NexGen Bench Tests - slot-tech.comslot-tech.com/members/magazine/lores/december12.pdf · 1 year -...

NexGenBenchTests

Randy Fromm's

Slot Tech Magazine

EditorRandy Fromm

Technical WritersJames Borg, Jason Czito,Vic Fortenbach, DianaGruber, Heno Kollar, ChuckLentine, Craig Nelson,Kevin Noble, Pat Porath

Slot Tech Magazine is publishedmonthly bySlot Tech Magazine1944 Falmouth Dr.El Cajon, CA 92020-2827tel.619.838.7111 fax.619.593.6132e-mail [email protected] the website at slot-techs.com

SUBSCRIPTIONSDomestic (North America)1 year - $60.002 years - $120.00International1 year - $120.002 years - $240.00

Subscribe online atslot-techs.com

Copyright 2012 under the UniversalCopyright Convention. All rights re-served.

Slot Tech Magazine

-EditorialPage 4-Repairing LCD MonitorsUnderstanding the Principles of the MicrocontrollerPage 12-Quick & Simple Repairs #91Page 16-TechFest 26 PhotosPage 17-A Fault Too FarFor Subscriptions - See the website @ slot-techs.com

Randy Fromm

Next TechFestwill be held at

Mystic Lake CasinoNear Minneapolis, MN

May 2013PublisherPublisherPublisherPublisherPublisherSlot Tech MagazineSlot Tech MagazineSlot Tech MagazineSlot Tech MagazineSlot Tech Magazine

Dear Friends of Slot Tech Magazine,

Every now and then, I meet a technician who impresses me with hisdetailed knowledge of electronics and “how things work.” You see,in general, as a repair technician, I am not generally overly con-cerned about “how things work.” I am more concerned with “howthings break.” My job (as a repair tech) is simply to find the faultand replace the bad component(s) (or repair a bad solder joint orbroken conductor, etc.). Or sure, I enjoy knowing precisely how acircuit is supposed to function but my bread-and-butter comes fromfixing stuff.

However, the sole purpose of Slot Tech Magazine is education andthe more you know about something, the easier it can be to fix. Withthis in mind, I reached out to super-tech Heno Kollar and asked himif he might consider penning an article for Slot Tech Magazine. Youmay know Heno better as “kondy73” on the Slot Tech Forum(slottechforum.com). In particular, I wanted him to concentrate onsome of the more advanced topics that Slot Tech Magazine hasignored as of late. In general, I prefer that Slot Tech Magazinepresents a mixture of “symptoms and solutions” (easy fixes such asthose presented by the venerable Pat Porath) along with moreadvanced circuit analysis and educational articles. Half of what Iknow about electronics, I learned from Popular Electronics Maga-zine.

In his premier contribution, Mr. Kollar presents us with a detailedlook at LCD monitors and how they REALLY work. As you readthis article, please keep in mind that this is doubly awesome becauseEnglish is not Heno’s native language. He is from Slovakia. Assuch, the gear he works on may be sort of “Euro-centric” but theelectronic principles are sound and universal, regardless.

Props to MotorCity Casino for hosting TechFest 26. MotorCity is aworld-class property. Let me just say that we ate VERY WELL atTechFest 26. The hotel and the casino are both very much worth avisit. I was (still am) impressed by the property and, especially, all ofthe people who work there.

December 2012Slot Tech Magazine

Slot Tech Feature Article

This month, I want tooutline how a normalLCD monitor works,

as used either in the gam-ing machine or as a PCscreen. I will describe theoperating principles andprocedures for the repair ofcomplex defects in LCDmonitors using VGA as avideo source and LVDSLCD panel for displayingimages.

Experienced technicianshave routinely replaced oldand faulty electrolytic ca-pacitors by their loss ofcapacitance and otherparameters directly affectthe proper function of anyelectronic device, so I willskip this topic. This articlediscusses what to do if,after replacing the electro-lytic capacitors in your LCDmonitor, it is still not work-ing properly.

Types of LCD monitors aredifferent but all use themicrocontroller to controlthe LCD monitor and videoprocessor for A/D imageprocessing - the converterwhich converts analog VGAsignal to digital LVDS sig-

Repairing LCD MonitorsUnderstanding the Principles of the Microcontroller

nal for the LCD panel.

Modern types also includeinput from the DVI (digitalvideo interface) connectorfrom which the digital videosignal is converted again toLVDS. LVDS is the “lowvoltage, differential signal-ing” that is used to commu-nicate between themonitor’s electronics andthe LCD panel itself.

Figure 1 shows a blockdiagram of our LCD moni-tor voltage of 12VDC pow-ered from an external AC/DC power supply.

The figure follows that afterpower up (connect 12V) to

LCD monitor, charging thecapacitor in the circuitresets the microcontroller.This means that severalhundred milliseconds afterpower-on, the reset inputlogic level is “high,” a logic“1.” While charging thecapacitor at the reset input,voltage is eventually re-duced to logical “low” orzero (0 volts) which tells themicrocontroller to start toexecute the program. Thisprogram is the basic soft-ware for the LCD monitorand is stored in either theon-chip microcontroller (inthe internal FlashROM) orin an externally locatedROM memory package.

By Heno Kollar

Figure 1

Slot Tech MagazineDecember 2012


Figure 2 shows a typicalconfiguration usingSyncMOS SM89516microcontroller with 128KBinternal Flash ROMmemory, an externalEEPROM 24C16, DC-DCconverter 12V to 5V with acontrol IC LM3485 andRealtec RTD2023B videoprocessor which is poweredby a 3.3 V and 1.8 V. Thespecific chips used will varybetween manufacturers butthe architecture is alwaysthe same.

Figure 3 shows a configura-tion where a video proces-sor and microcontroller areboth integrated into asingle chip, a Genesisgm2621 with externalmemory serial SST25VF010FlashROM, which is dividedinto the “program area” and

“EEPROM area” for usersettings.

Figure 4 and Figure 5shows a single chip Genesisgm2121 with externalmemory parallel FlashROM(PMC) PM39LV010 and alsowith external memory serialEEPROM 24C16.

One of the first steps andcommands to the softwaremicrocontroller is readingthe external serial I2CEEPROM (or FlashROMarea EEPROM of externalmemory).If the microcontroller de-tects that the memory isempty, then it immediatelywrites the default values forsettings for the imagingparameters in thisEEPROM. These imagingparameters include:

- basic values of brightness,color, contrast, picture size,etc.- setting values for imageprocessor mode and com-munication.

This method of storage inEEPROM has been chosenbecause of the universalityof software, using differentLCD panels of differentsizes and various displaymodes depending on usersettings but also on whattype of software used by themanufacturer of the par-ticular type of LCD monitor.So microcontroller softwareis set by the manufacturerof the new A/D board atthe manufacturer and itwill automatically put it into an empty EEPROM, allthe necessary informationaccording to which version

Figure 2


of the software we use. Forthese reasons, correct val-ues for the contents of thisEEPROM are very impor-tant for the future, trouble-free operation of an LCDmonitor.

Every time you turn it on,the microcontroller readsthe contents of thismemory and, if it finds anycontent, retrieves the pa-rameters used to initializethe image processor, re-gardless of whether theyare correct or not. Most ofthe software makers do notaddress EEPROM contentand therefore do not con-trol the content of theEEPROM checksum.

This explanation brings usto the heart of the problemwhen, after exchanging theold electrolytic capacitors inthe DC-DC converter sec-tion (by far the most com-mon faults) the monitor isstill not working properly.The reason is that the oldcapacitor DC-DC convertercauses voltage fluctuationsto 5V microcontroller. Volt-age can vary between 3-6Vat frequencies up to severalhundred kHz according tothe state of the damagedcapacitor. This leads to thegeneration of cyclic signalfor the microcontrollerreset. Moreover, the veryold capacitor in the resetcircuit causes a shorteningof the length of the reset tounacceptable levels, whicheventually causes a falsestart the microcontroller.This false start may lead toincorrect implementation ofthe program. It may alsooverwrite the contents ofuser EEPROM to random ormeaningless values.

This leads to a condition

Figure 3

Figure 4

Figure 5


Figure 9

where, after replacing the old electrolyticcapacitors, the LCD monitor still does nothave proper function. When you turn onthe monitor, the microcontroller reads theEEPROM incorrect values (which is mean-ingless data) and either no picture is dis-played or the image appears damaged butthere is nothing wrong with either theLCD panel or the VGA signal.

I recommend the replacement of the ca-pacitors in the DC-DC converters andreplacement of the capacitor(s) in the resetcircuit(if used and capacitors in the voltageregulator circuits for 3.3 V and 1.8 V forthe video processor.

To avoid misunderstandings of the faultsymptoms this monitor, I recommendbefore attempting to change the contentsof EEPROM that you do the following:

- Check all voltages: 12V, 5V, 3.3 V and1.8 V at best in completely connectedmonitor.- Try to choose the user monitor menu“factory reset” or similarly named eg. “Re-call” or “default values.”

Removal or Modification of EEPROMMemory Contents

There are many ways to change the con-tents of the EEPROM.

If you do not have a spare A/D board andalso you do not have file content of thememory then:- buy a new EEPROM memory of the sametype, eg. 24C16. As it is empty, after re-placing this EEPROM, the first time youturn on the microcontroller, it will restorethe correct contents in to new EEPROM.- Remove any old EEPROM memory of thesame type from any old board, erase it onthe chip programmer (all at FFH values)and solder this EEPROM in the A/D boardto fix.

A simple way to remove/desolder the serialI2C EEPROM 24xxx or any 8 pin smdintegrated circuits off a board is shown infigure 6.

Removing PLCC microcontroller and PLCCFlashROM and using special equipment inSMD to DIP in chip programmer is shown

Figure 6

Figure 7

Figure 8

Figure 9


in Figures 7,8,9,10 and 11.

For the future, it is advisable to back upthe content for each type of A/D board sothat you can reuse and return theEEPROM to the correct content.

Some A/D boards use a configurationwhere the signal processor and themicrocontroller are both on a single Chip.These types of hardware largely use exter-nal program memory stored in FlashROMand also external EEPROM.If you can not find the EEPROM in your A/D board or find there is only FlashROMmemory, then it is normal that thememory is divided within to “program area”and “EEPROM area.” In these cases, I donot recommend to clear contentsFlashROM memory precursor withoutbackup. I suggest you first create a com-plete copy of a good A/D before proceedingwith the next attempt.

- Heno Kollar - Heno Kollar - Heno Kollar - Heno Kollar - Heno [email protected]@[email protected]@[email protected]

Figure 10

Figure 11



Ticket Printer LEDTicket Printer LEDTicket Printer LEDTicket Printer LEDTicket Printer LEDTester for BezelsTester for BezelsTester for BezelsTester for BezelsTester for Bezels

Not long ago, we did aconversion on a bankof Bally Alfa games in

which the GEN 1 printerswouldn’t work with the newgame software. Ithaca Epic950 printers were installedas replacements. Alongwith the printers, newprinter LED bezels wereneeded so they were or-dered too. Everything wasinstalled and worked well.Now I have some extraprinter LED boards forspares to go through andtest to make sure they allwork properly or need to berepaired. A few were testedon the printer bench anddidn’t work. I was using aGEN 2 printer so theboards should have workedbut I didn’t know why theydidn’t. A few more weretested and failed. A co-worker brought a fewboards to our other shopwhere they tested finewhen connecting them upto 24VDC directly. I thentook a LED board directly toa game and sure enough, ittested good in the game.My test unit had a failure,not the boards! It workedbefore, why not now? As Ilater found out, it was a badprinter.

However, I wanted my ownway to test the printer bezelLED on the printer benchso here is what was done. A24VDC power supply waslocated, an Ithaca 950 typeMolex connector, a smallblack connector out of a“parted out” GEN 2 printer,and some wire. Since thepower supply had two ofthe same color output volt-ages I wasn’t sure whichwas the hot wire and whichwas the ground. A DMMcan be used to determinepolarity. In this case, Igrabbed a polarized LEDlamp to do a quick polaritycheck. On the printer bezelLED board, the light coloris positive and the darkercolor is negative. It alsoshowed right on the boardwhich was which too. Next,both connec-tors werehooked up tothe powersupply asshown in thepicture. Theywere heatshrinked andnow ready forthe test. Iconnected oneLED board tothe one con-nector and theother type tothe otherconnector.When voltagewas applied,they both litup great! Mak-ing a simpleLED boardtester did thetrick.

Atronic e-motionAtronic e-motionAtronic e-motionAtronic e-motionAtronic e-motionWouldn’t Boot UpWouldn’t Boot UpWouldn’t Boot UpWouldn’t Boot UpWouldn’t Boot Up

On an Atronic e-motion“Doggy Cash” progressivegame, it was trying toreboot itself but didn’t bootup all the way. The mainpower was turned off thenback on again withoutsuccess. It would only bootpart way then restart again.Next, the game was turnedoff and both the main pro-cessor board and the COMboard were reseated. Onceagain it started to boot up,only this time it went fur-ther. As I waited for it torestart itself the game fi-nally booted up all the wayand was ready for play. Itlooked like reseating theboards did the trick.

Quick & Simple Repairs #91By Pat Porath


Casino City’sWorldwide Gaming ExchangeBuy & Sell Your Gaming Equipment Online!

Domestic and international online marketplace for buyers and sellers of slot machines, parts, supplies – everything on the gaming floor!

industry professionals 24/7!

Older Konami Slant TopOlder Konami Slant TopOlder Konami Slant TopOlder Konami Slant TopOlder Konami Slant Top“CD Read Error”“CD Read Error”“CD Read Error”“CD Read Error”“CD Read Error”

While a customer was in abonus, I was told the game“froze up” so the game waspower cycled. In the firstpart of startup, right on thescreen it showed “CD readerror.” Hoping the disk onlyneeded to be cleaned, Iremoved it for inspection.Sure enough it was dusty. Ihave seen worse though.Maybe the disk was onlydusty or maybe the CDdrive needed to be re-placed? I had a customerwaiting for her bonus so Ihad to think of somethingfast. The quickest and easi-est would be to wipe thedisk off with a cloth andhope for the best. A quickwipe of the CD did notwork. Now what? I cleanedthe disk again and also verycarefully wiped off theLASER diode which is inthe CD drive. Power wasturned back on once again.This time the indicator lighton the outside of the CDdrive started to flash rap-idly. When the light flashesslowly, more than likely itisn’t reading a disk. Whenit flashes rapidly, there is avery good chance that thedisk is being read properly.Also on the startup screenof the game “CD check OK”appeared which meant thegame did in fact read thedisk. After the game fullyloaded, the customer con-tinued right where she leftoff in her bonus round. Aquick cleaning of the CDalong with quickly wipingthe dust off of the optic inthe CD drive fixed theproblem.

IGT S2000 Bonus ReelIGT S2000 Bonus ReelIGT S2000 Bonus ReelIGT S2000 Bonus ReelIGT S2000 Bonus ReelStrip ProblemStrip ProblemStrip ProblemStrip ProblemStrip Problem

This particular game hasthe standard three reelswith an additional fourthbonus reel but the fourthone wasn’t paying on thepay line. By looking at thereel strips I could tell theymust have been recentlyreplaced because all fourwere nice and shiny, notfaded at all. Since the gamewas an older one, the stripsprobably would have fadeda bit. My personal theorywas the reel strips werereplaced but the fourth reelwasn’t tested. I was told thereel strip “paid” off the linebut not when a winningsymbol was on the line.Luckily (and maybe a bitunusual) the customerplaying the game was TO-TALLY cool and calm aboutit. He cashed out and

played a game similar to it.

Right away I removed thefourth reel and looked forthe small square notch thatis usually molded into thereel basket assembly. Un-fortunately I could notlocate the notch on thisone, there were only somenumbers on it. Maybe thestarting point of the reelstrip needed to be at thenumber zero or one? Notbeing really sure, I talkedto the employee that wasdealing with the customerto see how far off it was. Tome it sounded like the reelstrip was attached to thereel basket “one step off.”First off, I started to take offthe reel strip and move iton the basket so it wassecure one step from itsprevious position. The reelassembly was put back inthe game, then power

Free Technical Serverslot-tech.com


turned back ON. After itbooted up, I accessed diag-nostics to do a reel striptest. A regular reel striptest didn’t affect the bonusreel at all so I couldn’t tell ifit was on correctly or not. Iexited “reel strip test” andfound “bonus reel striptest.” Bingo! That’s what Iwas looking for! Sureenough, each of the differ-ent stops were tested. TheVFD display showed whatwas supposed to be on thepay line and the symbolslanded on the fourth payline perfectly. With confi-dence I closed up the slotdoor. The game was fixed.

IGT AVP 3.5 Communi-IGT AVP 3.5 Communi-IGT AVP 3.5 Communi-IGT AVP 3.5 Communi-IGT AVP 3.5 Communi-cation Errorcation Errorcation Errorcation Errorcation Error

The communication prob-lem was between the game,the SIB board, the MysteryProgressive system, oreverything. It seemed likeevery other day, I wouldhave to reboot the SIBboard in the game, thenreset the error on the pro-gressive computer. It wouldlast a day or two then gointo a communication erroronce again. DIP switchesand jumpers were checkedon the SIB along with aquick look at the gameoption software. Nothinglooked out of place. FinallyI decided it was time to findout what the deal was. Oneof the first things I did wasmove the IGT COM boardfrom COM channel 2 tochannel 3 on the gamemother board. The nextmorning it had an erroronce again. This time areplacement SIB board wasinstalled (the mystery pro-gressive board in the game).Yet again an error occurred.A replacement IGT COMboard was installed on the

game mother board, whichdidn’t cure the communica-tion problem either. Eventhe main processor boardon the game was reseated.

What was left? What abouttaking a closer look at gameoption settings? Both theproblem game and a gamenext door were opened tocompare “protocol settings.”Under “protocol controlsetup” I noticed a differencebetween the two gamesettings. One showed“legacy bonusing” set at“none” and the knownworking game showed“legacy bonusing” set at“serial SAS 2.” Maybe thisincorrect setting was theproblem the whole time?“Key 7” was inserted in thegame to allow the option tobe changed. Now all of theprotocol options matched.Over a weekhas gone byand I haven’tseen or heardof a communi-cation problemfrom that gameyet. It looks likean incorrectsetting in the“protocol con-trol setup” areawas causing aproblem thewhole time.

JCM TicketJCM TicketJCM TicketJCM TicketJCM TicketPrinter Feed-Printer Feed-Printer Feed-Printer Feed-Printer Feed-ing Ticketsing Ticketsing Ticketsing Ticketsing Tickets

I was asked if Iknew a repairtrick to fix aJCM ticketprinter that keptfeeding outtickets continu-ously.

“Well as a matter of fact I doknow a trick, I replied. The‘feed ticket button’ is stuckin the downward, ON posi-tion. Simply take a smallpair of pliers and gentlymove the button upwardand downward a few timesto free it up.”

Problem solved. If the but-ton still feels sticky, try aquick spray of contactcleaner (with power off ofcourse). If the white capfalls off the feed button, it’sOK; the button will stillfunction.

Atronic e-motion “Pre-Atronic e-motion “Pre-Atronic e-motion “Pre-Atronic e-motion “Pre-Atronic e-motion “Pre-sentation Error” on thesentation Error” on thesentation Error” on thesentation Error” on thesentation Error” on theScreenScreenScreenScreenScreen

What is a “presentationerror” on an Atronic e-motion game? The problemwas simply a stuck ticket in


the ticket printer. I first tried a key resetand then a reboot but neither worked.Then, I took a look at the ticket printer.Sure enough, there sat a ticket jammed inthe printer. After it was removed and thereset key turned, the error cleared.

“Mikohn Mystery Progressive” Meters“Mikohn Mystery Progressive” Meters“Mikohn Mystery Progressive” Meters“Mikohn Mystery Progressive” Meters“Mikohn Mystery Progressive” MetersFrozenFrozenFrozenFrozenFrozen

We have banks of IGT S2000s that have a“Mikohn Mystery Progressive” systemconnected to them (a total of 40 games).While briefly chatting with a slot atten-dant, the individual pointed to a game inwhich the second level progressive meterwas mostly frozen. The other two meterswere totally frozen; they were notincrementing like the other games. I havenever seen an electronic progressive meterpartially frozen before. If anyone remem-bers the old “hard meter days” wheregames such as “Universal” used hardmeters, sometimes one of the meterswould partially freeze up. The last digit(farthest to the right) would only “click”but not increment to the next digit, some-what stuck in between digits. But in thiscase the meter is totally electronic andwouldn’t “flip” to the next number. Inother words, the progressive meters werestuck.

To resolve the problem I turned off thegame power then disconnected the 120VAC power cable which connects to thegame so ALL of the power was discon-nected, including the Mikohn progressiveboard (Slot Interface Board or SIB, some-times also called a “SMIB” for Slot MachineInterface Board. I waited around a minutethen reconnected the main power cable.The top monitor progressive box started toboot up along with the SIB. Next, maingame power was turned on. After every-thing was fully booted, all three of theprogressive meters took off incrementingfast. When the progressive numbers gotcloser to the other games they startedslowing down, then they caught up to theother games. A reboot of main power to thegame, SIB, and top progressive box in thegame did the trick.

Pat PorathPat PorathPat PorathPat PorathPat [email protected]@[email protected]@[email protected]


Slot Tech Event-TechFest 26 MotorCity Casino, Detroit, MI

Below: Three-time TechFestAlumus Michelle Dedmon enjoysthe wonderful buffet lunch.

Above: First-time TechFest presenterPaul Paroff (Esterline) presented alook at the WMS button assembly.l: Dan Petersen-JCMr: David Oldham-Suzo-Happbelow right: Brett Bruce-Ceronixbelow: Russ Wige-Transact Technolo-gies and the TechFest 26 class.



The phone rings, andan unfamiliar voice atthe other end asks

you to have a look at some-thing as it’s not working.Next second, the voicehangs up on you beforegiving you a chance to askwhat the something that’snot working properly is. Itcould be anything from asimple button to a completeslot machine. What is thefirst thing you do? What isyour first reaction? Wheredoes your mind go? Whattools or parts do you takewith you? Are you up to do

the job, or shall you wait forsomebody who knows thejob inside-out, so you cantackle the problem to-gether? Most times, there isnobody around when youneed a helping-hand, andreality can be cruel. Sadly,the bottom line is, you’vegot to roll up your sleevesand, with a certain amountof hesitation and apprehen-sion, go for it or die trying.

That said, it’s the easiest ofthe process. The tip of theiceberg if you wish. Thesecond part of the processis keeping your cool. Ide-ally, you follow the sacredrule of the three ‘C’s. Youhave to keep Cool, Calm,and Collected, not in any

essential order. Applyingthis rule helps you tremen-dously to focus on theproblem in hand.

Faults come in variousforms and sizes, and spanas wide as the distant hori-zon when viewed from therocks by the calm sea.(Editor’s Note: Mr. Borg is acitizen of the tiny island ofMalta so will forgive him hismaritime references fromtime to time). Even thoughsome are stock ones, otherfaults make your hair go onend when trying to tacklethem. The ‘hair on the endbit’ happens to the best ofthe best so a newbie neednot feel inadequate or at-tempt suicide when faced

A Fault Too FarBy James Borg


with this situation. Themost important issue is totry and dissect the problemone step at a time, piece bypiece. No piece of equip-ment out there is a whole.There are always modules,units, sections, boards, anda plethora of peripheralsthat you can eliminate inthe process to trace down aproblem. Depending on thenature of the fault, elimi-nating some of these ‘mod-ules’ blindly, can make thesituation even worse, soone has to be careful whichparts to pull out during thefault finding process.

The number of problemsI’ve come across are toonumerous to mention butnothing takes the biscuitmore so than the intermit-tent cases. Faults of thisnature are the nightmare ofany technician. You thinkyou’ve traced the fault, youthink you’ve found andeliminated the gremlin, andyou think nothing canstand in your way. Yousuddenly grow taller andthe stars are within reachso you root out a cham-pagne bottle and invite allyour friends over for a partyto celebrate what a brillianttechnician you are. You’reso good, you even manageto impress yourself. How-ever, as it would have it, thenext day another report isfiled. The same problemhas appeared again. Thishits you like a high-speedtrain travelling at maximumspeed. Your facial featureschange, you age years inminutes, your hair starts togo white and drop off, yourknees start to shake and

you lose your speech justbefore your mind blows outthrough your ears.

Unfortunately, the life of atechnician can be a toughand a lonely one, especiallyif you are the only techni-cian around. Just becauseyour title is that of a techni-cian and you enjoy your jobtremendously, you’re ex-pected to locate faults inseconds and performmiracles at the click of afinger. There can never bean excuse. Spare parts arealways available, equipmentis all ready and calibratedso what’s the big deal?You’re the technician, youfind the problem, you fig-ure it out. Ouch!

It takes a special breed ofpeople to carry out certainjobs. With the passage oftime, I realized that it takesa technician to understanda technician. They speak adifferent kind of languagefrom everybody else. Somecaring person even wrote‘The Dictionary of Electron-ics’, to help ‘all the others’try to understand somephrases and jargon techni-cians communicate with. Tothe normal person in thestreet, most of the conver-sation sounds . . . Klingon?Time and space permitting,I’ll elaborate a bit more onthese alien phrases lateron.

That’s the introduction overand done with. Now for thenitty-gritty, the scary bit,the bit you’re supposed tobe paid for to do, the bitthat keeps you awake atnight and makes you chew

your fingernails to thebone.

In a typical example, whichis quite common, you’refaced with a DEAD unit. Formany, this might be aneasy one. A blown fuse? Amains cable pulled out? Afaulty switch? No big deal,surely. WRONG! Beware, adead creature can be moredangerous than a live one.Just describing somethingbeing dead, as dead goes, isof little help to the techni-cian undertaking the repairjob. You’d like to find outhow it died, if it was a slowdeath, if a resurrection evertook place, if it ever came tolife when the machine wasswitched on after hours inthe dark, if it went out witha bang or if it smoked, if itthis or if it that. The list canbe quite long.

Why ask so many ques-tions, since dead is D-E-A-D, right? WRONG again!How the end of the linecame to be can be of theutmost importance. A tech-nician takes the role of aforensics expert gatheringall the evidence, all theclues, then piecing them alltogether to form a big pic-ture. That picture is whatyou will be working on tostart tackling your fault.You need to ask as many ofthe questions mentionedabove as you can (andmore) so you can at leaststart tackling the fault fromthe proper angle. Spendingor wasting hours on thewrong side of things canfrustrate even the elite ofthe dedicated staff in thisdelicate field of technicali-


ties. I’m going to go over thedifferent angles a piece ofequipment can go wrong,and your approach.

A Slow Death:A Slow Death:A Slow Death:A Slow Death:A Slow Death:

This type of death is notvery common, but it hap-pens. A typical case thatcomes to mind is thegradual loss of brightnessand quality of a CRTscreen. Although all manu-facturing has gone over toLCD monitors, there arestill a lot of CRT monitors inthe field that are likelyclose to or already in theprocess of dying. The dete-rioration process could takeweeks, or even months.Many CRTs tend to losetheir oomph after years andyears of faithful service.When they will eventuallyfade out so badly, theybecome next to useless. Indays gone by, there was aprocess applied, known asrejuvination. As the nameimplies, it rejuvinates thetube (see Slot Tech Maga-zine August 2001). How-ever, If the CRT isn’t madeof the tough stuff, it can bekilled, permanently. On theother hand, if it works,then there will be a signifi-cant improvement in thepicture but only for a lim-ited period.

The rejuvination process isbasically forcing the CRT toits very limits by means of aspecialized piece of equip-ment called, surprise sur-prise: a rejuvinator. Thisinvolves blasting the cath-odes and the heaters totheir extremes. If the CRTis old and past the point of

no return then no amountof rejuvination will bring itback. Since there’s notangible way to keep trackof how many hours themonitor has worked, no-body can be sure for howlong it will carry on workingproperly. However. thereare tell-tale signs to lookout for, a bit like wrinkleson a face, to give you arough idea of what you’redealing with.

Typically, a good CRTshould be sharply focusedall over the entire screenwith all thethree colorsbright andbreezy, notdull and hazy.The bright-ness andcontrastshould re-spond fineand set ataround midrange. In-creasing the

brightness, the contrastand the colors to theirmaximum, should still leaveyou with a good picturewith no signs of picturesmearing or tearing to oneside.

Armed with the informationabove, should the picturestart to fade out on you,you now have a pretty goodidea if it’s the CRT itselfwhich has reached its endor if something external toit is making it behave theway it is and your CRT isstill fine.

Check any Electrolytic Capacitor In-Circuit with100% Accuracy in 3 Seconds---GUARANTEED*

Automatically discharges capacitor

Checks DCR with alerts for shorts

Measures DCR to 500 ohms

Measures ESR from 0.1 to 20 ohms

Checks caps from .47uF to 2200uF

Beeps one to five beeps for quality

Three-color chart for good-fair-bad

*range 0.47uF - 2.2KuF 90-day money-back guarantee

Portable, Easy to Use, Inexpensive, Highly Recommended by

leaders in the industry. CapAnalyzer 88A by EDS, Inc.

Repair Monitors, Power Supplies, Gameboards?

At your favorite distributor, or call 561-487-6103 or www.eds-inc.comAt your favorite distributor, or call 561-487-6103 or www.eds-inc.comAt your favorite distributor, or call 561-487-6103 or www.eds-inc.comAt your favorite distributor, or call 561-487-6103 or www.eds-inc.comAt your favorite distributor, or call 561-487-6103 or www.eds-inc.com


A dark picture can easily bethe result of low voltagereaching the heater pins onthe CRT, although it’s notthat common an occurance.Cleaning the CRT socketmight help, in the eventual-ity that a substantialamount of oxide or someother nasty contact-inhibit-ing-agent has made its wayinto it.

Two words of warning.

SAFETY FIRST.SAFETY FIRST.SAFETY FIRST.SAFETY FIRST.SAFETY FIRST.

In simple terms, beforepoking and prodding insidea monitor, make sure themains plug is pulled out.Just to make sure nobodyplugs you back in whenyour back is turned, leavethe plug next to you andactually look for it whenstarting to work on themonitor.

Another word of warning.Even though you havepersonally pulled out themains plug and the monitoris ‘safe’ to handle, it canstill give you a nasty kick.There are specific areaswhere a charge is retained.This can be in the order ofhundreds of volts or even

thousands. In other words,don’t touch anything in-side, blindly. And try not todrop screws or other metalbits inside; that includesthe screwdriver itself.

Removing the neck board isno big deal, as long ascaution is exercised. Justpull the board out gentlyand straight. Don’t wedge itsideways or apply any par-ticular force to it. If it isreally difficult to pull out,there could be somethinganchoring it to the tube’sneck. The CRT won’t breakif handled gently but hit-ting it with a hammerdoesn’t qualify as ‘gently.’In some cases, the neckboard is glued to the baseof the tube with siliconerubber. This is applied sothe neck board won’t comeout of its seating should themonitor be moved about agreat deal. In some models,the CRT neck board isactually clamped to thetube’s neck by a roundmetal bracket, fastened bymeans of a screw.

In certain high-end moni-tors, the CRT neck boardwill be shielded to such anextent that you won’t even

be able to see the compo-nents or the solder-side ofthe CRT socket. You’ll haveto remove some of theseshields, known as a Fara-day Cage, to be able toaccess the components andthe print. Caution is alsorecommended here sincethe shielding can be quitesharp and slashing a fingeror two is quite easily done.The cage tags might needquite a bit of heating tomelt the solder holdingthem to each other.

If after a visual and, per-haps, spraying a bit ofcontact cleaner in the CRTneck board’s socket, thepicture is still weak, you’llhave to dig a bit deeper. Amore realistic approach isto turn your sights towardsa power supply failure oreven a flyback transformerproblem.

Heaters normally run at6.3V. This can either be DCor AC. DC is pretty straight-forward to measure using atrusty multi-meter. If it’sAC, chances are you won’tsee an exactly perfect read-ing using the same trustymulti-meter. Reason beingis that the heater would be


fed off a tap from the flyback transformerwhich is working at over 15kHz. An el-cheapo meter is really looking for a 60 Hzsine wave and may not respond properly tothe high frequency heater power. Trymeasuring the AC heater voltage on aworking monitor and see how your meterresponds, then you will know.

Focusing on the DC side of things, whichare more common, the DC on the heatersshould be DC, and only DC. In otherwords, there should be no AC presence atall. Normally, the heater is fed off a sec-ondary tapping from the power supply’sswitched mode transformer. In its simplestform, a secondary winding would be recti-fied by a diode, and filtered by a capacitor.Should you measure the voltage across theheaters with a multimeter (typically pins 9& 10, the two pins at the top of the arc ofpins that are the CRT connections) andthe DC level is low, just for kicks, turn themeter to read AC, and measure that aswell. When I say the DC level being low,I’m talking about 4 to 5 volts, instead ofthe proper 6.3V. The AC reading could bein the region of 2 volts, roughly. In suchcases, you have something wrong there. Tocheck this out properly, I do suggest usingan oscilloscope as that will easily show thepresence of an AC voltage superimposedon the DC line.

Nine out of ten times, your filter capacitorhas done a runner and lost its capacitiveproperties. In the circuit above, the valueof this capacitor is 470uF at 16V, desig-nated as C123. In worst case scenarios, I’veeven measured the capacity of this compo-nent to read as low as a 100uF. The resultwould be a messed-up DC voltage reachingthe heater, resulting in a poor picture allround. Just replacing this capacitorshould solve your problem.

So far, I’ve only come across a single casewhere the heaters went open circuit.Please note, this has nothing to do with aslow death, but simply for the sake ofmentioning it. The voltage feeding themwas next to perfect and yet no picture andno glowing heaters were to be seen. I even


turned out the lights in theworkshop just to make surebut no golden glow wasvisible anywhere. I had tocheck several times beforeit actually sank in. That wasstrange, as the heater ele-ment is very robust and iscapable of withstanding agreat deal of punishment.Having said that, there isalways a weak link and withheaters, the time whenthey are the mostsusceptable to damage iswhen they are hot. At hightemperatures, they becomemore susceptable shock. Asubstantial knock on thetube’s neck can easily getthe heater element to goopen circuit. Hit the neck abit harder and you’ll breakthe tube. You’ll know it’sbroken as you’ll hear a loudhissssssssssss coming fromit. If that happens, you

won’t have to worry aboutthe heater element anylonger and you’ll have tostart looking for a replace-ment CRT. Somethingworth keeping in mind:When moving a monitor,best to always let it cooldown, even for a few min-utes.

Before finishing off this firstpart of the article, I’d alsolike to mention that if youreally do have a weak CRTand the rejuvination pro-cess doesn’t work, and youdon’t wish to invest in anew CRT for reasons ofcost, then you can cheat alittle bit. Please be warned:You’ll be stressing theheaters somewhat. How-ever, I’ve done this and ittruly works.

If the 6.3V is perfect, youcan increase this some-what. I stretched mine upto 7V and the difference itmade was really impressive.What I did was by-pass aseries resistor feeding theheater. I know this isnaughty but at the time Ididn’t have anything to loseand luck was on my side.The monitor was still work-ing fine the last time Ilooked.

In the next part of thisarticle, I’ll tackle slow deathwhen it happens to a TFTscreen. Till then, remem-ber, SAFETY FIRST and ofcourse, the ever faithfulrule of the three Cs.

- James Borg - James Borg - James Borg - James Borg - James [email protected]@[email protected]@[email protected]


“OK. You asked and I listened. My new tech class eliminates obsolete CRTmonitor repair and the associated monitor repair lab. In just four or five days, yourslot techs can learn to repair Power Supplies, LCD Monitors, Ticket Printers, BillValidators and more. It’s easy and it’s fun.“- Randy Fromm

“I can help you bring down thecost of casino electronics repairs”

tel.619.838.7111 fax.619.593.6132

Randy Fromm

NexGen Bench Tests - slot-tech.comslot-tech.com/members/magazine/lores/december12.pdf · 1 year -...

Documents

Transcript of NexGen Bench Tests - slot-tech.comslot-tech.com/members/magazine/lores/december12.pdf · 1 year -...