Troubleshooting Advent 4002 re-cap

[mswer]

I've done a handful of crossover re-caps and hadn't had any issues with the previous ones, but after re-capping the first crossover in one of my 4002s (was waiting on the second to A/B them), I'm not getting any signal to the low frequency driver; I do get audio from the HF driver, but it sounds pretty thin, so not sure if I'm hearing everything I should from that driver, but in any case...it's not working as expected. This x-over is a bit more complicated than the others I've worked on, which so far were all single cap with no fuse, so this one is a bit more complex.

While doing the re-cap, I also replaced those awful screw terminals with 5-way binding posts. I do have a multimeter, but not really sure how I can use it to aid in troubleshooting, if I can. Including a picture of the original crossover, the clearest pictures I could get of each solder point. Thanks for the help!

 

[FatMaul]

Found this because I just got some 4002s. Well, let's start simple, what caps did you buy? Also what multimeter do you have? Can it measure capacitance?

 

[mswer]

Found this because I just got some 4002s. Well, let's start simple, what caps did you buy? Also what multimeter do you have? Can it measure capacitance?

Fair question, and probably should have mentioned. I looked at this thread for advice (good one for you to check on the topic you raised) https://audiokarma.org/forums/index.php?threads/recap-and-refoam-advent-4002s.316791/ and got 33mfd and 6.8mfd Audyn MKP caps

Audyn Cap Q4 33uF 400V MKP Metalized Polypropylene Foil Crossover Capacitor

Audyn Cap Q4 33uF 400V MKP Metalized Polypropylene Foil Crossover CapacitorAudyn has supplied European speaker builders with high quality electrical components for use in crossovers since 1973. Their Q4 series of non-polarized capacitors feature MKP metalized polypropylene foil and are tightly...

www.parts-express.com

Audyn Cap Q4 6.8uF 400V MKP Metalized Polypropylene Foil Crossover Capacitor

Audyn Cap Q4 6.8uF 400V MKP Metalized Polypropylene Foil Crossover CapacitorAudyn has supplied European speaker builders with high quality electrical components for use in crossovers since 1973. Their Q4 series of non-polarized capacitors feature MKP metalized polypropylene foil and are tightly...

www.parts-express.com

whoops, missed your second question. got this radio shack multimeter, it can.

 

[StimpyWan]

I'd try reflowing all of the solder joints, at a higher temperature, if possible? They look a bit cold. Plus, in the 3rd photo, is the lead from the inductor coil clean? Not much bare metal showing at the solder joint.

Good luck...!

 

[FatMaul]

Did you measure the caps to see if they are up to spec? Also, you can put the multimeter in resistance mode and connect one probe to the red speaker connector and then use the other probe to keep tracing back... to the other end of the inductor, the capacitor lead, the other side of the cap, etc....

 

[FatMaul]

Did you measure the caps to see if they are up to spec? Also, you can put the multimeter in resistance mode and connect one probe to the red speaker connector and then use the other probe to keep tracing back... to the other end of the inductor, the capacitor lead, the other side of the cap, etc.... if the ohmmeter says OL then you found your bad connection.

As far as my 4002s go, I don't plan to re-cap. The factory caps measure good so I don't see a reason to change them out.

 

[Mike_S]

Those solder joints don't look good. Need more heat, or better solder, or some flux.
on the coil, scrap it clean before you solder.

 

[mswer]

I'd try reflowing all of the solder joints, at a higher temperature, if possible? They look a bit cold. Plus, in the 3rd photo, is the lead from the inductor coil clean? Not much bare metal showing at the solder joint.

Good luck...!

Thanks for all the helpful comments, but this one in particular helped me understand what's happening. It now seems obvious that the red coating on the inductor is insulation, bc otherwise the entire thing would be conductive with itself and that makes no sense.

Upon paying closer attention to what's happening, and reviewing these responses, as shoddy as my soldering my be (and I know it's not great), the signal is making it to the tweeter. Where it's not making it is the woofer — I clipped the end of the inductor coil off with the old speaker terminal, and that didn't leave any bare metal exposed. I cleaned all the solder off the positive terminal, stripped a bit of insulation off the end of the inductor wire, and resoldered everything, and I'm back in business.

Along the way I learned some really valuable lessons like check connectivity before gluing the backplate back in Thanks for the help yall

As for the A/B...I'll be damned if I can hear a difference between the original electrolytics and the new film caps I put in but I'll do some more detailed listening tonight.

 

[StimpyWan]

Thanks for all the helpful comments, but this one in particular helped me understand what's happening. It now seems obvious that the red coating on the inductor is insulation, bc otherwise the entire thing would be conductive with itself and that makes no sense.

Upon paying closer attention to what's happening, and reviewing these responses, as shoddy as my soldering my be (and I know it's not great), the signal is making it to the tweeter. Where it's not making it is the woofer — I clipped the end of the inductor coil off with the old speaker terminal, and that didn't leave any bare metal exposed. I cleaned all the solder off the positive terminal, stripped a bit of insulation off the end of the inductor wire, and resoldered everything, and I'm back in business.

Along the way I learned some really valuable lessons like check connectivity before gluing the backplate back in Thanks for the help yall

As for the A/B...I'll be damned if I can hear a difference between the original electrolytics and the new film caps I put in but I'll do some more detailed listening tonight.

Awesome. Glad you got it figured out and working...!

As to hearing differences, that probably means the original electrolytic's were still OK. They weren't bad, so the comparison wasn't as stark, as when the NPE's have out and out failed. And give them some playing time, and they'll improve. Still, the new film caps will outlive us.

 

[FatMaul]

At least you know these will last a long time. Keep plugging away, it's a really fun hobby and a valuable skill. Maybe next time your dishwasher stops working you pull the circuit board out and notice some bad solder joint and save yourself $400.

 

[FatMaul]

Also keep me updated on what you do with your 4002s. I just ordered surrounds as well as new voice coils and ferrofluid for the tweeters. I noticed the cloth on my grills were actually different shades of tan, I thought maybe one was just faded but that combined with serial numbers that are far apart and slight differences in the tweeter design make me think my pair were more cousins than siblings.