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Post subject: Re: Hot Rod Deluxe LOUD hum
Posted: Sat Mar 08, 2014 10:35 pm
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I put the volume pot back in. No change, still a loud hum when certain tubes are inserted into V1. I inadvertently touched the black coax that is soldered from V1's pcb to the main pcb and the amp was dead quiet. This has to be a grounding issue?

I'm starting to question my sanity for modding this amp.


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Post subject: Re: Hot Rod Deluxe LOUD hum
Posted: Sat Mar 08, 2014 10:51 pm
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mattmcconnell wrote:
I'm starting to question my sanity for modding this amp.


Perhaps Fromel should petition the courts for a name change......

(Barnum might be appropriate)

:wink:

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Post subject: Re: Hot Rod Deluxe LOUD hum
Posted: Sat Mar 08, 2014 11:04 pm
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Assuming that you pulled the main circuit board, you might have broken one or more of the ribbon cable's solder connections, or a wire itself, or even some other solder connection. Did you reattach the green ground wire on the right side of the board, and use all six screws holding the board in place? Look closely at the coax cable, for the reverb, where it is soldered to the board.

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Post subject: Re: Hot Rod Deluxe LOUD hum
Posted: Sun Mar 09, 2014 2:45 am
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And what do you think about all the wiring layout ?

If you move or remove the PCB board you must be carefully bend all wire like they where before.

If not you may have noise and hum .


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Post subject: Re: Hot Rod Deluxe LOUD hum
Posted: Sun Mar 09, 2014 7:19 pm
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A few of the ribbon cables broke (those suckers are fragile) during the mod so I replaced all of them with discreet wires.

I went through the components today with my meter and everything seems to be in order, except for the serious hum. If I remove V1 it goes away. I have tried multiple tubes there but with the same outcome. If I put my hand about an inch from V1's pcb, the hum disappears. That side of the amp is missing most of the aluminum shielding tape, so maybe that is a factor but I don't think so. I'm totally lost here. If anybody has any other suggestions it would be greatly appreciated.


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Post subject: Re: Hot Rod Deluxe LOUD hum
Posted: Sun Mar 09, 2014 8:54 pm
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mattmcconnell wrote:
A few of the ribbon cables broke (those suckers are fragile) during the mod so I replaced all of them with discreet wires.

I went through the components today with my meter and everything seems to be in order, except for the serious hum. If I remove V1 it goes away. I have tried multiple tubes there but with the same outcome. If I put my hand about an inch from V1's pcb, the hum disappears. That side of the amp is missing most of the aluminum shielding tape, so maybe that is a factor but I don't think so. I'm totally lost here. If anybody has any other suggestions it would be greatly appreciated.


Did you replace the Fender input jacks with the ones from the Fromel kit?

"Switchcraft Input Jack - Your input jacks are soldered directly to the circuit board, apply some tension when the amp is plugged in and you could cause major damage to the circuit board in the amp. This mod gets rid of the wimpy plastic input jacks and replaces them with high quality metal switchcraft jacks that are panel mounted and NOT directly soldered to the circuit board. Included is a shoulder washer and isolation washer so the input jacks do not ground directly to the chassis and prevents ground loops. The jacks come pre-wired with high quality, Teflon Coated, Silver Plated Solid Copper Core wire. The solder I use is Silver bearing. This is the same quality you will find in high end boutique amplifiers costing thousands of dollars. Newer Hot Rod Deluxe amps have a better quality Neutrik input jack which are better than the older amps but they are still attached directly to the PCB."

Did you use the Fromel provided isolating washers that go between the jack and the metal front panel? If you did not use them, that could be your problem. The stock jacks are isolated from the front panel and grounded through the circuit board. Failure to isolate the new jacks from the front panel could result in an improper ground and cause a ground loop induced hum. Removing V1 would take the jacks out of the circuit and eliminate the hum.

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Post subject: Re: Hot Rod Deluxe LOUD hum
Posted: Sun Mar 09, 2014 11:41 pm
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mattmcconnell wrote:
I put the volume pot back in. No change, still a loud hum when certain tubes are inserted into V1. I inadvertently touched the black coax that is soldered from V1's pcb to the main pcb and the amp was dead quiet. This has to be a grounding issue?

I'm starting to question my sanity for modding this amp.


If you look at this black coax cable, there should be a woven outer sleeve that is soldered to a grounding point. Or at least, to a point that goes to ground. Maybe this wiring that comes off? Also, the opposite end of this same coax cable should NOT have any woven sleeve attached to ground. That is, one side has the sleeve grounded, and the other side not grounded.


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Post subject: Re: Hot Rod Deluxe LOUD hum
Posted: Mon Mar 10, 2014 2:15 am
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mattmcconnell wrote:
A few of the ribbon cables broke (those suckers are fragile) during the mod so I replaced all of them with discreet wires.

I suspected those wires ,they act like antenna




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Post subject: Re: Hot Rod Deluxe LOUD hum
Posted: Mon Mar 10, 2014 8:58 am
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I checked k all the coax cables and they are intact.

Do the ribbon cables make that big of a difference? Should I replace with aactual ribbon cable?

The input Jacks are isolated from the chassis.

Thanks


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Post subject: Re: Hot Rod Deluxe LOUD hum
Posted: Mon Mar 10, 2014 9:04 am
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Matt, I wonder what made the amp quiet, when you touched that coax cable? By quiet, do you mean no sound at all. Or no hum, at all? If it's no hum.... I think you should inspect that area where the coax cable resides. Check both ends of the cable's connections.

Good luck!


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Post subject: Re: Hot Rod Deluxe LOUD hum
Posted: Mon Mar 10, 2014 9:08 am
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mattmcconnell wrote:
I checked k all the coax cables and they are intact.

Do the ribbon cables make that big of a difference? Should I replace with aactual ribbon cable?

Thanks


Sorry I don't know .

I remember moving ribbon cables and other single wires close to the Power Transformer do som noise in the amp .


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Post subject: Re: Hot Rod Deluxe LOUD hum
Posted: Mon Mar 10, 2014 11:03 am
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Yeah when I touch the coax or even go near it the hum goes away. I'll check it out more thoroughly tonight. I'm positive it is something that I did to it during this whole process.

I appreciate the continued advice!


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Post subject: Re: Hot Rod Deluxe LOUD hum
Posted: Mon Mar 10, 2014 6:41 pm
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This is clearly a grounding problem that will only be solved by close inspection of all connections and wire routing.

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Post subject: Re: Hot Rod Deluxe LOUD hum
Posted: Tue Mar 11, 2014 1:51 am
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bluesky636 wrote:
This is clearly a grounding problem that will only be solved by close inspection of all connections and wire routing.



Some photos may help :)


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Post subject: Re: Hot Rod Deluxe LOUD hum
Posted: Tue Mar 11, 2014 4:14 am
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Is it possible that you have swapped the cables on the reverb tank?

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