(K-MOD101) TROUBLESHOOTING SUPPLEMENT

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(K-MO0) TROULSHOOTING SUPPLMNT With LG s installed, use this supplement to help: Measure voltage test points to identify major discrepancies and locate problem areas.

1 (K-MO0) TROULSHOOTING SUPPLMNT With LG s installed, use this supplement to help: Measure voltage test points to identify major discrepancies and locate problem areas. (Keep in mind that the voltage measurements will vary slightly from amp to amp. The voltages you measure should be in the same ballpark, but do not expect to get the exact same value.) opyright 00 by modkitsdiy.com

2 SFTY Tube amps operate at high voltages that have the potential to injure and kill. Please remember the following when troubleshooting this project. ly work on the amp when you are wide awake and sober. o not plug the amp in until you have gone through all of the instructions, checking and re-checking each step. o not turn the amp on until you have connected it to a speaker cabinet or dummy load. e aware that tubes become very hot when the amp is on and can take up to 0 minutes to cool down after power is turned off. lways follow the one hand rule when working with an amp that is connected to power or may have voltage present. (ny amp that has been plugged in at one time, may have high voltage present). The one hand rule (pictured below): is a safety precaution for working on an amp that is plugged in or could potentially have high voltages present. Using alligator clips with your MM, clip the ground side to the chassis and use the other side to probe at various test points with one hand. This prevents a fatal shock which can result from current passing through the heart. (Many people even put their other hand in their pocket or behind their back). NGR HIGH VOLTG MY PRSNT FILTR PITORS O NOT TOUH! Test point sections included in this supplement include: Page FILTR STI (TOP) FILTR STI (INSI) POWR TU IS SUPPLY PRMP TU LTROS POWR TU LTROS POWR SWITH FUNTILITY / TINUITY HK

3 Test Point Voltage Voltage HV V V V 0 V V 0 V V 0 V V 0 V V cathode. mv 0 V POWR: STNY: (UP POSITI) SS: 0 TRL: 0 VOLUM: 0 T0 T 0µF 0V 0K HV 0µF 0V 0K FILTR STI (TOP) See ssembly rawing Side View T W K µf 00V T V cathode µf 00V K.K µf 00V T µf 00V

4 FILTR STI (INSI) Test Point Voltage Voltage HV V V V 0 V V 0 V V 0 V V 0 V V cathode. mv 0 V POWR: STNY: (UP POSITI) SS: 0 TRL: 0 VOLUM: 0 HV T 0 0 0W 0Ω See ssembly rawing W Ω See ssembly rawing V * T 00K 00K K 00K V cathode See ssembly rawing See ssembly rawing

5 POWR TU IS SUPPLY See ssembly rawing.k T 0K 0K.K - V 0 V R(IS) -. V 0 V - V 0 V N00 N00 µf 0V.K T.K -0 mv. V V V. V. V POWR: STNY: (UP POSITI) SS: 0 TRL: 0 VOLUM: 0

6 PRMP TU LTROS See ssembly rawing V V POWR: STNY: (UP POSITI) SS: 0 TRL: 0 VOLUM: 0 Test Point V (pin ) V (pin ) V (pin ) V (pin ) V (pin ) Name V plate V grid V cathode V plate V grid Voltage V 0 V. V 0 V 0 V V (pin ) V cathode. V Test Point V (pin ) V (pin ) V (pin ) V (pin ) V (pin ) Name V plate V grid V cathode V plate V grid Voltage V V 0 V V V V (pin ) V cathode 0 V POWR TU LTROS See ssembly rawing V * V * POWR: STNY: (UP POSITI) SS: 0 TRL: 0 VOLUM: 0 Test Point V (pin ) V (pin ) V (pin ) V (pin ) Name V plate V screen grid V control grid V cathode Voltage V 0 V - V mv Test Point V (pin ) V (pin ) V (pin ) V (pin ) Name V plate V screen grid V control grid V cathode Voltage V V - V mv

7 POWR SWITH FUNTILITY / TINUITY HK Measure continuity with the amplifier unplugged. 0W 0Ω UNPLUG W Ω See ssembly rawing Switch Position Measure etween and ontinuity? Yes and and No Yes and No PT Power Switch ( POSITI) Switch Position Measure etween and and and ontinuity? No Yes No and Yes PT Power Switch ( POSITI)

8 0K INPUT M K 00K W V K 00p.0µ.0µ µ 0K TRL 0K SS.K 0 M VOL 00K W V.00µ K.µ M M 0 V V.K K W 00K W N00 µ.µ.µ 0K 0K R(IS) KL.K.K.K V IS V 0 0 LU LU/YL R RN/YL RN TR YL /YL LK/YL LK IMPN SLTOR OUTPUT LU TR R N00 K W.K W 0V 0 HZ LK WHIT POL POWR SLO LO LU/YL RN/YL RN VIO R/YL R N00 POL STNY 0K W 0K W 0µ 0µ HV 0 0W POL POWR W µ K W µ µ µ YL LK YL/LK LK/R WHT/LK YL V V V V V = X / TR = X /YL V = T / V = LG TR = 0P WHT V = LG opyright 00 by modkitsdiy.com K-MO0 Schematic

9 0K INPUT M K 00K W 0 V V. V V K 00p.0µ.0µ µ 0K TRL 0K SS.K 0 0 V M VOL 0 V 00K W. V V.00µ K.µ M V M 0 V V V 0 V V 0. V. V K W 00K W.µ 0K V.K - 0 V V mv 0 V IS..µ 0K - mv V V V 0.K - V. V - V 0 V V V N00 0 V R(IS) - V.K KL 0 V V µ.k. 0 V LU LU/YL R RN/YL RN TR YL /YL LK/YL LK IMPN SLTOR OUTPUT 0V 0 HZ LK WHIT POL POWR SLO LO LU LU/YL RN/YL RN TR R VIO R/YL R N00 N00 POL STNY 0K W 0K W 0µ 0µ V V HV 0 0W POL POWR W V 0 V µ K W µ V 0 V K W V 0 V µ.k W µ V 0 V YL LK YL/LK LK/R WHT/LK YL V V V V V = X / TR = X /YL V = T / V = LG TR = 0P WHT V = LG Indicated voltages were measured with bias pot set to coldest setting opyright 00 by modkitsdiy.com K-MO0 Schematic ()

Problem Set 4 Solutions

University of California, Berkeley Spring 212 EE 42/1 Prof. A. Niknejad Problem Set 4 Solutions Please note that these are merely suggested solutions. Many of these problems can be approached in different