Phase Linear 200 rebuild

[laatsch55]

Hang on a minute bud...we need to cut through the confusion created by me. I've printed out the scematic. Give me a few minuites.

 

[laatsch55]

What do you have for Q4, Q5?

 

[kl0neMan]

If the MJ15022's are used instead of 410's is that okay? I have them in and it did not draw excessive current through the DBT, With no input connected it appears to draw about 20 mA from the AC Mains. I have applied no signals nor speaker loads to it.

 

[laatsch55]

From the schematic, Q6 is the PNP pre driver, Q7 is the NPN pre driver, Q8, Q10 are the drivers and Q9, Q11 are the outputs.

Q8, Q10 should be the 410's, Q9, Q11 should be the 21196's

The 15022's are a lesser rated output than the 21196's

The 15022's could be used for Q8, Q10, but Q9, Q11 should be 21196's

 

[laatsch55]

The 410's (66546) make a better driver than the 15022's


Originally the 410's were outputs, on the 400 and 700's they were drivers. In the 200 application they were enough for drivers, apparently..

 

[kl0neMan]

Okay... I will replace the 15022's with MJ410's when I open it again tomorrow. I still need to figure out how to check and adjust the bias. At least it not become a Flame Linear right off the bat.

Thanks for a ton of help sir - The last time I repaired an amp was about 45 years ago...This will not be my last one, grin.

Dan

 

[laatsch55]

I'm sorry for the confusion, like I said I have not worked on a 200...What do you have for DC offset at the speaker terminals? DC volts on the meter, leads accross +, & -

 

[kl0neMan]

I'm sorry for the confusion, like I said I have not worked on a 200...What do you have for DC offset at the speaker terminals? DC volts on the meter, leads accross +, & -

Looks like just noise... Right 0.1mV -0.4mV, Left about the same. DVM is all over the place at first, then settles down. Outputs are cold to the touch too.

 

[laatsch55]

That's acceptable. I haven't found on the schematic where to adjust bias, you see an adjustable pot anywhere?

 

[kl0neMan]

That's acceptable. I haven't found on the schematic where to adjust bias, you see an adjustable pot anywhere?

There are no pots on either PCB. I saw a reference to R24, and R25 in the discussions about the error. I will add a pair of multi-turn pots to make this easy if I can figure out where they really go and what values they need to be.


The attached photo is of my primitive troubleshooting/repair setup. I made a DBT with a few twists. Plug is illuminated when power is applied. I split the outlets in the box and rewired to observe hot/return/safety ground, but snuck a current loop out. Top outlet is DBT load and bottom is UUT.
Dan

 

[laatsch55]

Is Q3 attached to the heatsink in any way, like that small right angled piece going from the heatsink to the board? Is Q3 under that ?

 

[kl0neMan]

Q3 has a snap on heat sink.

 

[kl0neMan]

The photo was taken before the subs arrived. This photo is current.

 

[laatsch55]

measure accross R25, see what ya got in DC MV...

 

[laatsch55]

And R24....

 

[kl0neMan]

I somehow lost my Service Manual. I will try to find it ( I will have to scan 5 hard disks and figure out what I called it) and accomplish these measurements tomorrow and post the results. Have a great and SAFE Independence Day sir!!!


Dan

 

[laatsch55]

Good nite Dan!!

 

[wattsabundant]

Here's the manual. Read the section on stability and thermal run away and the service bulletin. Ask yourself if it's worth it.

 

[kl0neMan]

Here's the manual. Read the section on stability and thermal run away and the service bulletin. Ask yourself if it's worth it.

I am this far in and will do my best to finish it. If there were later versions of the amplifier cards available, I would have updated the ones in this unit with them. Thank you sir, so much for the Service Manual on the model I have here. It provides answers to many questions I had !!!!!

I can see I am going to need to borrow a THD analyzer from a friend...

 

[laatsch55]

Hang on, talking to Ed now...,.