Service Manual Bel Toploading Balances
Contents
1. 7 to TP 16 Signal must be 5 VDC if not suspect U15 thermometer is faulty TP 7 to TP 15 Signal should be 2 5 to VDC if not suspect U16 thermometer is faulty TP 7 to TP 11 This is a reference voltage it should be 7 VDC If not suspect U18 Under Foam Insulator is faulty Removal of Magnet Remove top 3 screws from cover and remove Remove the two wires from the base of the magnet note they must be reattached in the same order Remove the three positioning grub screws and the two inner ones same threaded hole and withdraw magnet from unit Inspect and clean then Bel Toploading Service Manual doc Page 35 of 36 replace using 4 spacers to position the magnet in the exact middle of the unit only if you moved the level arm If there is drift in the balance and it is always in one direction then suspect that there is physical damage to the sy stem Start with magnet then gold connecting wires finally the flexure system Display No Power to Display Check power to jack plug 24 VAC If no power or not correct voltage then replace the complete unit If the above are OK connect meter to TP7 and TP2 DC voltage should read 5 volts 2 if not OK see section A 1 If voltage is OK then check TP7 to TP1 should read 3 3 volts 2 If not OK see section A 2 If OK then TP7 to TP5 should be 32 34 VDC for display See section A 1 If this is OK change the display Note Be sure to order the same build code as on2. the back of the display unit If the display has power but does not illuminate any segments when pushing the on off switch fit new keyboard K 8 Section A Change power supply board K 14 See ALINT Rev 4 B A 2 Check TP 7 ground to regulator U8 LM 3940 Should read 5 0 VDC input and 3 3 VDC output If no output change regultor or main board If none of the above cure the problem change the main board K 22 Bil 2407 A rev 1 It is possible for the optical group to cause interference and instability Replace complete group Display Error Codes Display shows 55 Underweight Condition Display shows Overweight Condition Following power up and pressing On Off display shows _ means balance is not stable Check for interference vibration air currents If OK remove top plate from magnet and clean Check that the lever is centered in the magnet and will return to the center when moved power must be connected Finally check flexures and vertical and horizontal springs for distortion or damage Poor Return To Zero 1 Check all flexures and vertical springs for damage or breakage and replace where neccessary 2 Remove magnet cover and clean Check lever for physical interference Bel Toploading Service Manual doc Page 36 of 36
3. CTION RING FIXING Bel Toploading Service Manual doc Page 22 of 36 WEGHNG wa wa SUPPORT FOR SQUARE PAN 0207008 WEIGHING PAN 110mm COMPLETE 01 00 0096 PLEXIGLASS WIND SHIELD 160 70 02 18 0420 COLUMNS CAP DP 562 SCREW REGULATOR CAP DP 500 COVER WIND SHIELD 02 09 0283 Bel Toploading Service Manual doc Page 23 of 36 Page 24 of 36 Bel Toploading Service Manual doc Page 25 of 36 Bel Toploading Service Manual doc Page 26 of 36 Bel Toploading Service Manual doc Bel Engineering Service Notes Balances Classic Centigram Binary Decigram Milligram Analytical Bel balances are calibrated and linearized in California prior to shipping using Class 1 weights traceable to NIST or Class M OIML weights traceable to OIML Europe Upon receipt they should only need calibtration to take account of local acceleration due to G factors The balances should always be placed on a solid stable and vibration free surface and free from drafts and air currents Do not use balances in bright sunlight as this may set up uneven temperature changes in the unit When the unit is positioned correctly power up the unit and for analytical or milligram balances do not press the On Off button for at least 25 minutes Following the warm up period press the On Off button Decigram Classic and Centigram balances can be used imme
4. UT 0202092 _ os LEVEL 0 1 02 12 0054 LEVEL TYPE 0 01 02 12 0055 E2 SUPPORT FOR COIL 02 04 0057 PLATE FOR COIL CLAMPING 02 02 0119 WASHER FOR SCREW FLAG 02 90 0265 Bel Toploading Service Manual doc Page 14 of 36 7 7 E 020807 Cem wasn ronson r option SY scmwroncomentmon eusironcomenennon es 1 Kan WEIGHING CELL ENBLOCK 0 1 0 01 01 05 0051 WEIGHING CELL ENBLOCK TYPE 0 1 0 01 02 05 0052 kkkkkkkk kkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkk kkkkkkkkkkkkkkkkkkkk Bel Toploading Service Manual doc Page 15 of 36 Page 16 of 36 Bel Toploading Service Manual doc A gt w 2 x ROR CM 0 19 0 019 Page 17 of 36 Bel Toploading Service Manual doc Page 18 of 36 Bel Toploading Service Manual doc Page 19 of 36 Bel Toploading Service Manual doc l 2 POSITION OF SENSOR Bel Toploading Service Manual doc Page 20 of 36 EXTERNAL PARTS FOR MARK BALANCES SHEET NAME L ANALYTICAL BALANCE M BALANCE TYPE 0 19 0 019 BALANCE 0 0010 Bel Toploading Service Manual doc Page 21 of 36 EXTERNAL PARTS L 1 WIND SHIELD COMPLETE L 6 WEIGHING PAN 80mm COMPLETE 01 00 0095 L 7 CAP FOR PROTE
5. al shown is below minus 3 3 volts See FIG 2 b Apply full load to balance Test between TP7 and TP6 It is important that the positive signal is 0 3 volts or more FIG shows correct reading Bel Toploading Service Manual doc Page 31 of 36 FIG 4 shows incorrect reading If either signal is not correct change the resistance at 70 No load no negative signal increase resistance Full load no positive signal decrease resistance Bel Toploading Service Manual doc Page 32 of 36 Note on analytical balances the balance should be returned to Intelligent Weighing Technology for fitting of specialized resistances To check the clock speed of DSP Test between 7 and TP 13 you should be able to clearly see equal distances between signal values and 3 3 volts positive between signal values If no signal Crystal Y1 is malfunctioning 7 3728 FIG 5 shows correct reading Test TP 7 to TP 12 Should show wide band on screen FIG 6 T OSCILLOSCOPE ago A thin band shows a malfunction FIG 7 Bel Toploading Service Manual doc Page 33 of 36 If the band is thin change crystal Y2 Test Thermometer Frequency to Analog to Digital converter Test TP 7 to TP 14 FIG 8 shows correct signal Go Bel Toploading Service Manual doc Page 34 of 36 See FIG 9 showing bad or no signal Possible cause is inverted signal wires on connections to magnet TP
6. ation Values for Bel Balances Point Point Point Point Model Resolution g 1 2 3 4 120A 0 0001 0 40 80 120 150A 0 0001 0 50 100 150 205A 0 0001 0 60 120 180 160 0 001 0 50 100 150 220 0 001 0 70 140 210 330 0 001 0 110 220 330 500 0 001 0 150 300 450 2040 0 001 0 01 0 130 260 390 2060 0 001 0 01 0 200 400 600 800 0 01 0 250 500 750 1000 0 01 0 300 600 900 1300 0 01 0 400 800 1200 1700 0 01 0 500 1000 1500 2200 0 01 0 700 1400 2100 3100 0 01 0 1000 2000 3000 3500 0 01 0 1100 2200 3300 4100 0 01 0 1300 2600 3900 2020 0 01 0 1 0 600 1200 1800 8055 0 01 0 1 0 1700 3400 5100 6045 0 01 0 1 0 1500 3000 4500 SSR 10000 0 1 1 0 3300 6600 9900 4500 0 1 0 1500 3000 4500 6500 0 1 0 2000 4000 6000 8000 0 1 0 2500 5000 7500 Bel Toploading Service Manual doc Page 29 of 36 12 16 20 K 30 0 1 0 1 0 1 0 1 4000 5000 6000 1000 0 8000 1000 1200 2000 0 Fault Finding on Bel Engineering Balances Test Points TP 7 is Analog Ground TP 8 is Digital Ground Symptom Display frozen 00000 No output 1200 1500 1800 3000 0 Check that all springs and flexures are intact and not bent or broken If damaged replace and reassemble Jigs are available on request for this purpose Check that Level E1 is centered i e moves up and down and when power is supplied to the balance the Level tries to return to the mid point If not centered check power supply voltage TP3 to TP7 Analog Gr
7. diately but correct use analytical balances should remain turned on for at least 2 hours before calibration or use Milligram balances should ideally be allowed to stabilize for 30 minutes after turning on Corner Loading Corner Load Error Corner load error is adjusted by the use of two adjusters in top of beam In most balances access can be obtained via access holes in the top of the balance cover O Display A screw adjusts XY OOO B screw adjusts P Q If Yis amp Xis turn A clockwise etc Bel Toploading Service Manual doc Page 27 of 36 Calibration Linearity In order to linearize the balance correctly the balance should be allowed to warm up for at least 2 hours for analytical balances and 30 minutes for milligram balances Press and keep pressing CAL then plug in the power supply The scale displays the notional thermometer reading and then 00000 Press CAL three times Display reads LIN Press PRINT Display shows ZERO Press CAL again no weight on pan Displays LIN 1 amp arrow at 2nd ZERO Load 1 3 weight See attached chart for linearity weights Press CAL when stable Displays LIN 2 amp arrow on 3rd ZERO Load 2 3rd weight Press CAL when stable Displays LIN 3 amp arrow on 4th ZERO Load Full Weight Press CAL when stable End by pressing On Off Always recalibrate after LIN EARITY adjustment Bel Toploading Service Manual doc Page 28 of 36 Lineariz
8. intelligent Weighing Technology Service Manual Bel Toploading Balances Binary Milligram Centigram Decigram Classic Analytical Intelligent Weighing Technology serves the scale industry in the USA Canada Central and South America We provide competitive pricing on a complete range of scales from floor scales to laboratory balance load cells for spare parts and scale manufacturing along with other specialist weighing and testing equipment Intelligent Weighing Technology has more than 50 years of experience in the scale business both in the USA and worldwide With contacts in over 50 countries including the USA we provide you with the weighing equipment you need 5528 Everglades Street Suite B Ventura CA 93003 Phone 805 642 3034 Fax 805 642 4034 Mobile 805 444 5657 Toll Free 866 920 3000 BEL ENGINEERING SERVICE MANUAL TOPLOADING BALANCES JANUARY 2004 REV 1 0P Note The power supply for Bel balances is 120 VAC input and 24VAC output All analytical Bel balances have a power supply conditioner fitted to ensure accurate weighing results BALANCE PARTS EXTERNAL VERSION OF BOARD ALINT REV4 B AC ADAPTER SCREW M4x45 FOR BALANCE CLOSING SCREW M4x25 FOR BALANCE CLOSING MINE Kau CON sms ALINT REV4 B scnwwseronsompruG _ Um sonewusaronenaooxFwna 2 1 SCREW 4 14 FOR ENBLOCK SHIELD FIXING Bel Topl
9. oading Service Manual doc Page 3 of 36 ENBLOCK SHIELD 02 01 0368 SPACER FOR ENBLOCK 02 07 0363 BOARD BIL 2407A REV1 6K 0 19 0 014 0 0019 SCREW M3x6 FOR BOARD FIXING SCREW M3x6 FOR SIGNAL RESISTOR FIXING kae CAP FOR HOLE CLOSING BASE 02 90 0398 IK LK Bel Toploading Service Manual doc Page 4 of 36 Bel Toploading Service Manual doc Page 5 of 36 Page 6 of 36 Bel Toploading Service Manual doc Page 7 of 36 Bel Toploading Service Manual doc Page 8 of 36 Bel Toploading Service Manual doc Page 9 of 36 Bel Toploading Service Manual doc WEIGHING CELL ENBLOCK FOR MARK BALANCES 0 19 0 01 0 0019 RESOLUTION rora sune cower e cron arate _ WEIGHING CELL ENBLOCK DETAIL OF OPTICAL GROUP AND SENSOR CABLE REGULATORS FOR CORNER ERROR Bel Toploading Service Manual doc Page 10 of 36 Page 11 of 36 Bel Toploading Service Manual doc PARTICULARS CELL ENBLOCK 0 1g 0 014 0 0019 Lm so as wasienronscrewne 1 FATSPRING eros ora K ara wewnronsomwis I ss Bel Toploading Service Manual doc Page 12 of 36 Bel Toploading Service Manual doc Page 13 of 36 Kas Kau 0290009 OOVENFORMAONETGORO
10. ound Voltage must be 12 VDC or more If not see Section If voltage at TP3 is correct check voltage at TP4 to TP7 This should read 12 5 VDC if not see Section b If this is OK remove J6 connector and check with meter that resistance between coil connections see diagram on page 19 of manual Resistance between right and left should be 38 42 If not correct or no resistance check connection from coil to optical group Board F1 Possible cause is the gold wires connecting monoblock to the level are broken If none of the above it is possible that the optical group itself has failed Remove and replace If this measurement is not correct remove J4 connector and check the output on U 7812 Rectifier This should be 12 volt If not remove and replace the power board If this measurement is not OK remove J4 connector amp check output on U3 7912 this should be 12 5 volt If not correct remove and replace the power board See drawing ALINT Rev 4 Optical To check veracity of signal from optical group a Bel Toploading Service Manual doc Group With the pan fitted but no load on pan at rest test between TP7 ground and TP6 the value should be minus 3 3 volts minimum signal See FIG 1 Page 30 of 36 OSCILLOSCOPE 605 6226 Generally factory set for 1 volt reading this will allow technicians to see a negative reading when the pan is removed rather than an underweight signal If the Sign
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