OT: Vintage Loudspeaker Refurbishment

[C40_guy]

Originally Posted by William

You aren’t going to find any quality speakers for a $100 or under on CL or OfferUp unless you get lucky. The market has seemed to soften a little in the last month or so but vintage/quality audio equipment isn’t cheap like it was a few years ago.

Maybe...

https://newhaven.craigslist.org/ele/...732104692.html

[William]

Originally Posted by C40_guy

Maybe...

https://newhaven.craigslist.org/ele/...732104692.html

No hoarders like that around these here parts.


W.

[C40_guy]

Originally Posted by William

No hoarders like that around these here parts.


W.

Well...

[oliver1850]

Here is the crossover. I have found capacitors that are close in value and dimensions. Will the resistors need to be replaced? I haven't been able to find a dual 15 ohm resistor like the original at top left above the level controls in the photo. Is it safe to just pry the old capacitors loose from the adhesive or is there a better method?

[Peter P.]

Resistors don't usually go bad; something else in the circuit typically shorts, drawing too much current through the resistor and overheating it. It's pretty obvious when they burn up. Even though removing the resistors from the circuit is the correct way to get an accurate reading, most of the time if you measure them in-circuit you'll get an accurate reading. You could remove them for measurement then solder them back in after confirming their values. If you replace them be sure to get the same wattage rating as well.

As for the capacitors, you want NON-polarized capacitors as replacements, with a similar voltage rating. It's safe to break them away from the adhesive; you could try heating up the board with a hair dryer to see if the adhesive softens but I'll bet no. I'd cut the leads as close to the capacitor as possible. Then you have something left to pull on if you want to unsolder the through-hole leads, or merely solder the new capacitors onto the leftover leads.

[Ken Robb]

Please remind me: do you have blown speakers to repair or replace?

[oliver1850]

Originally Posted by Peter P.

Resistors don't usually go bad; something else in the circuit typically shorts, drawing too much current through the resistor and overheating it. It's pretty obvious when they burn up. Even though removing the resistors from the circuit is the correct way to get an accurate reading, most of the time if you measure them in-circuit you'll get an accurate reading. You could remove them for measurement then solder them back in after confirming their values. If you replace them be sure to get the same wattage rating as well.

As for the capacitors, you want NON-polarized capacitors as replacements, with a similar voltage rating. It's safe to break them away from the adhesive; you could try heating up the board with a hair dryer to see if the adhesive softens but I'll bet no. I'd cut the leads as close to the capacitor as possible. Then you have something left to pull on if you want to unsolder the through-hole leads, or merely solder the new capacitors onto the leftover leads.

I tried checking resistance while on the board but didn't get readings close to the values printed on the resistors. I got reasonably close readings on the good drivers so I don't think my meter is way off. Will try another just to be sure.

I wondered about voltage ratings on the caps. The existing ones don't have have voltage ratings as far as I can tell. Is a 100V rating likely adequate for the new ones?

I have a Milwaukee heat gun and non contact thermometer that I can use to heat up the board. Any idea of a safe temperature limit to heat to?

[oliver1850]

Originally Posted by Ken Robb

Please remind me: do you have blown speakers to repair or replace?

I think I'm going to put new surrounds on the tweeters as all four are functional. At least one midrange will have to be replaced. There may be more than one bad but I've carried two of them off to a location that I don't remember. If three are bad I'll probably replace them all. They are 16 ohms and wired in parallel. If I replace them all I'll probably replace them with 4 ohm drivers wired in series. If I only need to replace two I'm not sure if it would be better to use one 16 ohm and one 8 ohm driver wired in parallel or to use both new drivers in one cabinet and both old ones in the other.

[Peter P.]

Originally Posted by oliver1850

I tried checking resistance while on the board but didn't get readings close to the values printed on the resistors. I got reasonably close readings on the good drivers so I don't think my meter is way off. Will try another just to be sure.

Originally Posted by oliver1850

Any chance you can unsolder one leg of the resistors, or remove them completely? Resistor size is directly related to power handling so if you can't read the values, after measuring you might be able to infer the wattage rating by comparing the size to dimensions listed in various catalogs.


I wondered about voltage ratings on the caps. The existing ones don't have have voltage ratings as far as I can tell. Is a 100V rating likely adequate for the new ones?

8 ohm drivers with speakers rated at 100W = 30V or the next highest voltage rating.
4 ohm drivers with speakers rated at 100W, 20V.

I have a Milwaukee heat gun and non contact thermometer that I can use to heat up the board. Any idea of a safe temperature limit to heat to?


No clue, sorry.

I don't know if you tried this, but have you done a search for the Pioneer CS88-A crossover diagram? It might help you.

[oliver1850]

I have the crossover schematic that was posted on hifiengine. Helpful to decipher which caps might be the ones causing loss of signal to specific drivers. I figured it was best to replace all the caps though.