Line in issue on Sanyo

[Radio raheem]

Update: I found that when I remove the cables from the rear, I need to put them in red first then white in order to get both channels to work. This procedure has to occur following flipping a record or changing to a new record. Not normal but it works. It makes me wonder if the sound quality could improve if this was fixed somehow. The order of inserting the red and white cables shouldn’t dictate whether or not both channels produce sound.
Also makes me think of the ground again. I’ll have more info when I apply the ground loop insulator also.

im not sure about this but spray the actual rca sockets themselves and try a better cable as others have suggested

 

[Jboulukos]

im not sure about this but spray the actual rca sockets themselves and try a better cable as others have suggested

The cables are directly connected to the inside of the turntable and cannot be removed or swapped without completely installing attaching new cables. I don’t think the cables are faulty because I have tried another turntable and had the same results using the cables connected to that turntable. Both are 37 years old so maybe the red cable for both players is faulty or damaged. I’m still thinking it’s the rca socket connection. Going to resolder i think.

 

[Radio raheem]

yea your correct i wouldn't tamper with the wires then as they are more than likely ok, im out of ideas now if you have done everything suggested already, you say if you connect the leads in a certain order she is ok, think you will have to live with that....all these old boomboxes have there quirks mate lol

 

[Jboulukos]

Definitely. Also, try a different cable. I'm serious, I've had a couple low-quality cables that couldn't maintain consistent volume. I had to twist and turn them to get full volume.
And regarding the "Function" switch on the front, don't bother spraying unless you can actually see the metal contacts inside the switch. Just spraying the black nylon lever isn't going to work. You need to be able to see the copper feelers behind that lever.

The ports (rca jacks) are soldered to the pcb and due to the force of inserting and removing the plugs, especially when the jack finish is no longer smooth, can and often do cause the solder connections to fracture resulting in poor or unreliable signal connections. To fix, you can usually reflow the solder joints, ideally adding some fresh solder.

Properly cleaning the function switch is critical on nearly all boomboxes. Another switch to check and clean on the Sanyo m-x650k is the Line In/Phono preamp switch on the back directly under the ground screw. Both left and right channels pass through this and a dirty switch could cause problems with one or both. When trying different turntables be sure to connect the ground wire to the ground screw. Some turntables like the PS-Q3 in the picture do not have a ground wire. This could contribute to your hum problem.
Also - many folks who were not around during the 70s and 80s are unaware of the need for preamplification on turntables from that era. Many just plug the turntable into the line in and expect it to work like an iPod or CD player. Luckily your Sanyo has a built in phono preamp and should be able to handle most turntables - just flip the switch to phono when using an old school turntable. To my generation this is obvious, but younger folks often miss this.

Update: I went into the boombox to tackle the recommendations you guys provided. The function switch was sprayed with contact cleaner in 3 places indicated by the yellow arrows and I turned the switch a bunch of times after each spraying.
Next I hit up the Record Bar again and sprayed contact cleaner in the front, back and center holes and pulled the record cable a bit.

I then payed a visit to the line-in/phono-in switch and sprayed that baby in the holes seen below and the sides.
Then I looked at the solder for the line-in/phono-in RCA connection time the circuit board. Solder sucked the 3 points and resoldered. I then check continuity and both red and white holes seemed fine. Nothing was odd about the old solder. I just wanted to be thorough. I have circled the new solder.

Next, I looked at the inside of the line-in and noticed a piece of metal that was bent a bit more (circled) than the corresponding metal piece that is identical on the line-out side. I took some needle nose players and straightened it a bit.
Then the radio was buttoned up and I went to test it. Sounded ok for a minute and then went back to varying declines in quality listed:
1. Both channels work but with significantly less bass
2. Left channel works, Right channel gives slight hum
3. Poor quality sound through both channels, mainly Left.


So, I have no other components at the moment to test with this to see if there’s a difference, besides 2 identical Sony model ps-q3’s which have built in RCA cables and no ground. So I started movement the cables side to side from the turntable unit and had some changes in sound, even opening the door up and down changed the sound output. I really wish I had some other piece of equipment to test it with. I may just change the RCA cables on one turntable and see if that changes anything. Again, the ground loop isolator is on its way. Also a vintage cassette deck Walkman is on its way and I can apply a headphone-to-RCA cable to the line-in to see how the sound output is.
If anyone has any other input or other ideas, feel free to comment. I always appreciate any info and enjoy learning and problem solving.

 

[Reli]

The spray won't really reach anything through those holes. The best way is to spray into the end of it. See the green arrow at the bottom. Turn the boombox upside down and stick the straw into the end of that bar.

 

[Jboulukos]

The spray won't really reach anything through those holes. The best way is to spray into the end of it. See the green arrow at the bottom. Turn the boombox upside down and stick the straw into the end of that bar.


View attachment 49652

I sprayed the crap out of it from different angles, ran the spray hose into the hole and down towards the green arrow. Contact cleaner was coming out of the area that you indicated.

 

[Jboulukos]

Fixed. Resoldered the 4 connections for the rca cable end inside the turntable. Consistent sound from both channels, no problem flipping the next side of the lp. At least I know everything is clean inside that Boombox now. Learned a ton and had fun. Much Thanks to all who helped. Love this radio. It’s come a long way.

 

[goodman]

Sometimes it takes a lot of patience to solve a problem. Congratulations.

 

[Radio raheem]

View attachment 49653
Fixed. Resoldered the 4 connections for the rca cable end inside the turntable. Consistent sound from both channels, no problem flipping the next side of the lp. At least I know everything is clean inside that Boombox now. Learned a ton and had fun. Much Thanks to all who helped. Love this radio. It’s come a long way.

It was the turn table then haha, glad she is fixed now mate, way to go

 

[Jboulukos]

Sometimes it takes a lot of patience to solve a problem. Congratulations.

Thanks man.

 

[Jboulukos]

It was the turn table then haha, glad she is fixed now mate, way to go

Yes. Crazy but true. Both turntables just needed more solder on the RCA attachments at 4 points. I couldn’t believe both had faulty RCAs. Thought for sure it was the boombox. Learned a ton and got some practice in.

 

[Radio raheem]

yes that also through me off, what is the chance that both turntables needed fixing haha, mind you i lost 2 pioneer amps at the same time so anything is possible lol

my biggest loss was 2 m90's in the same day lol...this was years ago though

 

[Jboulukos]

yes that also through me off, what is the chance that both turntables needed fixing haha, mind you i lost 2 pioneer amps at the same time so anything is possible lol

my biggest loss was 2 m90's in the same day lol...this was years ago though

What happened?

 

[Radio raheem]

So long ago mate and i was hard on the whisky but both the decks died on me...the m90 is all about the deck for me, did get them sorted again though some years later...do you plan on buying anymore radios then you can't stop at one lol

 

[Jboulukos]

So long ago mate and i was hard on the whisky but both the decks died on me...the m90 is all about the deck for me, did get them sorted again though some years later...do you plan on buying anymore radios then you can't stop at one lol

Well I found this one and it spoke to me, so I saved it. I don’t really plan on getting any more but if I see potential and a good deal, then maybe I’ll get more. I’m just content with having this one because I actually didn’t have a radio. And some music on cassettes are not available on any other format. I love vinyl but some albums are much cheaper on cassette as well. So instead of a $120 rare lp, I can get it on cassette and enjoy it. It’s fun to save things. I have more enjoyment cleaning and fixing things. Maybe I’ll get another box, fix it and give it to someone.