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Post subject: Hor Rod Deluxe 3 channel hum on clean but not Drive Channel
Posted: Thu Aug 16, 2012 2:43 am
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I turned on my HRDLx3 for the first time in a few weeks last night and found that the Clean channel had a loud hum, like when you have a guitar lead plugged in but forgot to connect the guitar. This was not the problem as it did it with nothing plugged in. If I changed channels to the drive channel it went away. At first I thought it might be a tube so turned it off and checked them, however looking at the cct dwg, there is no way it can be a tube without it also effecting the Drive channel so I was puzzled. I took the back off and was about to start investigating when it stopped, but then the clean channel distorted when I used the reverb, but not when it was turned off. On the drive channel the reverb was fine, with gains turned down, no distortion. Again the reverb is common to both channels so I'm slightly puzzled by this. Then after a last power off and then back on again it started to work correctly and there were no problems.

When I had the problems the channel lights were changing correctly with the footswitch or without, only the clean channel seemed to be effected.

I suspect that maybe one of the relay contacts had stuck open, or possibly in the middle, thus leaving the clean channel open circuit, maybe K2A, possibly it was not closing correctly and hence the problem with the reverb as well, which cleared up when the relay started to work again fully. I don't think this is the same problem as I have seen all over the web for channel switching and the PSU resistors, plus the LED's were switching correctly, my money is on a bad relay contact on K2A. A bad solder joint could be the cause, will have to spend some time and check the PCB over; bad news if I have to do this on a 2 month old amp, but flow solder boards can be troublesome.

Has anyone else seen this type of problem with this amp and did it come back?

Thanks and cheers to all that reply.


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Post subject: Re: Hor Rod Deluxe 3 channel hum on clean but not Drive Chan
Posted: Thu Aug 16, 2012 8:09 am
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If only two months old, take it back for warranty. Even the tubes are covered for 90 days.

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---> "The amp should be SWITCHED OFF AND UNPLUGGED before you do this!" <---

Por favor, disculpe mi español, no se llega a la práctica con mucha frecuencia.


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Post subject: Re: Hor Rod Deluxe 3 channel hum on clean but not Drive Chan
Posted: Fri Aug 17, 2012 1:48 am
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Not worth the effort of sending it back, it seems to have a fault where it has problems until it has been on for about 20 mins and then it seems to get better. I'm sure it's not a tube, I think it might be a dry joint on one of the boards. I could spend more time sending it back and forth to Fender than investigating the problem myself. In fairness to Fender, intermittent faults can be difficult to find, if I fail, then I'll send it back. I think once it warms up the joint sorts itself out, it could be a component that is faulty, but I suspect a joint or something, won't know till I get the PCB's out to have a look. If I find bad flow soldering I'll be pretty irked as these should be spotted before assembly and that would be down to Fender. I'll post what I find in the next few weeks.

I did wonder if anyone else was having a similar problem.

Cheers


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Post subject: Re: Hor Rod Deluxe 3 channel hum on clean but not Drive Chan
Posted: Fri Aug 17, 2012 8:21 am
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If you don't mind voiding your warranty, go for it. As you will find, removing the main circuit board can take some time, and you have to be very careful to avoid breaking something else while you are at it.

You might be on to something, and there is the possibility of a poor joint somewhere. To remove the main board, remove knobs, pot nuts, and jack nuts associated with the board. Remove the screw for the green ground wire to the right of the board. Remove the six screws holding the board in place. Remove the wire ties, then pull the board down enough for the pot shafts to clear the chassis so the top of the board can be swung out. This can be done without having to remove the power supply wires on the left, but be careful not to bend the ribbon cables at the board, breaking a cable or solder joint. And be careful of the resistors next to the bias pot, easy to break a trace in this area when removing the board. Check the filter caps while you are at it, if bad they can also cause noise.

Some other things that you might want to try first. Dressing the leads one pair at a time, noting their positions (first pic below), repositioning the ribbon cables as you mentioned that the noise stopped when the back was removed (second pic below), and check the reverb cables as you mentioned the noise wasn't there with reverb turned down.

"...if I fail, then I'll send it back..." It would be easy enough to tell if you've disassembled the amp, so you might want to expect that your warranty is gone if you attempt a repair.

Image

Image

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---> "The amp should be SWITCHED OFF AND UNPLUGGED before you do this!" <---

Por favor, disculpe mi español, no se llega a la práctica con mucha frecuencia.


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Post subject: Re: Hor Rod Deluxe 3 channel hum on clean but not Drive Chan
Posted: Fri Aug 17, 2012 12:18 pm
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6B4G wrote:
Not worth the effort of sending it back, it seems to have a fault where it has problems until it has been on for about 20 mins and then it seems to get better. I'm sure it's not a tube, I think it might be a dry joint on one of the boards. I could spend more time sending it back and forth to Fender than investigating the problem myself. In fairness to Fender, intermittent faults can be difficult to find, if I fail, then I'll send it back. I think once it warms up the joint sorts itself out, it could be a component that is faulty, but I suspect a joint or something, won't know till I get the PCB's out to have a look. If I find bad flow soldering I'll be pretty irked as these should be spotted before assembly and that would be down to Fender. I'll post what I find in the next few weeks.

I did wonder if anyone else was having a similar problem.

Cheers


1- Better after 20 minutes !!! Yes could be a tube , more warm up, better are the tube.

2- Lots of work to remove PCB assembly , better to be sure is not a tube before


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Post subject: Re: Hor Rod Deluxe 3 channel hum on clean but not Drive Chan
Posted: Sun Aug 19, 2012 6:07 am
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Thanks guys for the great advise, I will continue to monitor that it is not a tube, I have a spare on order so will also try that before attempting to remove the PC, but the problem seems to point to something like a bad joint rather than a tube as the Drive channel always works fine, I have it set as clean as possible currently to make sure it is OK, so when I have the problem on the clean channel I switch to the drive channel and there is no problem,most of the circuit is common to the drive, so if V1 or V3 or the power section were an issue it would show up on the drive channel too, but they seem to be fine. I'm guessing a problem round the relay connections,or even possibly a bad relay. I'll wait for the new tube and then if I continue to have problems I'll remove the board and have a look.

Thanks for the pictures and advise on board removal, very helpful indeed.

Cheers


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Post subject: Re: Hor Rod Deluxe 3 channel hum on clean but not Drive Chan
Posted: Wed Sep 05, 2012 3:06 am
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Well Stratele was correct, the PI tube finally failed last night. I went to turn the amp on and nothing. It had been unreliable for a while and I thought it might be a dry joint. As all the tubes were lighting up, at least the heaters were working OK, I checked out the various PCB's. In general the soldering was pretty good. Not sure I like the ribbon cable from the tubes pushed up against the sharp ribbon cable pins through the pcb, might one day pierce the cable, so flattened those out. All voltages checked out OK so I went for the PI tube as nothing was working, no hum or hiss from the speaker, and up she came. I guess the tube was on it's way out but seemed to recover after being on for 20 mins or so. It has fully failed now, does not work in any position. Always worth having a few spares.

Going to try a 5751 in V1 when the spare arrives. I like the combination I have of a 12AT7 in V1 but read it sucks the tone a bit and that a 5751 was a good choice, slightly more gain than a 12AT7 but not as much as the 12AX7 so it should still calm the amp down a little to how I like it. If it does not sound any better I'll go back to the 12AT7 which worked well for me.

Cheers


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Post subject: Re: Hor Rod Deluxe 3 channel hum on clean but not Drive Chan
Posted: Wed Sep 05, 2012 11:37 am
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Good to hear that the amp work well.


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Post subject: Re: Hor Rod Deluxe 3 channel hum on clean but not Drive Chan
Posted: Wed Sep 05, 2012 1:42 pm
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Quote:
" If you don't mind voiding your warranty, go for it. As you will find, removing the main circuit board can take some time, and you have to be very careful to avoid breaking something else while you are at it..."



@ shimmilou : Thank you so much for posting the clear picture of how to do the lead dressing on the wires! I'm going to use this for reference. :D


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