Crossover help?

imhififan knows his stuff, I would check for possible shorts and clean all the flux off the boards so you can examine it closely, 91% works better than 70%. Maybe something like a frayed strand of wire or solder splatter creating an intermittent short.

Thank you to everyone who contributed to this thread.

The strangest thing happened.

After checking the network as per imhififan's suggestion I had to go out, came back and plugged in the network.

Working!! wft?

Replaced the 2R7 still works, installed 56R still works.

Bolted everything back together installed fitted new tweeter and we have music.

First impressions admittedly with only 1 side done, the overall sound seems more open, there is definitely more HF on the upgraded side but with less glare. I thought the + upgrade reduced treble by using the 56ohm (about 1db?) and lowering the crossover from 3 to 2.5k

I've had to postpone the other side as when I was checking R values the 2R7 (which was installed) gave some odd readings then the lead fell out!

I'm now going to have to wait for a replacement before tackling the other channel.

Shame as my job tomorrow's has just cancelled due to covid.

Thanks again for your help.

Ian

Thanks imhififan thats exactly what I was hoping someone could come up with.

Just checked the network as you suggested.

HF input terms OL

HF output terms starts at 0 climbs to 3.1

HF - to HF - 0.00

Surely its not possible the 3.3 cap stops that particular tweeter from functioning?

The new tweeters have just arrived but I can play with them until later this evening

These are the photo OP posted on his system page, Seems like a simple two ways 2nd order xover with total 6 components.

The 3rd photo I believe is the original xover.

Based on the picture, I draw out the schematic:

1. Without tweeter connect to the board, use ohm meter test across the HF input terminals, it should be Infinite resistance.
2. Across the output terminals to tweeter, it should has a reading of about 3ohm or little higher ( 2.7ohm+DCR of the small inductor).
3. Ohm meter on HF negative input terminal to negative tweeter output terminal should has 0ohm reading.

Hope it helps and good luck 🤞

A little late perhaps but here is how you do it.

Notice the last few pictures are the crossover upgrade. The last one is annotated with measured values and the wires that attach. There are also pictures of the original xo that I didn't post but are the same, multiple pictures including one annotated with all values and connections. Also in addition to this the parts were physically labeled, both the wires inside the speaker and on the boards. All the wiring is point to point and every part on the original was measured individually. This is how you do it when you want everything to work right the first time. 

If you take real clear pictures from different angles showing clearly all the solder joints we might still be able to figure this out. That is your best bet, because no manufacturer is going to do anything but sell you another crossover, and probably not even that. If you were making speakers and a customer called saying he screwed it up would you trust him to not screw up installing the replacement? I wouldn't. So figure it out and fix it.

If there is a circuit board then clear pictures of both sides. Circuit board traces are pretty thin, it is real easy to burn one out if you're not skilled at soldering. 

Did you read that thread I mentioned, I find it hard to believe your tweeter not fried or board damaged. You have to make sure you haven't damaged voice coils, pretty fragile. Multimeter readings often of no use when everything in circuit. You have to put battery across speaker terminals, or send signal directly to tweeter bypass entire crossover, remove all crossover wires from tweeter terminals and test. If tweeter working, circuit board bad. Unless fried inductor.

You may have to find local tech or send board back to PMC. Too difficult to troubleshoot by forum. I just have to believe you've fried something.

I used a sucker and wick, the tracks are pretty robust.

I get a a bleep up to and away from the cap, can't test the cap but neither new or old refitted made any difference.

I'll play around again tomorrow see if I can find a break.

Really struggling with this one.

Any idea what reading I should get from the coil?

Its showing 0.9 .71mm

I searched and saw picture of upgrade, you have circuit board, per grannyring likely damaged pad or trace. Solder pads easily damaged in removal of original components, need proper desoldering equipment, don't force anything. Believe me I know from experience.

Above if you're 100% sure drivers working.

I don't see your system. Look at this thread,https://forum.audiogon.com/discussions/tweeter-blown-or-crossover-how-to-check

Hi and thank you for the replies.

The speakers are PMC FB1 they are well known for being overly bright.

Its been my intention to follow the + upgrade for years but had never found the crossover changes until recently. . I got hold of the layout with values and found a photo of the upgraded network.

The only changes are replace the 3.0 cap with 3.3 and add a 56ohm resistor.

I decided to change the ageing cap on the LF and resistors as a what the heck while I'm in there.

I removed the network, removed HF resistor, positioned the new, removed cap, positioned new, same for LF positioned 56ohm flipped it over and soldered everything in. clipped tails and reinstalled network, no HF.

Removed network desoldered 1 end of 56ohm, checked no change.

Checked tweeter operation, working.

Removed network checked for shorts, poor joints and poked around with continuity tester, nothing obvious.

Removed HF parts refitted originals checked, no change.

Since then I've been poking around trying to find anything amiss.

I've posted some pics on my system

This is example of why one should take photos, more photos and more photos of any equipment one working on. You cannot have too many pictures. If OP took photos prior and wired up exactly the same, only fried components could account for failure. Hand drawn schematic good back up. Also, get value of components in photos if possible.

When I did my last crossover mods, I took tons of photos, got stuck in middle of mods, luckily found the single photo that was at proper angle to see hidden wire.

what is the brand and model of your speaker?

To post pictures, go to https://systems.audiogon.com/

Click the "Create system" on the top menu bar, then type in a system name and you can start add images to it.

I've been unable to discover the issue or post pics.

Looks like I'm going to have to build point to point external crossovers.😣

I believe you can add photos to your post now, but haven't tried. You can also post photos at https://systems.audiogon.com/ 

by the way, the capacitor will never test positive on a "continuity tester" because it's not really an absolute connection.  You can try testing for capacitance if you are an LCR multimeter.

How do you attach images? 

It links to a url rather than to a location on the PC.

Are the parts point to point wired or circuit board? If board, you may have a lifted solder pad, possible short to ground plane etc… please let us know. Pics would help greatly. .

I do get a bleep from both terminals so assume thats the parallel resistor.

I think you wired the high pass crossover wrong. If there’s a parallel resistor, it should be after the capacitor and connect across the tweeter +/- terminal.

If the parallel resistor wired in front of the capacitor across the input side +/- terminal you will get a bleep on continuity test. If that’s the case, the resistor "shorted" the high pass crossover input hence no HF signal reach the tweeter.

I'm assuming you're talking about a passive crossover within your speakers, correct? Could you post some photos? Or a schematic of the original crossover? We can figure this out with just a multimeter.

Hi Thanks for the reply.

The crossover was removed completely.

The tweeter is still fine, checked.

I don't have any form of heat sink, i have previously soldered much smaller components with success.

The only items removed/replaced are resistors and a caps.

The continuity is from HF +/- which is assume to be the parallel resistor?

Regards Ian

Are you sure the tweeter is functional, did you disconnect all drivers prior to soldering. If you're getting continuity from binding post to speaker terminal has to be tweeter. if you applied too much heat for too long you may have fried something. Should always use heat sink, anti heat paste around fine gauge wiring.

Same thing , if you lost memory and call doctor, he is not help you , untill to visit to him.