Repair parts
R16 / R17 560R 5% 2.5w / W.W.Welwyn Type X2B
WELWYN 軍規精密電阻，低雜音、低感抗，兩端純銅封裝，英國製造. 適用於惡劣的環境 , 防滲透無鉛釉鍍膜玻璃 , 理想的超載保護電路 , 高穩定性和可靠性.
C7 47uF/63v / 5mm PCM
C9 / C11 220uF/63v 電源旁路濾波用
C12 / C13 6800uF/63v BHC ALT20A 整流濾波
R38 / R39 2.2K 5% 0.5w Carbon Film
C8 47p/350v 1% Silver mica
C10 47nF 5% 250v 輸出 電容 (.047uF) 濾高頻? 忘了
T15 NPN Med Power Transistor ZTX652-K 120V/2A/1W
T16 PNP Med Power Transistor ZTX752-K 100V/2A/1W
C2 input capacitor 100nF/0.1uF 100v
IC1 OP-Amp TLC271CP
* In case of Quad 606, 707 or 909 changing the opamp for a better one is useless as it is only to have 0V DC on the output, nothing more, it is not in the path of the signal as in the Quad 405.
* Better Opamp in QUAD 606/909 Power amp link
Swapping this opamp for a OPA134 opens up the sound, tightens the bass BUT on shut-down of the amp, huge noises appear via the speakers which means either offset is high or some problem that I'm not sure of exists. Two number 0.1uF/100V Vishay 1837MKPs were attached directly on the PS pins for Rail-to-Gnd bypass.
The TLC271 is very noisy. The OPA134 is a much better option, even for a servo, and I suspect it could be a clear audible improvement.
The OPA134 offset trim circuit is normally used with a trimpot between pins 1 and 8, with the wiper connected fo V+. This is just a guess, but using this opamp on a board with pins 6 (output) and 8 tied together, I would think at a minimum you would want to pull pin 8 so it is NC (bend it up or whatever).
Yes, pin 8 needs to be disconnected from pin 6 on the PCB. By other words, cut the trace that joins pins 6 to 8. 使用 OPA134 要切開 pin6 pin8 連結.
* The 120k R5 could be replaced by a series pair of 56k & 63k. The junction of this pair has a film cap connected to audio ground. A value of about 1uF might be about right. This mod would make the influence of the opamp even more inaudible.
What does r6 (22k) do? Is it an input bias adjustment?
Quad 606 Power Amplifier Specification:
Power Output: 140 watts per channel (8 ohms)
Distortion: < 0.01%
Input Sensitivity: 500mV
Input Impedence: 20Kohm
Crosstalk: -100db (100hz), -85db (1 khz) and -65db (10khz)
Hum and Noise: 105db
Voltage Rating : 220-200V AC (110-120V via simple power board modification)
Dimensions (WxHxD): 321 x 140 x240 (mm)
Weight: 12kg
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