Fender HR Deville delayed channel switching

[nsubulysses]

Hey all. I got a quick question if someone could please explain. I know these HRD channel switching fiascos have been talked about quite a bit, but as far as my particular scenario I could not find a thread about it.

The Hot Rod Deville I have has a delay in channel switching. It always switches reliably and both LEDs in the indicator light work. There is a just about a 1/2 second delay between when you push the button and when it actually switches channels. Switching to more gain is instantaneous. I know this is kind of regular. Is this just a poor design? Or possibly old caps in the relay circuit causing delay? I haven't dived (haha) that far into it yet. Was about to release this amp to the customer and noticed this little annoyance.

My +/- 16 rails are A-OK, reading 16.5V.

Also I do not have a footswitch with this amp. not sure if that would make a difference but I'm guessing not.

[Jazz P Bass]

Is there a delay in the indicator LED's or just the actual signal switching?

[nsubulysses]

Well, I guess it might be worth mentioning that it only is delayed when switching from distortion channel to clean. Both the LED and the actual switching of channels is delayed. When switching from clean to distortion it switches normally.

[52 Bill]

Well, I guess it might be worth mentioning that it only is delayed when switching from distortion channel to clean. Both the LED and the actual switching of channels is delayed. When switching from clean to distortion it switches normally.

I've noticed this before. I don't know if it is all of them or just some. While noticeable it really never seemed to be that much of a delay. I assume that it is just the slow reaction of the voltage switching circuit.

[Jazz P Bass]

Have we done any checking of the listed TP voltages?

[g1]

I'm wondering if C45 has to do with it, whether by design or by defect.

[Jazz P Bass]

Test Points, Test Points, Test Points.

[nsubulysses]

As per your request:

TP
setting // schematic voltage // measured voltage

TP31 (Ref pin channel select)
Normal / 1.39 / 1.316
Drive / 1.08 / 1.026
More Drive / 1.08 / 1.022

TP32 (Input pin channel select)
(Front panel switches, no footswitch available)
Ch. select out / .536 / .525
Ch select in / 9.69 / 9.76

TP33 (output pin channel select)
Normal / +16V / +15.77
Drive / -13 / -12.81
More Drive / -13.5 / -13.24

TP34 (Ref pin drive/more drive)
Normal / -12.5 / -11.36
Drive / - 4.9 / -5.0
More Drive / -4.14 / -4.68

TP35 (Input pin drive/more drive)
(with front panel switches)
More drive out / -.52 / -.52
More drive in / - 9.92 / -9.84

TP36 ( Output pin drive/more drive)
Normal / -15.5 / -14.94
Drive / - 15.4 / 15.73
More Drive / +16 / 15.69

Seems normal if +/-20% is still considered respectable in a switching circuit

Still checking other things

Edit: I replaced C45 and C50. Same results. I also replaced the relay itself because I had one on hand and the delayed switch remained. No more pop though. Maybe i'm chasing nothin.

[g1]

As you are only talking about a half second or so, I think you would have to scope the DC switching on those test points and see where the delay is/isn't. But really I think you would have to A/B with another amp of same model to see if it may be just normal.

[nsubulysses]

Well fortunately the same guy who brought me his HR Deville also brought me his friends HR Deluxe. For some reason I didn't think to compare the two. The Deluxe has been sidelined while I wait for a new OT. BUT now that I check it switches exactly the same. From clean to distortion instantaneous; from distortion to clean, slight delay.

I guess this is normal and I am a stickler.

I was getting all tech mystified. Good thinking to try something extremely simple

[Tone Meister]

I have two Hot Rod Deluxe amps here, one from 1998 or so and the other is a brand new HRDIII. Both amps switch from clean to distortion ----> distortion to clean instantly. No perceived delay in either direction in the audio output or with the panel and footswitch LEDs.

[nsubulysses]

The HR Deville and HR Deluxe I had here both had 1996 printed on the PCB. Wonder if this issue was sorted out somehow in later versions.

[Tone Meister]

That's a good question and I have no idea, but some of the old heads here may have some insight. I play professionally and see the HR series amps a LOT on backline and use all three "channels" (circuits) via the footswitch. I can't remember experiencing a delay in switching with any of the Blues series or Hot Rod series amps.

[Jazz P Bass]

Just a thought but maybe the normally closed contact (pin 2 & 4, ft sw jack) is corrupt.
You could try tacking on a small jumper at pin 2 & 4 to prove it out.

[Tone Meister]

Just a thought but maybe the normally closed contact (pin 2 & 4, ft sw jack) is corrupt.
You could try tacking on a small jumper at pin 2 & 4 to prove it out.

Or maybe it could just be dirty? Maybe a shot of Deoxit first to see and then try the jumper if that doesn't work.