2245 restoration-P700 issue

[liam rtr]

I am currently rebuilding my Marantz 2245, I did the power supply and tested the audio and everything was good, just a little noise, which I assume is because I haven’t yet biased the receiver. I started doing the P700, I put 22uf electrolytics in place of c703 and c704, I put 0.47uf 63v wima caps in place of c701 and c702. I replaced the electrolytic in the middle of the board with a 100uf 50v, and I replaced the two little sc458 transistors next to it with 992 transistors. I thought I should test the audio at that point and it was extremely distorted, I’m not sure what I should go back and check that could cause this.

 

[goldswimmerb]

I am currently rebuilding my Marantz 2245, I did the power supply and tested the audio and everything was good, just a little noise, which I assume is because I haven’t yet biased the receiver. I started doing the P700, I put 22uf electrolytics in place of c703 and c704, I put 0.47uf 63v wima caps in place of c701 and c702. I replaced the electrolytic in the middle of the board with a 100uf 50v, and I replaced the two little sc458 transistors next to it with 992 transistors. I thought I should test the audio at that point and it was extremely distorted, I’m not sure what I should go back and check that could cause this.

P700 only uses NPN transistors, there should be no KSA992 parts in that board. Only KSC parts.

 

[liam rtr]

P700 only uses NPN transistors, there should be no KSA992 parts in that board. Only KSC parts.

So I’ll have to remove the transistors and replace them with what? Sc1845?

 

[jd3rdcoast]

So I’ll have to remove the transistors and replace them with what? Sc1845?

Pretty sure that is correct sub. Do your research and double check E-C-B orientation. Also make sure all device orientation is same as what was factory installed as the 2245 manual has many misprint errors. You should review the Marantz manual error thread as well to help avoid common mistakes.

 

[EastPoint]

Either KSC1845 or KSC1815 in those spots. New ones are ECB—just use the board markings.

 

[liam rtr]

Thanks, I’m not sure why I read that 992s go in that spot, always good to verify things with multiple sources.

Either KSC1845 or KSC1815 in those spots. New ones are ECB—just use the board markings.

 

[EastPoint]

For sure. No worries, we've all done it.

 

[JJCalvillo]

Thanks, I’m not sure why I read that 992s go in that spot, always good to verify things with multiple sources.

Double check the orientation of the transistors next to the 100uf power cap. Pretty sure they should be facing in the same direction. They are marked the same on the board, and they look like they're facing in the opposite directions.

Always good to shoot a photo of the board before you start, so you can double check orientation.

 

[liam rtr]

Double check the orientation of the transistors next to the 100uf power cap. Pretty sure they should be facing in the same direction. They are marked the same on the board, and they look like they're facing in the opposite directions.

Always good to shot a photo of the board before you start, so you can double check orientation.

Yes, I had them wrong and fixed it but the problem didn’t go away, I need to do some more testing tomorrow