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Post subject: Re: Fender Hot Rod Deluxe (USA) Intermittent No Sound HELP!
Posted: Fri Nov 15, 2019 1:10 pm
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Do the clicks occur at a fixed, constant tempo?

Arjay

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Post subject: Re: Fender Hot Rod Deluxe (USA) Intermittent No Sound HELP!
Posted: Fri Nov 15, 2019 1:31 pm
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fenderguy81 wrote:
the clicking only seems to be audible when the guitar is close to and is facing the amp.



Because your ears are also close to the amp ?


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Post subject: Re: Fender Hot Rod Deluxe (USA) Intermittent No Sound HELP!
Posted: Mon Nov 18, 2019 10:31 am
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I tried plugging into the "power in" input and the same problem persists. As Arjay mentioned, it sounds like it must be happening in the power section of the amp. Since I've already tried swapping the power tubes, does anyone have any suggestions as to what else I should look for?

Thanks!


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Post subject: Re: Fender Hot Rod Deluxe (USA) Intermittent No Sound HELP!
Posted: Mon Nov 18, 2019 1:10 pm
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The power amp section includes the phase inverter, V3. You didn't say previously that you tried replacing that tube.

fenderguy81 wrote:
Bias is currently set to approximately 72.
Thanks!


How are you measuring that? Is that the mV reading at TP30?


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Post subject: Re: Fender Hot Rod Deluxe (USA) Intermittent No Sound HELP!
Posted: Mon Nov 18, 2019 2:53 pm
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fenderguy81 wrote:
I does anyone have any suggestions as to what else I should look for?

Thanks!


No !


nov 13 I wrote ;

It is not a easy amp to fix.

You need to be a amp tech to do a good circuit checkup.
A pro may see something wrong were you see nothing wrong.
You may not have knowledge to fix this issue.

Your amp must see a good amp tech.


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Post subject: Re: Fender Hot Rod Deluxe (USA) Intermittent No Sound HELP!
Posted: Wed Nov 20, 2019 9:30 am
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Yes, bias is 72mv at TP30. I am going to try replacing v3 as recommended above.


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Post subject: Re: Fender Hot Rod Deluxe (USA) Intermittent No Sound HELP!
Posted: Wed Nov 20, 2019 10:14 am
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In my opinion issue is not a tube.


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Post subject: Re: Fender Hot Rod Deluxe (USA) Intermittent No Sound HELP!
Posted: Wed Nov 20, 2019 1:59 pm
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stratele52 wrote:
In my opinion issue is not a tube.

I tend to agree.
But the schematic calls for a reading of 60 mV at TP 30. Without a measurement of plate voltage, we don't really know what the idle DC wattage is. Since it takes 15 minutes for the problem to present itself, it seems like it might be a heat related issue.

stratele52 wrote:
Retro is right !

Your amp may have many issue and you may need to find a good amps tech.
New Power Tube may need a new bias.

Agree again, it may be more than one issue.
I would start by adjusting bias to 60 mV at TP30, and see what happens. That only amounts to a 6mA difference per power tube.
I would also say that a USA made amp dates it to between 1996 and 2002, which means the electrolytic caps are suspect, although I doubt that they are causing the problem, it all depends on how many hours the amp has been operated.
Fenderguy81 may not have the possibility of a nearby amp tech, much less a good one.
fenderguy81 wrote:
started getting volume drops.
Thanks!

A "drop" is different from a disappearance of a signal. It implies a reduction in signal, but not a complete disappearance of signal. Which do you really have? An inaudible signal? or a noticeable reduction in signal?

Did the "drop" or "disappearance" of signal manifest itself when you plugged into the power amp input jack? After 15 minutes?
Details make the difference in an online diagnosis. If you omit them, then you shouldn't expect a reasonable diagnosis.


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Post subject: Re: Fender Hot Rod Deluxe (USA) Intermittent No Sound HELP!
Posted: Thu Nov 21, 2019 11:03 am
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I'll adjust the bias down to 60mV and replace v3 with a known good tube. At first I thought the sound was completely cutting out, but I came to realize that it is just a significant volume drop and the signal distorts. It is very indicative of a bad power power tube, but I already replaced them. It is possible that the new batch of power tubes could be damaged as well (unlikely but possible). I will pull some good power tubes out of my twin and test them on the HRD. Finally, the problem persisted even when plugged into input 1, input 2, and/or the power in.

I should note that I actually have a working HRD Bluesman edition (made in Mexico). I could put them both on the bench and make comparisons. I'm not sure how much the USA made version deviates from the one made in Mexico. Also, I am going to be buying some electrolytic caps for a Bassman 50 so I might as well also get some quality caps for the HRD. Would anyone recommend anything else to order for the HRD? I know it would be difficult without isolating the problem, but if there are known problematic resistors or diodes or something I could just add them on to the order.

Thanks for the responses guys!


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Post subject: Re: Fender Hot Rod Deluxe (USA) Intermittent No Sound HELP!
Posted: Thu Nov 21, 2019 11:20 am
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Try inspecting the power-tube sockets for any indication of fractured or cold solder joints. Marginal soldering could mimic the symptoms of a defective power tube. Also check the dielectric insulators of both sockets for cracks or fissures that could cause arcing.

Arjay

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Post subject: Re: Fender Hot Rod Deluxe (USA) Intermittent No Sound HELP!
Posted: Thu Nov 21, 2019 12:12 pm
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Fix the amp issue before buying some new caps.

Did you remove printed circuit board and look under ?

I'll heat all power supply bus ; from Power Transformer to Output Transformer
I mean ; power supply circuits and B+ going to all tubes and resistors


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Post subject: Re: Fender Hot Rod Deluxe (USA) Intermittent No Sound HELP!
Posted: Thu Nov 21, 2019 8:56 pm
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It sounds like you've grilled all the usual suspects and came up with no confessions. The next suspect I might point to is the output transformer shorting its windings. The clicking may be the OT warming up and shorting some of its windings. You can often hear the arcing as a clicking noise.
The giveaway is the smell. You can't mistake the nasty varnish smell of a burned transformer. It's not a common failure item, but your description fits.
The DC resistance of the primary windings will be close, but not identical. If one side measures more than 50 ohms difference, that may indicate a problem.
Remove one power tube at a time and see if one side doesn't click. That will remove the ground path for any arcing and silence the clicking.


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Post subject: Re: Fender Hot Rod Deluxe (USA) Intermittent No Sound HELP!
Posted: Fri Nov 22, 2019 6:00 pm
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The primary of the OT in the HRDlx is very imbalanced, by design. Approximately 115 ohms from red to blue, and 80 ohms from red to brown. Highly unlikely the the OT will have an intermittent short/arc. If it shorts or arcs even once, it is done.

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Post subject: Re: Fender Hot Rod Deluxe (USA) Intermittent No Sound HELP!
Posted: Sat Nov 23, 2019 12:00 am
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shimmilou wrote:
The primary of the OT in the HRDlx is very imbalanced, by design. Approximately 115 ohms from red to blue, and 80 ohms from red to brown. Highly unlikely the the OT will have an intermittent short/arc. If it shorts or arcs even once, it is done.

+1

That was always my understanding.

Arjay

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Post subject: Re: Fender Hot Rod Deluxe (USA) Intermittent No Sound HELP!
Posted: Sat Nov 23, 2019 11:03 am
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I've never had a hrdx blow an OT, so I know I'm grabbing at straws.
But I have had a 6L6 amp with a temperature sensitive short that had mechanical clicking sounds when it arced, presumably across a carboned pathway. Replacing the OT fixed it.
The resistance figures Shimmilou provided are within the 50 ohm variance I was describing generically.
The OP has seemingly covered all the bases in the suspect area. The only other thing that would fit is a fractured trace coming off the power tube sockets. That's a hard one to spot. But the resolder should have at least changed the symptom, if not cured it. Any other ideas??


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