'67 Fender Pro Reverb | Diagnosing Blown Fuses

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[@russellhltn1396]

That's how I was taught as well - the best tube tester is the circuit it's being used in.

[@whatsstefon]

Indeed. I use to have a few amps layering around that were my tube testers because an actual tester doesn’t test at full voltage or with a load, let alone bring up issues like microphonics.

[@johnhathaway3679]

That is an excellent sounding Fender ! And to think , Western Electric and other manufacturers gave these circuits to the world for free. Leo certainly utilised the information for the benefit of all.

[@tunasalad970]

I recently got a new solder sucker (a small one for PCBs) that has a little bit of silicone tube on the end, works fantastic for getting a good seal around the solder joint i'm looking to clear. It works way better than any others I've had in the past. A bit of silicone tubing on the end of yours may help get more solder out the first time.

[@jbrobertson2758]

At 11 minutes - "Aziz! More light!". More lumens, a bit dark at times. My 67 Drip Edge Bandmaster appreciates what you do.

[@goodun2974]

"The 5th Element", a favorite of mine. In the context of tube amp repair, perhaps the 5th element is the absence of any element, ie: a vacuum!

[@1Dougloid]

Intermittents are the hardest to identify. I use a Kill-a-watt that tells me how much current the amp is drawing under load and I have a pretty good idea what it should be. I recall one Pro Reverb that was drawing too much current and would randomly blow fuses and the fix was to cut a new insulator board and slide it in. I've also seen chafed wires going to the filter capacitor bank that would do this.

[@watkinscopicat]

my absolute favourite fender amp, these are so good.

[@TheStimpy60]

Thanks Lyle - great stuff as always. Willy Wonka indeed

[@BradsGuitarGarage]

These EL84's test good. The problem with my AC30 must be your fault. I've dealt with this logic and it's not fun.

[@zbaby82]

Wouldn't it be a good idea to go ahead and replace the standby switch just to be sure?

[@fiddlix]

Can’t beat testing tubes in circuit. Just use some safety precautions, current limiter is essential.

[@retread1083]

Might be worth knowing how much mains current you're drawing when taxing the amp a bit. Say a moderately clipped sine wave into a 4 ohm dummy load?

[@jimsalman7257]

Before re-soldering that eyelet, I would have run the amp on standby (with power tubes removed to be extra safe) and, while measuring the voltage at pin 5, tapped and wiggled that eyelet connection to see if it affected the bias voltage reading.

[@goodun2974]

Jim Salman, I've never liked how Fender grounded the bias resistor to the back of the bias pot because this relies on not just one but *two* mechanical connections to ground: 1) the pot bushing and shaft nut have to be securely tightened against clean metal (that chassis is anything but clean, although Lyle likely cleaned under the pot when he worked on this amp a few years back); and 2) the back cover of the pot contacts the bushing sleeve via 4 bent over tabs. I'd like to see that resistor soldered directly from the potentiometer terminal to the chassis. Also, the wiper of the pot should have a jumper to the terminal of the pot where the negative voltage comes *in*, so that if the wiper connection is intermittent, the bias voltage to the output tubes goes full up (cooling the bias and preventing the tubes from redplating) instead of disappearing entirely. By the way, I've seen a couple instances of Chinese or Russian tubes with an intermittent or cold solder joint (leadfree solder didease!) inside pin 5 of the tube base. In a cathode biased amp, this merely causes loss of audio to the grid, but in a fixed bias amp, an intermittent connection inside pin 5 also causes loss of bias!

[@christophersambuco9414]

BTW, before seeing your videos, I thought that I soldered fairly well. Maybe not so much. I think I'm going to blame the soldering iron and throw some money at a fancy Hakko

[@tjminasi1442]

Hmmm…? Mostly locals refer so causally as ‘ The Garden’. I’m guessing Brooklyn?…

[@PsionicAudio]

Do I sound like I'm from Brooklyn? Memphis. Just well read. ;)

[@ItsGiusto]

Why is it a concern that the filament leads are spliced? Is it that you're worried the splice could fail? Or that it would add too much resistance and eventually fail due to heating up and eventually melting the solder? How do you properly do a splice to avoid those concerns? I've had to splice wires in amps a few times, but haven't had problems yet.

[@christophersambuco9414]

Would a situation like this be like what you mentioned earlier in the video...the specified 2A fuse being a little too small?

[@PsionicAudio]

I'm thinking so.

[@christophersambuco9414]

@@PsionicAudio Thanks for the reply. It was a lucky guess on my part. And thanks for putting out your great videos.

[@goodun2974]

I like to use the captions when I watch videos so I can keep the volume down if my wife is working nearby or on her phone, but sometimes there aren't captions available. Is that something that you (and other KZbin channel creators) have to enable whenever you post a video?

[@PsionicAudio]

I don't have the resources. You can use the auto generated captions - my diction is pretty good. Though it will spazz on any technical terms.

[@goodun2974]

@@PsionicAudio on this particular video, captions are not being auto-generated, although the Vibrolux video you did earlier today did have them. I've seen this happen on other channels I subscribe to ---- sometimes the captions are there, and sometimes they're not! So this is a fluke of KZbin/ Google software? It's true that the software is flukey ---- when you say 12AT7 it reads "1287! "

[@russellhltn1396]

How new was the video that didn't have captions? I think the auto generated captions may take some time before they're added.

[@goodun2974]

@@russellhltn1396 hmmm, I think it was brand new, less than an hour old. So maybe that's it?!

[@goodun2974]

@@russellhltn1396 , update: it's a day later and now the auto-captioning works, so yeah, you're correct.

[@zachary1688]

What do you think of the Fender Pro Reverb reissues? Do they have issues like the Deluxe Reverbs do? I think I'd like one because they have more headroom to use a lot of pedals with. Thanks for any insight.

[@PsionicAudio]

All the Fender RI amps have the same issues, mostly heater connections and filter caps.

[@zachary1688]

@@PsionicAudio Dang thats disappointing from Fender. Thats for the reply and informative video btw. Also, what about the more expensive 64' reissue handwired ones? Any info on those?

[@PsionicAudio]

The '64 "HW" amps are pretty much junk for what you pay. Bad lead dress, cheap parts, not the correct vintage circuits.

[@BradsGuitarGarage]

RIP Roald Dahl.

[@jetsonIFY]

Why not dime it out for 1 min or so on each channel? I would be more comfortable ther was really no problem.