It is currently Mon Mar 16, 2020 10:03 am

All times are UTC - 7 hours



Post new topic Reply to topic  [ 6 posts ] 
Author Message
Post subject: HotRod Deluxe Volume Swells
Posted: Thu Jan 24, 2019 8:31 am
Offline
Hobbyist
Hobbyist

Joined: Thu Jan 24, 2019 8:25 am
Posts: 2
Hi everybody,

i have a problem with an HRD. The volume changes on the clean channel. It randomly jumps between two levels. Seems to me like a problem with one of the gain stages (V1A, V1B, V2A).
I definitely can exclude issues with the power amp, cannot reproduce the issue when I plug the guitar directly to the poweramp.

When I take the signal from the preamp out, I clearly see the phenomenon on recorded sound files, amplitude doubles, signal shape remains constant.

Any ideas?

Thank You
Georg


Top
Profile
Fender Play Winter Sale 2020
Post subject: Re: HotRod Deluxe Volume Swells
Posted: Thu Feb 07, 2019 11:56 pm
Offline
Rock Icon
Rock Icon
User avatar

Joined: Tue Jun 29, 2010 1:20 pm
Posts: 9640
Location: Indiana
Hey WasBass,

Sounds like a poor connection, maybe a wonky solder joint on a circuit board. You can inspect the solder joints on the tube socket circuit boards, by removing the back panel. Inspection of the main circuit board will require substantial disassembly.

Use caution when opening an amp, lethal voltages can be present even when amp is unplugged from electricity.

_________________
---> "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.


Top
Profile
Post subject: Re: HotRod Deluxe Volume Swells
Posted: Sat Feb 09, 2019 9:00 am
Offline
Professional Musician
Professional Musician

Joined: Thu Aug 07, 2014 3:25 pm
Posts: 1023
The HRDX is a single channel amp with switchable gain and volume circuits.
A symptom you describe should occur in the drive channel as well.
But if Q1, a j111 FET, is going south, it could be kicking in more gain. Its supposed to be off in the clean channel and on in More Drive to raise gain. But if its leaky, it could raise the gain without a control signal.
You could have intermittent contacts on K1b between pins 11 and 13. This circuit runs through the bright switch, so if you turn off the bright switch, the symptom should go away. Relay failures are rare though.


Top
Profile
Post subject: Re: HotRod Deluxe Volume Swells
Posted: Sun Feb 10, 2019 2:59 am
Offline
Rock Icon
Rock Icon
User avatar

Joined: Fri Feb 05, 2010 4:31 am
Posts: 14045
Location: Province de Québec, Canada
TimsAudio wrote:
The HRDX is a single channel amp with switchable gain and volume circuits.
A symptom you describe should occur in the drive channel as well.
But if Q1, a j111 FET, is going south, it could be kicking in more gain. Its supposed to be off in the clean channel and on in More Drive to raise gain. But if its leaky, it could raise the gain without a control signal.
You could have intermittent contacts on K1b between pins 11 and 13. This circuit runs through the bright switch, so if you turn off the bright switch, the symptom should go away. Relay failures are rare though.




Image[url=https://flic.kr/p/QUZcjR]


Top
Profile
Post subject: Re: HotRod Deluxe Volume Swells
Posted: Sun Feb 10, 2019 9:44 pm
Offline
Professional Musician
Professional Musician

Joined: Thu Aug 07, 2014 3:25 pm
Posts: 1023
Thank you Stratle, that's what I'm talkin bout.


Top
Profile
Post subject: Re: HotRod Deluxe Volume Swells
Posted: Thu Feb 14, 2019 1:54 am
Offline
Hobbyist
Hobbyist

Joined: Thu Jan 24, 2019 8:25 am
Posts: 2
Thank you all for your help!
My original post did take a long time to be approved, so I tried some things in between:

I know that the HRD is a one channel amp, could be that I just didn't notice the issue with the gain "channel".
It must have something to do with temperature, as it takes some time until the issue occurs

I resoldered all joints on the main and tube PCBs - issue is gone. However, I didn't have the opportunity to do a long testing session yet, so let's see..


Top
Profile
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 6 posts ] 

All times are UTC - 7 hours

Fender Play Winter Sale 2020

Who is online

Users browsing this forum: No registered users and 2 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum

Search for:
Jump to: