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Post subject: Filter Caps for a Hot Rod Deluxe
Posted: Wed Mar 22, 2017 7:34 pm
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Hey guys, I've got a 2002 Hot Rod Deluxe with the original light grey IC filter caps. One is starting to leak just a little bit, which is enough of a reason for me to swap them out. What brand do you all recommend? And while I'm in there, anything else I should swap or mod?

Thanks,
Skip B.


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Post subject: Re: Filter Caps for a Hot Rod Deluxe
Posted: Wed Mar 22, 2017 7:59 pm
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F&T makes the most durable electrolytic caps available.

Great for any amp, Fender or not.

Arjay

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Post subject: Re: Filter Caps for a Hot Rod Deluxe
Posted: Wed Mar 22, 2017 8:07 pm
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Great thank, Arjay.


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Post subject: Re: Filter Caps for a Hot Rod Deluxe
Posted: Thu Mar 23, 2017 1:10 am
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Retroverbial wrote:
F&T makes the most durable electrolytic caps available.

Great for any amp, Fender or not.

Arjay



+1


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Post subject: Re: Filter Caps for a Hot Rod Deluxe
Posted: Thu Mar 23, 2017 8:34 am
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While you're in there, a few maintenance items to take care of.
Resolder the white sandbox 5-watt resistors in the center of the board.
Resolder the zener diodes 1N5353 near those resistors.
Resolder all the jacks. Flow some hot melt glue between them to beef up their mountings.
Resolder tube sockets
Clean the NC switch contacts on the extension speaker jack.
Upgrade the reverb IC U2 with a TLE2072
Check all case and handle screws for tightness.
If you work with a bass player, consider changing C1 from 47uF to 2.2 uf.. This cuts your bass response in half and gives sonic territory back to the bass player. It also reserves more power to focus your guitar midrange band.
For cleaner treble, consider replacing the ceramic C7 250pF with a silver-mica equivalent


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Post subject: Re: Filter Caps for a Hot Rod Deluxe
Posted: Thu Mar 23, 2017 10:52 am
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That is a really helpful (and manageable) checklist. Thanks. A couple of follow-up questions:

1. Concerning the sandbox resistors, I saw a guy on YouTube who said that they get really hot and can lift or break the trace on the PCB, and, therefore, should be changed to a different kind. I also read on another board that some put a heatsink on them. What do you think?

2. Concerning upgrading the reverb IC to a TLE2072. What will that do? The reason I ask is that I find the reverb on my HRD almost unusable above about 1 or 2because it's so bright. Will the 2072 change it's tone?

Thanks again.


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Post subject: Re: Filter Caps for a Hot Rod Deluxe
Posted: Thu Mar 23, 2017 11:02 am
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SkipBurz wrote:
1. Concerning the sandbox resistors, I saw a guy on YouTube who said that they get really hot and can lift or break the trace on the PCB, and, therefore, should be changed to a different kind. I also read on another board that some put a heatsink on them. What do you think?


Lifting those concrete resistors away from the board will definitely improve their thermal resistance and extend their life. These resistors have always been problematic with the HRD and the Blues Deluxe amps.

Arjay

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Post subject: Re: Filter Caps for a Hot Rod Deluxe
Posted: Fri Mar 24, 2017 12:06 am
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Firstly, if it ain't broke, don't fix it! I wouldn't touch any solder joints that are good, only add solder if the joints are marginal or cracked, or if you see evidence of heat damage to the circuit board. For example, my HRDlx has little bumps on the sandbox resistors in the power supply that hold the resistor off of the circuit board, so very minimal evidence of heat damage to the board, and it is a '98 model, nearly 20 years old.

Ignore the advice to change the resistors to a different value (Fromel for one), it is pure hogwash. I ran the different values through simulation software to show that using different value resistors actually increases the heat produced. Raising the resistors off of the circuit board is a good idea, if necessary (heat damage), but this will require new resistors with longer leads in order to do that. :idea:

and +2 on the F&T caps.

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Post subject: Re: Filter Caps for a Hot Rod Deluxe
Posted: Fri Mar 24, 2017 1:27 am
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shimmilou wrote:
Raising the resistors off of the circuit board is a good idea, if necessary (heat damage), but this will require new resistors with longer leads in order to do that.


Correct.

Here's a good example of a properly-executed resistor mod......

Image

Arjay

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Post subject: Re: Filter Caps for a Hot Rod Deluxe
Posted: Fri Mar 24, 2017 5:05 am
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Very good advice from both of you, thanks. I wasn't considering changing the resistor values but just replacing the resistors with ones that have longer leads to get them up off the board. (Thanks for the photo, Arjay.)

I'm considering donating the amp to the jazz ensemble at the college where I teach, so I think I'll just change the caps, replace those resistors in the name of preventative maintenance, check all the solder joints and connections and be done with it. I also like the idea of floating some hot glue between the input jacks to stabilize them as well. They seem awfully flimsy.

One last general question while I have you: From where do you guys mail order you amp parts and components? When I build pedals, I usually get my stuff from Mammoth, and for tubes and tube parts from Tube Depot, The Tube Store or EuroTube. Am I missing a good source?

Thanks again.

Skip


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Post subject: Re: Filter Caps for a Hot Rod Deluxe
Posted: Fri Mar 24, 2017 7:14 am
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I order from many of the same sources as you but I use a few other companies as well like The Parts Guru, Angela Instruments, and Mojotone.

Arjay

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"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


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Post subject: Re: Filter Caps for a Hot Rod Deluxe
Posted: Fri Mar 24, 2017 9:12 am
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Fender reverbs are normally run at 2-3. Way more available than most pickers use.
The upgrade IC has 1/2 the noise and distortion and twice the speed. It makes the reverb more articulate.
The sand box resistors should be mounted securely to the board with silicone. They can vibrate with the speaker and break off otherwise.
I remove the 470 ohm 5-watt sandbox resistors and replace them with two 1000 ohm resistors in parallel, siliconed together and siliconed to the board. This reduces the temperature of the lower resistor to below burn stage.
You can also scrape the green solder mask away from those hot spots and tin them for effective heat radiation from the traces.


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