Axial to Radial electrolytic capacitor adapters.

Description

Buying for a Fender Hot Rod Deluxe/Deville or a Blues Deluxe/Deville? You might find the Hot Rod Deluxe repair Kit including components to be better value.

The IC (Illinois capacitor) TTAA model caps that Fender and Peavey (and a couple of other North American manufacturers) use have a deserved reputation for failure in guitar amps.

These boards will allow you to use a radial cap in place of a failed axial capacitor. You don’t even need to remove the PCB, provided your soldering skills are good you can snip the axial leads leaving 6-7mm and just slot the adapter on to the board.

Why use a radial capacitor adapter?

A few years ago, it was quite easy to replace the caps in a Fender amp with high quality Nichicon or F&T caps. Sadly Nichicon have discontinued their high voltage axial range. F&T Type A series are still available but only through specialist suppliers, and the superior F&T AH series are not available anywhere. Stock levels of F&T parts are vary variable in the UK and are not available from ISO9001 sources with traceable provenance.

In contrast, radial capacitors are experiencing something of a boom. Very high reliability switch mode power supplies are needed to in medical equipment and this has created a demand for high reliable high voltage radial capacitors that last for ages and actually do what they’re meant to do! Radial capacitors are widely available from RubyCon, Panasonic, Nichicon, EPCOS and other respected brands.

Which one do I need?

The sizes describe the original axial cap.

For a Fender Hot Rod Deluxe or Blues Deluxe, you need 1x 57, 1x 50.5 and 2x 48mm pitch, although I recommend upgrading the amp to Deville PSU spec. You can buy this as a kit here.

For a Fender Deville model, you need 2x 57, 2x 50.5 and 2x 48mm of each. You can buy this as a kit here.

For Fender Blues Junior, you need 1x 50.5 and 3x 38mm pitch. You can buy this as a kit, along with the other common blues junior parts here.

57:

Pitch: 57.00mm

Length: 50.0mm

Diameter: 23.0mm

50.5:

P: 50.50mm

L: 42.5mm

D: 20.0mm

48:

P: 48.00mm

L: 40.0mm

D: 16.0mm

Which radial caps should I use?

There’s loads of choice, thankfully. 105 degree caps are always the best choice for a valve amp, as explained here. I recommend the high reliability RubyCon BXC, BXW, TXW series. There are good 105 degree options available from Rubycon, Nichicon, EPCOS and Panasonic.

The recommended radial lead pitch is 7.5mm, but 5mm and 10mm pitch caps can be made to work with a bit of careful lead bending.

The recommended radial cap diameter is 16mm or less, but again, wider caps can be used with a bit of careful lead bending and maybe some heatshrink.

The recommended radial cap lengths are:

57mm adapter: 46mm

50.5 adapter: 40mm

48 adapter: 30mm

How do I install the adapters?

Video coming soon.

1. Cut the axial caps, leaving 6-7mm above the amp PCB
2. Install the new radial caps into the top of the adapter, observing polarity. Secure the caps using an electronic adhesive. I use Servisol 31665 silicone.
3. Solder the caps from the top side.
4. Flush cut the radial cap leads underneath the board, so that they protrude by no more than 0.5mm.
5. Smear a thin layer of silicon on the bottom of the adapter.
6. Observing polarity, place the adapter over the old axial leads on the amp PCB. Bend the axial leads along the pad towards the centre of the adapter.
7. Solder the axial leads to the board. It’s VERY important to do this quickly with a hot enough iron. Holding the iron on for too long may result in the old axial leads becoming desoldered from below the board.