I mentioned it already in my "300DC Repair" thread, but I also have an extremely problematic 1300DC that anatech and sakis have given me some advice on.
Several of the semiconductors have been replaced with odd parts. Most odd, the speaker protection board had electrolytic caps that had been replaced with ones that were twice the capacitance value specified in the service manual. This made the protection relay click-on after roughly 10 seconds (extremely annoying when you're troubleshooting, not to mention suspenseful).
I've already got replacements for some of the pre-drivers and whatnot (2sa1535a/2sc3944a) for (2sb717/2sd757) and (2sb861/2sd1138) for (2SA968B/2SC2238B). The pieces that are in there are a mishmash of NEC and NTE stuff that clearly isn't original. Some of the traces on the back are trashed, and I might actually end up fabricating new amplifier boards after Anantech made it sound very doable in his post in the 300DC thread. I'll definitely change out the drivers as well with the MJ21195/96 pair that seems to be so popular on here.
I seem to have isolated an odd channel cutout that occurs in the preamp. In the last thread I mentioned that the right channel on the 1300dc cuts out based on how the chassis is stressed. It seems to be a poor connection between the source selector assembly board (PJ00) and the tape EQ buffer amp assembly (PK00). depending on how i apply pressure with my finger the channel will cut out and return. this will probably be the last thing i attempt to remedy, since it's such an involved process to disassemble the preamp.
BUT
I can't seem to find an appropriate substitute for the 2SC735/2SA562 pair on the amplifier boards. 2SC1815/2SA1015 almost seems right, but I'd be trading down from an fT of 300Mhz to 80Mhz
Several of the semiconductors have been replaced with odd parts. Most odd, the speaker protection board had electrolytic caps that had been replaced with ones that were twice the capacitance value specified in the service manual. This made the protection relay click-on after roughly 10 seconds (extremely annoying when you're troubleshooting, not to mention suspenseful).
I've already got replacements for some of the pre-drivers and whatnot (2sa1535a/2sc3944a) for (2sb717/2sd757) and (2sb861/2sd1138) for (2SA968B/2SC2238B). The pieces that are in there are a mishmash of NEC and NTE stuff that clearly isn't original. Some of the traces on the back are trashed, and I might actually end up fabricating new amplifier boards after Anantech made it sound very doable in his post in the 300DC thread. I'll definitely change out the drivers as well with the MJ21195/96 pair that seems to be so popular on here.
I seem to have isolated an odd channel cutout that occurs in the preamp. In the last thread I mentioned that the right channel on the 1300dc cuts out based on how the chassis is stressed. It seems to be a poor connection between the source selector assembly board (PJ00) and the tape EQ buffer amp assembly (PK00). depending on how i apply pressure with my finger the channel will cut out and return. this will probably be the last thing i attempt to remedy, since it's such an involved process to disassemble the preamp.
BUT
I can't seem to find an appropriate substitute for the 2SC735/2SA562 pair on the amplifier boards. 2SC1815/2SA1015 almost seems right, but I'd be trading down from an fT of 300Mhz to 80Mhz
thanks sakis
Okay,
it looks like B&D Enterprises has the 2sa562, but not the 2SC735. instead, the datasheet that they have for the 2sa562 mentions that it's paired with the 2sc1959. it looks like a perfect replacement for the 2sc735, but i wanted to hear from someone else before i pulled the trigger on a 2sc1959/2sa562 pairing.
Okay,
it looks like B&D Enterprises has the 2sa562, but not the 2SC735. instead, the datasheet that they have for the 2sa562 mentions that it's paired with the 2sc1959. it looks like a perfect replacement for the 2sc735, but i wanted to hear from someone else before i pulled the trigger on a 2sc1959/2sa562 pairing.
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