Preamp Capacitor Questions

[PreCD]

I posted this over on the amp section but should have been here.

I am recapping my Adcom GFP-565 and was wondering what the forum members might recommend. My choices so far are:

Elna Silmic II
Panasonic FM
Nichicon Muse

The old capacitors are Panasonic.

I believe I have decided on the Panasonic FM. When measuring across the soldered leads of the caps in the preamp I find 7mm between the - and +. Should I go with a tapped lead of 5mm or stick to the 2.0mm leads?

I know this sounds trivial to some but this is my 1st project and with all the specifics dealing with components I want to make sure I get it right the 1st time especially when ordering.

[AndrewT]

If the holes in the solder pads are ~7.6mm centre to centre, then the actual spacing is almost certainly 0.3"
Buy capacitors that have 0.3" pin pitch. These will fit straight into the existing holes.

[PreCD]

Originally Posted by AndrewT

If the holes in the solder pads are ~7.6mm centre to centre, then the actual spacing is almost certainly 0.3"
Buy capacitors that have 0.3" pin pitch. These will fit straight into the existing holes.

Thank you sir for your response. The caps that I am looking at and that will fit next to each other in this unit are the Panasonic FM capacitors. Their data sheet does not reference 0.3" pitch but that translates to roughly 7.5mm. Here is the data from their sheet:
"When requesting taped product, please put the letter "B" or "H" between the "( )". Lead wire pitch B=5 mm, 7.5 mm, H=2.5 mm."

So Andrew I will add the "B" into the part number of any capacitor I am ordering for this unit that is Panasonic FM series. That would give me a 5mm or a 7.5mm pin pitch. I am curious to see how you get both pitches. I am hoping to have the caps flat on the board.

Thank you again for your time and your help.

Kevin

[gootee]

I think that (B) would get you 5mm LS and () would get you 7.5mm and (H) would get 2.5mm. Maybe () is not available for the taped ("ammo belt") versions.

But most places you could order from will have one or more specific lead spacings available, so you should be able to know what you're getting before you order.

[PreCD]

Originally Posted by gootee

I think that (B) would get you 5mm LS and () would get you 7.5mm and (H) would get 2.5mm. Maybe () is not available for the taped ("ammo belt") versions.

But most places you could order from will have one or more specific lead spacings available, so you should be able to know what you're getting before you order.

I think that I will end up calling the distributor and just speaking with them on the lead spacings. With me never using these capacitors that would be the only way to roll I think. Otherwise I may get stuck with a bunch of caps that I just cannot use. Thank you for responding.

[discrete]

Try Digikey.com for Panasonic caps.

Their 'search engin' allows to filter for series, lead spacing, voltage, etc.

I would go with the Panasonic FC series.
Digikey carries stock of a nice variety of physical sizes and voltages in this series, the FM series is somewhat limited re. sizes and voltages.

E.g.:
Digi-Key - P10310-ND (Manufacturer - EEU-FC1V222S)

...$67 for 50 caps.

Measure the actual DC voltage across the current caps and make sure the new caps are rated 25 to 50% more than this.

[PreCD]

Originally Posted by discrete

Measure the actual DC voltage across the current caps and make sure the new caps are rated 25 to 50% more than this.

I have not thought of doing this. What is the reasoning behind that procedure?

[discrete]

Originally Posted by PreCD

I have not thought of doing this. What is the reasoning behind that procedure?

Normally you should be OK with just replacing the current caps with units of the same voltage.

But it seems the current caps failed prematurely, so better to be sure you replace with units of sufficient rating. Also to verify that the voltage is within reason for operation of the rest of the amp.

Careful not to create any shorts with the meter probes - that capacitor bank contains significant energy and will do a nice bang.

[Conrad Hoffman]

Caps vary in quality. Some last for many decades, some for a couple years at best. The original designer may have been "encouraged" to use parts the company already used in other designs so they could stock fewer parts and save money. The size and voltage may not have been as carefully thought out as one might hope. By measuring the voltage and applying a safety factor, you can be sure of having a suitable rating. BTW, avoid caps rated for under 16VDC as they just don't seem to last. Physically larger is usually better than smaller. Stick with brand names that have a good history. Nichicon, Rubycon, Panasonic, Illinois, Sprague (do they still make 'em?).

[PreCD]

Originally Posted by Conrad Hoffman

Caps vary in quality. Some last for many decades, some for a couple years at best. The original designer may have been "encouraged" to use parts the company already used in other designs so they could stock fewer parts and save money. The size and voltage may not have been as carefully thought out as one might hope. By measuring the voltage and applying a safety factor, you can be sure of having a suitable rating. BTW, avoid caps rated for under 16VDC as they just don't seem to last. Physically larger is usually better than smaller. Stick with brand names that have a good history. Nichicon, Rubycon, Panasonic, Illinois, Sprague (do they still make 'em?).

Thank you Conrad. I will stick to those brands and be careful of using any capacitors that are rated under 16VDC.