Draining Filter Capacitors in a Fender Hot Rod Deluxe

[RxRotaryForLife]

Ok cool thanx for clearing that up for me!

[RxRotaryForLife]

Quick question. You said u use a 33k 5 watt resistor but it looks like a lil 1/2 watt resistor? What did u really use?

[tomfoyfx]

@RxRotaryForLife Oh yeah, you're right. It's 1/2 Watt. Search RN65D 3302F at mouser.com and you'll get the one I used.

[volesrock]

do i need to drain the caps to replace the two alpha pots on my jcm800?

thanks

[tomfoyfx]

@volesrock Yeah

[sexazzwill]

Well put together short Movie

[tomfoyfx]

@sexazzwill Thanks

[Ateamcaptain]

How long does it take for a capacitor to discharge on its own? I need to replace an ohm switch on my amp that busted off. Haven't played the amp in over a month.

[tomfoyfx]

@Ateamcaptain I don't know. If you have a multimeter, it's pretty easy to just check whether they're discharged enough. You might be able to find some info online about how long it takes, maybe on Justin Holton's site (url in video comments).

[Ateamcaptain]

@tomfoyfx K thanks. My multimeter died on me so I guess it's off to buy another.

[thedonace213]

I want to change the speaker on my Fender Champion 600 and to do that I have to remove the chasis, but I'm afraid of touching something and shocking myself, so how do I go about this?

[tomfoyfx]

@thedonace213 I haven't ever owned a champ, but it looks like you can take the chassis out pretty easily. Just don't touch anything on the actual circuit board and you'll be fine. You can handle the chassis and transformer cases without discharging the caps.

[pimorules]

ah ok just making sure :P didnt wanna go killing myself by accident or anything haha before the HRDx3 i had a crappy amp i borrowed for a while so this would technically be MY first amp i love it, i prefer the sound compared to what i used to have and the extra gain channel is fun to play with, i checked out an earlier version of this model and i hated the chrome plating or w/e where the knobs were it was kind of annoying reading it in store im glad they decided to go with black face this time

[pimorules]

you dont have to do this when you change the pre amp or power tubes do you? just recently got myself a hot rod deluxe III and i just wanted to know

[tomfoyfx]

@pimorules No, you don't have to discharge the caps to change tubes. You don't even need to take the back off. Btw, I've been meaning to go try out a HRDx 3, how do you like it?

[den098]

Aligator clip leads: pin 1 of v1 one side, ground the other side. thats the easy way!

[thedonace213]

I heard you can drain an amp by taking a screwdriver and making it touch the rods from the Outlet plug. will that drain everything? will it cause damage? how would I know if there are capacitors under the board?

[tomfoyfx]

@thedonace213 Do you mean just connect the prongs of the plug together by touching both at once with the screwdriver? If so, no that wouldn't do anything. The plug is isolated from the rest of the circuit by the power transformer.

[tomfoyfx]

@thedonace213 Some people bridge the capacitor leads (or bridge the positive lead to the chassis) with a screwdriver to drain it. It drains all the charge at once, and can be very violent - the leads can melt to the screwdriver, or burn marks are left on the chassis. Using a resistor drains the capacitor slowly, so sparks and exploding metal are avoided.

[tomfoyfx]

@thedonace213 You should be referencing the schematic of whatever you're working on, that's how you'll know whether there are capacitors you can't immediately see. In general, capacitors rated for 100V and above are the dangerous ones.

[tomfoyfx]

@thedonace213 You should be referencing the schematic of whatever you're working on; that's how you know if there are capacitors you don't immediately see. In general, capacitors rated for 100V and above are the dangerous ones.

What are you working on? In the HRDx, all the capacitors are visible when you take off the cover.

[thedonace213]

@tomfoyfx I'm just asking, I am thinking of doing some mods to my Fender Champion 600 so I can start learning how to mod amps and such. But I hear of the potential for injury so I want to be sure of what and how to do it.

[tomfoyfx]

@thedonace213 Ok. There's a schematic and layout for it on the fender site. C4, C5, C6, C7 are the filter capacitors in this amp. It looks like they're the kind with radial leads, which means they're not really exposed above the board. There are a few resistors that connect to these capacitors, though, so you could use a lead of one of these resistors and ground to drain the resistors.

[tomfoyfx]

@thedonace213 Take your multimeter, and put the positive probe on one of the leads of R11, and the negative probe on the chassis; you should get a DC voltage reading. If you want to use the capacitor draining method I use in the video, with the draining resistor, just touch one side of the draining resistor to one side of R11, and the other side of the draining resistor to the chassis (ground). Both sides of R11 are connected to the plus side of a filter capacitor, so I think this should work.

[tomfoyfx]

@thedonace213 You could also do this with the side of R9 that's closest to C7, and the chassis or other ground. Remember to check with your multimeter. If your amp has been on recently, you should see a DC volt reading across the capacitor. After you drain the cap, you should see it go down. Also, this seems like a good amp to mod, so there might be some tips on the internet somewhere about how to drain the caps in this amp. And follow all the safety guidelines I mentioned in the comments.

[tomfoyfx]

@thedonace213 Both sides of R12 are connected to the positive side of filter caps as well, so you could get a DC reading between either side of it and ground; and you could put the draining resistor between either side of it and ground to to drain the capacitors.

[bilbomarks]

Are those the only caps in an amp that need to be drained?

[tomfoyfx]

@bilbomarks Yeah the large electrolytics are the ones that hold dangerous charges. Some of the filter caps in the power supply for the solid state parts of the amp look pretty large, so it might be a good idea to drain those, too. C43, C42, C38, C39 (you can see them in the video below, and also below to the left, of the main filter caps). Those are radial type capacitors, so you might have to get under the board to get to them. Also, you can probably find Justin Holton's guide if you search it.

[tomfoyfx]

@bilbomarks Drain the larger, main filter caps first, before trying to get to the smaller ones, if you decide to.

[dividedbyjames]

Thanks for the info I'm more of a visual learner so having a video of this is cool. I know people think this is boring but for modding a Fender amp this info is crucial. It also matches the Justin Holton information but he uses the 25K 10W Cement Power Resistor in his directions.

[tomfoyfx]

@dividedbyjames Yeah I learned to do this from Justin Holton, too. He had such a great site; too bad it's not up anymore (although zipped pdf versions of the site are floating around).

[dividedbyjames]

@tomfoyfx I went to radio shack for some power resistors but they didn't have the same rating. They had 25w-8ohm, 10w-1ohm, 10w-10ohm, 10w-100ohm, 5w-0.47ohm. I was thinking the 25w-8ohm would suffice, but I slept thru my college physics classes and am not a fan of exploding resistors or electrocution. Should I try and find the specific one online (since I have to order parts anyway) or will any of those work temporarily?

[tomfoyfx]

@dividedbyjames Short answer: NO. Just went and looked this up: Power = Voltage^2 / Resistance (Ohms), so the difference between 25 k-ohms and 8 ohms is that the 8 ohm resistor will dissipate more power. Let's say possibly 400V is in the capacitor, so (400 V)^2/(8 Ohm) = 20000 W. So the 8 ohm resistor would need something like a 20000 W rating. I would go order a resistor online from mouser; they're pretty good about shipping things out quickly, so you won't have to wait that long.

[dividedbyjames]

@tomfoyfx good thing I asked... Thanks!

[Linefollower24]

idek whats happening but i was sent by guru to leave a comment so i am

[tomfoyfx]

@Linefollower24 Cool, thanks

[AvieBabie56]

Is it sad that a 14 year old girl like me knows what he is talking about? XD

[SonyslaveTV]

this is dumb.

[ConsiderMeGuru]

@SonyslaveTV ur one to talk matt:)

[tomfoyfx]

@SonyslaveTV Yeah

[XXVitalEagleXX]

hello, good sir, i wish I knew what you were talking about, but I don't and CMGuru sent me. ;P

[tomfoyfx]

@XXVitalEagleXX Lol thanks for stopping by. Yeah I know this video is not entertaining at all; it's really only meant to be educational. I'll be posting a list and demo of my modifications to this amp, and I wanted to make sure this information is readily available so that people don't hurt themselves trying to do what I did.

[AvieBabie56]

I WAS SENT BY CONSIDERMEGURU!

[tomfoyfx]

@AvieBabie56 Thanks!

[XXVitalEagleXX]

ConsiderMeGuru sent me!

[ConsiderMeGuru]

I will be your first comment.... FIRST! I had no idea what you were talking about dude :) IF YOU ARE READING THIS, LEAVE MY FRIEND THAT MADE THIS VIDEO A COMMENT:) He is new to YouTube, or at least video making wise he is :)

[tomfoyfx]

@ConsiderMeGuru Lol you do command some attention! Thanks, but I don't think any of your youtube friends will like this at all, unless by some chance they do.