[uniuniunium]

I spend all day putting the finishing touches on my RA-1 clone. When I plugged it in and turned it on, I got sound, but it was terribly distorted (scratchy) to the point that it would be unrecognizable if i didn't know what CD was in the player. There was also only sound on one channel. When I turned it off, both channels worked but only at low volumes, becoming scratchy if the volume was up too high. A couple of personal theroies on what might be involved with this problem: 1) I used 1/8W surface mount resistors (someone here reccomended them, i don't think they realized that they were surface mount) 2) I'm not at all sure if i have the wiring on the volume pot correct at all. I used the radio shack stereo volume control (made by alps, don't know the p/n), I had wanted the volume control to increase with clockwise motion, but that is reversed, so I think it's possible that i have something wired wrong (not just backwards) there. This is my first DIY attempt, so there's probably something else that could be going wrong. If you have any ideas or suggestions to go about troubleshooting this, I'd appreciate it.
Thanks,
-uni

 

[ADS]

It's probably the pot. Do you have the wiper going into the amp? And is the opposite end from the input connected to virtual ground? To get it to track right reverse the connections for input from jack and virtual ground. Leave the wiper connection where it is. (Could someone draw this? I'm having a hard time explaining it)

 

[was ist los?]

Did you remember to ground between the two batteries?

 

[uniuniunium]

yes, but one of the batteries may be dying, i'm going to make a wallymart run tomorrow and pick up some more as well

 

[uniuniunium]

Quote:

Originally posted by ADS It's probably the pot. Do you have the wiper going into the amp? And is the opposite end from the input connected to virtual ground? To get it to track right reverse the connections for input from jack and virtual ground. Leave the wiper connection where it is. (Could someone draw this? I'm having a hard time explaining it)

ratshack didn't include a wiring diagram, so i'm not entirely sure what should be wired where....if anyone has used this pot and could draw an ms-paint diagram perhaps i could figure out if i've got it wired correctly or not

 

[was ist los?]

Here you go:

 

[uniuniunium]

rewired the pot, but still no luck.

I'm wondering if it has something to do with the power supply, when i disconnect all the power it still makes noise (more than with the power on). I'm thinking there must be a short somewhere, but i have no clue where it might be.

Any other ideas folks?

 

[Squalish]

I thought it was wired like this:

(unused)*_____* ground(join from both decks w/ amp ground)
_____________* wiper(to input caps on amp)
_____________* input (from RCAs)

same for each deck, _ is a spaceholder char.

Same as was's post I believe, just horizontal instead of vertical.

Get some through hole resistors in there ASAP, SMT ones are a good candidate for a short.

Next, don't attempt to use it with a dead battery, you can fry your cans like that.

Do you have one leg of each cap grounded? Some have screwed that up because one of the ones in the diagram went over the +V rail.

 

[uniuniunium]

well, now i've got one channel (left) working, although it takes a good minute or so of warmup before it starts to work and even them i don't think there is any improvement in sound quality. i may just rewire the right channel to see if that makes any difference. thanks for your responses guys

edit: i also have a bunch of OPA2134A's laying around, i may pop one of those in if i find out they're pin compatible

 

[rickcr42]

jeez guys !

buy a damn multimeter and figure it out man !

Potentiometer=variable resistor

two of the ends make up a simple resistor of the value of the pot , the other is the "variable" connection that slides along the resitor changing its value

----------------------------------------------------------------------

since we are talking input attenuator (voltage divider)

one end of the resistor is connected to the input signal

the other end is connected to ground

the "wiper" is connected to the input stage of the circuit

/\/\/\/\/\/\/\/\/
l

------------------------------------------------------------------------

clip a test lead to ANY of the pot legs and measure to any other to figure out the wiring diagram .

cmon guys

 

[Pars]

Damn, Rick (and I haven't even been here long enough to remember you being here or leaving... hehe, no offense).

Sounds like there may be more going on here than just the pot being miswired. SMD resistors? With my aged eyesight, no f'ing way I would attempt to solder those in. You suppose that one or more resistors or other components may be miswired, other than the pot? He says that with the power off or battery(ies) disconnected that he is still getting (better) sound? Something other than the pot is f'ed up (the pot probably is also, but fix the basic circuit problems first, then deal with the pot).

But Rick is right on as far as basic troubleshooting... get a DMM and some magnification, and see what you can find versus the schematic. Take some stuff out and do measurements to see if what you should expect is happening at the right places in the circuit.

 

[rickcr42]

hehe

A bit strong you think ?

Even though it is kinda hard to tell with a one dimensional commuication format (the printed word or in this case the video monitor) you have my word that the majority of the time i have my tongue frimly planted in cheek

some would like to see it planted elswhere but that is another story.......


BLINDNESS ! YESSSS ! I RELATE MAN !

My vision started to go about two years ago .

I went from being able to read a novel in the dark to can't see crap without glasses and a good light !

Seriously cut back on my electronic contruction projects-the frustration level is more than i can take not being the most patient soul

we don't discuss AGE around these parts due to respect for elders-ME

My next birthday will be my 48th and I can honestly say i don't feel a day over 86 !

OK,back on topic


dammit;gotta go back and read the thread again and find out what went wrong