Citation II Built In Amplifiers
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Product Specifications:
- Model: Citation II – 2024
- Assembly: Rev 12A
- Power Supply: Rev 16A
- Power Requirements: Main fuse 5A
- Output Tubes: 4 KT88 tubes
- Input Voltage: 460 VDC
Product Usage Instructions:
Power Supply Setup:
- Mount the bridge diodes with the NOTCH end in square pin
1. - Ensure caps C2, C4 (1000uF 500V), C1 (470uF 35V), and C8 (220uF
200V) are mounted correctly. - Secure the transformer with bolts.
Main PCB Assembly:
- Insert 8 pin sockets with the notch pin toward the 9 pin
sockets, ensuring square pin is pin 1. - R46 & R44 (5K Pots) mount from the backside of the
board. - Follow the specified board stuffing order for component
mounting.
Main PCB Board Setup and Test:
- Connect all wire connections to the main PCB including
transformers, audio inputs, grounds, and power supply wires. - Adjust Bias pots R48, R49, R54, R55 fully counterclockwise
viewed from the front. - Check filament voltages and bias voltages as per
specifications.
Audio Signal Application:
Once all voltages are adjusted, an audio signal can be applied
to the unit for operation.
Frequently Asked Questions (FAQ):
Q: What should I do if the bias voltage drops after connecting
the main PCB power?
A: The bias voltage dropping to 69 VDC is normal once the main
PCB power is connected. Ensure connections are secure and follow
adjustment procedures.
Q: Is it necessary to use a shorting stick to drain the main
capacitors?
A: If no tubes are mounted on the PCB, a shorting stick should
be used to drain the main capacitors between Discharge pin and GND
for safety.
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Citation II – 2024 Assembly, Setup & Test Rev 12A
Power Supply Rev 16A :
1. The three bridge diodes mount with the NOTCH end ,in square pin 1. 2, Make sure the caps C2,C4, 1000uF 500V are mounted correctly. 3. Make sure the cap C1, 470uF 35V is mounted correctly. 4. Make sure the cap C8, 220uF 200V is mounted correctly. 5. I mounted to transformer with bolts.
Citation II – 2024 Assembly Rev 12A
July 8, 2025
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Main PCB Rev 12A
1. The 8 pin sockets notch pin goes toward the 9 pin sockets. The square pin is pin 1. 2. The square pin of the 9 pin sockets is pin 1. 3. R46 & R44, 5K Pots mount from the BACKSIDE of the board. 4. Mounting holes might need to be drilled out depending on hardward used to secure the
board. 5. Board stuffing order:
Do the 1/2 watt resistors first. Do the small caps next. Do the large watt resistors next Do the terminal block next
Citation II – 2024 Assembly Rev 12A
July 8, 2025
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Do the tbe sockets next. Do the 5k pots last from the bottom. Do the large caps next. Verify cap orientation
Power supply board test
1. Verify bias and main power supplies. Bias -102VDC +460 VDC. +12VDC
Note: Once the Main pcb power is connected, the bias voltage will drop to 69 VDC.
2. Main fuse 5A
NOTE:
460 VDC is present thoughout this pc board. Caution is advised.
You will need a shorting stick to drain the main capcitors if NO tubes are mounted on the pcb. Short the pins are between the Dischage pin and GND.
MAIN PCB Board setup and test.
1. Hook up all of the wire connections to the main pcb.
A. Both output transformers. B. Main transformer C. Both audio inputs and grounds. D. Both 8 ohm (+ Speaker termnal) to the 8 ohm on pcb. E. Bias meter wires if used. F. Three power supply wires, Ground, Bias and 460 VDC
2. Adjust the four Bias pots, R48, R49, R54, R55 – Fully Counterclockwise, Viewed the
FRONT.
3. With NO tubes mounted in the boards verify the follwing voltages
A. Check the 6.3VAC filament voltages on all the tubes. 1. Pins 4/5 to Pin 6 on all the 9 pin sockets. 2. Pins 2 to 7 on all the 8 pin sockets.
Citation II – 2024 Assembly Rev 12A
July 8, 2025
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B. Pins 3 & 4 of the 8 pin sockets should be 460 VDC. C. Pin 5 of all the 8 pin sockest should read the bias voltage -66 VDC.
If you adjust one of the bias pots, the voltage should change from -66 vdc to -40vdc .
You will need a shorting stick to drain the manin capcitors if no tubes are mounted on the pcb. Short the pins are between the Dischage pin and GND.
The 4 KT88 output tubes MUST be installes BEFORE adjusting the cathode bias voltages.
4. Make sure that the audio input connections ARE removed..
A. Using a bias meter switch,set the following positions too: This measurement is the voltage across the 4 cathode resistors. 1. Switch position 1 – OFF 2. Switch position 2 – V10 Adjust R49 for .6V. 3. Switch position 3 – V9 Adjust R48 for .6V 4. Swich position 4 – V5 Adjust R54 for .6V 5. Switch position 5 – V4 Adjust R53 for .6V 6. Run unit for an 1/2 hour, balance all settings as needed. 6. Turn switch OFF when done..
5. Once all the voltages have been adjusted an audio signal can be applied to unit.
Citation II – 2024 Assembly Rev 12A
July 8, 2025
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Citation II – 2024 Assembly Rev 12A
July 8, 2025
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Documents / Resources
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diyaudio Citation II Built In Amplifiers [pdf] Instructions 12A, 16A, Citation II Built In Amplifiers, Citation II, Built In Amplifiers, Amplifiers |