Marantz 3250B Phono Section Transistors

[Richs_Trains]

So here's the story, got a 3250b cheap and beat up. Got it cleaned, de-oxit, and recapped all the electrolytic caps. Powered it up and all is good except lots of white noise on the phone section. I found 2SA970's and 2SC2240's and replaced those. Still had the noise, tried to find 2SC1885's, but could not. Replaced with 2SC1845's and phono section is clean. Switched out my 3250 for the repaired 3250b and immediately was suspicious of the sound of the phono section. It does not seem to have either the fullness or punch of the 3250. I went ahead and re-capped the 3250 and switched it back. There is a definite difference in the phono sections.
Were the 1845's a bad choice, would these affect the sound that much, and what would be the best substitute for the 2SC1885's? (or if some one has 4) 2SA970's, 4) 2SC2240's and 2)2SC1885's, that would be special). Thanks Rich

 

[rBuckner]

I might have the 2240's - will look when I'm home for lunch.

 

[Richs_Trains]

Randy, Thanks for the offer, I did manage to find all the transistors but was hesitant to install them because of the way this forum feels about parts on auction sites. I pulled the c1845's last night and put the c1885's I got online in. I have both channels, no noise but haven't actually listened to an album (it is a real pain to switch these units out as this is my main system and pretty much buried).
My real purpose in this post is to educate myself about transistors and how they affect the sound. Were the c1845's the possible reason for my sound concerns? Since I re-capped the original 3250 and put it back in the, it sounds great and really have no need for the extra features of the 3250b (moving coil pick-up and headphone amp), so I am not going to switch it out.

Thanks again Randy and thank you all for any and all help that I have received on this forum, it is truly my go to resource for help with all things Marantz. Rich

 

[Richs_Trains]

So, before I switch out the 1845's for the 1885's, I checked them on my tester and the 1845's registered low 600 hfe on one and high 600 on the other, the 1885's both measured about 220, would the difference in gain cause a slight imbalance in the system. I felt one channel was lower with the 1845's installed? Thanks Rich

 

[rBuckner]

I don't think so on the imbalance as they are not set up to use nearly that much gain.

I do have six of the 2SC2240's if needed, just let me know.

 

[Richs_Trains]

Finally had the chance to put the 3250b back in the rotation. Instead of connecting it to the original SM-7 I was going to use it on (the re-capped 3250 just sounds too nice on the SM-7) I connected it to a 170dc which has the same model turntable and cartridge as the SM-7 system. Changing the transistors back to the c1885's brought back the sound of the pre-amp phono section. I am glad that I learned from this and now understand a little more about transistors and how the make sure the replacements match the originals. I will say I was surprised at the change in sound and how noticeable it was.

I do have six of the 2SC2240's if needed, just let me know.

Thanks Randy, I guess the ones I bought on the auction site turned out OK, with all the warnings on AK, I was concerned. The phono section is claen and quiet now, Thanks Rich