Linn-LK275-pwr-sm 维修电路原理图.pdf

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1、 Copyright 2000 Linn Products Limited. All rights reserved. Paul ONeillS rvice Manual for LK2 Series of Pow m sService Manual for LK2 Series of Power AmpsCovering LK2(60), LK275 & LK280For the purposes of this manual, we will refer to the three types as LK260,LK275 & LK280. The term LK2 will be used

2、 as an “umbrella term”,covering all three types, i.e. the LK2 series.CONTENTSINTRODUCTION . 2ABOUT THE LK2 SERIES. 2HOW TO DIFFERENTIATE BETWEEN TYPES OF LK2. 2ABOUT THIS MANUAL. 3RETAILER & DISTRIBUTOR OBLIGATIONS. 3SPARE PARTS AVAILABILITY AND LK2 REPAIR. 3HOW TO USE THIS MANUAL. 3IMPORTANT SAFETY

3、 INFORMATION & INSTALLATION ADVICE . 4MAINS CONNECTIONS. 4LETHAL VOLTAGES. 4PLACEMENT. 4PROCEDURE FOR DISMANTLING AND RE-ASSEMBLING THE LK2. 5FAULT FINDING ON THE LK2 HINTS & TIPS. 9POWER-UP PROBLEMS FAULT TABLE.10WONT POWER UP.10WONT SWITCH OFF.10FUSE BLOWING.11AMPLIFIER PROBLEMS FAULT TABLE.13NO O

4、UTPUT.13TRIP (PROTECTION) PROBLEMS.15DISTORTION / CRACKLING ETC.16DC AT OUTPUT.17RadioFans.CN 收音机爱 好者资料库 LK2 Service ManualPage2 Copyright 2000 Linn Products Limited. All rights reserved.ContentsPaul ONeillIntroductionAbout the LK2 SeriesThere were three versions of the LK2: The first version was kn

5、own at the time simply as the LK2. It gave an output of 60 watts perchannel (into 8 ohm load) and used PCAS 003 type boards. For the purposes of this manual, we willrefer to this version as the LK260. The second type was also usually known as the LK2 but was often called the LK275 to differentiate i

6、tfrom the 60-watt version, as it gave 75 watts per channel. Also used PCAS 003 type boards but withseveral improvements over the 60 watt version the most obvious being the increased power output, butalso had improved protection circuitry and better sound. The third and last type was known universall

7、y as the LK280. 80 watts per channel used PCAS 020boards. PCAS 020s, at first glance are similar to PCAS 003s, in that they are roughly the same size,shape and layout, but they are a completely different design of board (i.e. not just a modified version ofPCAS 003) as a closer examination shows. The

8、 LK280 sounded considerably better than either of itspredecessors.How to differentiate between types of LK2There are several methods of determining the specification of an LK2: Looking at the serial number of a unit and using the LK2 Product History (accessible via Linfowebsite Product Information)

9、will tell you which revision it was sold as. Since, however upgrade kitswere sold by Linn in large quantities to allow customers to convert their early version LK2 into the latestspec, many units are not what they seem. The following information will help you to determine thespecification of a unit

10、if its exact history is unknown. LK280s had “LK280” printed on the facia earlier units (LK2 & LK275) had “LK2” printed there, butbeware an earlier version may have been upgraded to LK280 spec. LK260s and LK275s had a red power LED and LK280s had a green LED. This is handy as a quickand easy indicato

11、r but is not 100% reliable (LEDs are easily changed) The best way to determine a units spec is simply to remove the sleeve and look at the boards thatare fitted (see below).Distinguishing Features of Different Board TypesPCAS 020 usedin LK280Small heatsink barwith transistors fittedto it found on PC

12、AS020 onlyCapacitor &resistor (bridged)not fitted to 60watt boardThese diodes andcapacitors not fittedto 60 watt boardsPCAS 003 usedin LK260/LK27560 watt type used same boardbut with some differences, asshown belowSmall “Hybrid” boardfitted here at 90 degreesto main board found onPCAS 020 onlyRadioF

13、ans.CN 收音机爱 好者资料库 LK2 Service ManualPage3 Copyright 2000 Linn Products Limited. All rights reserved.ContentsPaul ONeillAbout this manualThis manual deals effectively with three quite distinct amplifiers. The amps have enough in common to justifythis approach and this avoids the confusion that might

14、come with separate manuals. Any differencesbetween the types will be dealt with in the “Circumstances” column e.g. Applies to LK280 only.This manual is designed to help you, as a Linn Retailer or Distributor, to repair as many LK2 faults at yourrepair centre as is practical and so provide the best p

15、ossible service for your customer should a problemarise.If you have any suggestions or comments regarding this manual, please contact Paul ONeill at LinnProducts Ltd: By E-mailPAULOLINN.CO.UKBy Phone+44 (0) 141 303 5005By Fax+44 (0) 141 644 4262 Marked for attention of Paul ONeillRetailer & Distribu

16、tor 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 und

17、er 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 LK2 repairPlease note that the LK2 has been discontinued for some considerable time now and as such, we c

18、annotguarantee the supply of spare parts many are simply no longer available and some others are no longer instock. Some part numbers are listed throughout this manual, but these are provided for information only andthis does not imply that these parts will be available should you request them.Linn

19、guarantee that we will support 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 availabi

20、lity of spare parts, asexplained above, it is occasionally not possible to repair a product or supply parts for repair, if the necessaryparts are not available.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 co

21、nfronted with a faulty product and so it is arranged by fault symptom as the symptom is usually allthat you will know about the fault.Also read the “LK2 fault finding Hints & Tips” section below as the information contained there may saveyou a lot of time.If you are unsure about the meaning of any w

22、ords 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

23、the problem is resolved quickly and permanentlyTable of contents & fault symptomsLook 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.

24、CircumstancesThen 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.Possible causesThe next column details possible causes this is

25、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). For LK2 Service ManualPage4 Copyright 20

26、00 Linn Products Limited. All rights reserved.ContentsPaul ONeillsome 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) listedCureQuite simply the a

27、ction that you must take to cure the problem.Important Safety Information & Installation AdviceMains connectionsThis appliance must be earthed both for Safety and functional reasons.Lethal VoltagesInside the LK2, lethal voltages are present, avoid powering up an LK2 with the sleeve removed or with a

28、nylive parts exposed. If you must work under such circumstances, DO NOT touch any part of the circuitry orany electrical connections and take great care to avoid electrocution.PlacementLocation & EnvironmentDo not locate near electronic products that may transmit RF, such as computers, fax machines,

29、 TVs etc, orconnect them to the same mains socket as these devices. Also avoid close contact with the mains or signalleads of such products careful routing of the cable may be required.Although the LK2 can usually be stacked along with other products with no problem, it is better if possible tokeep

30、it apart from other products to prevent its operation being adversely affected by the heat and strongelectrical field emitted by some products; also - since the LK2 can emit a considerable amount of heat andhas a fairly strong electrical field, it is better to keep it away from other devices that ma

31、y be adverselyaffected by this.Avoid locations that have high humidity or the chance of the unit getting wet.Avoid locations where there is a lot of dust.Handling & general maintenance.Always handle the LK2 with great care IT IS VERY HEAVY.Always turn off the LK2 and wait at least 30 seconds before

32、connecting or disconnecting any plugs to/fromthe sockets at the back of the unit to avoid damage to the speakers.If you are carrying out any work on the LK2 with its sleeve removed, ALWAYS take anti-static precautionsas tiny static discharges from your body, which you may be completely unaware of, c

33、an 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. LK2 Service ManualPage5 Copyright 2000 Linn Products Limited. All rights reserved.ContentsPaul ONeillProcedure for Dismantling and Re-

34、assembling the LK2Step 1. Remove the boards from the LK2Remember to keep all the screws and other parts that you remove from the LK2 in a safe place to re-uselater.1. Disconnect LK2 from everything and especially the mains (or Spark).2. Place a soft cloth on the workbench & lie the LK2 upside down o

35、n the cloth. Using a No2 posidrivscrewdriver, remove the 4 screws that hold the sleeve on to the LK2. Stand the LK2 on its facia and slidethe sleeve up and off. Carefully set it aside in a safe place where it will not get scratched or damaged.3. Remove the 4 allen bolts or screws (older units used s

36、crews) holding the speaker sockets on to theback panel. Do this to both channels.4. Disconnect both transformer connectors (the cables going from transformer to board) from the board5. Lift the LK2 up so that it is standing on one of the heatsinks. Each channel is held into the tray by 2countersunk

37、screws that attach to the heatsink on the underside. Hold the channel that is nowuppermost (to prevent it from falling once it has been freed) and remove the two screws from thischannel only. Lie the LK2 down (correct way up) and remove the channel that you have just loosened this can sometimes be t

38、ricky so follow these instructions: Pull the board slightly toward the front of the unit until the 3-pin cannon input socket at the rear isclear of the back panel it may sometimes be necessary to push the back panel slightly in theopposite direction until the socket is completely clear. Lift the end

39、 of the board containing the 3-pin cannon socket upwards (see picture) until that endof the board is clear of the tray. Some delicate manoeuvring may be necessary, but dont force it. By carefully moving the board backwards & upwards, it should now be possible to lift it up and out ofthe tray. Repeat

40、 the above instruction for the other channelStep 2/1. Lift this end up untilclear of tray2. Move theentire board inthis direction LK2 Service ManualPage6 Copyright 2000 Linn Products Limited. All rights reserved.ContentsPaul ONeillStep 2. Remove the heatsinks from the boards (if required)1. Using th

41、e 5.5mm spanner or nut-runner, loosen the single nut/bolt found beside the 3-pin cannon socket(see picture below) do not remove the nut completely, but loosen it to the point where only a very smallamount of the bolt is protruding from one side of the nut.2. The board is now held on to the heatsink

42、by 4 allen screws or 4 nuts/bolts (see picture below). If nuts/bolts are fitted, loosen them but do not remove them (as with single bolt above), pull the boardupwards until there is a gap between the board and the heatsink and then slide the board to one side. Ifthe board will not move easily, check

43、 that you have loosened all 5 nuts/bolts. If all are loosened correctlyand it is still not free, the board may be held on by the heatsink compound and will require some slightpressure to free it. If the board is held on by allen screws, completely remove all 4 screws, lift the board away from thehea

44、tsink and slide the single bolt beside the cannon socket sideways to free the board.3. Use a tissue or paper towel to clean the heatsink compound from the board and from the heatsink (if youdont, you will find out very quickly that heatsink compound has a knack of ending up all over yourclothes, han

45、ds, face etc)Step 3/Loosen thesingle boltfound hereNuts & bolts orallen screwsfound at these 4locationsDo not removethese two screws LK2 Service ManualPage7 Copyright 2000 Linn Products Limited. All rights reserved.ContentsPaul ONeillStep 3. Re-assemble the LK21. Re-attach the heatsink:Apply heatsin

46、k compound in a single line along the centre of the coupling block as shown belowIf board was attached to heatsink by nuts & bolts follow the instructions below: Remove all five bolts from the board and slide the bolts into the slots, arranged as shown below Place the board onto the heatsink so that

47、 all the bolts pass through their respective holes on theboard (some readjustment is usually necessary). Screw the nuts onto the bolts but do not tighten fully. Adjust the position of the board with respect to the heatsink so that the two are matched up i.e.the two are parallel with each other and n

48、either the board nor the heatsink are protruding at eitherside (see pictures below exaggerated to show problems clearly) Once heatsink and board are matched up, tighten bolts.If heatsink was attached with allen screws:HeatsinkSlide the bolts into theslots - positioned asshownHeatsinkprotrudingfrom o

49、ne sideHeatsinknot parallelto boardHeatsinkcompoundhere LK2 Service ManualPage8 Copyright 2000 Linn Products Limited. All rights reserved.ContentsPaul ONeill Slide the single nut/bolt (still attached to board) into the middle of its slot do not tighten Rest the board on the heatsink in a central pos

50、ition. Line up the screw holes in the board with those in the heatsink and screw in all four screws but do nottighten fully. Line up the board and heatsink so that they are parallel and level with each other (as diagrams above)and then tighten the screws fully. Tighten the nut/bolt2. Refit boards in