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What is the best way to attach the small heat sinks to the TO92 transistors on the WO Board- would a dab of hot glue suffice- or should I rely on the mechanical grip? The heat sinks all needed a slight adjustment to fit the transistors, and I wnat to make sure they do not come off inadvertently...

so one step forward, two backward. The original 410 pre drivers all measured OK, however, when installed, the 10ohm resistors want to provide magic smoke and the current draw hits 1.5Amp plus - so is the MJ15022G a decent replacement for the 401's? There is also the speaker protection board...

thanks agian, I will clean and touch up now that is working-

@Gepetto- I did get the phoenix kit, but not the 3 pin sockets, the bias wires do reach here is the bottom photo thanks for your insight Best Peter

@Gepetto -thanks so much- pin 6 is 0v....:) would you advise putting the speaker protection in next or populating the drivers and outputs?

thanks so much for your keen observation, I will get on it and report back

rear one to follow

ok will do

I have measure the voltages on Q7, Q8 and Q9 on the left (faulty) channel- Q7 b 10v, e 10v, q8 e 8.4v b9.3v. This suggests that Q8 is functioning (b-e=0.9v), however on the good right channel Q7b 0.2v and e 1.5v and Q8 b 0.6v and e -0.5v. Q9 on the left b 6v and e 8.7v, where as on the right...

no outputs or drivers fitted

The low voltage +15 and -15 both measure correctly

the +/- 15v test points both measure correctly- and yes at 60v both channels measure 0v at pin 6

I have run the unit at 60v (0 on pin 6 both channels) and then at 120v (0v on the right and 15.17v on the left). Checking the diodes/transistors for correct positioning and all look OK I am thinking Q7 or Q8 as the likely culprits?

Not as yet- I am planning to install the speaker protection board after the white oak tests OK. However there are no output transistors or driver transistors fitted as yet. So if I use the variac and bring it up form zero, I should expect the voltage on pin 6 to rise and then as the devices...

Thanks @laatsch55 - I did wonder, I generally just use the sencore, and watch the amperage- which is a very good indication of if there is a problem. So perhaps set up for ~ 60v AC and then measure pin 6?

Hi- So I have assembled the board and installed it into the PL400, with all the output and TO3 driver transistors removed. I then, following the instructions provided, set the board up for testing, removing the cables as described by white oak, inserting the bridges, and the two 47ohm resistors...

thanks @Gepetto- quasi comp it will be

I have the White Oak board and the MJ21196G transistors, should I wire the WO PL14 board for qausicomp or fully comp? thanks

Diane sticker will remain untouched. I have opted to put the WO PL14 board in and will post some photo's when done Thanks agian

Thanks @Gepetto will these work if I continue with the original PL 14 board?