ADC XLM MkII Improved Repair?

[jjbunn]

I inherited an ADC XLM MkII Improved cartridge. Unfortunately, the Left winding is open circuit (the Right winding measures 830 Ohms). Perhaps the internal connection from the winding to the pin has come off?

How difficult is it to open up the cartridge and perhaps repair it?

 

[JamVal]

I have an older ADC G-U cartridge. The cartridge body is the same or similar to your XLM body.
Mine didn't have the same problem as yours, but what might help you is the metal cover came off mine easily once when I removed the stylus. I think I gripped the stylus too hard. I had to glue the metal cover back on.
I took some photos of it with the metal cover off which gives you a view of what's inside. (disregard the red arrows)
If there is a disconnect between the winding and the pin it would be easy to see with a magnifier. Reattaching maybe not so easy, the wires are fine as baby's hair.




This is the link to the thread I started on my issue of the metal cover coming off. Based on the replies it sounds like these ADC cartridges come apart fairly easily.
https://audiokarma.org/forums/index.php?threads/adc-cartridge-came-apart.831861/

 

[jjbunn]

Thanks, JamVal - very useful. I am going to try to remove the casing and take a look inside. I''m hoping it's as simple as a wire that's become detached ....

 

[jjbunn]

I took the cover off, with a bit of gentle wiggling. Unfortunately, inside I found that the wires are all connected. So the Left winding must have burned out or something. I don't see any way of fixing it.

 

[JamVal]

Too bad, but it was worth the try. I have an AT P-mount that is dead on one side. I've always wondered what would cause it. It's not like a voice coil that could be overdriven or clipped.
My AT cartridge that went bad is similar to the one in the attached video and looks like it couldn't be repaired.

 

[Wolfie62]

Those coils don’t “burn out.”

You have a a bad connection to one of the pins in back.

Those fine wires are actually easy to work with if you have a 10x loupe. You just wrap the wire around the pin and solder it. The solder burns off the enamel from the wire, the flux cleans and attaches solder to the wire and pin.

If it were me, I’d resolder the connections inside on the pins where the connection has likely failed. Both pins to the open coils.

The other possibility is there is a break in the wire that connects 2 coils. Each diagonal coil is part of a coil pair for a channel.

 

[jjbunn]

Those coils don’t “burn out.”

You have a a bad connection to one of the pins in back.

Those fine wires are actually easy to work with if you have a 10x loupe. You just wrap the wire around the pin and solder it. The solder burns off the enamel from the wire, the flux cleans and attaches solder to the wire and pin.

If it were me, I’d resolder the connections inside on the pins where the connection has likely failed. Both pins to the open coils.

The other possibility is there is a break in the wire that connects 2 coils. Each diagonal coil is part of a coil pair for a channel.

OK I'll try re-flowing the solder, but my hunch is that there is a break in the coil, although how that could happen other than an excess of current at some point, i.e. burning out, I don't know?

 

[Wolfie62]

OK I'll try re-flowing the solder, but my hunch is that there is a break in the coil, although how that could happen other than an excess of current at some point, i.e. burning out, I don't know?

Where would that much excess current come from? Meter perhaps? Wouldn’t it have burnt out both coil sets, one after the next, L channel and R channel? Excess current like that wouldn’t come from the cantilever armature’s motion.

There could be a break between coils. There are 4 coils; 2 in series for L channel and 2 for the R channel.

 

[jjbunn]

Where would that much excess current come from? Meter perhaps? Wouldn’t it have burnt out both coil sets, one after the next, L channel and R channel? Excess current like that wouldn’t come from the cantilever armature’s motion.

There could be a break between coils. There are 4 coils; 2 in series for L channel and 2 for the R channel.

Faulty phono stage that's putting out significant voltage on the Left input somehow? I'll reflow the solder joints on the pins and report back.

 

[Wolfie62]

Very unlikely, as there is a capacitor (picoFarads) across the input of each channel. It’s an open circuit to dc.

Hopefully reflowing the solder works.

 

[jjbunn]

No luck reflowing the solder. Looks like the coils are open circuit inside somewhere, as feared :-(

 

[Wolfie62]

Remove the yellow tape, check connection between the open coils. If you want. I would.

 

[jjbunn]

Perhaps I should pop it in the mail to you ?!

 

[Wolfie62]

Maybe not a bad idea.... I have 5 good gold bodies. 1 I had to repair several years back. I’m glad they aren’t potted inside. The one I repaired had a pinched wire inside between the coils that finally broke. Got pinched during factory assembly.

 

[jjbunn]

If you're up for taking a look that would be super ... PM me your address and I'll put it in the post to you

 

[Wolfie62]

Actually, I have 6 gold body ADC cartridges. All of these are 820 ohms/580 mH late model types.

What I’ll do is send you a good one, untouched by me. Then I can work on your bad one. (I have plans!) I want to try something with it, namely damping the coils from mechanical vibration.

1 on a straight arm Denon headshell here:



4 unmounted here:



And an additional 1 here. This is the one I repaired between the coils.

 

[jjbunn]

A kind offer I cannot refuse! I'll PM you.