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Marantz transistor substitutions

TellMeWhy

TellMeWhy

Active Member
Hi everyone. Recently I had some transistors replaced on my 2230 preamp board and the resulting sound quality is actually duller and less dynamic than before. Can anyone confirm that the transistor choices are correct?
Original: 4x 2SC1000 vs. Replacement: 4x 2SC2240
4x 2SA493 vs. Replacement: 4x 2SA970
I know that the 2SA493 is normally recommend to be replaced with KSA992 or 2SA1015 . Any transistor experts out there know the ins and outs of transistor spec who can advise? I checked and they are correctly matched Y and GR... Thanks in advance, Jon
 
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Type Designator: 2SC1000
Material of transistor: Si
Polarity: NPN
Maximum collector power dissipation (Pc), W: 0.2
Maximum collector-base voltage |Ucb|, V: 55
Maximum collector-emitter voltage |Uce|, V: 50
Maximum emitter-base voltage |Ueb|, V: 0
Maximum collector current |Ic max|, A: 0.1
Maksimalna temperatura (Tj), °C: 125
Transition frequency (ft), MHz: 40
Collector capacitance (Cc), pF: 10
Forward current transfer ratio (hFE), min: 300
...................................................................................
Type Designator: 2SC2240
Material of transistor: Si
Polarity: NPN
Maximum collector power dissipation (Pc), W: 0.3
Maximum collector-base voltage |Ucb|, V: 120
Maximum collector-emitter voltage |Uce|, V: 120
Maximum emitter-base voltage |Ueb|, V: 5
Maximum collector current |Ic max|, A: 0.1
Maksimalna temperatura (Tj), °C: 150
Transition frequency (ft), MHz: 50
Collector capacitance (Cc), pF: 3
Forward current transfer ratio (hFE), min: 200
...................................................................................
Type Designator: 2SA493
Material of transistor: Si
Polarity: PNP
Maximum collector power dissipation (Pc), W: 0.2
Maximum collector-base voltage |Ucb|, V: 50
Maximum collector-emitter voltage |Uce|, V: 40
Maximum emitter-base voltage |Ueb|, V: 5
Maximum collector current |Ic max|, A: 0.05
Maksimalna temperatura (Tj), °C: 125
Transition frequency (ft), MHz: 100
Collector capacitance (Cc), pF: 10
Forward current transfer ratio (hFE), min: 200
Noise Figure, dB: -
..............................................................................
Type Designator: 2SA970
Material of transistor: Si
Polarity: PNP
Maximum collector power dissipation (Pc), W: 0.3
Maximum collector-base voltage |Ucb|, V: 120
Maximum collector-emitter voltage |Uce|, V: 120
Maximum emitter-base voltage |Ueb|, V: 5
Maximum collector current |Ic max|, A: 0.1
Maksimalna temperatura (Tj), °C: 150
Transition frequency (ft), MHz: 100
Collector capacitance (Cc), pF: 4
Forward current transfer ratio (hFE), min: 200
 
What else did you do while inside it?
From an untrained eye, the only thing that sticks out is Base voltage. (2sc2240) but i am not sure how, or if, it effects anything.
 
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KutzlerTrans said:
What else did you do while inside it?
From an untrained eye, the only thing that sticks out is Base voltage. (2sc2240) but i am not sure how, or if, it effects anything.
Click to expand...
Thanks guys. I didn't do the work myself, it was a helpful semi-pro eBay seller trying to sort an issue with uneven sound between L and R on the preamp. He had already replaced the 3 larger electrolytics on that board and then in this job replaced all the remaining. Same values, not sure of the brand. Sound before was beautiful and airy from one channel and weak and dull from the other. Sound now is balanced, strong and good separation but not with the same warm tone. I am not a tech guy, and a relative newcomer here. For all I know, the receiver may be correct now, and just not so well matched to my speakers. Any thoughts?
 
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Did he remove any brown or grey capacitors? (films)

Patfont is one guy to ask. He has done some crazy capacitor experiments and would be one of the best guys to ask . He is a nice guy and he's always willing to help..
 
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He replaced just the electrolytic capacitors (now all are new), the original mylar caps are still in place (though they're green not brown or grey). I will get some internal pics up here asap but too busy with work right now! Thanks again!
 
How long have you ran it with the new caps? You may also want to clean the Pre/Main jumpers and jacks real good also
 
KutzlerTrans said:
How long have you ran it with the new caps? You may also want to clean the Pre/Main jumpers and jacks real good also
Click to expand...
It's only ran for about 10 hours so far. Maybe needs some burn in!!! The unit has been properly cleaned inside and out so I don't think that should be an issue.
 
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