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This was an estate of a single man in his 80's who passed away. I think he was a radio type. Quite the hoarder. A young guy bought the house. There was a bunch of 60's bakelite radios I passed on. He also had a pile of tapes. I hoped there would be a tube amp lying around. No such luck...

Scored several boxes of tubes from an estate yesterday. Most will likely go up on EBAY.

VRLA's (valve regulated lead acid) are notorious for thermal runaway. I had a set do that in our battery lab a few months ago. The valve opened on a couple cells and spewed like a geyser. Stunk up the building. Fortunately the rack is on a concrete floor.

Derek, Looking at your set up you are mixing battery types. It is desirable not to mix different types of batteries in the string. The possible result is different charging voltages on different jars that could lead to thermal runaway and a mess. You're not actively monitoring jar votages...

Here's another thought. I sat on row 41 on the 30 yard line at Lambeau Field (Green Bay) Chistmas day. On third down, late in the game, the scoreboard showed crowd noise SPL's with occasional peaks of 110 db and was continuous above 100 db. All I could hear in my left ear was a roar not...

I heard Lee's set up in the "chair." We didn't hurt any amps or drivers. My ears hurt for 2 days afterwards. I've never looked at an amplifier output with a spectrum analyzer. Here is a link that kinda shows it. Harmonics analyzed. The short summary is that a sine wave driven into hard...

From time to time I pull fan panels out of the scrap barrel at my day job. Most of them hold 2 x 4" muffin fans. There are also 3 fan panels. The 2 fan panels sit nice behind 400's and 700's. If anybody wants one I'll ship them to a U.S. address for $10 which is the about the cost of...

As frequency drops, the size of the iron core of a transformer increases. So if the input transformer is rated for 50 Hz it will have no problem at 60 HZ. Also the ripple frequency of the power supply will be higher and the bulk caps would provide slightly less ripple voltage although it's not...

Yea, I had the industrial version. I ran it on single phase 208 and derated it.

About 20 years a friend bought a truckload (literally) of 10kw Crown amps. They only put out about 30 volts but would go down to about 0.5 ohm load. They came out of an MRI system. Input was 208, 3 phase. I used one as a variable frequency source and ran a 480:120 volt transformer backwards...

Perry, You're right, the Pace is ADS200. 2.00 reading glasses at a distance is my excuse. Can anybody explain the difference between the Weller bases and what irons are compatible with what base?

I use a Pace AD5200 for board level work. The fact that it its 700 degree in about 5t seconds appealed to me. Will the Weller's mentioned here work for the 40 amp bridge rectifiers and 12 gauge stranded cables etc? I bought one of the hot air SMD that I've used on back planes. Have to be...

I'm not a fan of whoesale parts replacement, especially on the board. Without good techniques and the right desoldering tools it is very easy to damage the board. If it's not blowing fuses the outputs are probably good. R101, 7.5K/2W is a common failure. For less than $400 you can get an...

Attached is the page from the 400 manual on how to test outputs. It's not in the 700 manual. It works for just about any traditional amp. Read it 2 or 3 times and do what it says and you'll find the shorted device(s). Note that replacement of fuses multiple times does at least $100 worth of...

Working on a 400/416 driver board is a PITA. Doing so will certainly mess up a neat assembly job. Thank the tech who labeled stuff and left it for the next tech.

I bought a 400, PAT5, and a FM6 at an estate sale last year. The assembly had to be factory as it was so neat. The amp and preamp had a few bad coupling caps. Barely made 200 watts at 8 ohms. Otherwise it was fine. Sold the set on EBAY. In the early 90's I did sub contract work for Sound...

Here's the manual

Back in the late 80's and early 90's I tested about 500 driver boards for this amp and it's siblings the 410 and 416. I didn't necessarily like the totem pole output section but it met spec and was reliable. If i didn't have a 200 W/C amp I wouldn't hesitate to jump on this one. It uses all...

Yep, they're OEM and with that comes more broken jacks and cracked solder joints.

The loud pops that are mentioned in the article are not likely to be caused by outputs. The more common issue is the TO92 transistors on the front end.