VVR3 In Hot Rod Deluxe

[wallaceguitars]

Hello,

I installed a VVR3 in my friends Hot Rod Deluxe. I need some help. The new pot has very little change to the volume. When it is turned all the way down, there is a hum. Once I turn it up a bit, the hum goes away. However, it's like there is no gain with the VVR3 pot.

I have attached a picture of the connections. The B+ Out is connected to the + side of the first Cap. The cap was clipped from the board and only the B+ out of the VVR3 is connected. The B+ In comes from the rectifier and is piggy backed off the terminal below the filter cap.

Any help would be appreciated. At this point, I really don't know what and where to check for values with my meter. If anyone has experience with the Hot Rod Deluxe, please take a look. Thanks!

[vibratoking]

It looks like you put it between the rectifier and first cap. The rectifier wants to see the cap directly. This could damage your rectifier. Otherwise, it looks connected properly from what I can see.

The FET is static sensitive and your description of very little volume change is consistent with a failed FET, IME. The FET can also fail from too much heat. Did it ever work or did it stop working at some point?

[wallaceguitars]

Thanks vibratoking.

I think you have my wiring correct. I searched everywhere trying to figure out how to wire this thing up. The unit works now, but as stated I just don't have any gain on the VVR3 pot. I am not sure what I need to do and I agree I may have some component damage. I can crank the amp up and it is loud. The VVR3 is just not giving me the control it is suppose to and I am unsure of the problem.

Thanks again. Any and all input is appreciated.

[Tillydog]

The B+ Out is connected to the + side of the first Cap. The cap was clipped from the board and only the B+ out of the VVR3 is connected. The B+ In comes from the rectifier and is piggy backed off the terminal below the filter cap.

Your connections are wrong.

You have not broken the connection between the rectifier and the rest of the amp. From your description, all you have done is to isolate one smoothing cap and connect it to the VVR.

Somehow you need to re-connect that cap and find a way of breaking the link between the rectifier and the amp (before / after the smoothing cap is up for debate) and putting the VVR across the gap.

I don't know your amp to give specific advice - Maybe study the instructions again?

[wallaceguitars]

Thanks Tillydog. I think I know what I need do and this makes sense. I will correct the wiring and try it again.

[wallaceguitars]

Based on all the great responses I am getting, I have made changes to the connections for the VVR3. The red wire from the rectifier, originally on P18 under the first filter cap, has been connected to the B+ In. The B+ Out is now connected to P18 and the filter cap is reattached to the board.

I basically have the amp back to it's original state as the VVR3 is having no effect on the volume. I can turn the pot up and down and it does not change. At this point, I am not sure where to go next. Maybe I still have something wired incorrectly?

Thanks for all the responses. I have included a picture of how the VVR3 is currently wired.

[Tillydog]

Maybe I still have something wired incorrectly?

The 'In' and 'out' look like they should work. It is arguably better to have the VVR after the first filter cap, but that wouldn't stop it working IMHO (might mean that it gets hotter than it should, etc.).

Where is the ground of the VVR connected? Just double-check that it's making a proper contact.

It is a VVR2, isn't it? (Cathode biased amp?)

Edit: Shoud have read your first post properly! - You could try moving the VVR ground to the -ve side of the B+ supply (e.g. at the -ve end of the filter cap). Maybe the chassis isn't common to the DC supply.

[wallaceguitars]

Thanks Tillydog. I have have attached a new picture where I have ran this through the first filter. This was completed about an hour ago. I saw a lot of threads relating to making this modification. Now I am back to having some control on the pot, but only a small amount of gain on the VVR.

This is a VVR3.

The ground is ran to a screw on the chassis. Since it is DC, I will check to see if I have any conflict. I am wondering if this may be a cause for the issue I have with the gain? I am trying to understand why I don't have any gain. The amp is very quite now with pot turned down and fully turned up. The mosfet does not appear to be getting very warm at all. I would expect it to get a bit warmer than it is currently.

I double checked the bias and it is set a 70mV when the VVR3 is set to zero gain.

As far as reading the instructions, there were no instructions with this retrofit kit. I searched the web for instructions and it lead me to the Hall Amplification site. I could not find anything on the Hall site and this is how I ended up at The Amp Garage. Several weeks of reading before I posted.

Thanks again to those who have helped diagnose this issue. I think I am close, but I must figure out the gain issue. Right now, I am not sure exactly why this exists, but I will definitely check the ground.

[Bob S]

Did you search over on Doug Hoffman's EL34World.
There's a bunch of VVR3 info on there.
Good Luck,
Bob

[Tillydog]

Thanks Tillydog. I have have attached a new picture where I have ran this through the first filter

Sorry - that's plain wrong. Stop now!

What I wrote was:
"You could try moving the VVR ground to the -ve side of the B+ supply (e.g. at the -ve end of the filter cap)"

Look at the diagram at the bottom of page 8:

http://notinteractive.com/stuff/guitar/VVR2.pdf

This may not be the latest revision, it's just a random file I found on the internet - you should request a copy of the latest installation instructions from Hall Amplification (Dana Hall is UR12 on this forum) and study them and correct your wiring before switching the amp on again or lifting a soldering iron. (I'm not going to try and explain in text, because the opportunities for misunderstanding are clearly too great! )

(I had it in my mind that the VVR2 was for cathode biased, and VVR3 for fixed bias amps, but I see there is a VVR3 for both. Sorry for that confusion.)

You risk doing serious damage, or even blowing things up if you continue as you are. Post back here with a clear scheme when you thnk you're got it sorted and someone (me?) can check it over *before* you power up.

[UR12]

Did you recieve the instructions from me on the VVR? If not I can send them. There are testing procedures and troubleshoorting procedures written in the VVR instructions. Iwould highly advise anyone to go through the testing procedures with the tubes out of the amp and make sure the VVR is connected properly and working before installing the tubes in the amp for testing. Can you give us some voltage measurements on the B+ in and B+ out of the VVR with the wire going to the B+ out disconnected from the VVR board?

Just A note to clear up any confusion. I offer two models. The VVR, which is for cathode biased amps and the VVR3 for fixed biased amps. The VVR2 is an older model that was replaced by the VVR3 and the newest instructions for the VVR3 have a couple of sections for testing and troubleshooting to make sure the board is working properly BEFORE firing up the amp with the tubes inserted.

[wallaceguitars]

UR12, I did not get any instructions for the VVR3. You can send these by email to randy@wallaceguitars.com. If you need a mailing address, please let me know.

Thanks for the responses. I truly want to get this amp going. The testing procedures would be a plus, especially where I am on this project right now. This instruction set will also help with some of Tillydog's thoughts on this installation.

Thanks all!

[UR12]

instructions have been emailed.

[timgibbs]

Hi All:
Wallaceguitars is helping me with this project on my amp. Ive been keeping up with the post here & after Dana's post i'm very confused. When i contacted Hall Amplification about the VVR, i was told i needed the VVR3 for my amp which is NOT fixed bias. Do we have the wrong VVR?

[UR12]

Hi All:
Wallaceguitars is helping me with this project on my amp. Ive been keeping up with the post here & after Dana's post i'm very confused. When i contacted Hall Amplification about the VVR, i was told i needed the VVR3 for my amp which is NOT fixed bias. Do we have the wrong VVR?

The Hot Rod Deluxe is in fact a fixed biased amp and yes you are fitting a VVR for cathode biased amps which is wrong. You need a VVR3 for fixed biased amps not the one you have in the pictures. contact me at info@Hallamplification.com and I will help you get this sorted out.