Marantz 2270 bias slowly climbs

[catrafter]

If you replace the NPN driver (2SC680) then you should replace the PNP driver (2SA566) also. I would use original TO-66 parts, but if you decide on TO-220, use complementary parts.

Tom

 

[gogofast]

Still waiting for the transistors. Amazon has ruined my patience with their free one or two day shipping. Anything that takes longer feels like forever now.....

Anyways, let me ask this question:

If I'm gonna use the receiver mainly for phono and aux, and maybe am/fam only a few times a year, is there a reason to recap those boards? I mean, I'll probably not spend money on aligning the am/fm anyways. Does it make sense to recap and not re-align? Should I just leave those boards alone? I do have all the caps, but just getting lazy.

 

[mbz]

Haven't checked the sm, but generally I'd recap the power related caps, those that provide local storage, since that power rail might
be shared with other boards. You could elect not to recap audio path etc...

 

[Steven Tate]

Just to answer your question about recapping and alignment — I have recapped a dozen 22xx receivers and never had one aligned. The tuner sections always worked after recapping about the same as they did before. I can’t say it always works that way because my experience is limited. But I don’t believe recapping the tuner related boards significantly affects alignment.

 

[gogofast]

Just to answer your question about recapping and alignment — I have recapped a dozen 22xx receivers and never had one aligned. The tuner sections always worked after recapping about the same as they did before. I can’t say it always works that way because my experience is limited. But I don’t believe recapping the tuner related boards significantly affects alignment.

Haven't checked the sm, but generally I'd recap the power related caps, those that provide local storage, since that power rail might
be shared with other boards. You could elect not to recap audio path etc...

Well, whether limited or vast, your experiences count. I guess recapping at least the 'lytics will benefit.

 

[Steven Tate]

Well, whether limited or vast, your experiences count. I guess recapping at least the 'lytics will benefit.

Yep. That's generally all I do on the tuner boards. I will sometimes replace small electrolytics with WIMA films -- usually if I have seen it recommended by one of the trusted techs here on AK. It just stands to reason to me that if the lytics are aging in the amps and power supplies that they are aging in signal processing boards too.

 

[gogofast]

Got the transistors this morning. Replaced all outputs just to be sure. Also installed a new set of LED lights.

The bias is stable after about 30 minutes. The offsets are close to zero. So far, it sounds pretty good. Only thing left to do is clean the pots. Since I ran out of deoxit, I'm waiting for a bottle.





Realized the messiness around the transistors and cleaned up after posting the pictures.

 

[Steven Tate]

Looks great! Hope it sounds as good as it looks once the face is back on. As far as the compound, someone on here said something like, get it as thin as you can and then remove a little more. Exaggeration, but you get the idea.
Steve

 

[gogofast]

It's now fully put back together. Played some jazz and classical earlier - now playing Sade through SF Concertino's. Very nice sounding - airy and crystal clear and so dynamic. Keeper for sure. These LED lights really give it a fresh look.