Need help with Marantz HD-55 L-Pads

[BoilermakerF]

I picked up a set of Marantz HD-55 speakers this weekend at a yard sale. I figured the L-Pads were probably shot and that's why they didn't work. The cabinets are pretty well shot, but I hooked them up and one speaker's tweeter didn't work and the other's midrange didn't work. That is, until I pressed in on the L-Pad. The tweeter is on a 5ohm pad and the midrange is on a 10ohm. The L-pads appear to be made well enough that they can be easily disassembled, cleaned, and reassembled. I'm willing to try that first to see if I can get them playing again. What should I use to clean them with? 90% Iso alcohol? If it doesn't work, is my best option to replace them with higher wattage resistors or replace them with 8ohm and 16ohm L-Pads realizing that has an impact on the XO frequency due to the changed load?

Thanks,

BMF

 

[Army]

I'd use a little steel wool followed by Caig deoxit :thmbsp:

 

[BoilermakerF]

Thanks.

What "grit" on the steel wool? 0000?

 

[BoilermakerF]

I'd use a little steel wool followed by Caig deoxit :thmbsp:

Ok, I opened up two of the L-Pads on one speaker and they definitely need the deoxit and the wipers need to be bent back out a bit for more friction, but should I buy the aerosol and spray the whole thing, or just the pen to treat only the spring and wiper contact points? The metal half that holds the shaft and wiper was pretty corroded on one, but I know steel wool will clean this out. Would the deoxit Gold help prevent this in the future, you know, over the next 32 years?

Thanks again.

 

[Army]

I've used a pen knife to scrap the heavy corrosion on the wipers, if you use steel wool make sure you can blow all the dust off and any strands that might get caught on the wiper. If the coils are bad a light sand paper or emery cloth would be better on the coils. Then follow with deoxit and Progold if you like for longer lasting resistance to corrosion.

 

[BoilermakerF]

Thanks again. I discovered that one of the tweeters is now dead, measuring infinite resistance, but I have a pair of Boston Acoustic soft dome tweeters to replace them with. I also noticed that both woofers have two cracks in foam surrounds. These speakers had a very large enclosure for an 8" woofer and they were stuffed with egg crate foam to boot. I planned to use the drivers in an old Silvertone console I'm refurbishing since it had an 8" FR and 4" FR speaker in it. I plan to mount the tweeter approximately the same distance from the two drivers as the original HD-55. The console has a perforated back and I was going to use some of the foam in a trial-and-error approach until I achieved the sound I wanted. Now it looks like I need to find a high Vas 8" replacement woofer. :sigh:

 

[Army]

If all they need is new foam...refoaming isn't hard to do. Do a search here and you should find plenty of handy tips :thmbsp:

 

[BoilermakerF]

Thanks. For now I just ordered a pair of lower cost 8" replacement woofers from Parts Express. I also ordered the Deoxit and Deoxit Gold for the L-pads and tubes. Thanks for that tip.

I'll keep the Marantz woofers and try to refoam them after all my other projects are done, but I have a que that is at least 9 audio projects deep and one of those projects is designing/building my own retro console which should take me a while... It was just a matter of time and I need to get my first console retrofitted. The Marantz woofers will be a good learning experience though so I can use that when I go to restore a truly valuable old console. :thmbsp: