Marantz 2225 Phono crackle

[marcthisdate]

My 2225 has recently developed a crackle on the left channel in the phono section where the sounds starts t break down and eventually just goes away. I tried a few basic troubleshooting steps like swapping out phono carts, checking cables, moving the phono cable from left to right, deoxit'ing the switch etc to no avail as it stays on the left. Its intermittent and for some reason will go away temporarily if I change the selector to radio and then back to phono but eventually will come back. Every other source works fine except phono.

I've read somewhere on AK where this could be a bad set of transistors in the phono stage? Could this be the case and if so would any one know how many and of what type of transistor I would need to order from mouser etc?

Thanks for any help you folks can lend here.

 

[catrafter]

It could be, although yours doesn't usually have the failure prone 2SC458 transistors that are in some models.

Tom

 

[marcthisdate]

It could be, although yours doesn't usually have the failure prone 2SC458 transistors that are in some models.

Tom

Thanks @catrafter. I’m assuming I can’t test the transistors with just a multimeter?
If not the transistors, anyplace else to be looking?

 

[audiocrzy]

Thanks @catrafter. I’m assuming I can’t test the transistors with just a multimeter?
If not the transistors, anyplace else to be looking?

You can but a transistor tester is more accurate.

 

[marcthisdate]

I'm leaning on picking up a donor phono board to rebuild and swap into the receiver. One question though, the wires attached to the board are wrapped and I would like to keep using that method rather than soldering them back on the posts. I'd like to get a wire wrap tool but have no idea what gauge I would need to choose. Any one know and maybe have a tool they would recommend?

 

[catrafter]

Most transistor testers don't test for noise.

Wire wrapping takes experience gained by practice. Also, you can't reuse the previously 'wrapped' wire, it is nicked and will break, you need enough length to cut and re-strip.
Another method is to un-solder the existing post from the old board with the wire intact and install it in the hole on the replacement board.

Tom

 

[marcthisdate]

Most transistor testers don't test for noise.

Wire wrapping takes experience gained by practice. Also, you can't reuse the previously 'wrapped' wire, it is nicked and will break, you need enough length to cut and re-strip.
Another method is to un-solder the existing post from the old board with the wire intact and install it in the hole on the replacement board.

Tom

Thanks Tom, the unsolder the pins from the board makes sense. I‘ll give it a try.

 

[marcthisdate]

I've got the donor board and parts for the phono rebuild and have an observation that I was wondering if anyone has seen before. The crackle is in the left channel and it basically crackles till it cuts out (right is fine the whole time). If I put the 2225 in mono the left will play fine. Nothing else if affected with this syndrome except the phono stage. Before I start removing things, I want to make sure I am working on the correct area. Any thoughts?

 

[marcthisdate]

Well, now I think I have something a bit more serious going on. Same issue occurring on the AUX now. Left side crackle which leads to an intermittent lack of sound. Any idea where to start looking?

 

[marcthisdate]

This is very cathartic... Did a bit of digging around in the threads, since I rule out it just being phono it made searching much easier. Took the thing apart, checked for any obvious bulging caps, bad solder joints etc. Deoxit'ed. all switches and worked them like mad and cleaned all of the RCA inputs etc... Since it was opened up anyway cleaned the insides, faceplate and case... 2 hours in and no channel drop. . Man, this site is still the most incredible source of vintage audio trouble shooting info, bar none!

Below find some picts from when it was opened up...