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White Oak has a modification for this issue to bring the bias adjust into the center of range if you are using their driver board. Mine is a Rev E Board. It involves changing out one resistor and changing a diode in the boas string to a Schottky type diode. I did it to mine and it's fine now. A...

Anita is 98% completed and back together playing music, just waiting on some white LED's for the meters. The front panel cleaned up way better than I thought it ever would with just a few dings. Meter bezels are re-painted and both Honeywell meters are scratch free and working fine. I just have...

I finished my WOPL conversion a few months ago and its been working just fine except I still had the NTE- 129A transistors in the bias sense. I could only get the bias down to about 400 mv and everyone on here said...."No! You need 2N5088's in those spots so it'll adjust correctly." So today I...

Anita is almost all back together again... If I could find my honkin soldering gun to solder the grounds to the copper buss I'd have already fired it up... This weekend for sure... Mark

Going Back Togther.... All parts have been cleaned up and they cleaned up amazingly well considering how brutal this amp was treated over the years. Power transformer has been cleaned of rust, re-varnished and dried in the oven. Everything has been re-mounted and new fuse holders and output...

Anita On The Bench Lots of clean up to do... Picking up some transformer varnish tomorrow...

Anita is moaning right now. She's apart all over my bench. Going to attack the slight corrosion on the core of the power transformer first. Clean it up and apply some fresh transformer varnish. Transformer is good fortunately. Will bake the varnish on in the oven.

A friend got this PL400 off Ebay and brought it over today. Seller told him it has been sitting in a storage locker for many years... Sure looks like it to me. Transformer is good and so are the meters but it's gonna be a complete tear down and a new White Oak driver board and all new outputs...

Thanks! But apparently there are not many other builders on this site..... Mark

I've built quite a few different amplifiers over the years and was curious if any of you on here also have. A few that I've done are the Krell KSA-50 MK2 and the KSA-100 MK2 and a number of pass labs Aleph circuits including the Aleph 30 and A pair of Aleph 2 mono blocks. Till I acquired the...

I need one top cover to complete my amp which is an early Series 1 Model 700. It's an easy part to duplicate, but it would be nice to have an original. If you have one you'd sell please let me know... Thanks! Mark Allen ksa50amp at yahoo.com

__________________________________ Will order a dozen on Monday.... Funny thing is I live just 3 miles from a huge Fairchild Semi plant! Mark

It did have the PLO-171 board.... I can order some 2N5088's... but comparing the two the NTE's have quite a bit higher operating voltage and current 75 volts vs. 30 volts for the 5088. The thermal tracking is actually pretty good too. The amp doesn't run nearly as hot as it used to without the...

Listening to the amp..... I cleaned up the grounding, still have to get a large enough piece of copper for the ground buss... so my ground buss is still as it was from the factory but with no ground loops any more. Input ground also cleaned up. Fed a signal into it and all was well. Went to set...

I had an Eminent Technology air bearing linear tracking arm on a VPI HW-19 for many years and it was great as far as vinyl went. I sold it about 15 years ago then scrapped all my LP's except my Direct to Discs which remain packed away. I went to CD and SACD exclusively. Today I run a DAC that...

_________________________________ Agreed and thanks again for the new grounding diagram. I do still have some more work to do in there and tomorrow I'm picking up a piece of 6 gauge copper for the ground buss that's also large enough to mount the bridge on to and then I can eliminate that blue...

____________________________________________________________________________________________________________________________________ Email has been PM'd. The resistors don't land on the speaker terminal ground. They land on the ground lug that's screwed to the chassis... Mark

6:00 News Part 3.... Left Image: I replaced all the emitter resistors with 1% tolerance. Right Image: I noticed the positive regulator seems to be running quite a bit hotter then the negative regulator is. Is this normal? I can't quote any temperature specs yet but I will tomorrow. Positive...

6:00 News Part 2.... Left Image: New Jacks were too small for the original PL hole and insulator. So I devised a trick using a piece of cut off resistor lead wrapped around the threaded part of the jack. Right Image: Rewired input section. The back to back diodes are gone and the PL ground...

The 6:00 News... First image is the amp fired up on my bench running at full 106 volt rails off the variac. Second is where I found a short between the positive rail and the base of Q-11. I had to bend the collector tab over so it would clear the base pin. It's amazing this amp never had any...