Scott-LT-110-Alignment 电路图 维修手册.pdf

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1、Aligning the Tuner Two methods are provided for aligning the tuner. One is the unique EZ-A-LINE method which eliminates the necessity of using test equip ment, while insuring top quality results. The sec ond method is the conventional process employing standard Iaboratory techniques and instrumenta

2、tion. This is outlined in the enclosed Service Bul letin. For the EZ-A-LINE method the following items are necessary: a special alignment tool, a small screwdriver, an FM dipole antenna, a standard audio cable, a CC .05 capacitor, and two alligator clips, all of which are provided. You must provide

3、an amplifier and a speaker. One end of the alignment tool is for adjusting the IF transformers and the other end is for the detector. See fig. 17. As part of the detector align ment procedure, a unique method bas been devised which utilizes a small capacitor (CC .05) which will be found in one of th

4、e small hardware en velopes. For ease of use, connect each end of the CC .05 to an alligator clip.Make a good mechanical connection to the clips. Y ou may solder if you wish. 1. Connect the dipole antenna wire sup plied to the antenna terminais on the rear of the tuner. Connect one of the leads to t

5、he G terminal and the other to the 300 ohm terminal. See fig. 18. After the antenna has been screwed on tightly, spread the antenna wire out on the table or tape it on the wall. Make sure that no part of the antenna wire touches the ch assis of the tuner. 2. Connect the shielded audio cable from the

6、 Left Channel audio output on the rear of the tuner to the tuner input of the amplifier. Connect a loudspeaker to the appropriate amplifier terminais and SLOTTEO . (NO FOR HEXAGONAL END FOR D(HCTOA TRANSFOAWER FIGURE 17 1. F. TRANSFOJtMER 35 make sure that all the amplifier controls are set properly

7、 to reproduce the tuner signais. For the moment leave the ampli fier turned off. 3. Make sure the tuner is turned off ( the Selector knob, the second from the left, in the OFF position, fully counterclock wise). Set the Sonic Monitor switch to the LISTEN position. Set the Stereo Noise Filter switch

8、to the OUT position. Set the AGC control to NORMAL .posi tion. On the rear apron of the tuner, set the right and left LEVEL controls to zero (maximum counterclockwise). In sert the tuner line cord into an AC wall outlet (do not use with DC). 4.Turn the tuner on its side as shown in fig. 19. Turn the

9、 selector switch to the mono position. This automatically turns the tuner on. Watch carefully for any signs of overheating or smoking, either under the chassis or on top. Ail the tubes and bulbs should light up normally and not show evidence of unnatural bright glowing. At the first sign of difficul

10、ty turn off the tuner immediately. Refer to the section on In Case of Difficulty. The meter will probably swing down to a low reading (about 2 or lower) un less you happen to be tuned to a strong station. Rotate the tuning dia! slowly from one end to the other. Each time a station is tuned in, the m

11、eter will move up to a higher number. The amount of meter deflection ( e.g., meter swing) will depend on the strength of the stations signal, its distance from you, and how well the tuner is aligned. If there are no indications on the meter and you live some distance from any FM broadcast ing statio

12、ns, see section following on CONNECTIONS - Antenna, Extreme Fringe Areas. FIGURE 18 CONNECTION or FOi.OED DIPOLE ANTEN,C,. RadioFans.CN 收音机爱 好者资料库 Normal areas-if you are in an average listening area, you will tune in some strong stations that make the meter move up over 4 and some weak sta tions th

13、at barely manage to wiggle the meter at ail. Tune in one of the strong stations, setting the tuning dial so that the meter is at its highest position for that particular station. Extreme fringe areas -if you live many miles from any transmitter, you may find that it is impossible to note even a wigg

14、le on the meter. Try raising the antenna off the table and taping it to the wall. If that does not help, connect the tuner to the antenna wire coming from an outdoor television antenna. A final approach is to use the amplifier as a guide. Turn the input selector of the amplifier to the tuner input.

15、Turn up the left channel level control on the rear of the tuner. Adjust the volume control of the amplifier so that the sound from the tuner itself can be heard. Turn the tuning knob of the tuner until a station is audible. It will undoubtedly be very distorted, faint, and noisy. Start the alignment

16、 procedure at this position. Once meter deflection occurs, readjust the tuning knob so that the meter is at its highest reading for the station. Ignore the sound quality from then on (in fact, you can turn down the vol ume) ; however, you may find that in making the following adjustments the presenc

17、e of some volume will be helpful. You will find that when the volume is approximately at its highest point, you will be very close to maximum meter de flection. This meLhod of locating the peak point in the can will eliminate the necessity of going from one end of the canto the other. THE SOUND AT T

18、HIS POINT WILL BE DISTORTED. DO NOT MAKE REFERENCE TO THE SOUND QUALITY. Should neither of the above methods give you a me ter reading, the f ollowing procedure should be used: Connect the Alligator clips to each end of an 11 wire. Connect one clip to Pin 3, D3MA on the Z-FM-1. Connect the other cli

19、p to Pin 1, D4C. Connect another wire from Pin 4, D4C to any good ground point on the tuner. (You can run the end of the wire through one of the holes in the bottom fi.ange of the set and twist 36 it around.) You should now be able to locate at least one station which gives a meter reading of betwee

20、n O and 2. N ow start aligning your tuner. AS SOON AS YOU HAVE ALIGNED THE TUNER ENOUGH TO SUSTAIN A METER READING WITHOUT THE USE OF THESE TWO WIRES - REMOVE THE WIRES. If this procedure gives you no meter reading, refer to the section on In Case of Difficulty. 5. Carefully adjust the tuning knob s

21、o that the meter is at its highest position for the station tuned in. NOTE: The passage overhead of an air plane will cause the meter indicator to swing up and down. Hold up the align ment until this stops. Set the tuner on its end with the black transformer side down, and the front panel facing you

22、 (see fig. 19). 6. Insert the IF alignment tool (see fig.17) into the top ( above the chassis) of T2 (skip Tl for the moment) until the end of the tool makes contact with the tuning slug inside. The slug may be over a half inch inside the transformer. Rotate the tuning slug slowly back and forth wit

23、h the alignment tool while carefiiUy watching the tuning meter for the high est reading. At this time the meter ac tion may be small, so you have to look carefully to insure getting the highest point. You will have to rotate the slug both clockwise and counterclockwise to locate this maximum positio

24、n. A scrap ing noise will be audible as the slug is turned. This is normal. At the extreme clockwise and counter-clockwise position of the slug there is a stop beyond which you should not turn. Do no force beyond this point as this will damage the trans former cans. It is possible for the maxi mum r

25、eading to occur at a stop. 7. Insert the IF alignment tool into the bot tom (below the chassis) of T2, and ro tate for highest reading on the meter. 8. Carefully readjust the tuning knob to make sure that the station is still tuned to the maximum reading on the meter. Insert the IF alignment tool in

26、to the top of T3 and rotate for maximum meter reading. RadioFans.CN 收音机爱 好者资料库 9.Insert the alignment tool into the bottom of T3 nd rotate for highest reading on the meter. 10. 11. 12. At this point, retune to a different sta tion, one that has a lower reading on the meter. If possible, find a stati

27、on that is only 4 or lower. Sometimes a weak signal will cause the needle to wander up and down due to the inherent fading found with these signais. Try and pick a station that is quite stable. Carefully adjust the tuning knob so that the meter is at its highest position for the station tuned in. In

28、sert the IF align ment tool into the top of Tl ( on the silver-plated front end) and rotate for maximum reading. Repeat for the bottom of Tl, top and bottom of T2, and top and bottom of T3. At all times make sure the tuning knob is tuned to maximum. Each time adjust ments take meter above 4, change

29、to a station having a lower reading. At this point only a very slight movement of the aligning tool will be necessary. Aligning the Detector 13. 14. This part of the alignment requires ex h-eme care to insure a clean, undistorted signal. Using the detector end of your alignment tool, insert into the

30、 bottom of T4. Rotate counterclockwise until you reach the stop at the end of the rotation. DO NOT FORCE THE STOP Very carefully start rotating clockwise and count off 3 and turns on the align ment tool. The lettering on the side of the tool will guide you in figuring a full turn. Carefully remove t

31、he aligning tool from T4. Tune to the strongest station you can :ftnd. Make sure .that you are tuned to the absolute maximum reading for this station. Once you are sure you have tuned to the precise maximum point, turn off the tuner and do not touch the tuning dial under any circumstances. If the am

32、plifier volume has been up, turn it down. Take the CC .05 with the alli- 15. 16. 17. 37 gator clips. Clip one to pin 1 of Vl and the other to pin 4 of VI. Watch for short circuits. Check to see that the amplifier is turned on. Make sure it is set for tuner input. Turn up the bass control toits maxim

33、um position clockwise. Keep volume turned down. Turn up the level on the tuner all the way ( on the rear of the tuner) - DO NOT TOUCH TUNING KNOB. Turn on the tuner. Turn up the volume of the amplifier until a loud hum is clearly audible. Hum re fers to a low frequency noise very deep in the bass re

34、gion. Do not confuse with noises of higher frequency. Insert the alignment tool, detector end, into the top of T4. Turn clockwise or counter clockwise, until the hum begins to dis appear. As the hum fades you may have to turn up the volume on the amplifier again. The desired point is the spot where

35、the hum is at its absolute lowest point. At this point other noises will still be audible, but the hum will be virtually non-existent. Carefully remove the aligning tool. Turn off the tuner. Remove the alligator clips. Turn the amplified bass control to normal. Turn on the tuner. Most stations shoul

36、d sound clear and undistorted. If none of them do (assuming no amplifier or speaker difficulties) repeat the entire alignment procedure. If there are no problems, the tuner is now ready for final assembly. No adjustments are re quired for the multiplex section and none should be made. However, it is

37、 rec ommended that you carefully read the section on Separation towards the back of this booklet. FIGURE 19 RadioFans.CN 收音机爱 好者资料库 Final Assembly, Part 2 A3-l A3-2 Mount the bottom cover by sliding the two clips under the lip of the chassis towards the front of the tuner. Screw two H-SMS- 6 x HW sh

38、eet metal screws into the two inner holes on the bottom rear of the chassis. If the tuner is not going to be used in one of the regular H. H. Scott metal or wooden cases, you will want to install the plastic feet now. These will be found in one of the small envelopes, entitled ZP-1. Mount the four p

39、lastic feet with the four sheet metal screws provided. If the tuner is to be custom mounted in a cabinet, instructions for doing this are on the mounting template provided. Congratulations ! Now . sign your persona label This kit was built by - . turn your tuner on . relax . and listen to one of the

40、 finest FM tuners ever made. For complete enj oyment of your tuner you will want to read the actual Operating Instruc tions which start on page 39. ln Case of Difficulty No matter how careful you are, a mistake is possible. Dont panic! First, make sure each tube is in the proper location. Then go ba

41、ck to the as sembly notes and check off each step with the written instructions and the pictorials. Or if pos sible, have someone else do this for you. Often a fesh approach may disclose mistakes that you might be consistently overlooking. While check ing for errors, carefully probe each and every w

42、ire, lead, component, and part to make sure there are no short circuits and poor solder joints. In case the fuse bas blown (the unit will not light up) it is very likely that there is a short circuit. Before replacing the fuse (instructions for this will be found in the service notes en closed) sear

43、ch for the cause. 38 In case the unit lights up but does not operate properly, voltage readings are supplied on the schematic. If you can obtain a good vacuum tube voltmeter (VTVM) use the voltage readings for locating the portion of the circuit that is mal functioning. If none of the above suggesti

44、ons help in curing the problem, you should write to our Laboratory Kit Service Dept. for prompt assistance. There is no charge for this help. The engineers in this de partment are thoroughly familiar with all aspects of the kit, and can probably localize the cause of your difficulty. However, you mu

45、st be very ex plicit in describing your problem. Mention all the approaches you have undertaken to cure it. De scribe all the symptoms and signs that may be involved. With complete information supplied, the possibilities of a cure through the mail are greatly increased. Service When all else fails t

46、he facilities of the H. H. Scott Laboratory Kit Service Department and the vast network of Authorized Warranty Serv ice Stations are available to you. A fixed inspec tion fee of $2.50 will be made should your unit be submitted either to the factory or to a Warranty Station. If it is found, however,

47、that it is neces sary to go into the unit and touch up any solder joints, miswires, etc., then an additional $7.50 charge will be made. This fee will be in addition to any parts that have to be replaced. If the unit is still within the 90 day warranty period (see de scription of the Warranty Policy

48、below), then the charge for parts will be governed by this policy. In case you receive sound from one channel but not from the other, you should check the inter connecting audio cables. Occasionally audio cables become intermittent or shorted. Reverse the cables, one for the other, and again listen

49、to the system. If the dead channel switches to the other channel, then you should replace the cable in the dead channel. Many H. H. Scott dealers have service facilities and are fully competent to repair this kit. These dealers are not governed by our price policy and can charge any fee they wish. This fee should be ascertained before service is begun. Only the factory and certain of the warranty stations have the necessary equipment to service the multiplex section. Before any servicing is done to this section,