berge92
New member
- Joined
- Feb 21, 2015
- Messages
- 1
most recent aquisition for my studio - funky little ramsa wr133. got it for a steal and i'm very happy with it. just using it to sum stems and it does exactly what i wanted - adds some nice analog breakup on the preamps and mix buss.
channels 1-7 all seem to be working correctly. as you step through the different preamp gain settings, they all react similarly. channel 8 however, that bad boy is the subject of our story here. at the 0dB and +10dB settings, it doesn't pass any audio. once you step up to -20dB and above it passes audio, but line level signals through a mic pre at the -20dB setting get pretty narsty. this is sometimes cool (synth bass anyone?), but i'd rather have the option to choose a lower gain settting to match channels 1-7.
i'm a total newb when it comes to ripping apart circuit boards and finding the source of an issue, but i've jumped in on this thing. the board itself breaks down fairly easily and i was able to pull a couple channel cards out to check them out. i'm handy enough with a soldering iron and was able to mess around a bit. a techy friend suspected a faulty op amp may have been the culprit, so i pulled the op amps, socketed the slots, and popped in some new ones - same result. i've put the orginal op amps back in just for consistency's sake.
just comparing good channel 7 vs bad channel 8 visually, the main differences are the resistors. good channel has all original small yellow resisitors from what i can tell, but bad channel has all different big blue resistors on board (clearly i'm not the first person to dig around inside this thing). there's even a resistor that's been tied on the back of the PCB! from the looks of the solder points on the back of the PCB, it also looks like the transistors on the bad channel have also been replaced.
so at this point, i come to you my fellow analog enthusiasts. is this as simple as replacing the resistors to match the originals? could those transistors be at fault? maybe a capacitor isssue (i know they are usually replaced on these old things)? regardless of the issue, i need help identifying the problem and getting the correct component models to get this funky channel back up to snuff.
i've uploaded pictures of everything here - http://imgur.com/a/MHQeA
images are arranged in a left -> right kind of way. think of channel input on the left and the pics slowly pan right down the channel. good channel is shown first followed by bad channel. the images aren't perfect, but they should get the gist across.
any help here is greatly appreciated! also, if anyone has a service manual on this thing, you would be a god. i haven't found anything on this after a lot of googling....
channels 1-7 all seem to be working correctly. as you step through the different preamp gain settings, they all react similarly. channel 8 however, that bad boy is the subject of our story here. at the 0dB and +10dB settings, it doesn't pass any audio. once you step up to -20dB and above it passes audio, but line level signals through a mic pre at the -20dB setting get pretty narsty. this is sometimes cool (synth bass anyone?), but i'd rather have the option to choose a lower gain settting to match channels 1-7.
i'm a total newb when it comes to ripping apart circuit boards and finding the source of an issue, but i've jumped in on this thing. the board itself breaks down fairly easily and i was able to pull a couple channel cards out to check them out. i'm handy enough with a soldering iron and was able to mess around a bit. a techy friend suspected a faulty op amp may have been the culprit, so i pulled the op amps, socketed the slots, and popped in some new ones - same result. i've put the orginal op amps back in just for consistency's sake.
just comparing good channel 7 vs bad channel 8 visually, the main differences are the resistors. good channel has all original small yellow resisitors from what i can tell, but bad channel has all different big blue resistors on board (clearly i'm not the first person to dig around inside this thing). there's even a resistor that's been tied on the back of the PCB! from the looks of the solder points on the back of the PCB, it also looks like the transistors on the bad channel have also been replaced.
so at this point, i come to you my fellow analog enthusiasts. is this as simple as replacing the resistors to match the originals? could those transistors be at fault? maybe a capacitor isssue (i know they are usually replaced on these old things)? regardless of the issue, i need help identifying the problem and getting the correct component models to get this funky channel back up to snuff.
i've uploaded pictures of everything here - http://imgur.com/a/MHQeA
images are arranged in a left -> right kind of way. think of channel input on the left and the pics slowly pan right down the channel. good channel is shown first followed by bad channel. the images aren't perfect, but they should get the gist across.
any help here is greatly appreciated! also, if anyone has a service manual on this thing, you would be a god. i haven't found anything on this after a lot of googling....
