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Post subject: Fender Hot Rod Deluxe clean clipping
Posted: Wed Dec 25, 2013 2:39 pm
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Hey, I just got a used (but mint) Hot Rod Deluxe and I had an issue regarding the cleans. The clean channel, at any volume seems to be clipping and having a bit of rough distortion. I was wondering a) is this a common issue b) how would I fix it? I plugged my guitar straight into the power amp in and it had the same issue. could it be a tube issue? Maybe biasing?

Any solutions would be appreciated- thanks.


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Post subject: Re: Fender Hot Rod Deluxe clean clipping
Posted: Wed Dec 25, 2013 2:49 pm
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[quote="bradleycoy" could it be a tube issue? Maybe biasing?

[/quote]

Yes both , check Phase Inverter tube too , V3

Resistors in Phase Inverter circuit needed to be check . Desolder one side of the resistor to read with Ohmeter. Good luck , it's hard to work on this amp.


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Post subject: Re: Fender Hot Rod Deluxe clean clipping
Posted: Wed Dec 25, 2013 10:00 pm
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What guitar are you using? Hum-buckers, single coils?

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Post subject: Re: Fender Hot Rod Deluxe clean clipping
Posted: Thu Dec 26, 2013 11:27 am
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It's a squier j mascis jazzmaster with single coils. I get perfect cleans with my super champ xd


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Post subject: Re: Fender Hot Rod Deluxe clean clipping
Posted: Thu Dec 26, 2013 12:32 pm
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Have you tried input 2? As stratele52 suggested, the bias is probably cold.

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Post subject: Re: Fender Hot Rod Deluxe clean clipping
Posted: Thu Dec 26, 2013 2:18 pm
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shimmilou wrote:
Have you tried input 2? As stratele52 suggested, the bias is probably cold.

I'm assuming it's a bias issue, as even with my SCXD preamp and guitar straight in it's still clipping a bit. So yeah I'll try rebiasing it, any recommendations for how it should be set?


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Post subject: Re: Fender Hot Rod Deluxe clean clipping
Posted: Thu Dec 26, 2013 2:34 pm
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Assuming approx 430 VDC on the Plates, a minimum of 70 mV at the bias test point, maybe 80 mV would be about right. Always check the Plate voltage to be certain. The idea is to bias between 50% and 70% of the output tube's max rating. The reading at the test point is for both output tubes, so divide that reading by two, then multiply times the Plate volts. IIRC, mine is at about 75 mV at the test point.

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Post subject: Re: Fender Hot Rod Deluxe clean clipping
Posted: Thu Dec 26, 2013 4:22 pm
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shimmilou wrote:
The reading at the test point is for both output tubes, so divide that reading by two, then multiply times the Plate volts. IIRC, mine is at about 75 mV at the test point.



What happened if one tube is very bad, weak ? You will biased the only one which work fine until red palting to reach 75 mv ?
This amp do not work properly , you must know if the two tubes are good before .

For a good tone each tube must have cathode current close to 3 to 9ma between each

With reading both on same test point you won't know .


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Post subject: Re: Fender Hot Rod Deluxe clean clipping
Posted: Fri Dec 27, 2013 5:00 am
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Good point. A set of bias probes would be better, but sometimes you have to make due with what you have.

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Post subject: Re: Fender Hot Rod Deluxe clean clipping
Posted: Fri Dec 27, 2013 5:32 am
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shimmilou wrote:
Good point. A set of bias probes would be better, but sometimes you have to make due with what you have.


Before I had Bias Probes , I often use 1 ohm resistor between output tubes 's plate and ground . And I live them in the amp.

About this Hot rod , we must be sure BOTHS tubes are good with close bias , not guess if we want to fix clipping........


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Post subject: Re: Fender Hot Rod Deluxe clean clipping
Posted: Sat Dec 28, 2013 6:16 pm
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Opened it up and the right power tube wasn't glowing. tried switching the two and in the right slot it still wouldn't glow. I'm taking it to a tech but any ideas as to what's wrong?


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Post subject: Re: Fender Hot Rod Deluxe clean clipping
Posted: Sat Dec 28, 2013 6:50 pm
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The right slot is missing the heater voltage. Likely a poor connection, solder joint, broken trace or even a burnt trace. :idea:

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Post subject: Re: Fender Hot Rod Deluxe clean clipping
Posted: Sat Dec 28, 2013 7:03 pm
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shimmilou wrote:
The right slot is missing the heater voltage. Likely a poor connection, solder joint, broken trace or even a burnt trace. :idea:


+1

Check the trace to the tube socket with your DVM. Remember, you're looking for AC volts, specifically 6.3 or thereabouts. Set your meter's range accordingly.

Arjay

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Post subject: Re: Fender Hot Rod Deluxe clean clipping
Posted: Sat Jan 11, 2014 6:42 pm
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Check the solder joints on the tube socket. Gently wiggle the tube and watch the solder connections for fractures.

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