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While we try to be respectful of other people's opinions on controversial things like speaker wires, etc., when it comes to modifications that directly affect safety I feel that those of us who have a technical background have a duty to point out proposals that are inherently unsafe. No matter...

Wow a 7 year old zombie thread! Short answer, though, is that improperly cured PVC insulation will leach chlorides into the copper, causing the copper to eventually form copper chlorides--which would be green in colour. Cuprous oxide--formed by copper reacting with oxygen from the...

Don't worry about those plate voltages, 6L6's often run very high plate voltages in guitar amps. Musicman ran them at insane voltages...a few models had 700V B+ on 6L6's

It's a capacitor, nothing more, nothing less. Without knowing where it fits into the circuit exactly--from seeing a schematic--we cannot say much more. "Between a 5Y3 and 6V6" is far too vague. Is it a coupling cap, or a HF bandpass, or ??? We must know the operating parameters including...

Here is a site with TONS of free downloadable technical books from the early days. Some of these are quite complicated textbooks, others are for more casual readers. Guaranteed to teach you anything you want to know about radios or tubes. http://www.tubebooks.org/technical_books_online.htm

There used to be an electronics part store downtown, but they closed a few years back. I moved out of Nashville a year ago, but the last few years I was there I mail-ordered everything from Mouser or Parts Express.

I hope my Databass never croaks, I can't quite grasp servicing the Class D stuff. Seems like a good amp design though, Peavey's only mistakes on the Databass were a) driving the amp's full 450 watts output into a single 4 ohm 15" Black Widow and b) the output terminal lugs were on the bottom of...

They also used it in their Databass amps, that's where I noticed it. Peavey received a patent for their Class D "digital" design used in the Deca and Databass, let me see if I can attach it; it may help explain how it works.

You might actually try Peavey, they do keep some of their old stuff on hand. That's a Peavey part number 7040240 right? Call and ask for their Parts department, they've been surprisingly helpful to me in the past.

I do agree that the drivers are highly suspect as well, and check the emitter resistors too to see if they've opened. When replacing drivers, I don't automatically trust that the new device will match the legs of the old device. I use my little Peak transistor checker to identify with...

Use a Dim Bulb Tester to avoid blowing fuses on startup. I highly recommend the DBT over a Variac since the DBT offers instantaneous automatic current limiting, as well as the visual indication that something is wrong. Whereas if you're watching the ammeter on a Variac, by the time you realize...

It is indeed plausible that hum could be heard through the speakers without any power tubes in the amp. Here's a couple of possible ways: 1) The OT secondaries are typically tied to ground at one point, but another winding is typically a tap for the NFB. Since the power supply usually has...

I would check that Variac with your VOM to ensure it truly is isolated, since if it is not truly 100% isolated you may be killed. See if you have continuity between the corresponding primary and secondary points on ground, neutral, and hot. I suspect that Variac has only an isolated "hot" but...

One consideration though: when folks are "tube rolling" to determine how they like the sound of a particular brand, their sample size is usually 1, maybe sometimes 2. That's not meaningful, from a statistics point. Forming a generalization about a whole brand--thousands of tubes...

I too have had to resort to shotgunning small areas, for example a particular power amp driver board was giving me fits. I spent hours measuring voltages versus the schematic, meticulously looking at signals across every component, it was a convoluted mess. Finally I bit the bullet, pulled the...

Yes I do a lot of amp repair and rebuild. For a relatively simple receiver with STK modules, it's not too bad so that's why I'd say 8 to 12 hours; for larger Sansui or Marantz stuff with a dozen boards and lots of fragile internal connections, yes I agree--the time can easily balloon to 40...

It's my opinion that if it's a receiver that you intend to keep, to enjoy, and to treasure for a long time (for whatever reason), a full recap (replacement of the electrolytic capacitors) is good preventive maintenance, and will allow the unit to function as intended for another 25 or 30 years...

The phono jack is for a mono ceramic cartridge, not magnetic.

Okay, you did as well, sorry! That was pre-coffee.

I totally disagree. The blade is exposed, yes, but it's mounted on a linear track! Keep one hand on the saw handle, and the other hand to the left of the blade, it's impossible for the saw blade to cut you. It cannot jump sideways and cut you. Whereas with a table saw, you are pushing work...

Whoaru99 is exactly right, the early Fender guitar amps were merely well-publicized amplifier circuits found in the various manufacturers' literature of the era. The manufacturers had not yet distinguished "guitar amps", it was just a gain stage, some tone control(s) and a power amp. Sag...

I've got an ancient Dewalt RAS. Other than replacing a couple of motor bearings and installing a new table, all it needed was a little tune-up. There's a book by Jon Eakes (?) "Tuneup your Radial Arm Saw" (or something like that) which covers all 3 major RAS brands. Great saw. The RAS has...

A 12AX7 has two sections, so you can get two gain stages out of a 12AX7.

Available on the guitar amp sites like mojotone, or perhaps Antique Electronic Supply.

Don't be so quick to assume they're all wire-wound! Carbon comps are commonly found in the dog-bone style like your picture. Sometimes I have trouble telling them apart, I've broken some open to find out they were carbon.