Blues Deluxe Reissue low volume

[rymac]

I have a Fender Blues Deluxe Reissue that is two years old and have not used very much. I plug a Strat straight into input one and turn the normal channel volume all the way up. At practice with drums, bass and another guitar player the volume is low. The reverb also seams to come and go. We don't practice that loud.
Details on the amp. It has a Celestion Vintage 30 spkr. Tube amp doctor 6L6WGC-STR these are the short bottle tubes. The Bias for both tubes at the test point is -70v DC. The amp had a terrible buzzing sound and I found some bad solder joints on the main circuit board. They were on the two big white, I think 5watt resistors. Re soldered connections and buzz was gone. I also replaced the 470 ohm resistors on the power tube screen grids to 1K 5watt power resistors. I think this is suppose to help the tubes last longer.The V1 and V3 tubes are Electro-Harmonix 12AX7. The middle V2 tube is one of the original Groove Tubes.
Is the the amp just not that loud? All I use is the normal channel. Any help would be great.

[rymac]

I measured the resistance on the neck pickup at 6.2K at the end of a 10 foot guitar cable.

Blues Deluxe Reissue

[rymac]

I have been reading about all the problems with these Fender amps.
I sounds like I need replace the 470 ohm 5W cement resistors in the +/- 16V supply with 330 ohm 5W cement resistors. The amp also has a lot of cold solder joints. To fix these is it best to remove the old solder and use new?

I had replaced the 470 ohm resistors on the power tube screen grids to 1K 5watt power resistors. Does this help the tubes last longer or should I change them back? I also noticed the the shielded cable in the preamp and the shield is connected on both ends. I thought you always just connected one end?

I found a lot of info at
The Unofficial Fender Hot Rod Deluxe Owner's Guide.

I hope the amp is worth the work. I have a SF Pro Reverb that I completely rebuilt and have tweaked. I left out the vibrato circuit. It sounds great to my ears.

Rymac

[Enzo]

Please do not reduce the resistors from 470 to 330. THIS WILL MAKE THEM RUN HOTTER. The voltage across them is set by zener, not voltage division. There will always be the 15v on the one end and the same whatever higher volts on the other. Lower resistance means higher current and more dissipation.

Just add a little new solder when you reflow, mainly to get the flux.


I don't think the screen resistor change was necessary, but I don't know that I'd bother changing them back either. I doubt they will affect tube life in any substantial way.

I also noticed the the shielded cable in the preamp and the shield is connected on both ends. I thought you always just connected one end?

Leave it alone. Is the amp doing something wrong that seems related to the cable?

Always - and its friend never - is a long long time, and we shouldn't use it lightly. Grounding the shield all depends upon the job at hand. How well would a guitar cord work if the shield were only connected at one end?

[rymac]

Thank you Enzo.

I got the amp apart and I'm looking at the back side of the circuit boards (no components on this side) Except for the resistors I replaced, the 5W resisters and the caps close to them that I resoldered, all the solder joints look grey and dull. Could all these solder joints be cold? If I'm going to fix them all advice on wattage of iron, size of tip and soldering technique.

One of the wires on the ribbon cable broke. The one closest to the V3 tube. I guess just cut out that wire and replace with new 22 gauge hook up wire. These ribbon cables don't inspire confidence in this amp. It looks like a lot of work. Time to rest.

[Mars Amp Repair]

I realize I'm a little late here,
but I've found that replacing the 470ohm resistors so that you can get longer leads & stand the resistors off of the board really helps to dissipate the heat before it gets to the pcb.

Also we scrape the coating off of the pcb & extend the resistor leads about 1/4" from the original holes & solder the that 1/4" length to also help dissipate the heat from the board.

I use small metal collars to stand the resistors off the pcb as just letting them float above the board will most likely result in there breaking off from vibration as the amp is moved around...esp if it has wheels.

We also found that we have to solder the metal collars to the resistor leads as they tend to rattle!

I have 750 ohm resistors that I haven't had the opportunity to try as of yet. I really don't believe these 16V supplies draw enough current to 'fan out' even with a 750ohm dropping resistor. I'll have to experiment. I believe the + & - 16v supply only the switching relays as well as the preamp opamps. Not much current there.

Anyone else have any clever countermeasures they'd like to share? Always looking for better ways to do things...thanx, glen

[Gtr_tech]

I have been reading about all the problems with these Fender amps.
I sounds like I need replace the 470 ohm 5W cement resistors in the +/- 16V supply with 330 ohm 5W cement resistors. The amp also has a lot of cold solder joints. To fix these is it best to remove the old solder and use new?

I had replaced the 470 ohm resistors on the power tube screen grids to 1K 5watt power resistors. Does this help the tubes last longer or should I change them back? I also noticed the the shielded cable in the preamp and the shield is connected on both ends. I thought you always just connected one end?

I found a lot of info at
The Unofficial Fender Hot Rod Deluxe Owner's Guide.

I hope the amp is worth the work. I have a SF Pro Reverb that I completely rebuilt and have tweaked. I left out the vibrato circuit. It sound great to my ears.

Rymac

I'd change the screen resistors back to 470.....6Ls don't draw that much screen current so larger values aren't needed.

[rymac]

Thank you Mars Amp Repair.

You are not late at all. I'm taking my time with this project and trying to gather as much info as I can to do things right. I was thinking about getting new resistors so I could extend the leads. I'm not sure what these metal collars are. Where can I get them?
On the Unofficial Fender Hot Rod site he has this suggestion.

" If you have some Silicon Rubber Sealer apply some under the resistor. Use it to prop the resistor up off of the PCB a little. This will help keep the resistor from vibrating when it's trying to dissipating heat, which in turn will prevent cold joints from reforming. Solder the resistors into place. NOTE: Be sure to give the silicon 24 hours to cure before turning on your Hot Rod. Once it has cured it will be completely inert to electrical current."

I don't know if the silicon is a bad idea or if the metal collars are better.

Gtr tech
I will change the screen resistors back to 470 for sure.
I still wonder if all the other solder joints could be bad. They do not look shiny.

Thanks for all the input. I have been working on my tube amps for a few years with out any other help other than my books. I'm grateful for this resource. What took me so long to find this site? I've worked on my amps longer than I've had the internet.

Rymac

[Mars Amp Repair]

Well,
we tried the silicone glue & the cust called a few days later complaining of the smell of it getting hot, so we decided to leave off the glue part.
As far as the collars goe, I just found these in my stock of old crap. I'm not really sure where they came from, so I can't help you there. they just help anchor the resistors so they're not flappin' in the breeze, however I'm always open to ideas others have.

As far as the value of the resistors goes it's pretty much the consensus here that lowering the value (given the zener diodes) only causes more current to flow to the zeners & thereby dissipate more heat from the resistors as well as put an undue strain on the zeners.

If you're messing with this, I'd try a higher value & then be certain any config of the amp settings as well as switching back & forth from channels does not ever make the + or - 16V supplies drop below 16V. I feel that the draws on those supplies via the op-amps or relays can't possibly be anywhere near the current those zeners are drawing from the dropping resistors. So, it is very unlikely that the supply would ever 'fan out' (exceed the current the zeners are drawing to remain forward biased).

good luck & let us know if you experiment with the value of those dropping resistors, what you find. I believe they can be raised to about 750ohms & possibly even be cool enough to just mount them directly on the board.

the next one I get, I'll have to try it. I'll let you know. glen

[Enzo]

Not only that, but metal tubing around the wire leads of the resistor act as additional heat sinking. One reason to mount resistors sticking up off the board - aside from allowing air circulation - is that the wire leads themselves act as heat sinks. Oh, nothing like aluminum fins of course, but small amounts like that can help.

If I had to come up with somehting like that, I'd look in my hardware drawers for metal spacer posts - standoffs - or in my hobby supplies or the hobby/craft store for small brass tubing and cut off a length of it.

[rymac]

I'm going to order new 470 resistors from mouser
Part # is 280-CR5-470-RC
I'll see if I can track down some copper tubing.
I've also ordered a new soldering iron tip
WELLER REPLACEMENT TIP FOR WLC100/WP35, CONICAL TIP

It looks like it should be good for this circuit board work.

[rymac]

I bought 3/32 Brass tube at Hobby Lobby. I'm waiting for 470 ohm power resistors.
When I get this amp back together I'll try to post my results.