What is the most safe method of desoldering filter capacitors from fender red knob twin pcb?

[Jquijano]

I've worked on a lot of these amps, with numerous different faults - but problems with the power resistors haven't been one of them. I wouldn't change them unless there's a fault - you unnecessarily risk damaging the amp or making a mistake.

The PCBs are no different to any other Fender PCB of this era. I have a desoldering station, which minimizes risk. For the many years before that I just used a soldering iron and desolder pump. Much damage is done to traces by heat-soaking the pad with an iron that is too small, underpowered or not hot enough. 'Hot and fast' is the way I work. X-pro's suggestion is what I would do in your position. Slice through the glue, cut the leads off and leave enough length to grab hold of. You can then quickly heat the joint and pull the lead through from the other side of the board. If necessary, remove any surplus solder afterwards with fluxed braid or a good quality desolder pump.

F&T caps are good, but so are Miec, which are very reliable.

Evaluate the amp first. Play through it, make observations and think about it before replacing parts that may be good. Whilst the grey Illinois caps in the Hotrod/Deville series are often high ESR or leaking/bulging, the caps in these amps hold up much better.

I recommend this cap removal and soldering video:

https://www.youtube.com/watch?v=DP_dWlIXz9I

[g1]

Can you point out which plate resistors must be changed if it starts to crackle and generate popcorn background noises?

Those on your attached list are all the preamp tube plate resistors. Any one of them could cause crackling or background noise.
It is best to isolate the noisy one by tube removal, then replace the ones responsible for the noise.

[Mick Bailey]

Almost any component or connection either directly or indirectly associated with the signal path can cause pops or crackles. Assuming it's a resistor problem before you've done further tests could give you more trouble than the original fault. Each time you disturb a PCB there's a risk of making things worse. It would be wise to narrow down the fault to a single stage and then take it from there.

[Jquijano]

So how do you test the actual filter caps before deciding if they need to be desoldered and replaced? I only have a fluke 117 digital multimer to test them.

[Pixel]

So how do you test the actual filter caps before deciding if they need to be desoldered and replaced? I only have a fluke 117 digital multimer to test them.

How about looking in the manual for your meter?

Also search these forums and the internet for information. An ESR tester is good to have. You really need to do more reading so you have the background to understand what is going on.

[Jquijano]

Well im taking the amp to my experienced Tech who is a Cuban. I told him to check everything and eliminate all the hum possible as i am selling this amp. I already purchased another red knob from a single user. Ill post pictures of the guts once it arrive before removing any caps or resistors.

[Jon Snell]

So how do you test the actual filter caps before deciding if they need to be desoldered and replaced? I only have a fluke 117 digital multimer to test them.

If they are not bulging or leaking, they are probably OK.

[Chuck H]

If they are not bulging or leaking, they are probably OK.

Wow! I don't know. It's an old amp. Though I don't do repairs for a living I'd say that less than fifty percent of the failing caps I've had to replace were showing physically obvious signs of failure.

[Jon Snell]

I use 105° capacitors as they do not fail and leak like the stock 85° capacitors do.
F&T is fine, Panasonic or Nichicon are excellent. Get what you think as long as they are not from any untrusted ebay seller, as you never know what you will get.

[Chuck H]

I use 105° capacitors as they do not fail and leak like the stock 85° capacitors do.
F&T is fine, Panasonic or Nichicon are excellent. Get what you think as long as they are not from any untrusted ebay seller, as you never know what you will get.

THIS^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

[Jquijano]

WHat about using this MESR capacitor tester to test the capacitors inline meaning within the PCB ciricuit before cutting and removing them before spending any money on F & T filter capacitors?

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

[The Dude]

Yes.

[Helmholtz]

I think the MESR is only an ESR meter, not reading capacitance.

[The Dude]

Doing a quick ESR test would certainly at least point out caps that are definitely defective. That is how I'd start. Then, if there are still hum/filtering problems, we move on to more in depth testing.

[g1]

That one (MESR) will do it.
But I think for units that will only check ESR you can get cheaper ones (like LCR-T7). Or you can spend more money and get an LCR meter that will also tell you the capacitance, and can measure coils and resistors (Yertai ET430).