Post by Mark on Jun 12, 2022 18:48:25 GMT
Hi Ron. Thanks in advance : ) Mark
After replacing all Lytic and Tantalum Capacitors in a TSA10 amplifier, I want to understand what calibration adjustments need to be made. The TSA10 has 5 potentiometers: R5112 Right Gain pot; R5144 Left Gain pot; R5143 Speaker Overload Timing pot; R5121 Left Channel Bias Adjustment pot; R5121 Left Channel Bias Adjustment pot.
The Service Manual TSA10 Amp page 3 adjustments for the speaker overload and both gain pots requires a “signal generator” which I don’t own so therefore I assume I never attempt to adjust these 3 pots.
The Service Manual TSA10 Amp page 3 indicates the 2 bias adjustment pots located on the right and left circuit boards “should not be touched unless board components are changed. For proper adjustment of bias see Note Number 9 on the schematic. “
Note 9 Bias Adjustment states: “Allow Amplifier to stabilize under no drive conditions at 120V line. Adjust right and left channel bias pots to give a 40 MV drop across R5129 & R5152 respectively.”
Therefore the TSA10 needs to be removed from the USC Bandshell Jukebox to measure and adjust. I understand I need to hook up woofers as a load to the amp but does it matter which wattage terminals I attach wires to? When it says “under no drive conditions”. That means don’t plug anything into the mech RCA plugs - please correct me if I am wrong. Also don’t plug into a dim bulb tester which could affect 120V line.
On the schematic, I located R5129 and R5152 are two of the four big white .75 WW 5W resistors on the chassis sitting in a row. The problem is, from the schematic, I cannot determine which of the four resistors sitting side by side are R5129 and R5152.
Looking at the 4 resistors in relation to the boards which are 5129 and 5152? I need to know which to measure as I turn either the right or left bias pot?
Then “how to measure voltage drop and adjust the pots?” When I set my multimeter on DC mV with positive and negative probes on each side of a resistor, the four resistors read: 11.4 mV; 5.6 mV; 10.3 mV; and 3.9 mV. My understanding is this is the voltage drop therefore I would turn a pot until the reading is 40 mV?
When attaching DMM to a resistor, does it matter + and - leads on the resistor for voltage drop? If yes which is the positive side?
I understand they wrote the service manual for trained seeburg technicians and my knowledge level is way below this. My hope is you will mentor me here a bit so I can learn and perhaps even write a sticky on this.
After replacing all Lytic and Tantalum Capacitors in a TSA10 amplifier, I want to understand what calibration adjustments need to be made. The TSA10 has 5 potentiometers: R5112 Right Gain pot; R5144 Left Gain pot; R5143 Speaker Overload Timing pot; R5121 Left Channel Bias Adjustment pot; R5121 Left Channel Bias Adjustment pot.
The Service Manual TSA10 Amp page 3 adjustments for the speaker overload and both gain pots requires a “signal generator” which I don’t own so therefore I assume I never attempt to adjust these 3 pots.
The Service Manual TSA10 Amp page 3 indicates the 2 bias adjustment pots located on the right and left circuit boards “should not be touched unless board components are changed. For proper adjustment of bias see Note Number 9 on the schematic. “
Note 9 Bias Adjustment states: “Allow Amplifier to stabilize under no drive conditions at 120V line. Adjust right and left channel bias pots to give a 40 MV drop across R5129 & R5152 respectively.”
Therefore the TSA10 needs to be removed from the USC Bandshell Jukebox to measure and adjust. I understand I need to hook up woofers as a load to the amp but does it matter which wattage terminals I attach wires to? When it says “under no drive conditions”. That means don’t plug anything into the mech RCA plugs - please correct me if I am wrong. Also don’t plug into a dim bulb tester which could affect 120V line.
On the schematic, I located R5129 and R5152 are two of the four big white .75 WW 5W resistors on the chassis sitting in a row. The problem is, from the schematic, I cannot determine which of the four resistors sitting side by side are R5129 and R5152.
Looking at the 4 resistors in relation to the boards which are 5129 and 5152? I need to know which to measure as I turn either the right or left bias pot?
Then “how to measure voltage drop and adjust the pots?” When I set my multimeter on DC mV with positive and negative probes on each side of a resistor, the four resistors read: 11.4 mV; 5.6 mV; 10.3 mV; and 3.9 mV. My understanding is this is the voltage drop therefore I would turn a pot until the reading is 40 mV?
When attaching DMM to a resistor, does it matter + and - leads on the resistor for voltage drop? If yes which is the positive side?
I understand they wrote the service manual for trained seeburg technicians and my knowledge level is way below this. My hope is you will mentor me here a bit so I can learn and perhaps even write a sticky on this.
