elgrillo
El Grillo
Hello everybody, I just got a Marantz 7T(SN: 18,437) this week , its in nice shape for how much I paid for it. Maybe someone can help me across this journey of trying to restore it.
I know how to solder and use the multi meter . In the past I already restored a marantz 32 with a lot of help of some kind people from here, and also I recapped an change some pieces of a marantz 250 with some help also.
Well the 7T is in working condition but (always problem ehh) some little problems with it.
1- When I move the selector knob, estranges sounds comes from both speakers . This only happens when changing between *Tape-head and *Microphone. In all the rest is perfect and smooth.
2-When I try to plug some headphones (while operating) (ON) A very loud sound comes from the speakers , very loud (afraid to break my speakers).
3-After opening it I found that some one already make some repairs. One Electrolytic Cap from the Power Supply (C601 A,B) has been changed with a 330 mf /200v + 170mf / 200v in parallel. The other cap (c602) of the PS is original but it has leak signs.
4- I think that the bridge rectifier has been changed also, and I don't know if it is a good one.
5-On the Main Output RAEF Board, one of the transistors is not original, and I doubt that this one is a good replacement. I can`t get to see any numbers on the transistor to check if its a good one or not.
6- This is not important but a little bit annoying ,the volume pot starts to produce sound just passing 10.
The rest of the parts looks to be original and in good shape.
The Idea is to recap all the electrolytic and tantalum's, and replace the assumed bad parts for good new replacements. I don't know if i need or not change the Mylar caps on some of the boards as I saw in some pictures of a Japanese website ( http://amp8.com/tr-amp/marantz/pre_amp/7t.htm ) , they also put some mica bypasses in some of the caps.
I see that a lot of people are modding this preamp with very good results, and if some one gives me some (not too difficult) tips, i think with a little bit of guide i will be not afraid to do them also.
If i get to do this I will take photos of all the process, and try to put all the information as organized as I can.
Thanks a lot in advanced!
I know how to solder and use the multi meter . In the past I already restored a marantz 32 with a lot of help of some kind people from here, and also I recapped an change some pieces of a marantz 250 with some help also.
Well the 7T is in working condition but (always problem ehh) some little problems with it.
1- When I move the selector knob, estranges sounds comes from both speakers . This only happens when changing between *Tape-head and *Microphone. In all the rest is perfect and smooth.
2-When I try to plug some headphones (while operating) (ON) A very loud sound comes from the speakers , very loud (afraid to break my speakers).
3-After opening it I found that some one already make some repairs. One Electrolytic Cap from the Power Supply (C601 A,B) has been changed with a 330 mf /200v + 170mf / 200v in parallel. The other cap (c602) of the PS is original but it has leak signs.
4- I think that the bridge rectifier has been changed also, and I don't know if it is a good one.
5-On the Main Output RAEF Board, one of the transistors is not original, and I doubt that this one is a good replacement. I can`t get to see any numbers on the transistor to check if its a good one or not.
6- This is not important but a little bit annoying ,the volume pot starts to produce sound just passing 10.
The rest of the parts looks to be original and in good shape.
The Idea is to recap all the electrolytic and tantalum's, and replace the assumed bad parts for good new replacements. I don't know if i need or not change the Mylar caps on some of the boards as I saw in some pictures of a Japanese website ( http://amp8.com/tr-amp/marantz/pre_amp/7t.htm ) , they also put some mica bypasses in some of the caps.
I see that a lot of people are modding this preamp with very good results, and if some one gives me some (not too difficult) tips, i think with a little bit of guide i will be not afraid to do them also.
If i get to do this I will take photos of all the process, and try to put all the information as organized as I can.
Thanks a lot in advanced!
