Thank you for this video. I found myself taking capacitors completely out to measure capacitance and had forgotten you need only de-solder one end to get the same reading. A time saver method thank you again.

I really enjoyed your video. When I rebuild an amp, I gut out all the old caps and carbon resistors. I want the amp to be dependable and sound as good as it did new. A vintage amp once had new circuitry and somehow sounded great. No "mojo-pixie dust" excuse needed, just a well built circuit that's been maintained. I understand if you're a collector wanting the history, but If you're an actual player you want dependable gear and no drag on the circuit.

"...because people 'believe' that they affect the tone...". Well DONE, Sir! : )

Thanks Stuart another knowledgeable video. I tend to agree with you regarding a lack of difference in sound quality when changing the signal capacitor/s is necessary. Personally whilst I haven't noticed any difference it is nice to appreciate the vintage quality by keeping the original components. Very thorough and methodological trouble shooting. It's nice to see a expert with a passion for vintage AMPS.

As someone who recently started their own tube amp shop, I’m very pleased to have found this channel! Thank you!

Thanks a lot. Superb video as always.

Thanks for the great video. I’ve just acquired an amp and it would seem a couple of the smaller caps are damaged, so I’m going to do those tests on them to see if I need to replace them. Cheers

Very helpful, thank you.

Fantastic, and thank you!

Fantastic lesson. I would have loved to see a merger showing some leakage. Not a complete fail but one that showed a volt or two. Enough to effect bias of the subsequent stage.

Thank you, Stuart. Very informative and clear. Very useful.

Very good video thank you! Do you know if there's 25uf/25v caps that are not electrolytic (polyester)? Need to change quite a few on a 70s Italian amp and I'd rather not put ELs back in, thanks and Merry Christmas!

Ty for sharing!! How can I test for leaky Orange drops in circuit? The way that I've been doing it is with a standard digital voltmeter. I put the black probe on chassis ground. Then use red probe to check across other side of OD. For example, in tone stack, there's high DC present from plates. On the other side of OD it reads .4 or .5 mv. Is that cap fine or am I doing it wrong. Ty for your time! , Jim

Hello Stuart. Thanks for all the freely available information you have provided. It is helping me to try and fault a 14 year old Orange 50w Mark 2 Rockerverb at the moment. Orange do not seem to like providing Schematics for their amps - so I am trying to trace out a schematic for it. I have a 50W Head at the moment which was blowing only the 2 HT fuses. It is the 2x EL34 output valve version. My main question here, looking at testing the capacitors, what voltage would you select on the Mega? I have a mega that can output 250 Volts up to 1000V. I presume you set the mega to below the stated Max Voltage on the cap? Thanks again. Keith

Hi Stuart, thank you for all the great videos, I watch them regularly. I have some questions about this one, are there any benefits of using this method over using an ESR-meter? It's the first time I see someone using a megger for testing capacitors, isn't the voltage too high for some capacitors or is it too momentarily to do any harm?

Hello there great channel 👍🏼, yo know I have a Mesa Boogie Stiletto Ace combo but is cutting out, I just changed preamp tubes using Chinese tubes as recommended by mesa and changed the rectifier tube and the power tubes, even though the amp Is still cutting out, I cleaned the loop fx jacks too, I think could be a capacitor but I'm not sure. Any advice thank you 😉

I really like the amp tone on the intro 🤣 What amp was it recorded with ?

When applying the voltage, does the polarity of your meter need to match the capacitor i.e. positive and negative.

I know this video is 3 years old but perhaps you might still see this comment and be able to answer a couple questions for me... - The last capacitor you tested, you de-soldered one end from the board. Is that the way to do it or can the same testing be done - and done as effectively - _without_ de-soldering one end of the capacitor from the board? - I understand and agree that with the larger, electrolytic caps (in an old Fender, the ones on the other side of the chassis where the tubes/transformers are and usually under a "dog house" type cover) the premise of "if they're older, just replace them" - but for information sake, would the testing procedure for those electrolytic caps be the same as the procedure you demonstrated here for these smaller caps? - the devide you used for testing leakage and putting a voltage across the capacitor, could you clarify what it's called? A meg/meggo I think you referred to it as? - Lastly, assuming this procedure is the same for all the caps (these and the bigger electrolytics) should I assume that if a larger cap has a designated positive(+) and negative(-) end, that I should use the corresponding +/- probes on my multi-meter and/or meg(?) devices when testing? Thanks so much, regardless if you see this comment or can answer these questions. People like you posting videos like this are extremely helpful.

Stuart - I need to replace an original electrolytic capacitor on a 1963 Danelectro DM10 amp, but I can't find a replacement with the same specifications. The original cap is a Sprague 0.47MFD at 200V, but the closest I can find is a Vishay 0.47MFD at 450V. Is it okay to replace an electrolytic with a new cap that has a much higher voltage rating like this?

Is there a modern day Mega tester to test the cap from passing DC voltages?

Wonderful! Is there a newer tool to measure leakage? I have some resistors that measure lower values than they should; is this an issue? They are in an old early Fender Concert 6G12. Also a question about wattage; how do you determine resistor wattage so they can be replaced with correct resistors?

Can I check capacitors, including leakage with a standard multi tester? Any tips appreciated, Thanks

I wonder why my 65 Park 45 sounded huge, warm, creamy, in reality... nothing like any other jtm45 I've tried, which have all been more recent....... I don't know.. but it was a great amp....

Excellent!

Why did you lift one leg on the second capacitor for the testing?

Is there anyway to check for leakage with a multimeter? Checking if there is any voltage when one leg of the capacitor is disconnected from the circuit and the amp is turned on?

I understand lifting one end of the caps to measure capacitance. Assuming you did not need to do that............. the amp puts high voltage across the cap. There should be no DC across it or on the grid of the following tube. Why can we not just measure from ground to tube grid or from ground to the Non-DC side of the cap.? Thank You