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Fair enough!:)

I'm on a learning curve here. Why change to a Schottky diode? Also why not D6, D7, and D8?

Well, it seems to be working again. Looking at the schematic, I started with Q7 and all the voltages were unstable. I pulled it and tested it. All seemed good. Powered up and found I had no wild voltages. I noticed the bias transistors were dissimilar so I replaced them with 2n5088s. Put Q7 back...

I seem to recall a substitution list for the obsolete transistors on the control board. Anyone got a link?

I likely won't stick any money in it unless I have the part on hand, but I want to run this down for the experience. Mild OCD doncha know... o_O

Guess I spoke too soon. 20 minutes after I posted above, it popped. Put a voltmeter on the right channel output and I'm getting a large DC spike. This is going to be a bear to run down as it's so intermittent.

Ok, so here is where it stands; Sorted thru 3 full sets of output transistors from previous rebuilds. Came up with 8 FPL 909's, 2 RCA410's, 4 RCA 66546's that were indicated good on my transistor tester. Installed 6 FPL 909's and the RCA 410's in columns 3 & 4. Been running now for 2 hours...

Took a chance and hooked up to my cell phone for input and a pair of cheap test speakers - All seemed well for about 15 minutes then I was getting intermittent popcorn noise in the right channel. Enough to peg the meter so I shut it down. I think I'm gonna make sure I got good transistors and...

Took the DBT out of the circuit and brought it up on the variac. Rail volts are 75.4vdc and -75.4vdc Left channel bias at .475vdc. Reset to .350vdc - stable Right channel bias at .438vdc. unable to set below .384vdc - stable Right channel output transistors are all RCA D3937-6 with No name...

I've got plenty of like drivers if that might be dragging down the rail voltage. Will the bias voltage be valid at this point? With the rail voltage down 20%?

Well, I fired it up on my DBT just to see.... didn't blow any fuses, DBT worked like it should. No magic smoke. All seemed well so I checked rail voltages. Positive rail was 60.2 vdc. Negative rail was -60.2 vdc. AC input was 50vac both sides of secondary to center tap. No dc on the output...

Hexis22, that's some NASA level soldering there!

By the way, anybody got a top panel they want to get rid of? Only issue is the top panel is missing.

Got another Linda today. Beautiful condition. Nary a scratch on the face. Seller said she is blowing fuses. Has 3 service tags on it. Last one dated 10/4/89. I'll have to find out how she comes up on the variac and dbt. Interior and exterior is very clean. Well cared for if nothing else.

Managed to snag a cheap 400 on ebay. Exploring ideas on what to do with it. Full comp WOPL is mandatory. Bridging it for a mono sub driver is my first thought. Is this doable? Open to other ideas. This will be my fourth 400 and my third full WOPL when complete. ...hello, my name is Harold and...

It's a noun.

All good advice. Just have to see what's available when my budget says ok.

I rarely push my 400s beyond 25 watts. A series II uses LEDs instead of analog meters which are unobtanium. Personal preference. No need to make up for shortcomings in other areas... :):):):p

Just daydreaming for now. I'd likely go 400 series II.