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Anyone got a discord link for shit like this?

It would be great to see which cap was causing the problem.. ..layout or schematic, great video btw

I much prefer to install a IEC on the back plate to swap cords vs hard wire.

Love saving old equipment

What cable would be the most ideal for this? Can I use instrument cable?

I happen to have one of these anamolies. CBS did some weird stuff with this circuit.

Is it possible to add an extra bass reduction mod? I have built my own 64 PR but the bass is too much even with the knob at 1.

I wonder what vintage that spider is? 🤣 That old Jensen is hanging in there.

What kind of wire can I use for this?

Picked up a broken FMMB. I had built a head unit for my Rivera-era Champ II chassis(that I found without the cab) when the FMMB came along. Decided to put the Champ II in the FMMB cabinet and let the FMMB go into the head unit. I'm pulling the FMMB board and installing a Riveria-era Bassman 20 board and tone stack instead. Keep the FMMB interstage transformer for phase inverting in the bassman 20 circuit. Remove the FMMB faceplate and replace it with a generic champ faceplate so I can drill out room for Mid/Bass knobs. I'll screw it into the inside base of the head unit so they stay together. Heads up about the FMMB fiberboard. Check for voltage leaking across the waxy surface. I think after 1972, fender went overheard spraying the fiberboard with wax. Over time it gets contaminated and begins to conduct. Acetone and naptha can wipe off some excess wax if you find voltage on the board. I liked all the suggestions in this video. I noticed that the input jack wiring was overlooked in forums but is an obvious place to increase gain. Adding a fuse holder is a great safety feature. Add a reverb and tremolo pedal and you're there already!

This is an easy one, try working on an 80 lbs MC7300 !

Id be tempted to try a 50k. Vool vid . Thanks

How about installing a properly grounded female IEC connector in place of the auxiliary power socket, thus eliminating the hard-wired power cord install as well as the possibility that a connected power cord could be accidentally yanked out? Wouldn't that be a neater way to go? Thanks in advance for your reply.

I did your mods based on this video, and the only problem I had, that I can't solve, is that after adding the 1M ohm resistor, one channel has great volume and the tone control is very good, but the other channel has a much weaker volume. I've checked and wired and rewired but no luck, regardless of the jack I install the resistor on. Any suggestions? Thanks.

can someone explain to me the point of the aux speaker jack? what is the point of it? in order to run a cab you have to disconnect the internal speaker anyway.

Thank You!

Thanks !

wish you lived nearby....i need a cap job on my 59' gibson les paul ga-40 amp

Thank you very much for this video!

I have a 73 fender twin reverb that’s been trying to kill Me. Does it have a death cap. It’s got a 3 prong cord installed

Hi there. I just did exactly this to my ‘68 AC568 bassman. I also changed all plate resistors to metal film because of popping and crackling. And I had dc on the pots so I had to change some coupling caps too. And 2 microphonic tubes. Now I’m waiting for the ordered filter caps to arrive but the amp already sounds great! Thanks for the video, I just needed some confirmation bias (instead of kathode bias 😅).

It's a piece of history - molested like tranny kids.

ooof!

Will the amp still need to be plug but turned off and standby switch on if it has it??

The viddy helped and is going to keep helping Guitar players for years, thanks. I don't have that amp but just for showing us the wiring tips I thankyou.

It's good safety practice to leave the green ground wire long enough that if you were to yank the cord out of the chassis, the ground wire would be the LAST to break. This way whatever happens if the cord is still plugged into the outlet, the chassis remains grounded and safe. And the ground wire must be attached to a lug which is MECHANICALLY secured, via nut and bolt, to the chassis. Solder alone is not sufficient. Solder alone is not an acceptable means of making a chassis ground by various regulatory codes such as UL in the USA, CSA in Canada, and CE, Europe.

People! Adding wires to a jack causes even more problems. Wires move and vibrate and will fail waaay sooner than the box jack. Damn. And I’m an actual Fender tech, not just some guy with a card table and a soldering gun. Ps, you do not have to remove the speaker pcb. Plastic is not the enemy here.

I wish you would have told us which wires were hot, ground and neutral while you were at it.

Les paul guys will go bananas for the bumble bees . If they haven't drifted too far

Tri sodium phosphate ( tsp) will take the tobacco off of that super easy. Painters use it to clean walls. Main ingredient in detergent. Leaves a milky residue, but wiping with a wet rag will remove it. Try it out on the bottom . You'll be shocked how well it works. No scrubbing nessasary.. wonderful stuff

Nice job laying out a reasonable method for diagnosing a failed circuit. The 15 Amp fuse was scary as hell. I haven't worked on any of the originals or the later reproductions but I've built three from scratch. Thanks for sharing and please keep them coming. I subscribed because I don't want to miss any new vids you post.

I do amp work as a hobby for about 30 years. For my friends mostly. I’m retired and I rarely charge them. Since the 70s I’ve acquired 7 caddies full of tubes, i have more than I’ll ever use in my golden years. If they need it and I have I give it away. It keeps me as busy as I want to be. I mostly work of my stuff. I don’t see $700+ of work there. Possibly some double charges on cap kits. I think it thirty years I’ve only found one Ajax cap

I can remember when the silverfaces were the dreaded scum of the amp world. People finally woke up ... And good on you that you got one of these jewels! I'll give you $425 for it! 🙂

These things sound fantastic. I'll get mine when the Millennium gets here. Sure miss Magnetic Components.

Why would you leave that useless switch in the circuit? There's no reason to leave it in there whatsoever.

I have one of these, don't know what to do with it though.

I pretty well cut my teeth playing guitar through my brother's 1960 PRO ... boy, what a sweet sounding amp. Doesn't look like anything's been changed in this amp ... ever (other than that OT)! Too bad Magnetic Components went out ... Cab looks much better. But I'm hearing some distortion in there ...

I love this channel!

Thank you for being a decent person and for pointing out this kind of theft.

Very helpful for DIY! Had same problem. Got it done perfectly Thanks a lot!

Power cord ground is a bad connection. Should not have been connected to the ring on the riveted tube socket. Should have been connected to the chassis via a correctly installed grounding stud for the best bonding.

Parallel, right? You threw me for a minute, had to back up to a good shot of the speaker wiring.

I'm just a guitar player (61 years, now retired from playing out), but I think things sound a bit sweeter when they've had lots of juice run through them. But boy, I like reliability. Good to change that stuff on something THIS old if they are looking crummy! Boy that sounds good!

I've watched several of your videos, but did not realize that you were located in Conway. I live just down the road in Dardanelle.

I'm at the beginning of the video and I know those blue caps are going right back in.

Unfortunately, amp techs are few and far between in some places.

Pete Townsend used one of these to record "Who's Next" after Joe Walsh advised him to do so. I think Rory Gallagher also had a blackfaced one (with 1-12" and 2-10"s); yes, these were smoking hot amps, well worth their weight in gold. Thank you for the loving attention to this gem.

The use of an interstage transformer in lieu of a PI (as Gibson did in several amps in the '60s) was an effective cost saving device, but in that, it also could sound very good. Had budgetary constraints not ruled the day here, and another pre-amp tube added (along with more tone controls), this might well have been a great platform for a budget line of amps..but that possibility was lost many years ago...

Thanks for describing the mods, and providing a sound demo. I have a few questions though: 1) Since this is a bass amp, why was it modded into a 5F2 Princeton, and then demoed with a guitar? 2) The clean tone (e.g. 12:33 to 12:54) actually sounds bad to me. It has a rough, random "tremolo-like" quality to it. Could this be due to a faulty tube?

Great job.