[I<3SQ]

I was going over to my friends house on Saturday for his little girl's birthday party and I spotted a receiver in his neighbor's garage, I couldn't tell what brand it was cause it was facing backwards. I went over to his house again today and this time his neighbor was in his garage so I walked over and asked him if he was interested in selling his receiver. He said it didn't work but if I wanted he'd just give it to me, of course I was cool with that cause my other buddy is an electronics repair man by trade so I figured I'd have him fix it.

When he handed it to me I noticed it was a Yamaha RX-750, sweet, then he proceeded to tell me that it only works when the "Pure Direct" button is pressed. I got home and looked it up and found that "Pure Direct" gives you a pure source output because it bypasses the bass/treble/loudness circuits elimination any muddying of the signal due to circuit routing.

I haven't hooked it up yet, will do so tomorrow. Just wondering if anyone has any experience with this receiver/amp/preamp. If it works, I'll just use it instead of the AudioSource Amp100 I was gonna order to run my Insignia NS-B2111's on my PC setup. Won't I be able to play with the bass/treble settings via my AudioTrak Prodigy HD2 soundcard once it gets here on Wednesday?

 

[Orcin]

The "direct" button bypasses all tone and loudness adjustments, just as you say. The filters are not bypassed. The way to check it is to adjust the bass/treble and switch it in and out. If you hear no change, then the switch is stuck in the "on" position.

Your buddy might be able to replace that switch (plus clean the pots to remove crackling) and you should have a pretty decent amp.

Yes, whatever tone controls you apply via your source will still be in effect.

 

[I<3SQ]

Quote:

Originally Posted by Orcin /img/forum/go_quote.gif The "direct" button bypasses all tone and loudness adjustments, just as you say. The filters are not bypassed. The way to check it is to adjust the bass/treble and switch it in and out. If you hear no change, then the switch is stuck in the "on" position. Your buddy might be able to replace that switch (plus clean the pots to remove crackling) and you should have a pretty decent amp. Yes, whatever tone controls you apply via your source will still be in effect.

Cool, I just got home so i'm gonna hook it up real quick and see how it is, brb.

.........Alright, well, good news and bad news. The good news is that it powers up, the display lights up fully and I was able to get sound out of it with the pure direct button pressed as explained to me. However, i'm getting alot of crackling. It's clearly an issue with either a dirty pot as you said or even an intermittent solder joint cause the light on the source knob goes out sometimes if you touch it, and when that happens that's when I get the crackling goodness.

I was able to confirm that without the pure direct switch on, I got no sound, and of course am not able to adjust any tone settings with it on. So I guess I'll take it over to my buddy's house this weekend and have him look at it and see if he can work it out for me.

 

[obobskivich]

you're sure it doesn't have a coupler missing? I have the RX-770 (i'm sure they're related somehow), the Pure Direct switch will bypass the following:

mains coupler
bass/treble control
balance control
variable loudness

mine came with a pair of U shaped metal brackets (they actually DO have insulation on them, so you can't short them into each other if you brush something metal against them), but those were quickly tossed aside as I got a Pro Logic processor with the unit (so its wired through that, instead of with the couplers, and with Pure Direct enabled, it bypasses the PL processor)

looking at the user's manual for hte RX-550/750, it does require couplers or something between the Pre Out and Main In section (but Pure Direct bypasses this) so if you've got some RCA cables laying about, hook it together proper and it should go just fine (it doesn't really care if its a cable, a loop of devices, etc, as long as the signal can go from the pre-amp out to the main input)

the crackling is something my 770 developed a while ago, I ended up giving it a nice how's your father with some DeOxit 5, into the input select switch (I have no idea what it looks like inside of yours, mine is DC actuated and a pain in the behind to get at cleanly, its still possible, yours is probably similar (they look nearly identical in pictures) the reason I said i have no idea, is because the newer model, the RX-797, has the input select UNDER the VFD (which I don't want to imagine getting access to))

that cleaned up the crackling and issues entirely, and its back to perfect output quality, even if you wiggle the knob about, so that'd be worth a try (I also got in there with a flashlight and whatnot, and made sure nothing was rotting or falling apart (given this thing is nearing the big 2-0) and nothing looked out of order, so that tells me it wasn't built as a throw-away)

i got the manual here:
Yamaha RX-750 Manuals, Support and Troubleshooting

its free

hope this helps

 

[I<3SQ]

Quote:

Originally Posted by obobskivich /img/forum/go_quote.gif you're sure it doesn't have a coupler missing? looking at the user's manual for hte RX-550/750, it does require couplers or something between the Pre Out and Main In section (but Pure Direct bypasses this) so if you've got some RCA cables laying about, hook it together proper and it should go just fine (it doesn't really care if its a cable, a loop of devices, etc, as long as the signal can go from the pre-amp out to the main input) the crackling is something my 770 developed a while ago, I ended up giving it a nice how's your father with some DeOxit 5, into the input select switch (I have no idea what it looks like inside of yours, mine is DC actuated and a pain in the behind to get at cleanly, its still possible, yours is probably similar (they look nearly identical in pictures) the reason I said i have no idea, is because the newer model, the RX-797, has the input select UNDER the VFD (which I don't want to imagine getting access to)) that cleaned up the crackling and issues entirely, and its back to perfect output quality, even if you wiggle the knob about, so that'd be worth a try (I also got in there with a flashlight and whatnot, and made sure nothing was rotting or falling apart (given this thing is nearing the big 2-0) and nothing looked out of order, so that tells me it wasn't built as a throw-away) i got the manual here: Yamaha RX-750 Manuals, Support and Troubleshooting its free hope this helps

Thanks for all the lovely info man, I looked at the back of my receiver and it's only got one coupler, can you take a pic and show me how the coupler/loop should be installed? I have a set of cheap rca's that I can use instead of the couplers, I just need to know what plugs to put them in.

As for the source selector knob, I think I may have a hairline crack in the solder joint cause the led flickers, or maybe the pot is bad/dirty. I'm gonna spray some electrical cleaner in there first and blow it out with compressed air and see if that makes a difference. If not, I'll try your method, I just have to find some of that DeOxit stuff.

 

[obobskivich]

Pre Out L -> Main In L
Pre Out R -> Main In R


basically get a red/white RCA pair cable (or whatever colors you use, or just two mono cables) and connect white to white and red to red

the book has a picture (I know, all B&W and using the u-shaped couplers), but a single stereo to stereo cable, like you'd connect a CD player or phono deck with, will bridge it just fine (and yes, I've used a 20ft length just to see what it does, theres no difference btwn that, the couplers, and the loop with the PL processor that I've got)

after that, just disable pure direct, and it should play

sucks to hear about the crack in the solder joint, which LED is flickering though, the volume knob one? (or does it have one on source select?)

 

[I<3SQ]

Quote:

Originally Posted by obobskivich /img/forum/go_quote.gif Pre Out L -> Main In L Pre Out R -> Main In R basically get a red/white RCA pair cable (or whatever colors you use, or just two mono cables) and connect white to white and red to red the book has a picture (I know, all B&W and using the u-shaped couplers), but a single stereo to stereo cable, like you'd connect a CD player or phono deck with, will bridge it just fine (and yes, I've used a 20ft length just to see what it does, theres no difference btwn that, the couplers, and the loop with the PL processor that I've got) after that, just disable pure direct, and it should play sucks to hear about the crack in the solder joint, which LED is flickering though, the volume knob one? (or does it have one on source select?)

sweet. I have a cheap set of rca's that came with my Onkyo setup that I'll use for this application. I sure hope that's the problem, it makes sense that it would be since I only have one coupler in there now.

The source selector knob has an led on it, that's the one that flickers.

 

[obobskivich]

oh, mine doesn't have an LED on that knob, although none of my other LED pots flicker, so I can say it is not a normal trait of Yamaha components (but you already knew that,

)

I'd say open it up (if you haven't) and give it a peak, the illuminated knobs on mine (which are motorized and continuously variable, instead of stepped, but still probably similar to yours in construction) have the "pot part" inside of the casing, thats where I'd give it some electrical cleaning

the LED part is inside of the knob itself, so it can rotate without wires getting caught up, tbh I haven't had the desire to rip one of them apart (for fear of never getting it back together, and because it feels glued), but theres a small circuit board inside of the knob, with the power lines and the LED, you might look a that and see if its got some visible issues (or the wire that connects it to the inside of the system, to feed it power)

 

[I<3SQ]

Quote:

Originally Posted by obobskivich /img/forum/go_quote.gif oh, mine doesn't have an LED on that knob, although none of my other LED pots flicker, so I can say it is not a normal trait of Yamaha components (but you already knew that, ) I'd say open it up (if you haven't) and give it a peak, the illuminated knobs on mine (which are motorized and continuously variable, instead of stepped, but still probably similar to yours in construction) have the "pot part" inside of the casing, thats where I'd give it some electrical cleaning the LED part is inside of the knob itself, so it can rotate without wires getting caught up, tbh I haven't had the desire to rip one of them apart (for fear of never getting it back together, and because it feels glued), but theres a small circuit board inside of the knob, with the power lines and the LED, you might look a that and see if its got some visible issues (or the wire that connects it to the inside of the system, to feed it power)

on mine, the led is affixed to the rod coming out of the pot that the knob attaches to. There's just a transparent sliver on the knob that lets the led shine through. I have no desire to open this thing up and dig into it but if the loop thing works and I can get sound with and without pure direct on, I'll be motivated to do just that.

 

[obobskivich]

yeah, that setup sounds a bit, unique (not like "jesus son of the lord god" unique, but like "seven of nine, tertiary adjunct of unimatrix zero-one" unique)

lemme know how the coupler hook up goes, and if cleaning it helps the static