediate attention you may require In less populated areas a growing number of suppliers have initiated 24 hour tech support hotlines This makes it possible to at least talk to a human being at 2 a m who un derstands how the bloody piece is supposed to be working Tools of the Digital Repair Trade Servicing digital electronics is fundamentally the same as any other form of technical repair Working at a component level is sometimes not only feasible but mandatory particularly with a piece of out of production gear that still retains its most favored status among a studio s cients and engi neers Digital based equipment of this nature will often re quire special attention since the methods outlined above may not apply with older gear In addition to the standa
15. rd armada of technical aids digital repair is expedited with additional tools such as system diagnostics logic analyzer logic comparator logic probe IC clips surface mount clips and surface mount soldering desoldering tools Every system has a user s manual As systems become more complex and expensive the manuals get heftier They ILLUSTRATION ALAN OKAMOTO are your most important tools as they usually include sys tem diagnostic procedures Diagnostics in the form of embedded or free standing software will usually point to where the fault lies Unfortunately today s generally avail able diagnostics are often of limited value to the end user Logic analysis typically occurs only in the realm of the manufacturer where the analyzer records the data and address bus activity of a system rather than just telling you that UI is latched low on input A Logic stimulation and pattern recognition is the benefit of this type of equipment The Universal Logic Programmer is a useful new PC based tool Its primary function is to burn EPROMs PALS GALS and such Since programming modern devices re quires using a set of A D and D A converters this tool can exercise and test logic devices However it only works with 24 pin and smaller devices The primary equipment tested are 74 series and with an extended IC clip hooked to a fe ae header it operates with in circuit
16. rithmic increases in the junction temperature Operating equipment at elevated temperatures can lead to two different results soft failures such as timing errors and hard failures like com ponent degradation or failure Com ponent degradation is an insidious problem as it leads to component failure at some future time through a weakening process Continued op eration at higher temperature is one of the reasons that certain pieces of equipment become a service problem A good rule of thumb is when the room is too warm for your personal comfort the equipment is probably not happy When the air conditioning system breaks you jeopardize the future reli ability of your equipment by continu ing to use it Humidity is also affected when the air conditioner breaks Although it s a lesser problem than temperature when the humidity is high the heat sinks work less efficiently The two main consequences of excessive hu midity are an increase in the overall capacitance of the exposed circuitry which lowers the operating speed and the increase in surface oxidation Generally humidity is not a concern unless you see condensation trails Field radiation is less of a problen now that the world is going digital but is nevertheless worth mentioning More common are problems relating to the fields radiated by our digital de vices Unterminated lines or data bus extenders will sometimes ring and this can drive
17. tronics is fundamentally the same as any other form of technical repair Working at a component level is sometimes not only feasible but mandatory particularly with a piece of out of production gear that still retains its most favored status among a studio s cients and engi neers Digital based equipment of this nature will often re quire special attention since the methods outlined above may not apply with older gear In addition to the standard armada of technical aids digital repair is expedited with additional tools such as system diagnostics logic analyzer logic comparator logic probe IC clips surface mount clips and surface mount soldering desoldering tools Every system has a user s manual As systems become more complex and expensive the manuals get heftier They ILLUSTRATION ALAN OKAMOTO are your most important tools as they usually include sys tem diagnostic procedures Diagnostics in the form of embedded or free standing software will usually point to where the fault lies Unfortunately today s generally avail able diagnostics are often of limited value to the end user Logic analysis typically occurs only in the realm of the manufacturer where the analyzer records the data and address bus activity of a system rather than just telling you that UI is latched low on input A Logic stimulation and pattern recognition is the benefit of this type of equipment The Universal Logic Programmer is a us
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