SVT-VR Fan Operation

Alex1984 · #1 11-14-2010, 04:54 PM

How is this fan wired? Is it supposed to turn on when the amp turns on? Or only if it gets to a certain temperature?

Jerrold Tiers · #2 11-14-2010, 08:45 PM

The SVT and VR fan is just "on" when the amp is on.

If the unit is wired for 230V, the fan will only run when NOT in standby.

Alex1984 · #3 11-14-2010, 11:20 PM

Hmm. Seems like I have a lemon. Is it connected by a harness or anything? Or should I take it in to a tech?

Everything else seems fine. Would it be safe if I run at low volumes? Would an external fan help?

Jerrold Tiers · #4 11-15-2010, 06:52 AM

The fan is connected by a harness, so it could be loose, or the fan/harness could be bad.

Look and see if it seems to be jammed by anything. Any tech can replace it.

The fan is probably not "essential", tubes do get hot regardless. But it DOES help to keep everything else cooler, so the tubes don't "cook" the chassis, particularly the preamp.

Think of all the units that have worked since the 1950s or 60s with the tubes hanging off the bottom of the chassis, hot air rising and heating the chassis, no fan.

That said, I'd get the fan problem resolved if I were you.

beans-on-toast · #5 11-15-2010, 07:20 AM

It is possible that the wires to the fan have become disconnected as Jerrold mentioned.

The VR fan has two male spade connectors on it. There should be two wires with female connectors pushed onto it. At the other end of the wire is another pair of connectors that push onto some pins on the chassis. These pins are located behind the transformer.

You will need to check that the connectors are plugged in and seated properly. To do this, make sure that the amp is turned off and unplugged. Remove the rear metal corners on the amp cabinet. Remove the screws for the rear chromed panel. Tilt the top of the panel back a bit. Be careful not to scratch the power amp chassis. The fan is bolted on to this panel and the wire is just long enough to pull it back a bit and allow you to unplug the two wires on the fan. Remove the chromed panel. Move the fan blades. They should spin freely. Try to reach around the transformer on the back right hand side and check that the fan wires are plugged in properly. If you can't get to them you will have to remove the cloth covered panel on the front. Remove the front bottom metal cabinet corners. There are velcro type snaps holding this in place on the left and right sides. Get a long wooden spoon or something similar and from the back carefully but firmly push on each side, a bit at a time, until the front panel pops off. This will allow you to see where the fan wires plug in. Check that they are seated properly. If you want you can plug in the speaker cabinet, connect the wires to the fan, turn on the amp, and test that the fan is now working. Then reassemble in reverse order. Make sure that you didn't unplug any of the other connectors while you were working. Check that they are all seated properly by pushing on them.

If the fan still doesn't work you will need to have someone service it.

This sounds complicated but it isn't that difficult. You should feel comfortable doing something like this before you start. Always be very careful to take precautions against being electrocuted when working inside an amp. Especially an SVT!

Alex1984 · #6 11-15-2010, 10:40 AM

Thanks a lot for the response, I'll try it first thing after I get home today!

Does anyone have pics of what this looks like?

beans-on-toast · #7 11-15-2010, 12:10 PM

All I have is a pic of what the fan spade connector looked like on my VR.

Alex1984 · #8 11-15-2010, 12:24 PM

Thanks a ton! I'll check back later tonight!

Hmm...the link wasn't quite working...

Alex1984 · #9 11-15-2010, 11:12 PM

Hey TB! You guys saved the day!

After 20 minutes of fiddling around, and thanks to the detailed pic, I was able to open it up and find the fan disconnected. After reconnecting, everything is fine and dandy!

Great head overall, although I still prefer my SVT-II by a small margin.

Can I jack my own thread and ask for some recommended tones for alternative/classic rock?

OldHack · #10 11-15-2010, 11:19 PM

Quote:

Originally Posted by Alex1984

Can I jack my own thread and ask for some recommended tones for alternative/classic rock?

I hear a VT Bass into one of those MarkBass amps does it pretty good

OldHack · #11 11-15-2010, 11:22 PM

Seriously, congrats on the VR, glad you got the fan sorted.

beans-on-toast · #12 11-16-2010, 03:54 AM

It's nice to be able to fix things yourself.

When you can afford it, replacing the tubes will improve your tone. Try good quality NOS pre-amp tubes and a matched sextet of SED "Winged C" SV6550C power tubes.

I start with the tone controls set at noon, flat on the SVT's, and the tone switches off, midrange switch in the middle. Then tweak the tone knobs a slight amount according to how my hearing is that day.

You can also try using a short instrument cable plugged into the front inputs to jumper channel 1 to 2. Then both sets of channel controls can be used to contour your sound.

Alex1984 · #13 11-16-2010, 11:21 AM

I think the main difference is that I found the high ends on the SVT-II to be more crisp. Then again, I'm running this one through a 215 rather than 810, that's probably gonna be quite different.

Don't think I could ever afford NOS tubes given the price range that they go for.