ebay Phase Linear 700B rescue

[laatsch55]

At power levels that had a truncated waveform before??

 

[Billboard]

Yes, at same level and load as before, no distortion, if this does not make sense I can solder D9 and D10 back in and verify that the distortion is back.

 

[laatsch55]

Makes all the sense in the world. To test those 1304's and 1305's the forward voltage on those on a diode test is 120- 190, that's the range I've seen. Quite a bit lower than a silicon junction which would give a figure of 500 to 600....

 

[laatsch55]

Yes, at same level and load as before, no distortion, if this does not make sense I can solder D9 and D10 back in and verify that the distortion is back.

Next time you want to isolate the protection circuit all you have to do is desolder one end of D9 OR D10....

 

[Billboard]

Thanks Lee, I did only lift one end each of D9 and D10, I was referring to placing them back in the circuit, not placing the diodes back on the board...

 

[laatsch55]

Gotcha, test the 1304 and 1305 and see what ya get. I gotta get to bed. Up early....

 

[Billboard]

Will do, thanks Lee, will catch you when you get back.

 

[laatsch55]

Ok Bud, doin good....

 

[Billboard]

Q9 2N1305 has a dead short between the collector and emitter leads.

 

[laatsch55]

PM your address, cause you ain't gonna get those at Mouser....

 

[Billboard]

PM sent, thanks Lee

 

[laatsch55]

Welcome Sir...

 

[Billboard]

Replaced the defective Q9 2N1305 on the right channel negative side, placed D9 and D10 back in the circuit. The distortion remained on the negative side of the right channel. The distortion does not come on until the output reaches 40V P/P. Removed D9 and D10 from the circuit and the right channel was clean all the way to 100V P/P.

I then replaced Q8 2N1304, no difference, now that I am taking a closer look at the schematic, this was a waste of time.

I then tested D9 and D10, and then noticed there was discoloration on R25 (5.6K ohm), the resistor is reading 7.9K ohms.

 

[Billboard]

Replaced R25 with a new 5.6k ohm resistor, who knew Sprint/Radio Shack still carries components.

Dim bulb test, bulb would not dim!

I took a close look and I accidentally put in two 2N1304 transistors rather than a 2N1304/2N1305 pair.

quick swap and all seemed good, cranked her up to 100 volts peak to peak and no distortion! yay, then my baby advent speaker went up in smoke!!

lets see 100 volts p/p at 8 ohms equals 12.5 amps, that put the output at roughly 1,250 watts!! when my speaker blew (ok maybe my math is wrong )
Need my 1000 watt 8 ohm speaker load to arrive so I can put this amp through the factory load sharing test.

 

[Billboard]

just curious about the power out.

100 volts peak to peak = 35 volts RMS divide by 8 ohm load = 4.375 amps multiply times 35 volts= 153 watts

sound about right??

 

[Gepetto]

just curious about the power out.

100 volts peak to peak = 35 volts RMS divide by 8 ohm load = 4.375 amps multiply times 35 volts= 153 watts

sound about right??

156.29W to be more exact

 

[Northwinds]

Damn, too bad you did not have a vid of the Baby smokin'

I tried to capture an Infinity RS-1 catching on fire but my amp worked and only Black Sabbath was released LMAO!!!

 

[Billboard]

Nothing exciting, just a 600 hz tone, a Fitz sound, then the whole basement had a smell of burning plastic. Speakers measure wide open, I ordered generic 6 inch woofers and new old stock tweeters.

 

[Billboard]

156.29W to be more exact

Speakers: baby advent speaker are rated at 50 watts, so:.....ya.

In my defence the tweeters were already blown, and they sounded like poo.

 

[laatsch55]

One needs no defense when blowing up speaks....