20th August 1999

20th August 1999 LK1 Service Manual

Page1 Copyright © 1999 Linn Products Limited. All rights reserved.

LK1 LK1 PreAmplifier Service ManualPreAmplifier Service Manual

CONTENTS

INTRODUCTION .................................................................................................................................... 2

ABOUT THIS MANUAL.............................................................................................................................. 2RETAILER & DISTRIBUTOR OBLIGATIONS ................................................................................................... 2SPARE PARTS AVAILABILITY AND LK1 REPAIR ............................................................................................ 2HOW TO USE THIS MANUAL...................................................................................................................... 2

INSTALLATION ..................................................................................................................................... 3

IMPORTANT SAFETY INFORMATION............................................................................................................ 3INSTALLATION INSTRUCTIONS................................................................................................................... 3PLACEMENT.......................................................................................................................................... 3

POWER-UP PROBLEMS........................................................................................................................ 5

POWER UP PROBLEMS ............................................................................................................................ 5FUSE BLOWING...................................................................................................................................... 6

DISPLAY & CONTROL PROBLEMS....................................................................................................... 7

GENERAL DISPLAY & CONTROL PROBLEMS ................................................................................................ 7REMOTE CONTROL PROBLEMS ................................................................................................................ 9CONTROL VIA FRONT PANEL ...................................................................................................................10

AMPLIFIER PROBLEMS .......................................................................................................................11

AUDIO (LISTEN) OUTPUT........................................................................................................................11TAPE (RECORD) OUTPUT .......................................................................................................................13



Contents

Introduction

About this manualThis manual is designed to help you as a Linn Retailer or Distributor to repair as many LK1 faults at yourrepair centre as is practical and so provide the best possible service for your customer should a problemarise.If you have any suggestions or comments regarding this manual, please contact Paul O’Neill at LinnProducts Ltd: By E-mail [email protected]

By Phone ++44 (0) 141 303 5005By Fax ++44 (0) 141 644 4262 Marked for attention of Paul O’Neill

Retailer & Distributor ObligationsLinn Specialist Retailers or Distributors are obliged to carry out the repairs in this manual under the terms ofthe contract & warranty agreements. You should return a faulty product to Linn for repair, only if the fault isnot covered in this Service Manual. If a product, which is under warranty, is returned to Linn for repair andthe fault is covered in the service manual, Linn may levy a charge and this charge should not be passed tothe customer.

Spare Parts Availability and LK1 repairPlease note that the LK1 has been obsolete for some considerable time now and as such, we cannotguarantee the supply of spare parts – many are simply no longer available. Some part numbers are listedthroughout this manual, but these are provided for information only and this does not imply that these partswill be available should you request them.Linn guarantee that we will service a product until 5 years after the final build. We take this obligation veryseriously and also go much further. Beyond this date, we will repair any Linn product that we possibly can,where it is within our power to do so. However, due to the difficulty with the availability of spare parts, asexplained above, it is occasionally not possible to repair a product or supply parts for repair, as thenecessary parts are not available and can no longer be sourced.

How to use this manualThe main body of this manual, the fault table, is designed to be as quick and simple as possible to use whenyou are confronted with a faulty product and so it is arranged by fault symptom as the symptom is usually allthat you will know about the fault.If you are unsure about the meaning of any words or phrases, look in the Glossary. (accessible via LinfoWebsite - Product Information)Before embarking on any Service work, you should read the Service Procedures section (accessible viaLinfo Website - Product Information), as there are certain procedures that must be followed in order toensure the problem is resolved quickly and permanently

Table of contents & fault symptoms

Look firstly at the table of contents and find the category that covers the symptom you are seeing, then lookdown the list of faults in that section until you find the symptom or symptoms that best describe the problem.

Circumstances

Then simply follow the table along – the table specifies circumstances surrounding the fault symptom – e.g.whether the fault is likely to be intermittent or constant, if the fault only occurs within a range of serialnumbers etc.



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Possible causes

The next column details possible causes – this is effectively the most important section, probably the mainreason you are looking at this manual at all. There may be several possible causes for the symptom youhave – it is worth checking out all of these (and bear in mind that there may be more than one fault). Forsome faults, simple checks are detailed that you can use to rule out the problem without replacing any parts,whereas for other faults, the simplest way to rule out the problem is to replace the component(s) listed

Cure

Quite simply the action that you must take to cure the problem.

InstallationImportant Safety InformationMains connections

This appliance must be earthed – both for Safety and functional reasons.

Lethal Voltages

Inside the LK1, lethal voltages are present, although normally these are inaccessible inside the transformercasing and at the mains switch (which is insulated with heatshrink sleeving.) If the mains switch is properlyinsulated, none of the wires to/from it are damaged and the transformer casing is closed, the LK1 is quitesafe to work on while powered up as only low voltages are found on the circuit boards (maximum 38Vac and22V dc)

Installation InstructionsImportant – the LK1 Inverts the phase of the signal to the power amp, therefore to achieve absolute phase,connect the positive output of the power amp to the negative (black) loudspeaker terminal and the negativeoutput to the positive (red) loudspeaker terminal.If, however, you use a speaker switching box or a headphone adaptor box however, these must be wired INPHASE or damage to the power amp, headphones etc can result.

PlacementLocation & Environment

Do not locate near electronic products that may transmit RF, such as microcomputers, fax machines, TVsetc, or connect them to the same mains socket as these devices. Also avoid close contact with the mains orsignal leads of such products – careful routing of the cable may be required.Avoid locations where direct sunlight can shine on the display as sunlight (even diffused sunlight) is a strongsource of infra-red light & this causes problems with the unit’s remote control circuitry.Avoid certain types of artificial lighting, such as low energy bulbs, fluorescent light etc, as these emit stronginfra-red patterns that can lock up the LK1 control functions.Although the LK1 can usually be stacked along with other products with no problem, it is better if possible tokeep it apart from other products to prevent its operation being adversely affected by the heat and strongelectrical field emitted by some products.Avoid locations that have high humidity or the chance of the unit getting wet.Avoid locations where there is a lot of dust.



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Handling & general maintenance.

Always handle the LK1 with great care.Always turn off the LK1 and any Power Amps connected to it before connecting or disconnecting any plugsto/from the sockets at the back of the unit. Wait at least 10 seconds after switching off the power ampsbefore unplugging from the back of the LK1 to avoid damage to the speakers.If you are carrying out any work on the LK1 with its’ sleeve removed, ALWAYS take anti-static precautionsas tiny static discharges from your body, which you may be completely unaware of, can damage electroniccircuitry and cause major problems. Anti-static earth mats & wrist straps must be used when handling any ofthe circuit boards or any spare parts.



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Power-up problemsPower up problems

Symptom Circumstances Possible Cause(s) CureWon’t power up.Display dead &no function

Constant Fuse blown in unit and/or inmains plug.

Replace fuse(s) with correctvalue & type.Fuse in mains lead should be 5A.Fuse in LK1 should be “SlowBlow” – look for a ‘T’ before therating on the fuse. Correct typesare:110/115V - T300mA antisurge220/240V - T200mA antisurge

Won’t power up -Power LED dead,no display & nofunction

May be intermittent Mains lead faulty Replace faulty mains lead.

Display diesintermittently &unit stopsworking for awhile.

At any time Mains voltage dropping toolow for LK1 to functioncorrectly (known as ‘Brownouts’ as these voltage dropsalso sometimes cause thehouse lights to dim.)

Consult an electrician or yourpower company.

Doesn’t power uporPowers up(display LED lit)but no function.

May be intermittent Wrong mains voltage for LK1type – mains voltage is toolow. (e.g. 240V LK1 beingused with 115V mainssupply.)

Check voltage rating at rear ofLK1. If wrong, transformer willrequire replacement. Correct partnumbers are:MCAS 002/100 for 100V mainsMCAS 002/115 for 115V mainsMCAS 002/220 for 220V mainsMCAS 002/240 for 240V mainsOur stock of these transformers isvery limited, so it may not bepossible to supply the part yourequire.

Doesn’t power uporPowers up(display LED lit)but no function.

May be intermittent One of the power supplies isdead or at an incorrectvoltage level.Power supplies can bechecked at the points listedbelow:+15V - U10 (regulator)output – middle leg.-15V - Q78 emitter (squarepad)+Vref - U9 pin 7-Vref - U9 pin 8+8V - Q77 emitter (squarepad)

Cannot suggest a simple fix assome fault finding is required totrace the cause of the fault.See PCAS 001 Circuit Diagram(accessible via Linfo Website -Product Information)



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Fuse blowingSymptom Circumstances Possible Cause(s) CureFuse blowing May be intermittent Wrong type of fuse fitted Replace fuse(s) with correct

value & type.Fuse in mains lead should be 5A.Fuse in LK1 should be “SlowBlow” – look for a ‘T’ before therating on the fuse. Correct typesare:110/115V - T300mA antisurge220/240V - T200mA antisurge

Fuse blowing May be intermittent Mains surges Consult an electrician or yourpower company.

Fuse blowing Constant Wrong mains voltage for LK1voltage setting - mainsvoltage is too high, e.g. a115V LK1 connected to 230Vmains.

Check voltage rating at rear ofLK1. If wrong, transformer willrequire replacement. Correct partnumbers are:MCAS 002/100 for 100V mainsMCAS 002/115 for 115V mainsMCAS 002/220 for 220V mainsMCAS 002/240 for 240V mainsOur stock of these transformers isvery limited, so it may not bepossible to supply the part yourequire.

Fuse blowing May be intermittentbut usually constant

Transformer faulty. To checkif it is definitely thetransformer, power down theunit, replace fuse, disconnectthe transformer output fromthe Main board and powerup. If the transformer IS thecause, the fuse will continueto blow. If the fuse remainsintact, the fault is more likelyto be on the Main board.

Replace transformer. Correct partnumbers are:MCAS 002/100 for 100V mainsMCAS 002/115 for 115V mainsMCAS 002/220 for 220V mainsMCAS 002/240 for 240V mainsOur stock of these transformers isvery limited, so it may not bepossible to supply the part yourequire.

Fuse blowing Constant Bridge rectifier – D3 on mainboard faulty (probablyinternally short circuit).

Replace D3 – Linn part no:MISS 002

Fuse blowing Constant Fault inside LK1, e.g. shortcircuit or similar.

See Introduction to FaultFinding section (accessible viaLinfo Website - ProductInformation) for tips on tracing thefault. Also see circuit diagrams.



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Display & Control problemsGeneral Display & Controlproblems

Symptom Circumstances Possible Cause(s) CureDisplay dead orlocked up.

Possiblyintermittent

Unit not powering upcorrectly.

See ‘Power up problems’ sectionabove

Flashing lights ondisplay(sometimesknown as ‘Discolights’ or‘Christmas treelights’)LK1 will notfunction.

Sometimesintermittent – maystart doing thisoccasionally andthen become more& more frequent.

Symptoms mayvary.

C12 on control board faulty Replace C12 – Linn part no:CAP 022


Ensure that theabove ‘Flashinglight’ fault (C12)has been ruled out.


Symptoms mayvary.

U9 (EEPROM) on controlboard faulty.

Please NoteU9 is unlikely to be the cause ofthis fault (perhaps a 1 in 50chance) but is easy to rule out IFyou have another LK1 or acontrol board or a spare U9 thatyou can try in the faulty product.If you do not have the partavailable, ignore U9.Linn part no: IC 016 (ensure U9 isprogrammed – a programmed U9will have its window covered witha sticker that will normally read‘MK3’)


Ensure that the‘Flashing light’ fault(C12) above hasbeen ruled out.


Symptoms mayvary.

U7 and U8 on control boardfaulty.

Replace U7 & U8 – Linn part no:IC 015 for both parts.



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Display locked up– no function andno sources canbe selected –input LEDs willnot illuminatewhen inputselection buttonis pressed.

Occurred after unitwas switched offand then on again.

Battery faulty – if the batteryis dead and the unit isswitched off, the unit loses itsmemory. On most units,when this happens the unitfunctions okay afterwards butloses memory. On someunits, however the displaylocks up and must be re-activated.

To re-activate the display, pressand hold one of the inputselection buttons for about 5seconds. Once the display is re-activated it will stay active andwork as normal until the unit isswitched off and then this mustbe repeated.To fix permanently, replace back-up battery (BATT 1 on controlboard) and then re-activate thedisplay.

Display locked up– probably one,two or moreLEDs on frontpanel constantlylit.No function.

Probably constant Control board requiresupgrade.Check for the following oncontrol board:Is a Pot (variable resistor)fitted at location VR1?Is a capacitor fitted at C16?Does the EEPROM (U9)have MK3 written on it?If the answer is yes to any ofthese questions, the controlboard requires upgraded.

See LK1 Control BoardUpgrade sheet (accessible viaLinfo Website - ProductInformation)

Display dead orlocked up.May haveoccasional ‘DiscoLights’

May be intermittentand symptoms mayvary

Battery has leaked fluid ontocontrol board, damagingcomponents in that vicinity

Remove battery, clean board,replace any components thathave been contaminated withbattery fluid.Replace battery with a new one –Linn part no: MISS 011

Display locked up– amp will notfunction, perhapsone or twodisplay LEDspermanently lit.May haveoccasional ‘DiscoLights’

Probably constantSymptoms mayvary

U7, U8 or C12 on controlboard faulty.

Replace C12 first (easy toreplace) then replace U7 & U8.

Display dead orlocked up.

Probably constant Power supply fault on mainboard. The control boardpower comes from theemitter (square pad) of Q77(attached to one of theheatsinks) on the mainboard. It should measure+8V

Firstly check which board iscausing the fault – it could be themain board failing to supply thecorrect voltage or it could be thecontrol board pulling the voltagedown. If you have another LK1 tryreplacing the control board. SeeIntroduction to Fault Findingsection (accessible via LinfoWebsite - Product Information) fortips on how to trace fault. Seealso circuit diagrams.If the fault is located on the mainboard, try replacing Q77 – Linnpart no: TRAN 006.

One or moredisplay LEDs dimor dead

LK1 works okayotherwise.

Faulty display LED Replace LED – Linn part nos:MISS 004 (green LED)MISS 005 (red LED)



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LK1 loses allsettings (volumesetting, inputselected, memorysettings etc)when unit isswitched off andback on.

Probably constant Battery – BATT1 on controlboard faulty. To check,measure across the batteryfrom one side to the other – itshould measure about 3.5Vdc. If it measures lower thanabout 2V, the battery isfaulty.

Replace battery – Linn part no:MISS 011.

LK1 takes actionsby itself – i.e.volume changes,selects inputs,unmutes etc.

Intermittent andrandom.

U7, U8 or C20 on controlboard faulty.

Replace C20 first (easy toreplace) and if that does not fix it,try U7 & U8Linn part numbers:U7 & U8 - IC 015C20 - CAP 003

Remote Control ProblemsSymptom Circumstances Possible Cause(s) CureLK1 cannot becontrolled viaremote handset.Works okay viafront panelcontrols

Probably constant Remote handset faulty orremote handset batteriesrequire replacement.

Try fitting new batteriesTry another working handset.

LK1 cannot becontrolled viaremote handset.Works okay viafront panelcontrols

Probably constant Remote control is notenabled on LK1 controlboard. On the LK1 remotehandset, there is a buttonmarked ‘Pre’ and severalother buttons beside it in thesame group. If one of theseother buttons is pressed, thisdisables the remote controlof the LK1 – to enable theremote again – press ‘Pre’.

Press ‘pre’ on remote handset.

LK1 cannot becontrolled viaremote handset.Works okay viafront panelcontrols

Probably constant Remote receiver diode (D15on Control board) is faulty.

Replace D15 – Linn part no:MISS 007

Poor control or nocontrol via remotehandset.Works okay viafront panelcontrols

All the aboveRemote faults havebeen ruled outMay be intermittent

U2 (remote receiver IC) orU6 (main processor IC) onControl board faulty.

Replace U2 (Linn part no: IC 010)or U6 (Linn part no: IC 017)



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Control via Front PanelSymptom Circumstances Possible Cause(s) CureOne or morebuttons either donot work at all ordo not work well

May be intermittent Membrane & switch contactrequire cleaning

Remove control board fromFacia.With a dry, clean tissue or cloth,vigorously wipe the switchcontacts on the control board.Clean membrane contacts (theblack circular pads) in a similarway as switch contacts but withmore care as it can be torn byrough handling.

No control viafront panel – oneof the displayLEDs may bepermanently lit.

Probably constant U1 on control board (encoderIC) faulty.

Replace U1 – Linn part no:IC 009.

Some buttonswork and somebuttons do not

May be intermittent Control board requiresupgrade

See Control Board Upgradeprocedure (accessible via LinfoWebsite - Product Information)



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Amplifier problemsIt is assumed at this point that the LK1 is definitely the cause of the fault – that you have traced thefault to the LK1 and ruled out all other aspects of the system (e.g. interconnect leads, power amp,speakers, sources etc.). If you have not, please do so before proceeding to ensure that you are notfault-finding on a product that is not faulty while the fault remains in the system.

Audio (Listen) outputSymptom Circumstances Possible Cause(s) CureNo output fromboth channels

May be intermittentDisplay & controlmay be affected

Power up, display, or controlfault – see these faults aslisted above.

See Power up and Display &Control faults listed above.

One channel islouder than theother on all inputs

Probably constant Balance is set off centre. Centre the balance setting

Cross-talk fromone (or more)input to otherinputs.May also have aloud cracklingnoiseintermittently

May be intermittent One of the display LEDs oncontrol board is leakingcurrent.

See LK1 Cross-talk RepairProcedure (accessible via LinfoWebsite - Product Information)

Loud crackling,buzzing orelectronic noisethrough speakersintermittently.May also havecross-talkbetween inputs.

Intermittent

Symptoms mayvary.

One of the display LEDs oncontrol board is leakingcurrent.

See LK1 Cross-talk RepairProcedure (accessible via LinfoWebsite - Product Information)

Cross-talk fromone (or more)input to otherinputs.May also have aloud cracklingnoiseintermittently

Probably constantIf the switcheswithin the IC gofaulty, they usuallyget jammed in the‘Closed’ position.This means that theaffected input willbe permanentlyswitched on andthis causes cross-talk. E.g. if AUXswitching IC isfaulty and you aretrying to listen toTUN while a sourceis playing on AUX,one channel of theAUX source maybe heard on theTUN input.

Switching IC(s) faulty.Each input has its ownswitching IC, which switchesListen & Record for thatinput.If one input’s IC fails it canaffect the other inputs.The IC’s in question are U1 –U6 and they are configuredas follows:U1 – PhonoU2 – PhonoU3 – TP2U4 – TP1U5 – AUXU6 – TUN

Either replace all the switchingIC’s listed – Linn part no: IC 001for all IC’s; or by carrying outsome checks, you may be able tonarrow the fault down to the faultyIC(s) and replaced it/them only.If the symptom is cross-talk, thenusually the faulty input will cross-talk to other inputs, but theseinputs do not cross-talk back tothe faulty one.If the symptom is loud thump,then usually the faulty input willbe least affected by the fault.



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Crackling and/orrustling noise atthe output of onechannel

Firstly rule out theLED fault above.

Probablyintermittent. Noisevaries in volumeand intensity.

Transistor breaking down.

You may be able to narrowdown the fault by checkingexactly what inputs/outputsare affected, whether thefault increases/decreaseswith volume etc.

See Introduction to FaultFinding (accessible via LinfoWebsite - Product Information) fortips on how to trace.

No output from allinputs.

Happens after unithas been switchedoff and then onagain.

Backup battery (BATT1 oncontrol board) faulty –causes sound to mutecompletely (volume is atabsolute zero) on all inputs

To temporarily fix, simply turn upthe volume when unit is firstpowered up.To fix permanently, replace theback-up battery – Linn part no:MISS 011

Output of one orboth channelsdead on all inputs

Probably constant Volume control DAC faulty Replace DAC – Linn part no:IC 003

When volume isset to minimum,the music is stillheard.

Constant This is normal. The lowestvolume setting of the LK1 isNOT absolute zero. Ifabsolute zero is required,press Mute.If the lowest volume is tooloud, a mod can be done toreduce the gain of the LK1 by8dB.

See LK1 Gain Modificationsheet (accessible via LinfoWebsite - Product Information).

Slight hum onboth channels ofMM or MC input

May be intermittentand/or vary involume & intensity.

A certain amount of noise isto be expected on the phonoinputs due to the massivegain level required there.

Compare noise levels to anotherLK1 or another pre-amp phonostage – some low level hum isnormal and unavoidable andcannot be eliminated.

Hum on bothchannels of MMor MC input

May be intermittent Earthing lead between arm &LK1 casing is broken or notproperly connected

Ensure continuity of Groundconnection.

Loud hum on onechannel of MM orMC input

Probablyintermittent.Ensure firstly thatthe fault is notcaused by turntableor interconnectleads etc.Rule out Phonohum faults above.

Ground (black) wire betweenphono socket and mainboard inside the LK1 isbroken or not making goodcontact.

Repair the connection – re-solderor replace wire as necessary.

One channel ofMM or MC inputdead or distorted.Some cracklingmay occur

May be intermittentSymptoms mayvary

Signal (red) wire betweenphono socket and mainboard inside the LK1 isbroken or not making goodcontact

Repair the connection – re-solderor replace wire as necessary.



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No output fromone or bothchannels

All inputsMay be intermittent

Faulty:-Power ampSpeakersInterconnect leadsSpeaker cables

Find & repair or replace faultypart. Do not assume LK1 or anyother part of system is faulty –check & fault find system.See Introduction to FaultFinding section (accessible viaLinfo Website - ProductInformation) and also ServiceProcedures section (alsoaccessible via Linfo Website -Product Information) for tips onhow to fault find in a system.

No output fromone or bothchannels

May be all inputs orpossibly limited toone or two inputs.May be intermittent

Check that all input & outputleads are inserted in thecorrect placesCheck that all input & outputleads are pushed fully home.Check that the sourceselected on displaycorresponds with the sourceconnected to the input.Check that the source ispowered up, is playing and isworking okay.

Find and fix the problem.See Introduction to FaultFinding section (accessible viaLinfo Website - ProductInformation) and also ServiceProcedures section (alsoaccessible via Linfo Website -Product Information) for tips onhow to fault find in a system.

Tape (record) OutputSymptom Circumstances Possible Cause(s) CureTape (record)output dead or –no recordings

Constant Tape deck faulty Repair/replace Tape deck.

Tape (record)output dead

Constant Interconnect lead from LK1to tape deck is wronglyconnectedInterconnect lead from LK1to tape deck is faulty

Check, repair connections

Tape (record)output faulty.Possible Cross-talk from onerecord output toothers.Possible loudthump whencertain recordoutputs areswitched.

Probably constantIf the switcheswithin the IC gofaulty, they usuallyget jammed in the‘Closed’ position.This means that theaffected input willbe permanentlyswitched on andthis causes cross-talk. E.g. if AUXswitching IC isfaulty and you aretrying to recordfrom TUN while asource is playing onAUX, one channelof the CD may beheard on the tape.

Switching IC(s) faulty.Each input has its ownswitching IC, which switchesListen & Record for thatinput.If one input’s IC fails it canaffect the other inputs.The IC’s in question are U1 –U6 and they are configuredas follows:U1 – PhonoU2 – PhonoU3 – TP2U4 – TP1U5 – AUXU6 – TUN

Either replace all the switchingIC’s listed – Linn part no: IC 001for all IC’s; or by carrying outsome checks, you may be able tonarrow the fault down to the faultyIC(s) and replaced it/them only.If the symptom is cross-talk, thenusually the faulty input will cross-talk to other inputs, but theseinputs do not cross-talk back tothe faulty one.If the symptom is loud thump,then usually the faulty input willbe least affected by the fault.

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20th August 1999