Volume dropping out

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GrantB
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Re: Volume dropping out

Post by GrantB »

Polar Bear wrote: Sun Nov 29, 2020 10:56 am
If you’re gigging regularly with the amp, 6 years is a long time for valves. You’d be wanting to change them every year or so ideally.
My 1973 Princeton was used every week for the first 30 years and since I've had probably every second week for a jam. Original RCA tubes.

But yes, this sounds like maybe a loose tube/poor connection (most likely)...or a bung one (less likely). Pull the tubes, wipe a tiny amount of WD40 on the pins, and re-insert them. Do that ahead of anything else.
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Re: Volume dropping out

Post by Polar Bear »

GrantB wrote: Mon Nov 30, 2020 9:15 am
Polar Bear wrote: Sun Nov 29, 2020 10:56 am
If you’re gigging regularly with the amp, 6 years is a long time for valves. You’d be wanting to change them every year or so ideally.
My 1973 Princeton was used every week for the first 30 years and since I've had probably every second week for a jam. Original RCA tubes.

But yes, this sounds like maybe a loose tube/poor connection (most likely)...or a bung one (less likely). Pull the tubes, wipe a tiny amount of WD40 on the pins, and re-insert them. Do that ahead of anything else.
It’s fair to say that the my don’t make them like they used to...
Also, if it sounds good now, imagine how much better it would be with a fresh set of valves to really let it sing.
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Re: Volume dropping out

Post by calling card »

My 800 was dimming, new power valves seemed to fix it.
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Re: Volume dropping out

Post by RectifiedAmps »

GrantB wrote: Mon Nov 30, 2020 9:15 am Pull the tubes, wipe a tiny amount of WD40 on the pins, and re-insert them. Do that ahead of anything else.
At the risk of getting banned, I have to say this is not a good idea. WD40 should not be used for anything electrical- it’s a mechanical lubricant, not an electrical contact cleaner. It could actually make the connection worse since it leaves a non-conductive film behind.

You should only use electrical cleaner (usually isopropanol spray) for amp sockets, jacks, pots. If you like to use lube (!), then use a dielectric grease - I think they’re silicone based.

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Re: Volume dropping out

Post by GrantB »

RectifiedAmps wrote: Mon Nov 30, 2020 11:24 am
GrantB wrote: Mon Nov 30, 2020 9:15 am Pull the tubes, wipe a tiny amount of WD40 on the pins, and re-insert them. Do that ahead of anything else.
At the risk of getting banned, I have to say this is not a good idea. WD40 should not be used for anything electrical- it’s a mechanical lubricant, not an electrical contact cleaner. It could actually make the connection worse since it leaves a non-conductive film behind.

You should only use electrical cleaner (usually isopropanol spray) for amp sockets, jacks, pots. If you like to use lube (!), then use a dielectric grease - I think they’re silicone based.
Hey, it's OK...we're allowed to disagree. I don't endorse the use of contact cleaner alone as it strips the metal clean, which is good until it oxidises and causes issue. Pots are a case in point. Strip them clear of lube using contact cleaner alone and you'll hear about it!

Maybe I could explain it this way - if one doesn't want to front the $35 for a real good electrical cleaner/lube, then WD-40 actually will work. Most people have some in their garage. Just use a dot. I use proper electrical cleaner/lube but only because I have lots of use for it. Not everyone will.

Skip Simmons who knows a bit about amps talks about using WD-40 frequently. I don't think everyone agrees with him either. 12:50 on this podcast

https://vintageamps.libsyn.com/ep-8-alcohol-and-what
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Re: Volume dropping out

Post by GrantB »

Polar Bear wrote: Mon Nov 30, 2020 9:31 am
GrantB wrote: Mon Nov 30, 2020 9:15 am
Polar Bear wrote: Sun Nov 29, 2020 10:56 am
If you’re gigging regularly with the amp, 6 years is a long time for valves. You’d be wanting to change them every year or so ideally.
My 1973 Princeton was used every week for the first 30 years and since I've had probably every second week for a jam. Original RCA tubes.

But yes, this sounds like maybe a loose tube/poor connection (most likely)...or a bung one (less likely). Pull the tubes, wipe a tiny amount of WD40 on the pins, and re-insert them. Do that ahead of anything else.
It’s fair to say that the my don’t make them like they used to...
Also, if it sounds good now, imagine how much better it would be with a fresh set of valves to really let it sing.
I did try a new set of JJ's. Ended up putting the RCA's back in. Full disclosure - I did test the original RCA's about 6 months ago and one of the power tubes read pretty low (still sounded great). I put in another set of NOS coin base RCA's. Ready for another 40 years.
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Re: Volume dropping out

Post by Cdog »

Air compressor is always my first port of call for scratchy pots. Then CRC... Contact cleaner is last resort for my 2c.
I once 'contact cleansed' a pot to death in my enthusiasm... the internal grease on the shaft washed away :lol: Pot sounded good but lost all it's turning friction :thumbdown:

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Re: Volume dropping out

Post by RectifiedAmps »

This stuff from Jaycar is actually pretty decent for cleaning and lubing potentiometers: https://www.jaycar.co.nz/contact-cleane ... n/p/NA1012

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Re: Volume dropping out

Post by jimi »

Finally had some time to look, (been doing 12+ hr days all week with issues at work).

Bit of extra hum with nothing plugged in which isn’t normal, tapping the tubes gave a good crackle from the preamp tube nearest the fuse.

Don’t know if I have WD40, probably just CRC and Singer sewing machine oil.

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Re: Volume dropping out

Post by MikeC »

Preamp tube at that end may well be the phase inverter. And don't use WD40 or CRC - it's oil!
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Re: Volume dropping out

Post by jimi »

Well put the tube back in, that one has a lot more wiggle than the others, which feel firmer in place, but the hum was gone for a short play.

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Re: Volume dropping out

Post by mr_sooty »

RectifiedAmps wrote: Tue Dec 01, 2020 9:32 pm This stuff from Jaycar is actually pretty decent for cleaning and lubing potentiometers: https://www.jaycar.co.nz/contact-cleane ... n/p/NA1012
Agreed! My shop repair guy put me on to this stuff. It's magical.

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Re: Volume dropping out

Post by sizzlingbadger »

mr_sooty wrote: Sat Dec 05, 2020 6:01 pm
RectifiedAmps wrote: Tue Dec 01, 2020 9:32 pm This stuff from Jaycar is actually pretty decent for cleaning and lubing potentiometers: https://www.jaycar.co.nz/contact-cleane ... n/p/NA1012
Agreed! My shop repair guy put me on to this stuff. It's magical.
I use that too, its good.
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