The SU-A200 (photo 1) was manufactured from 1985 to 1989 and was designed to work with the SE-A100 power amplifier.
Its successor was the SU-C5000, manufactured from 1990 to 1995, with the dedicated SE-A5000 power amplifier.
Both preamplifiers had virtually identical electronic circuitry, but they suffered from a serious problem – the playback and recording source selector was prone to failure.
Due to the failures of the SU-A200 selector, a modernization was carried out in 1987, introducing additional protection against damage to the uPD6364CA integrated circuits.
This change brought improvements, but failures still occurred. Damage to even one circuit (there were three in the preamplifier – IC201 and IC202 as the recording selector, and IC203 as the playback selector) caused the preamplifier to stop functioning properly.
Damage to the circuits was most often caused by electrostatic discharge when connecting or disconnecting RCA cables while the devices were powered on.
Therefore, in 1991, Technics carried out another, this time extensive, modernization of the SU-C5000 preamplifier.
The C-MOS uPD6364CA switches have been eliminated and replaced with uPD6360C controllers.
This information is not entirely certain. It is unclear whether production of the SU-C5000 on the old motherboard was completely discontinued and subsequent preamplifiers had a new motherboard, or whether the new solution was only used during warranty repairs. The uPD6360C controller, as IC204, was used in the earlier version of the playback selector to control the CD and Digital inputs and also operated the Direct input selector with these two sources.
Five uPD6360Cs were used in the playback selector to control the nine line inputs and the phono line.
The recording selector used six uPD6360Cs – three of them handled the six source lines, while the remaining three handled the three tape loops.
The low-level line of all six chips, connected in series, handled recording from the turntables.
Since it was not possible to fit 11 integrated circuits on the motherboard, the motherboard was redesigned and six uPD6360s were placed on it for the recording selector.
The playback selector, with its five chips, was built on an additional board as a top-mount unit (photos 2 and 3). The uPD6364CA chips have been discontinued and are currently unavailable.
Consequently, there are many damaged, unusable SU-A200 and SU-C5000 preamplifiers on the market.
I encountered this problem myself, and from three damaged SU-A200 preamplifiers, I managed to create one fully functional one. Unfortunately, the other two were unusable.
Some time ago, while browsing auctions for Technics preamplifiers, I came across photos of the inside of an SU-C5000 preamplifier with a different motherboard design.
This inspired me to create an alternative SU-A200 and SU-C5000 input selector solution with an old motherboard based on uPD6360C chips. I designed the electronic schematic, which was used to create an additional PCB with uPD6360C circuits. I also designed a mounting bracket for the additional PCB, as well as the routing and connection of the control and signal cables (photos 4, 5, and 6). It turned out that the new solution integrated with the remaining preamplifier circuits without the need for additional modifications.
Playback and recording from all sources to the three tape recorders, recording between tape recorders, equalizer input with and without equalization, and muting all work correctly.
I was finally able to repair the damaged preamplifiers.
Its successor was the SU-C5000, manufactured from 1990 to 1995, with the dedicated SE-A5000 power amplifier.
Both preamplifiers had virtually identical electronic circuitry, but they suffered from a serious problem – the playback and recording source selector was prone to failure.
Due to the failures of the SU-A200 selector, a modernization was carried out in 1987, introducing additional protection against damage to the uPD6364CA integrated circuits.
This change brought improvements, but failures still occurred. Damage to even one circuit (there were three in the preamplifier – IC201 and IC202 as the recording selector, and IC203 as the playback selector) caused the preamplifier to stop functioning properly.
Damage to the circuits was most often caused by electrostatic discharge when connecting or disconnecting RCA cables while the devices were powered on.
Therefore, in 1991, Technics carried out another, this time extensive, modernization of the SU-C5000 preamplifier.
The C-MOS uPD6364CA switches have been eliminated and replaced with uPD6360C controllers.
This information is not entirely certain. It is unclear whether production of the SU-C5000 on the old motherboard was completely discontinued and subsequent preamplifiers had a new motherboard, or whether the new solution was only used during warranty repairs. The uPD6360C controller, as IC204, was used in the earlier version of the playback selector to control the CD and Digital inputs and also operated the Direct input selector with these two sources.
Five uPD6360Cs were used in the playback selector to control the nine line inputs and the phono line.
The recording selector used six uPD6360Cs – three of them handled the six source lines, while the remaining three handled the three tape loops.
The low-level line of all six chips, connected in series, handled recording from the turntables.
Since it was not possible to fit 11 integrated circuits on the motherboard, the motherboard was redesigned and six uPD6360s were placed on it for the recording selector.
The playback selector, with its five chips, was built on an additional board as a top-mount unit (photos 2 and 3). The uPD6364CA chips have been discontinued and are currently unavailable.
Consequently, there are many damaged, unusable SU-A200 and SU-C5000 preamplifiers on the market.
I encountered this problem myself, and from three damaged SU-A200 preamplifiers, I managed to create one fully functional one. Unfortunately, the other two were unusable.
Some time ago, while browsing auctions for Technics preamplifiers, I came across photos of the inside of an SU-C5000 preamplifier with a different motherboard design.
This inspired me to create an alternative SU-A200 and SU-C5000 input selector solution with an old motherboard based on uPD6360C chips. I designed the electronic schematic, which was used to create an additional PCB with uPD6360C circuits. I also designed a mounting bracket for the additional PCB, as well as the routing and connection of the control and signal cables (photos 4, 5, and 6). It turned out that the new solution integrated with the remaining preamplifier circuits without the need for additional modifications.
Playback and recording from all sources to the three tape recorders, recording between tape recorders, equalizer input with and without equalization, and muting all work correctly.
I was finally able to repair the damaged preamplifiers.
