RCA-RS2625-cs-sm 维修电路原理图.pdf

《RCA-RS2625-cs-sm 维修电路原理图.pdf》由会员分享，可在线阅读，更多相关《RCA-RS2625-cs-sm 维修电路原理图.pdf（63页珍藏版）》请在收音机爱好者资料库上搜索。

1、SAFETY PRECAUTIONSPage 1-2DO NOT OPERATE THIS INSTRUMENT OR PERMIT IT TO BE OPER-ATED WITHOUT ALL PROTECTIVE DEVICES INSTALLED ANDFUNCTIONING. SERVICERS WHO DEFEAT SAFETY FEATURES ORFAIL TO PERFORM SAFETY CHECKS MAY BE LIABLE FOR ANYRESULTING DAMAGE, AND MAY EXPOSE THEMSELVES AND OTH-ERS TO POSSIBLE

2、 INJURY.READ AND COMPLY WITH ALL CAUTION AND SAFETY-RELATEDNOTES ON OR INSIDE THE RECEIVER CABINET, AND THE RE-CEIVER CHASSIS, OR ON THE PICTURE TUBE.SAFETY GLASSES SHOULD BE USED WHEN SERVICING ELEC-TRONIC INSTRUMENTS. INADVERTENTLY OVERSTRESSING COM-PONENTS MAY CAUSE THEM TO SHATTER, DISCHARGING S

3、MALLPARTICLES.DESIGN ALTERATION WARNING - Do not alter or add to the mechanical orelectrical design of this instrument. Design alterations and additions may alter thesafety characteristics of this instrument and create a hazard to the user. Designalterations or additions may void the manufacturers w

4、arranty and may make you,the servicer, responsible for personal injury or property damage resulting there-from.BEFORE RETURNING AN INSTRUMENT TO THE CUSTOMER, alwaysmake a safety check of the entire instrument, including, but not limited to, thefollowing items:FIRE AND SHOCK HAZARD1. Never release a

5、 repaired unit unless all protective devices such as insula-tors, barriers, covers, strain reliefs and other protective hardware have beeninstalled in accordance with the original design.2. Be sure that there are no cabinet openings through which an adult or a childmight be able to insert their fing

6、ers and contact a hazardous voltage. Suchopenings include, but are not limited to: (a) spacing between picture tubeand cabinet mask, (b) excessively wide cabinet ventilation slots, and (c) animproperly fitted or incorrectly secured back cover or cabinet.3. Observe original lead dress. Take care to r

7、estore leads to their originaldress. Make sure that leads are not in contact with sharp edges or thermallyhot parts. Always inspect in all areas for pinched, out-of-place or frayedwiring. Do not change spacing between adjacent components, or betweencomponents and printed circuit board. Check the AC

8、power cord for dam-age.4. Be certain to remove loose solder balls and all other loose foreign particles.5. Check components, parts and/or wiring for physical evidence of damage,overheating or deterioration, and replace if necessary. Determine the causeof damage and/or overheating and, if necessary,

9、take corrective action toremove any potential safety hazard.6. Parts Replacement - Many instruments electrical and mechanical parts havespecial safety-related characteristics, some of which are often not evidentfrom visual inspection, and the protection they give cannot necessarily beobtained by rep

10、lacing them with components rated for higher voltage, watt-age, etc. Parts that have special safety characteristics are identified in thisservice data by a ( ) on schematics and in the parts list. Use of a substitutereplacement that does not have the same safety characteristics as the recom-mended r

11、eplacement part in the service data parts list may create shock, fireand/or other hazards. Always consult the appropriate current service litera-ture for the latest information.7. Some instruments chassis normally have 85VAC (RMS) between chassisand earth ground, regardless of the AC plug polarity.

12、Some instrumentchassis are electrically connected directly to one conductor of the AC powercord. Some instrument chassis have a secondary ground system in additionto the main chassis ground. This secondary ground system is not isolatedfrom the AC power line. The two ground systems are electrically s

13、eparatedby insulating material that must not be defeated or altered. Thus, whenservicing any unit always use a separate isolation transformer for the chas-sis. Failure to use a separate isolation transformer may expose the servicerto possible shock hazard, and may cause damage to servicing instrumen

14、ts.8. Many electronic products use a polarized AC line cord (one wide pin on theplug). Defeating this safety feature may create a potential hazard to theservicer and the user. Extension cords that do not incorporate the polarizingfeature should never be used.PICTURE TUBE IMPLOSION WARNING - If the i

15、nstrument beingserviced incorperates a picture tube it will employs integral implosion protection.For continued implosion protection, replace the picture tube only with one of the sametype number.Do not remove, install, or otherwise handle the picture tube in any manner with-out first putting on sha

16、tterproof goggles equipped with side shields. People not soequipped must be kept safely away while picture tubes are handled. Keep thepicture tube away from your body. Do not handle the picture tube by its neck.Some “in-line” picture tubes are equipped with a permanently attached deflectionyoke; bec

17、ause of potential hazard, do not try to remove such “permanently at-tached” yokes from the picture tube.X-RADIATION AND HIGH VOLTAGE LIMITS - Because the picturetube is the primary source of X-radiation in solid-state TV receivers, it is speciallyconstructed to prohibit X-radiation emissions. For co

18、ntinued X-radiation protec-tion, a replacement picture tube must be the same type as the original. The pictureshields, mounting hardware and lenses (projection TV) may also perform an X-radiation protection function, and they must be correctly in place. Anode connec-tors contain an X-radiation shiel

19、d - use only the manufacturers specified anodeconnectors. High voltage must be measured each time servicing that involvespower supply, horizontal deflection or high voltage circuits is performed. Correctoperation of the X-radiation circuits must also be confirmed each time these cir-cuits are servic

20、ed (X-radiation circuits may also be called “horizontal disable” or“hold-down” circuits). Read and apply high voltage limits and, if the chassis is soequipped, the X-radiation protection circuit specifications. These limits and speci-fications are given on instrument labels and are included in this

21、service data. Highvoltage is maintained within specified limits by close-tolerance safety-related com-ponents (and adjustments) in the high voltage circuit. If high voltage exceedsspecified limits, check each safety related component specified on the schematicand take corrective action.ANTENNA LEAKA

22、GE RESISTANCE CHECK - With the instrument ACplug removed from the AC source, connect an electrical jumper across the two ACplug prongs. Place the instrument AC switch (if applicable) in the “on” position.Connect one lead of an ohmmeter to the AC plug prongs and touch the otherohmmeter lead, in turn,

23、 to each (exposed) antenna input terminal screw and/orcoaxial connector. If the measured resistance is less than 1.0 Megohm, or greaterthan 5.2 Megohm, an abnormality exists which must be corrected before the in-strument is returned to the customer. Repeat this test with the AC switch in the“off” po

24、sition.LEAKAGE CURRENT HOT CHECK FOR 2-WIRE OR 3-WIREGROUNDED CORD SETS - With the instrument completely reassembled,plug the AC line cord into the mains AC outlet at normal line voltage via a non-polarized adapter. DO NOT GROUND THE 3RD PRONG OF THE ADAPTERAND DO NOT USE AN ISOLATION TRANSFORMER. U

25、se a leakage currenttester or metering system that complies with American National Standards Insti-tute (ANSI) C101.1 Leakage Current for Appliances and with Underwriters Labo-ratories (UL) 1492 (Section 67). With the instrument AC switch first in the “on”position and then in the “off” position, mea

26、sure from a known earth ground (metalwater pipe, conduit, etc.) to all exposed metal parts of the instrument (antennas,handle bracket, metal cabinet, screwheads, metallic overlays, control shafts, etc.).Any current measured must not exceed 0.5 milliampere. Reverse the adapter plugin the outlet and r

27、epeat the test. ANY MEASUREMENTS NOT WITHIN THELIMITS SPECIFIED HEREIN INDICATE A POTENTIAL SHOCK HAZ-ARD THAT MUST BE ELIMINATED BEFORE RETURNING THE IN-STRUMENT TO THE CUSTOMER OR BEFORE CONNECTING THEANTENNA OR ACCESSORIES. If a leakage current tester is not available,connect a 1.5 Kohm, 10 Watt

28、resistor, in parallel with a 0.15 F, 150V capacitor,between earth ground and each exposed metal part of the instrument (as shownabove). Use an AC voltmeter with at least 5000 ohm/volt sensitivity to measurethe potential across the resistor. The potential measured for any exposed metalsurface must no

29、t exceed 0.75 volts.Safety page 01/02? ?!#?$?%?&(?$#?)?*!? ?*!?$?#?+?,? ?#?-?!?.RadioFans.CN 收音机爱 好者资料库RS2625RS2625Page 3-2Page 3-1ALIGNMENT PROCEDURESOperating ConditionsUnless otherwise noted, the following conditions must beobserved when aligning the RS2625:1. Chassis must be operated from a 120V

30、AC isolationtransformer, with line voltage set to 120VAC (2.0V).2. Set controls (Volume, Tone, Balance, etc.) to mid-range.3. Procedures must be performed in the sequence given.4. A 10X probe must be used for oscilloscope and fre-quency measurements.5. Minimum warm-up time is 10 minutesRequired Test

31、 EquipmentIsolation Transformer:Digital Voltmeter: Range .1V DC to 1000V DC, Accuracy: .5%/True “RMS” Voltmeter: Range: 01 to 1000 Volts .5% Ac-curacyDC Voltage Supply: Range: 0 to 50V, 2AWell FilteredTemperature Controlled Soldering Station: Grounded TipTypeTip Temperature 500F to 800F AdjustableFr

32、equency Counter: Range: 50Hz to 100 MHz Sensitivity:25mV to 5V. Equipped with Lo-Cap Probe (10:1 Attenua-tion)AC Variac: Continuously Variable. Isolation Type PreferredRF Signal Generator:Dual Trace, Delayed Sweep Oscilloscope: 25 MHz withChannel invert capability. Sensitivity 5mV/cm MaximumSweep Ra

33、te: .1us/cm.Hot Air Desoldering Station:ALIGNMENT PROCEDURESFM IF ALIGNMENTTest Points:Input:TP 001TP001G (RFGND)Output:TP 003TP009G (AGND)1.Connect an FM IF signal to TP004 (Pin 39 of UIC001)and TP004G (IFGND) through a 1nF capacitor in serieswith a 10K resistor.2.Connect an Oscilloscope to the IF

34、signal output at TP009(Pin 10 of IC001) and TP009G (AGND) through a 4.7uF capacitor.3.Align TF006 to obtain an undistorted display on the os-cilloscope without any interference.4.Ensure that the curve is not saturated.5.Tune the set to 98.10 MHz6.Apply an un-modulated mono RF signal at 98.10 MHzwith

35、 RF input level of 1 mV to TP001 and TP001G(RFGND).7.Connect a frequency counter to TP003 (Pin 33 of IC001)thru a capacitor 0.1 uF8.Check TP003 and align TF006 to get 10.7 MHz 10KHz. TUNER SECTION 4.7uF IN OUT 10.60 10.70 10.80 TP-004 TP-004G TP-009 TP-009G 1 nF 10K Figure 1.Figure 2.FM OSCILLATOR A

36、ND RF ALIGNMENTTest Points:Input:TP001TP001G (RFGND)Output:TP007/TP008TP009G (AGND)Tuning(VT):TP002TP009G (AGND)1.Set frequency to 87.5 MHz.Adjust FM Osc coil (L004) to obtain 1.0 to 1.05V atTP002 (VT) and TP009G (AGND).2.Set frequency to 108.10 MHz.Adjust Vari-Cap (CV002) to obtain 7.0V 0.5 at TP00

37、2and TP009G (AGND).3.Repeat steps 1 and 2 above until the band coverages fallswithin the specified VT voltage.4.Feed an FM RF signal to a matching balanced pad (50ohm - 75 ohm) at TP 001 and TP001G (RFGND).5.Use the circuit in figure 3 to detect the signal from TP007/008 and TP009G (AGND).6.Set freq

38、uency to 90.10 MHz and adjust L003 until maxi-mum amplitude is reached.7.Set frequency to 106.10 MHz to see whether approxi-mate amplitude is the same as in step 6.8.Set frequency to 98.10 MHz and check for approximateamplitude. TUNER OSCILLOSCOPE DC Voltmeter IN OUT TP-001 TP-001G TP-007/008 TP-009

39、G 4.7uF FIGURE 3 TP-002 1.00V TP-001G FM STEREO ALIGNMENTTest Points:Input:TP001TP001G (RFGND)Output:TP005TP010G (DGND) 98.10MHzTP-001TP-001GTP-005TP-006152.000kHzFrequency CounterTUNER SECTIONFIGURE 4FM Signal GeneratorTP-010RV-0011.Apply an un-modulated mono RF signal at 98.10 MHzwith RF input lev

40、el of 1 mV to TP001 and TP001G(RFGND).2.Search to 98.10 MHz (Remove the VT probe duringsearch)3.Connect a 10K from TP005 to TP010G (DGND).4.Connect a frequency counter to TP005 (Pin 24 of IC001)and TP010G (DGND), short TP010 (Pin 27 of IC001)to TP010G (DGND, Pin 26 of IC001).5.Check TP005 and align

41、RV001 to get 152 KHz 1 KHz.6.Apply a stereo 98.10 MHz signal to the set. Ensure theStereo indicator lights up. Signal strength must be lessthan 32dB.7.Remove the 10K resistor from TP005 and TP010G in-stalled in step 3.RadioFans.CN 收音机爱 好者资料库RS2625RS2625Page 3-4Page 3-3ALIGNMENT PROCEDURESALIGNMENT P

42、ROCEDURESAM OSCILLATOR ALIGNMENT (MW)Test Points:Input:AM Antenna LoopTP001G (RFGND)Output:TP007/TP008TP009G (AGND)Tuning(VT):TP002TP009G (AGND)1.Set frequency to 530 KHz .2Adjust MW Osc coil (TF003) to obtain 1.4 0.05V atTP 002 and TP009G.3.Set frequency to 1710 KHz. Ensure the MW-VT at TP002and TP

43、009G is 8.0 1 VAM OSCILLATOR ALIGNMENT (LW)Test Points:Input:AM Antenna LoopTP001G (RFGND)Output:TP007/TP008TP009G (AGND)Tuning(VT):TP002TP009G (AGND)1.Set frequency to 150 KHz.2.Adjust MW Osc coil (TF003) to obtain 1.51 0.01V atTP 002 and TP009G.3.Set frequency to 283 KHz. Ensure the MW-VT at TP002

44、and TP009G is 4.6 1VAM IF AND AFC ALIGNMENTTest Points:Input:AM Antenna LoopTP001G (RFGND)Output:TP011TP004G (IFGND)1.Connect an AM IF signal to AM OSC, TP012 (pin 6 ofIC001) and TP001G (RPGND).2.Detect the output signal at TP009 (pin 10 of IC001) andTP009G (AGND) as shown below in figure 5.3.Adjust

45、 TF005 & TF008 until maximum amplitude isreached4.Send an un-modulated RF signal at 1000 KHz with RFlevel of 100mV.5.Tune the receiver to search up/down (remove the VTprobe during search). It will stop after acquiring thissignal.6.Connect a frequency counter to TP011 (pin 36 of IC001)and TP004G (IFG

46、ND) thru a capacitor 1uF7.Check TP011 (pin 36 of IC001) and align TF007 to get450 KHz 1 KHz. TUNER 4.7uF IN OUT 445 450 455 TP012 FIGURE 5 1uF TP004GTP009TP009GAM RF ALIGNMENT (MW)Test Points:Input:AM Antenna LoopTP001G (RFGND)Output:TP007/TP008TP009G (AGND)1.Apply a modulated (400 Hz) MW RF signal

47、at 630 KHzwith low RF level of 300 uV.2.Detect the signal from TP 007/008 and TP009G(AGND). Adjust TF001 for the maximum amplitude.AM RF ALIGNMENT (LW)Test Points:Input:AM Antenna LoopTP001G (RFGND)Output:TP007/TP008TP009G (AGND)1.Apply a modulated (400 Hz) MW RF signal at 170 KHzwith low RF level o

48、f 300 uV.2.Detect the signal from TP 007/008 and TP009G (AGND.Adjust TF001 for the maximum amplitude.MAIN BOARD TAPE ALIGNMENTAlignment for the cassette portion should be done at thesemi - encased stage.AZIMUTH ALIGNMENT1.In tape transport 1, playback a test tape (TCC-153) freq.10 KHz.2.Connect the

49、speaker outputs to a dual trace oscilloscope.3.Adjust the azimuth screw at the tape head to obtain themaximum amplitude on both channels. (Both channelsmust be in phase).TAPE SPEED ADJUSTMENT1.Rewind the test tape (MTT-111 DN 3khz) until both thespools on the left and right hubs are equal.2.Connect

50、the output to the WOW -FLUTTER METER.3.Adjust the trimmer in the motor to obtain a playbackfreq. of 3KHz 60 Hz.RECORD BIAS OSCILLATOR ALIGNMENT1.Place a tape inside the set. Ensure that the tape is notrecord protected.2.Select Tape mode and engage the Record button.3.Monitor TP60 and TP60G (ground).