Part 1: Regulated Power Supply & Protector Circuit Board (F-2663) - Cont'd
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The C601 capacitor filters the raw DC from the diode pair (D601, D602) in the protection circuit and was originally rated at 47µF/50V; the replacement was a 100µF/63V low ESR type. The C604 capacitor, which with R609 determines the turn-on delay of the protection relay, was orignally rated at 470µF/10V (listed as 330µF/10V in the schematic) and was replaced with a 470µF/25V low ESR type. The C605 capacitor which shunts the ZD602 zener, was originally 33µF/50V and was replaced with a 47µF/50V low ESR type. The capacitors C606 and C607, both rated at 4.7µF/50V, are part of the power/protection LED indicator circuit and were replaced with low ESR capacitors of the same rating. The bi-polar capacitors C29 and C30, rated 220µF/6.3V (listed as 100µF/6.3V in the schematic) are part of the abnormal output voltage sensing circuit, for the left and right channels, respectively. The capacitors were replaced with 220µF/25V bi-polar types. The capacitors C606 and C607, rated at 4.7µF/50V, are part of the power/protection LED indicator circuit and were replaced with low ESR capacitors of the same rating. The VD1212 dual diode (D604) was replaced with a pair of 1N4148 diodes in series. The protection relay (RL601) was replaced with an OMRON MY2-02-DC24 which is a "drop-in" replacement for the original Taiko RAB-K2.
Part 2: Tone Control Circuit Board (F-2720)
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Signal Path Capacitors:
With the tone controls "defeated", the signal first passes through the input high-pass filter capacitors (C05, C06) which were 0.33µF polyester film types; these were upgraded to 0.33µF Panasonic polypropylene film types. The stock capacitors in the low-pass filter (C07, C08) were ordinary ceramic capacitors at 22pF (listed as 10pF in the schematic); these were replaced with same value C0G capacitors. Similarly, C23 and C24 were ordinary ceramic capacitors at 22pF (listed as 10pF in the schematic) and these were also replaced with C0G cpacitors of the same value. The output high-pass filter consists of a pair of polarized 100µF/6.3V capacitors in series (forms a "bi-polar" capacitor) for each channel (C27/C29 and C28/C30). Each capacitor pair was replaced with a single 47µF/16V Nichicon ES bi-polar "audio grade" capacitor (jumpers were installed in the vacant capacitor positions). Also, the film by-pass capacitors for the output capacitors, C25 and C26 which were 0.47µF polyester film types, were upgraded to 0.47µF Panasonic polypropylene film types.
With the tone controls "on", the signal additionally passes through the high-pass filter capacitors (C21, C22). These capacitors were originally polarized types rated at 10µF/25V; the replacements were 10µF/35V Nichicon ES bi-polar "audio grade" capacitors. Similarly, the capacitors C45, C46 capacitors in the output high-pass filter of the tone control circuit were originally low-leakage polarized types rated at 10µF/25V; the replacements were 10µF/35V Nichicon ES bi-polar "audio grade" types.
With the subsonic filter engaged, the signal additionally passes through a pair of polarized 4.7µF/50V capacitors in series (forms a "bi-polar" capacitor) for each channel (C33/C35 and C34/C36). Each original capacitor pair was replaced with a single 2.2µF/50V stacked film capacitor. Also, the film by-pass capacitors for subsonic filter, C31 and C32, were removed.
Non-signal Path Capacitors and other Components
The local decoupling capacitors C39, C40, C41 and C42 were originally rated at 47µF/50V; the replacements were low ESR types rated at 220µF/50V. The VD1212 dual diodes (D01, D02) were each replaced with a pair of 1N4148 diodes in series. And the notorious failure-prone 82ohm fusitors (R37-R40) were replaced 82.5ohm/0.25W metal film resistors.
View attachment 3608610
The C601 capacitor filters the raw DC from the diode pair (D601, D602) in the protection circuit and was originally rated at 47µF/50V; the replacement was a 100µF/63V low ESR type. The C604 capacitor, which with R609 determines the turn-on delay of the protection relay, was originally rated at 470µF/10V (listed as 330µF/10V in the schematic) and was replaced with a 470µF/25V low ESR type. The C605 capacitor which shunts the ZD602 zener, was originally 33µF/50V and was replaced with a 47µF/50V low ESR type. The capacitors C606 and C607, both rated at 4.7µF/50V, are part of the power/protection LED indicator circuit and were replaced with low ESR capacitors of the same rating. The bi-polar capacitors C29 and C30, rated 220µF/6.3V (listed as 100µF/6.3V in the schematic) are part of the abnormal output voltage sensing circuit, for the left and right channels, respectively. The capacitors were replaced with 220µF/25V bi-polar types. The capacitors C606 and C607, rated at 4.7µF/50V, are part of the power/protection LED indicator circuit and were replaced with low ESR capacitors of the same rating. The VD1212 dual diode (D604) was replaced with a pair of 1N4148 diodes in series. The protection relay (RL601) was replaced with an OMRON MY2-02-DC24 which is a "drop-in" replacement for the original Taiko RAB-K2.
Part 2: Tone Control Circuit Board (F-2720)
View attachment 3608607
View attachment 3608608
View attachment 3608609
Signal Path Capacitors:
With the tone controls "defeated", the signal first passes through the input high-pass filter capacitors (C05, C06) which were 0.33µF polyester film types; these were upgraded to 0.33µF Panasonic polypropylene film types. The stock capacitors in the low-pass filter (C07, C08) were ordinary ceramic capacitors at 22pF (listed as 10pF in the schematic); these were replaced with same value C0G capacitors. Similarly, C23 and C24 were ordinary ceramic capacitors at 22pF (listed as 10pF in the schematic) and these were also replaced with C0G cpacitors of the same value. The output high-pass filter consists of a pair of polarized 100µF/6.3V capacitors in series (forms a "bi-polar" capacitor) for each channel (C27/C29 and C28/C30). Each capacitor pair was replaced with a single 47µF/16V Nichicon ES bi-polar "audio grade" capacitor (jumpers were installed in the vacant capacitor positions). Also, the film by-pass capacitors for the output capacitors, C25 and C26 which were 0.47µF polyester film types, were upgraded to 0.47µF Panasonic polypropylene film types.
With the tone controls "on", the signal additionally passes through the high-pass filter capacitors (C21, C22). These capacitors were originally polarized types rated at 10µF/25V; the replacements were 10µF/35V Nichicon ES bi-polar "audio grade" capacitors. Similarly, the capacitors C45, C46 capacitors in the output high-pass filter of the tone control circuit were originally low-leakage polarized types rated at 10µF/25V; the replacements were 10µF/35V Nichicon ES bi-polar "audio grade" types.
With the subsonic filter engaged, the signal additionally passes through a pair of polarized 4.7µF/50V capacitors in series (forms a "bi-polar" capacitor) for each channel (C33/C35 and C34/C36). Each original capacitor pair was replaced with a single 2.2µF/50V stacked film capacitor. Also, the film by-pass capacitors for subsonic filter, C31 and C32, were removed.
Non-signal Path Capacitors and other Components
The local decoupling capacitors C39, C40, C41 and C42 were originally rated at 47µF/50V; the replacements were low ESR types rated at 220µF/50V. The VD1212 dual diodes (D01, D02) were each replaced with a pair of 1N4148 diodes in series. And the notorious failure-prone 82ohm fusitors (R37-R40) were replaced 82.5ohm/0.25W metal film resistors.
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