Fedner 65 DRRI Mercury Mag upgrade (radio freq pickup help)

[W1Jrv]

just recently had my '65 DRRI upgraded with these mercury mag parts:
fdr-pri, fbfdr-o-fs, fbfdr-c & fbfrt

also had a 1.5k 1/2W resistor put across the standby switch to stop the loud pop when turning standby on. that was fixed though i thought a suppressor cap would have been used.

without having a guitar cable plugged in the amp emits a faint, though noticeable, radio freq type noise. like a faint morse code stream or repeater signals, something along that type of noise. if vol is increased that faint freq noise is too.

this wasn't there prior to this upgrade.  maybe a grounding error somewhere or a coil of wire lumped somewhere picking up this noise?

can i get some tech trouble shooting tips regarding this and see if i fix this without having to take it back to the tech shop.

[HotBluePlates]

just recently had my '65 DRRI upgraded with these mercury mag parts:
fdr-pri, fbfdr-o-fs, fbfdr-c & fbfrt

also had a 1.5k 1/2W resistor put across the standby switch ...

without having a guitar cable plugged in the amp emits a ... noise. ...

this wasn't there prior to this upgrade. ...

Did you install the new parts, or did someone else? If someone else did it, I'd take the amp back to them and demand the job be re-done right until the noise is gone.

The problem with giving you troubleshooting tips for where to look is that everything that was altered is now suspect. It could be as simple as a poor solder joint o intermittent connection. Or maybe a bad ground. Or it could be wire routing for the new parts. Or, if the installer attempted to solder to the existing p.c. board, there could be damaged parts.

It's very hard to say without seeing the amp in person to see the present condition.

[eleventeen]

If the "rf noise" you hear changes with the volume control, then it is before the volume control and thus early in the preamp section. I'd suspect the first (non-reverb channel) 12AX7 or 2nd 12AX7 (rev channel) tube (those most distant from the power trans) and swap it/them out; could also be a dirty tube socket. Do the tone controls affect it? If you rarely use the non-reverb channel like 97% of Del Rev users do, maybe you can get away with just swapping V1 with V2. 

[stratele52]

also had a 1.5k 1/2W resistor put across the standby switch to stop the loud pop when turning standby on. that was fixed though i thought a suppressor cap would have been used.

No more " pop " with the resistor !!!  Shure , with this resistor you never be in "Standby mode " 

[stratele52]

just recently had my '65 DRRI upgraded with these mercury mag parts:
fdr-pri, fbfdr-o-fs, fbfdr-c & fbfrt

also had a 1.5k 1/2W resistor put across the standby switch ...

without having a guitar cable plugged in the amp emits a ... noise. ...

this wasn't there prior to this upgrade. ...

Did you install the new parts, or did someone else? If someone else did it, I'd take the amp back to them and demand the job be re-done right until the noise is gone.

The problem with giving you troubleshooting tips for where to look is that everything that was altered is now suspect. It could be as simple as a poor solder joint o intermittent connection. Or maybe a bad ground. Or it could be wire routing for the new parts. Or, if the installer attempted to solder to the existing p.c. board, there could be damaged parts.

It's very hard to say without seeing the amp in person to see the present condition.

+1

[Ed_Chambley]

I don't see those part numbers on the Mercury site, but I assume you have gotten bitten by a little snake oil.  It seems you may have had the Power Transformer, Choke and Output Transformer replaced with the hopes of tonal greatness.

The only part that Might make a difference is the Output Transformer and even that is debatable.  It all has to do with what you want from the amp.  A great sounding amp is the sum of all its parts and a One power transformer with the same specs as another will deliver the exact same power to the amp.  Does not change the tone.  Theses "upgrades" of Mercury Iron to create tonal nirvana is not true.

That being said, Mercury makes great products and will most likely outlast you.  A reissue will never sound like a 65 Black Face Deluxe Reverb, but neither does another 65 Deluxe Reverb.  What I am saying is I have played them and they sound good.

Take the amp back to the tech and if they cannot get it repaired, demand they put it back like it was and get a full refund.  Any yes, your standby switch is basically bypassed.  I hope this is a reputable tech, but I am already questioning that.

[stratele52]

Take the amp back to the tech and if they cannot get it repaired, demand they put it back like it was and get a full refund.  Any yes, your standby switch is basically bypassed.  I hope this is a reputable tech, but I am already questioning that.

Sure it is not a qualified tech.

[Colas LeGrippa]

check for grid stoppers . You gotta have grid stoppers on preamp and power tubes to get rid of rf freq. Example : the 68k resistor on the input is a grid stopperand it's purpose is to stop rf signals to reach the grid and thus being amplified.

Colas

[W1Jrv]

just recently had my '65 DRRI upgraded with these mercury mag parts:
fdr-pri, fbfdr-o-fs, fbfdr-c & fbfrt

also had a 1.5k 1/2W resistor put across the standby switch ...

without having a guitar cable plugged in the amp emits a ... noise. ...

this wasn't there prior to this upgrade. ...

Did you install the new parts, or did someone else? If someone else did it, I'd take the amp back to them and demand the job be re-done right until the noise is gone.

The problem with giving you troubleshooting tips for where to look is that everything that was altered is now suspect. It could be as simple as a poor solder joint o intermittent connection. Or maybe a bad ground. Or it could be wire routing for the new parts. Or, if the installer attempted to solder to the existing p.c. board, there could be damaged parts.

It's very hard to say without seeing the amp in person to see the present condition.

http://s1129.photobucket.com/user/OOfzDW/embed/slideshow/65%20DRRI%20Merc%20Upgrade

i had a guitar amp shop tech do it here in town. i posted this same link over on a strat/amp forum thread too to gather as much info as i can.

maybe these images will help a bit. they start with prior to new merc parts, then the old parts that were removed and the new parts installed.

appreciate your insights

[W1Jrv]

If the "rf noise" you hear changes with the volume control, then it is before the volume control and thus early in the preamp section. I'd suspect the first (non-reverb channel) 12AX7 or 2nd 12AX7 (rev channel) tube (those most distant from the power trans) and swap it/them out; could also be a dirty tube socket. Do the tone controls affect it? If you rarely use the non-reverb channel like 97% of Del Rev users do, maybe you can get away with just swapping V1 with V2. 

i don't recall the tone controls having a effect but the volume would increase the level of interference heard.  i'll try your suggestion after i get the box back together. i took some images as noted in above post. thanks

[W1Jrv]

also had a 1.5k 1/2W resistor put across the standby switch to stop the loud pop when turning standby on. that was fixed though i thought a suppressor cap would have been used.

No more " pop " with the resistor !!!  Shure , with this resistor you never be in "Standby mode " 

thats funny. it actually does go into standby mode. i took some pictures so you/others can see. i'm not even sure where that particular resister was used. i don't see it across the standby switch. i do see two large caps there but they could be original that came with it.

[sluckey]

i do see two large caps there but they could be original that came with it.

Those caps are not original. They were added and they are the reason for no more pop.

[HotBluePlates]

also had a 1.5k 1/2W resistor put across the standby switch ...

Those are caps, marked "15k" which would equate to 15,000pF or 0.015uF each.

Looking at the pictures, all the connections to the board still appear to be with push-on connectors. I'd bet one (or more) of those have a loose connection, and are the cause of your noise.

Take it back to the shop. The fix should be free (because they should have done it right the first time). If you mess about, they're no longer responsbile for fixing the problem (because now there is doubt about whether their error or yours caused the problem).

[W1Jrv]

i do see two large caps there but they could be original that came with it.

Those caps are not original. They were added and they are the reason for no more pop.

good to know. thanks

[W1Jrv]

also had a 1.5k 1/2W resistor put across the standby switch ...

Those are caps, marked "15k" which would equate to 15,000pF or 0.015uF each.

Looking at the pictures, all the connections to the board still appear to be with push-on connectors. I'd bet one (or more) of those have a loose connection, and are the cause of your noise.

Take it back to the shop. The fix should be free (because they should have done it right the first time). If you mess about, they're no longer responsbile for fixing the problem (because now there is doubt about whether their error or yours caused the problem).

they said they would make it good. wanted to post here and the other forum just to get a handle on it for my own brain just in case.  appreciate the help

[W1Jrv]

also had a 1.5k 1/2W resistor put across the standby switch ...

Those are caps, marked "15k" which would equate to 15,000pF or 0.015uF each.

Looking at the pictures, all the connections to the board still appear to be with push-on connectors. I'd bet one (or more) of those have a loose connection, and are the cause of your noise.

Take it back to the shop. The fix should be free (because they should have done it right the first time). If you mess about, they're no longer responsbile for fixing the problem (because now there is doubt about whether their error or yours caused the problem).

they left a package of resistors in the box not caps. that could be just something they misplaced and didn't even use. anyways, i'll just get it back to them and they can figure it out.

[Ed_Chambley]

also had a 1.5k 1/2W resistor put across the standby switch ...

Those are caps, marked "15k" which would equate to 15,000pF or 0.015uF each.

Looking at the pictures, all the connections to the board still appear to be with push-on connectors. I'd bet one (or more) of those have a loose connection, and are the cause of your noise.

Take it back to the shop. The fix should be free (because they should have done it right the first time). If you mess about, they're no longer responsbile for fixing the problem (because now there is doubt about whether their error or yours caused the problem).

they left a package of resistors in the box not caps. that could be just something they misplaced and didn't even use. anyways, i'll just get it back to them and they can figure it out.

That is the thing to do.  After seeing what they have done, I think they will take care of it.  Probably something simple.