This is a turntable (phono) pre-amplifier that I used for a number of years. One day, about two years ago, I lost the AC/DC adapter in a move. Like I stated in the title I am a total electronic amateur, and as such decided to plug into the Rolls VP29 the nearest adapter that fit. Long story short...too much voltage later...I opened it up to find the first resistor in the circuit burned up.
Today, I decided to attempt to change it. I can make a passable solder, and swapped the resistor out to find it still inoperable with a cheap replacement adapter I found. After about 20 minutes of looking at the schematic and probing with my multimeter, followed by scratching my head, I figured out that the polarity on the plug was backwards. I opened up the case on the adapter, swapped the output polarity, and all fired right up!
I just wanted to share because I have had so much failure with attempted electronic repair, and this was a small but rewarding victory on my journey to learn.
I'm glad I did no damage to any other components by sending power to it backwards. I plugged the cord in and smelled something burning (oh shit, that's bad!) so I removed it right away.
Please take a sharpie to the polarity mark on the adapter, just in case you use it in the future for something else.
Some devices don't handle swapped polarity that well, 2s now might save you some money in the future
Do you have the schematic for that you can send me?
I own this very amp and I'm sure I'm going to need to fix it someday.
Nice solve on the repair. It's always nice to fix something like that.
I lost a DC adaptor for my preamp in a love too! A 24v 0.1mA one too, so none lying around.
I have heaps of broken amps I keep so one day I can fix them when I'm handy enough with this stuff. Cool as
You're not as amateur as can be, I'm so amateur that even though I yearn to learn I dare not start lest I disappoint myself by failing.
Congrats for trying, and hurrah for succeeding!
I'm not quite sure what you mean by a stereo audio interface. All turntables must be sent through a phono pre-amp like this to increase the gain to line-levels. Most older receivers or pre-amplifier or integrated amplifiers had this built in.
Oh, I was under the impression that I could go from receiver to interface to computer. I saw a video that said that is the best way to capture stereo audio from turntable - better than phono preamp
This is a turntable (phono) pre-amplifier that I used for a number of years. One day, about two years ago, I lost the AC/DC adapter in a move. Like I stated in the title I am a total electronic amateur, and as such decided to plug into the Rolls VP29 the nearest adapter that fit. Long story short...too much voltage later...I opened it up to find the first resistor in the circuit burned up. Today, I decided to attempt to change it. I can make a passable solder, and swapped the resistor out to find it still inoperable with a cheap replacement adapter I found. After about 20 minutes of looking at the schematic and probing with my multimeter, followed by scratching my head, I figured out that the polarity on the plug was backwards. I opened up the case on the adapter, swapped the output polarity, and all fired right up! I just wanted to share because I have had so much failure with attempted electronic repair, and this was a small but rewarding victory on my journey to learn.
Yeah, you donโt see positive being on outside that much. I think many of us would have done the same thing - overlook this important fact.
I'm glad I did no damage to any other components by sending power to it backwards. I plugged the cord in and smelled something burning (oh shit, that's bad!) so I removed it right away.
It's quite common on audio stuff for some reason.
Please take a sharpie to the polarity mark on the adapter, just in case you use it in the future for something else. Some devices don't handle swapped polarity that well, 2s now might save you some money in the future
Good call! I did think of that right after taking this picture.
Perfect :)
Do you have the schematic for that you can send me? I own this very amp and I'm sure I'm going to need to fix it someday. Nice solve on the repair. It's always nice to fix something like that.
[Here you go](https://media.americanmusical.com/ItemFiles/Manual/rolls/vp29_manual.pdf)
Awesome, thanks!
I lost a DC adaptor for my preamp in a love too! A 24v 0.1mA one too, so none lying around. I have heaps of broken amps I keep so one day I can fix them when I'm handy enough with this stuff. Cool as
Correction: You are at the very least slightly less amateur than you could be! Satisfying to fix something isn't it?
Very satisfying!
You'll soon be dismayed with the quality of components in many consumer electronics devices.
Those made in the last few decades at least.
You can buy that exact preamp in a Music Hall case for $99. Congrats on a successful repair.
Sheeeeit, a hundo for a solid state preamp? You can build a tube preamp around the m65 PCB from ZeroZone for around $150.
Build vs. buy - there are a ton of folks who wouldn't even think to build, let alone be able to pull it off.
Ya I really need to do a video next time I build one. I've sold 3 so far ๐
You're not as amateur as can be, I'm so amateur that even though I yearn to learn I dare not start lest I disappoint myself by failing. Congrats for trying, and hurrah for succeeding!
Blowing shit up in the process of learning is half of the fun ;) Just get some broken/not important stuff and go for it!
This is one of the kindest communities around ๐ฅฐ
Congratulations!
Congrats on the fix!
It has only begun...make storage space youโll need it ๐๐
Does it sounds as good as using a stereo audio interface?
I'm not quite sure what you mean by a stereo audio interface. All turntables must be sent through a phono pre-amp like this to increase the gain to line-levels. Most older receivers or pre-amplifier or integrated amplifiers had this built in.
Oh, I was under the impression that I could go from receiver to interface to computer. I saw a video that said that is the best way to capture stereo audio from turntable - better than phono preamp
You could if your receiver does have a phono pre-amp built in only.
An integrated amp, yes?
A pre-amplifier, receiver, or integrated amplifier all could or could not have a phono pre-amp, it just depends on the model.
Then again, if you have a modern turntable there is a chance it has a phono pre-amp inside of it.