Search results

Not sure what the case number is.

Most of the vintage receivers used a diode mounted on a heatsink as a bias regulator to prevent thermal runaway. I've got a Marantz 4230 quad receiver. The bias regulator diode has a broken lead. It's listed as M8513 in the parts list with a reference designator of H718 & H719. They used to...

I seem recall the Leach amp in Audio magazine. I may still have the edition it was introduced and will search for it. As for matching transistors, I don't believe it's necessary in a proper design. A proper design takes into account that there are differences in production runs of components...

I bought a stacking set of LG washer dryer during bathroom remodel about 10 years ago. The only trouble so far was a clothing item got stuck in the washer pump and the pump failed. On second thought, I did replace bearings in the dryer during covid.

Perfect! I bought 20. Many thanks.

I saw that, but I need more than 2. Want all of them to be the same.

Thanks Hexis forf the link. I'm hoping to find a socket that insulates the collector screws like the modern TO-3's do.

I've got a Marantz 4230 (Quad receiver) on the bench. One channel blown. Has 2SC789 outputs (TO220 case) that is hardwired. Heatsink is drilled for a TO-66 device such as a 2N3054. Anybody know where to find a TO-66 socket?

We had a few pops the first night which left me a little sore the next day. After making the rounds on day 2 we stopped at the golf course to fix a shabby connection on the irrigation pump. It felt like I had been working with Lee for 30 years.

Anybody know anything about the Quicksilver Mono tube amp?

The web site is outdated. It was converted from an Earthlink account to WordPress. I haven't yet taken the time to learn WordPress. Retirement should help that. To clarify, the 700 does call out 2 relays. The 400 has 1.

Worst case condition would be at about 25 volts (78 watts ) at 8 ohms. The output stage dissipates the most heat at 1/3 power. When I work on an amp I check device temps with one of the cheapie infrared guns. I've also used a FLIR camera with good results. The absolute value is not as...

I don't believe matching is necessary. The emitter resistors force load sharing. The test procedure has you check the voltage drop across the emitter resistors to confirm they share.

The dumpster ain't pilfering. It's recycling.

I use Belden 12 guage speaker cable and Pomona MDP dual banana jacks. I got the cable in the 80's when I did pro sound. The cable runs are less than 8 feet. Exotic cable may make a difference. Before I dropped a load of cash on speaker cables I would look elsewhere for improvements.

I haven't seen a 700 in ages (90's I think). After studying the photos and reviewing the manual, the 700 used 2 sets of input jacks (direct and capacitor coupled). The 700B?700II used one set of input jacks and a micro switch to short out the cap for direct coupled. If I was doing this I...

There is a misconception that gobs of heat sink grease (post #1) with the mica insulators is a good thing. It is generally accepted that the silpads are preferred. However if mica is used a drop of grease about a 1/4" in diameter between the base emitter pins is all that is needed. I tighten...

This division was in Columbus, Ohio. They made underground coal mining machines. I worked in engineering and occasionally went out in the field. The last mine I went to, the face was 5 miles underground. Coal mines leave pillars of coal 10 feet square to help hold the roof up. You can only...

I already sent Gene a new board plus a chip and relay to repair the old board. Now he'll have a spare.

The emitter resistors are a surprise. The only time I recall them fail is when I found foil wrapped around the fuses. It suggests the fuses were slow to open. The blown chip is a surprise also. During development of the board, I pulled two of the 3 outputs in one channel and ran the amp...