SDA-CRS Repair

vectordirector

Help SDA experts. I am the original owner of circa 1984 SDA-CRS's. Up until a recent flood, they have performed perfectly. My sump pump broke and I wound up with a couple of inches of water in the basement theater. The system was on (not playing, but powered on) and the speaker wires and interconnect cable were submersed for a few hours. System was uninstalled floor dried and system reinstalled. Upon power up, speakers output a loud oscillating hum. Immediate power down and troubleshooting of wires, etc ensued. Removal of interconnect cable solved the problem and system operated as normal except for expected loss of output from dimensional driversand SDA effect.
Inspection of interconnect showed some cracks and holes in the insulation, probably from my trying to shove it under the baseboard and the carpet tacks penetrating the insulation. I tried to build a new interconnect using information from this forum, but still have the same problem with the loud hum. I expect this is a crossover problem in one or both of the speakers, eithier due to age or a short due to the flood.
I don't have any type of multimeter or skill in using one, I assume I would have to test the crossovers somehow. Can someone walk me through this? I have zero soldering skills, so rebuilding a complex crossover is probably not something I can do.
To tell the truth, they still sound great, but I know in my mind that they are not performing as well as they should. If it is more work than I am able, I may just sell them and move on to something else.

Any help would be appreciated.

Vectordirector

hearingimpared

Welcome to Club Polk vectordirector!!!

You've definitely come to the right place. I own a set of CRS's and I love them. There are many, many gurus here who can help you with everything from xovers all the way to revaneering them. Hang on and I'll give you a bump up to the top here so that other can help you out.

Joe

BTW Mine have the Rd0194 tweeters and vampire binding post with a beautiful veneer job done by F1nut. YOu will be bless if Jesse (F1nut) see this and chimes in.,

thsmith

Could'nt the amp be the problem too? The hum is only when the SDA cable is connected completing the circuit.

I am probably wrong but for s&g I would try a differnt AMP before ripping the XOs out.

vectordirector

Thanks for the replys. I've been doing this for 30 years and know what I'm doing. I'll be the first to admit hooking something up wrong. We have all done it , especially when in a hurry. That being said, I checked the connections again and all is as it should be. I'm running without the interconnect. Nothing other than the cables got wet. Amp is an Outlaw 7125 (7x200@4ohms) and has been driving this system for over 6 years without issue.
I wish I could describe the sound. It is like a mains hum but really loud, no matter what volume the system is at. I'm no electrical engineer but it sounds like the amp is going into oscillation and playing a waveform, square, sine, sawtooth maybe, I don't know. Sounds like a lower frequency euro ambulance. dee-dah dee-dah but maybe around 100hz and probably at full power. It hasn't blown the fuses on the speakers, because I immediately unplug it. I don't hear it in my sub which is sent from the prepro (outlaw 990) via xlr crossed at 80Hz. I unplugged the sub output thinking it was a ground loop but it didn't matter. I guess I'll try another amp and see what happens. Anybody know if a Behringer EP1500 ( my sub amp) is common ground?

Vectordirector

hearingimpared

vectordirector wrote: »

Thanks for the replys. I've been doing this for 30 years and know what I'm doing. I'll be the first to admit hooking something up wrong. We have all done it , especially when in a hurry. That being said, I checked the connections again and all is as it should be. I'm running without the interconnect. Nothing other than the cables got wet. Amp is an Outlaw 7125 (7x200@4ohms) and has been driving this system for over 6 years without issue.
I wish I could describe the sound. It is like a mains hum but really loud, no matter what volume the system is at. I'm no electrical engineer but it sounds like the amp is going into oscillation and playing a waveform, square, sine, sawtooth maybe, I don't know. Sounds like a lower frequency euro ambulance. dee-dah dee-dah but maybe around 100hz and probably at full power. It hasn't blown the fuses on the speakers, because I immediately unplug it. I don't hear it in my sub which is sent from the prepro (outlaw 990) via xlr crossed at 80Hz. I unplugged the sub output thinking it was a ground loop but it didn't matter. I guess I'll try another amp and see what happens. Anybody know if a Behringer EP1500 ( my sub amp) is common ground?

Vectordirector

If your sub amp is a single channel then yes it is common ground. However it may not be on common ground with your other amplifier used to connect to the speakers. That being said be very careful.

Joe08867

I am guessing there is water in the interconnect cable and it is causing a short.

FTGV

vectordirector wrote: »

Anybody know if a Behringer EP1500 ( my sub amp) is common ground?

It is as long as it 's not used in bridged mono mode.

vectordirector

I'll try another amp sometime soon and see what happens. I'll remember to reset the Behringer to stereo. I built a new interconnect using the ends from the old one. Didn't make a difference. I have to recheck the wiring of the new interconnect to make sure I did it right. Common ground is straight or crossover? I can't find the post with the information.

vectordirector

Actually it is a blade/blade. These are very early CRS's purchased in mid 1984. Still searching for information on the wiring of that cable. Hopefully finding time this weekend to try a different amp. I'll keep everyone advised.

Thanks again all.

vectordirector

F1nut

Wide blade to wide blade, narrow to narrow.