Static in left channel - phono only

DCrews

DCrews

Active Member
Hi everyone:

I have a Sansui 5500 receiver and I'm getting constant static/popping in the left channel. This happens when it is switched to Phono 1 and Phono 2, but not FM, AM, or AUX. It gets louder depending on how the volume is adjusted, and it happens whether there is music playing or not. I've ruled out the possibility of it being the speakers because I've tried two different pairs.

Anyone have an idea of what could be causing this? I'm hoping it's something I could fix myself although I've never really worked on a receiver.

Any advice is appreciated!
 
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Are we to assume the same tt was used to test function of phono 1 and 2? Did you try the tt on a different receiver to rule out the tt being the problem?
If the tt is not the problem, then when was the last time the controls were cleaned? On those, you could get to the function selector control inside without too many problems, but getting at the pushbuttons to clean them requires some disassembly..not for the faint at heart or the inexperienced. You may want to find the Idiots Guide To Deoxit sticky found at the top of General Audio Discussion.
It could be a problem in the phono section of the receiver, but its a tough call until all of the easy stuff is eliminated first.
 
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Thanks. I didn't try another receiver, but I did try two different turntables and got the same result with both. Not sure when it was last cleaned. I've had it for about two years. I have never cleaned it. Not sure about before that. I will take a look inside and give it a good cleaning. We'll see what happens.
 
Well, I tried cleaning the volume and function selector. It didn't have any effect on it. Could any of the other switches have anything to do with this? It seems like if the switches were to blame, the static would be present in FM, AM and Aux as well?
 
That would be my assumption, none of the pushbuttons are tt specific that Im aware of., though maybe low filter would only be used with the tt it still works for the rest of the functions.
Anyway, exhausting the cheap easy fix with no result is no fun, sorry.
 
I was looking at the Sansui 5500, nice receiver. Your problem does sound like the function switch is dirty, it appears to be a wafer switch and they can be a real booger to clean, in extreme last resort cases I have had to use brasso in some of my vintage Hamradio gear that has been used by smokers. If you have not done so get the dedicated cleaners from Caig, they have some nice spray contact cleaning flushes you can hose down a whole chassis with. Of course the gold standard is DeoxIT. Another thing to check is the left channel RCA input, they can go bad, cold solder joints, loose center conductor, etc. they are only good for so many inns and outs.
 
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transmaster said:
I was looking at the Sansui 5500, nice receiver. Your problem does sound like the function switch is dirty, it appears to be a wafer switch and they can be a real booger to clean, in extreme last resort cases I have had to use brasso in some of my vintage Hamradio gear that has been used by smokers. If you have not done so get the dedicated cleaners from Caig, they have some nice spray contact cleaning flushes you can hose down a whole chassis with. Of course the gold standard is DeoxIT. Another thing to check is the left channel RCA input, they can go bad, cold solder joints, loose center conductor, etc. they are only good for so many inns and outs.
Click to expand...
Thanks. I will give that another look. The static actually went away for a little while this morning, but it came back after about 20 minutes.
 
I gave the cleaning with Deoxit another try, but still nothing. I'm pretty well convinced it's something with the phono stage. I talked with someone else who suggested it might be a bad capacitor. Just now I flipped the connected/separated switch to separated and the static went out. If I understand correctly that switch cuts out the power amp and the preamp. I know how to identify a bad capacitor, but I honestly have no idea which part of this thing is the phono stage. Thoughts?

IMG-20121013-00033_zpscc6d848b.jpg
 
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I'd check the solderings.They might be cracked.The ones of the connectors,on the back panel and on the board.
If that's not the case,I'd check the power supply caps,though the static should be on all inputs.
Does it make noise when the TT is not connected?
 
Do you have a line level input on the back you are not using,
Tape input, Aux. Instead of trying to track down this problem right
now, or ever, how about purchasing an external phono
pre-amp and using one of these other ports. I was looking
over a number of them and they are not expensive, and
would probably improve the sound quality of anything the
dedicated phono input could give you even if it was working.
Pyle has a bunch that are $25 dollars or less. PhonoPreamps.com
has a very interesting collection. I don't know anything
about the TCC line up but they seem to be well thought of
on the dedicated Vinyl/turntable forums. The Technolink TC-754
($73.50) is one that is under discussion right now. This unit would be
great up grade for a vintage stereo rig, a dedicated MM pre-amp plus
adding additional line level inputs to your receiver.
TCC has dedicated phono pre-amps for Moving Coil cart's as well.

http://www.phonopreamps.com/index.html#Features

754ST.jpg

754SR.jpg
 
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Let's hope not.It's easier to fix some cold solder or some dirt.
You'd have to track it down,find replacement.
We shall see.I think
 
costellom5 said:
Let's hope not.It's easier to fix some cold solder or some dirt.
You'd have to track it down,find replacement.
We shall see.I think
Click to expand...

Be sure to check out the solder joint in the center conductor on the Left channel RCA input. If you are going to venture into the vintage electronics an simple test lead you can put together is a set of female RCA jacks on one end with hook clips on the other and 6 to 12 inches of shielded cable in between are nice to have,

http://catalog.e-z-hook.com/category/test-hooks?
 
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If you feel the need or want, shoot me an email addy to send to, I have a copy of the service manual on zip..I was hoping for your sake it wouldnt have evolved to all of this.
 
Transmaster - I had thought about getting an external phono preamp like you mentioned. I was using both Phono inputs on the Sansui. Would there be any way to run two turntables through a seperate preamp or would I need to buy two?

I took a look at the solder joints but didn't see anything that looked out of the ordinary.

bobaloninny - Thanks. I actually downloaded a copy of it from HiFi Engine.
 
I checked in over at the Vinylegine forum and they advised me two pre-amps is in order if both inputs are noisy. You can use two of the other line level inputs on the Sansui or go through a line level swithbox (below) such as is available at the Preamp website. I can find no two channel phono-amp's that let you switch between two moving magnet cart'ed turntables that are less then plus or minus $1000 dollars. It seems people who are using two turntables have a moving magnet cart on one, and a moving coil on the other.
http://www.phonopreamps.com/tc716pp.html

TC716siltilt400.jpg

tc716r.jpg
 
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Dcrews, This is Justin, Allens brother in law. I sent you a few emails this morning on this. Were you able to ID the preamp circuit? Looking at your pictures it should be the in the top right of the first picture you posted. Its a smaller square circuit board. reading through a few of the posts i'm thinking its a component part in the preamp stage. I had guessed a cap but the thought a transistor is possible as well. Luckily its a pretty simple preamp section. If it is a transistor there are only two in each channel so those could be easily replaced (granted the transistors are still available) If its a cap there are quite a few to track down.

Like i said in my email, i will be down for a while over thanksgiving and i can take some of my electronics gear and we could go through it. Can look at all the solders and re flow any that may look suspect.

Another option, and i may do this with one of my own receivers that is having preamp issues, is to pull that preamp and swap it with a known good one. There are quite a few preamp kits that can be purchased for a fair price and then get swapped in place of the old one. In the end this could be a quicker and easier swap than trying to chase electrical issues and replacing components in the old preamp.

Justin
 
Did a bit more reading on popping in amps cross referenced with the transistor that is in the preamp (2SA726) it looks like replacing those transistors helped in most cases. That transistor is no longer available but it looks like a KSA992 is the best option to swap them with. Looks like mouser.com has them in stock for .07 a piece. would probably be worth buying 4 and swapping out all 4 that are found in the preamp circuit and see if that fixes the issue
 
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This illustrates what I tell a lot of people. I enjoy getting old hamradio gear going. What I have always found interesting is it is easier to get parts and repair old vacuum tube rigs then so many recent SS stuff. You can get tubes for radios made in the back before 1930. It is much harder on SS rigs made circa 25 years ago. Transistors, and IC's especially are the problem. Discrete transistors are not so bad you can usually find something that works, but IC's unless they are a generic part good luck trying to find one. But that doesn't mean it can't be fun. The pleasure you have when you get any old electronic device functioning makes it all worth the trials and tribulations.

The hook probes I called your attention too are very important in your adventure in SS repair. If the transistors in the phono pre-amp are setting above the circuit board the micro hooks can clip right onto the leads on the transistor. A most modern multimeters have a transistor tester setting so you can test the transistors hopefully without having to remove the board to do it.

I assume the line coming from the phono inputs is a shielded wire. I have run into such feeds with a foam center insulator with breaks down over the years and will cause a scratchy sound like a bad interconnect cable. If you discover this is the problem you can replace the lead with something like Belden 9221 a coax with an OD of .097" which is much, much better then what is there now.
 
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