Replacing can capacitors

[t_byrd]

Hi all,

I've recapped a few amps recently and have been replacing the multi-section can caps with multiple discreet radial or axial capacitors. This has worked fine for me so far, I have been leaving the old can cap in and tying all the new caps to a ground point and routing each one to their destination.

Currently working on a Guild Thunderstar and the power amp section has 3 can caps with many of the power section's ground points connected to the various ground tabs on the cans. Is it bad practice to leave some of the ground points connected to the can cap and only rerouting what I need to for the new caps? Seems like it would be ok to me but I haven't done something like this yet.

Just wondering if there is anything wrong with leaving the old cans in and continuing to use them as ground points.

Thanks!

[nevetslab]

In a word, YES. If that capcan has any sections that are bad, such as dead short, it shorts out the circuit, as well as drags down circuits it's filtering, causing further calamity.

I had recently removed an old 3-section capcan from an Altec Lansing 316A AM/FM Tuner. I had heard some folks have been able to pull apart the removed Capcan, and extracted the insides I selected the replacement caps for this part that would be able to fit inside the can, assuming I WAS able to pull it apart. Turned out the original part was well potted, and NOTHING was going to get that out of the aluminum housing. BUT, I did at least extract the Ground Ring from that capcan, which has the twist-lugs, offering three grounding terminals. I ended up using that ring along with a copper plate cut to fit between the terminals, and soldered that plate to the plated chassis. I had punched mounting holes in that copper plate to install insulated terminals and installed the Radial caps between the ground tabs and the insulated terminals.

Since then, I purchased some FR4 fiberglass material so I could cut/fit the fiberglass to pick up the mounting holes if available, or if not, extract the ground ring and then punch holes in the fiberglass base to swage in Turret Terminals, where I could then insert the new radial caps thru the turret (has thru-hole) and glue/solder the new radial caps' lead wires to the turrets, now swagged into the fiberglass base to retrofit into the space of the failed capcan.

AS you're dealing with high voltage (usually) in replacing the capcans, using swaged Turrets, you have to keep the spacing appropriate for the applied voltage. 10mm spacing works well. 7.5mm won't with the turrets being swagged into place.

[Helmholtz]

A don't see a problem with re-using the ground lugs as long as all positive can lugs are disconnected from circuit.

[nevetslab]

Just wondering if there is anything wrong with leaving the old cans in and continuing to use them as ground points.

Thanks!

I see I overlooked this question as it was stated. Sorry about that.

[t_byrd]

I see I overlooked this question as it was stated. Sorry about that.

Thanks anyways! I probably could have been clearer in the way I worded it. All the positive lugs will be disconnected from the circuit.

[xtian]

Yes, you can. But usually you can improve the original (crappy) grounding scheme.