Recent content by wattsabundant

I doubt you'll notice any difference but it shouldn't hurt anything.

... Thanks for the kind comments. It's rare that I get any feedback and good or bad, much appreciated.

The date code is 40th week of 2001. (0140) they appear to be legit RCA's. Ideally all drivers would be RCA410's. If you're buying transistors, pick up Berquist silpad insulators. No grease required.

Ed, It's good to see you still sharing your infinite P/L wisdom.

are the meters analog?

The schematic for this amp is nearly impossible to read and understand. There is a time delay relay on the transformer primary acting as a soft start. Q508 controls the relay. I would check it.

As for the grease, less is more. All that is needed is a pencil eraser size dot between the two pins on both sides of the mica.

Last year I drew up the conversion in power point and saved to pdf. I used a lot of Ctrl-c, Ctrl-v. See attached. As for silpads I've only installed a thousand or so with only a handfull that I over tightened. Use thumb and index finger to lightly grip the nut driver. Turn until it slips...

Is this amplifier quasi complimentary or full complimentary? Quasi complimentary will have all NPN outputs such as MJ15024, TP9054, or 2SD555. Full complimentary has PNP and NPN outputs. The manual was written for quasi-comp. That could explain differences that conflict with the manual...

I don't understand what the high resistance is. The most common failure mode of transistors is zero ohms across one or both the junctions. In other words, if it's not shorted, it's good. Take that approach first. On the board, R101, 7.5k/2w has shown failures in the past.

There are shorted output transistors. The 700II manual is attached. Read the troubleshooting section for checking transistors and do exactly what it says. Note that the manual was written before digital meters were available.

I second what he said, with the exception that "anf" should be "and". Sorry Lee, you were 99% correct. The RCA 410's (located at the bottom of each heat sink) are a must for stability. Mj15024's can be used for outputs. See service bulletins in attached manual

Attached is the manual.

The contact only provides base drive to the pass transistor in the power supply. The design allows the use of a low power switch. The condition stated above suggests Q1 has shorted.

I'll bet they don't publish any time/current curves.