a simple question about a Fender delux RI

[24 track]

hey guys, I was given a Delux RI to repair , severe popping switches , the power was easy to do , I installed a snubber
.47 Uf 630 Volt across both rails of the power switch, instant gratification .
but the standby switch pops when the live amp goes in to standby mode, albeit much reduced in level
I did a complete set of tube swap , one tube at a time and cleaned all contacts plus exercised the pins , all was good and reduced a little more noise in the process , checked for loose components and broken traces , you know , maintenance etc.

I still have a pop when I turn on the standby ,
here's my question would it be prudent to put a snubber across the standby switch or would I pooch something in the process ? I dont think I would but it's some one elses amp.
these RI amps are not my favorite I seen too much sloppy technique .

any help here would be great and appreciated

 

[Phrygian77]

Put a resistor across it, like a 47k or 56k.

 

[Lowerleftcoast]

The Valve Wizard recommends a resistor between 47k (2 watt) or 150k (1watt).

 

[24 track]

Put a resistor across it, like a 47k or 56k.

The Valve Wizard recommends a resistor between 47k (2 watt) or 150k (1watt).

thanks guys, its good to know , I will try that.
rest of the amp is dead quiet , I use my guitar with the Lace alumatone buckers , super quiet for testing. all noise is from the amp and not from the guitar

I got all silly and impatient so i slapped the cap across it and now its a a tiny ffft sound and it works great when the switch is shut off. I'm goint to try the resister tomorrow to see if its any better than the cap.

thanks again

 

[corliss1]

For what it's worth, the official Fender answer is "let it pop"

 

[24 track]

For what it's worth, the official Fender answer is "let it pop"

that little pop just made me a few bucks LOL

 

[24 track]

OK final analysis ,
1)I placed the snubber on the power switch as indicated ,

2)tried the 47K resister on the standby switch , no real joy , better but still there ,

3)watched a few associated vids on YT ,
one had an interesting result, it stated that under the dog house where the filter caps reside the high voltage caps are in close proximity to the metal casing of the doghouse and that may cause an arcing to ground when the standby switch is turned off ( in standby mode ) .
So acting on this I put some non conductive tape around the inside of the doghouse , still abit of a pop but nothing serious ,

4) I reinstalled the .47Uf cap across the standby switch, this dropped the pop down a few more notches.

5) Then noticed there was a small hole in the upper end of the standby switch , that revealed the active switch contacts , in went a few drops of Deoxit and a quick exersize of the switch dropped the pop to an acceptable level ,almost negligable by all standards .

the owner of the amp bypassed the standby switch for a few years due to the popping so the contacts may have become dirty / corroded from lack of use added to the other issues created his problems.

thank you every one for your help , some times its a benifit just to vocalize a problem to see another aspect I may be missing. you guys Rock!

 

[SoK66]

I get around it by never using standby switches.

 

[24 track]

I get around it by never using standby switches.

that i think is what caused this issue to begin with, lol

 

[Phrygian77]

@24 track it's a terrible idea and implemention to begin with. Just switching high voltage DC like that alone is bad, add to that the inrush from the discharged screen filter on down when you flip the switch. I like adding a parallel resistor since it at least lets a bit of voltage through.

 

[andrewRneumann]

I'm a little late to this party.

I think you might have some flyback voltage on that HT secondary that is causing the pop and the degradation of the standby switch. This snubber network across the HT secondary leads might be exactly what you need for long-term health. It goes from one HT lead to the other... not across the standby switch.

 

[24 track]

@24 track it's a terrible idea and implemention to begin with. Just switching high voltage DC like that alone is bad, add to that the inrush from the discharged screen filter on down when you flip the switch. I like adding a parallel resistor since it at least lets a bit of voltage through.

I'm a little late to this party.

I think you might have some flyback voltage on that HT secondary that is causing the pop and the degradation of the standby switch. This snubber network across the HT secondary leads might be exactly what you need for long-term health. It goes from one HT lead to the other... not across the standby switch.

View attachment 986464

thanks guys some great info here ,
I was able to reduce the pop to nearly nothing , no louder than the pop i get from my 65 BF twin RI. part of the issue was the the owners operation of the amp . but proper maintenance was in order huge , the RI's are notoerious for bad build tecniques, I've repaired quite a few, including one so bad I took my own apart to see if i had the same issues, ( thank gawd i did not,whew) today i tried the 47K resister 2watt resister it made no difference really but the .47 UF 650 volt cap did and this got reduced again once once i cleaned the switch with deoxit , the switch had been left open for a few years as the owner never used it so probably it had gotten dirty or corroded contacts

I like it when i get different processes to resolve an issue , i file them away for next time if I cannot solve the problem.

On a different repair i was reballing a graphics card in a 24" Imac computer ,something i have done at least 50 times with great sucess , on PC's and Macs
No joy, over heating issues maintained blowing out the graphics card , after my 4 th attempt it dawned on me it was not the card that was failing , the copper radiator the graphics chip was attached to, some how got a pin hole in the copper , releasing the coolant . a new radiator and 5 years later I'm talking to you now on that machine BTW the graphics card is running at 90 degrees F and has been on non stop 24hrs a day for 5 years,

my point being is you have to look at every thing to determine the repair, even if it seems wierd, and all possibilities need to be explored , so for the info you posted, I thank you.

 

[NTC]

I am impressed that you can reball a BGA....

 

[24 track]

@24 track it's a terrible idea and implemention to begin with. Just switching high voltage DC like that alone is bad, add to that the inrush from the discharged screen filter on down when you flip the switch. I like adding a parallel resistor since it at least lets a bit of voltage through.

I'm a little late to this party.

I think you might have some flyback voltage on that HT secondary that is causing the pop and the degradation of the standby switch. This snubber network across the HT secondary leads might be exactly what you need for long-term health. It goes from one HT lead to the other... not across the standby switch.

View attachment 986464

I did some more digging and i found this , it confirms what you are saying !

intersting , read , this was also confirmed bt DR Z on his YT post, you learn sumpin' new everyday!

I did reduce the power switch noise issues with the snubber so that was good!

I replaced the standby snubber with the 47K 2watt resister , although noisier it is safer when looking at the circuit and function of the standby switch

Thanks @Phrygian77

 

[2L man]

You could install a resistor between HV switch NO contacts. Something like 100k allow some current flow thru tubes when filaments are hot and filter capacitors pre charge slightly. This should also prevent "cathode poisoning". If amp has a capacitor discharge circuit depending its resistance perhaps lower value resistor is needed to "lift" voltages higher when amp is on Standby?