Harman Kardon Citation 16A

[MickP]

Hi all hoping for some advice. I am currently working through my citation 16A power amp recap and refurbishment. I need to replace both Dual NPN differential pair transistors on the driver boards marked as Q1. They are marked with a part number SD3119724 might be Motorola. Can’t find an alternative replacement anyone who has refurbished or has knowledge on the Citation 16A able to help with a substitute? Would be much appreciated. Cheers Mick

 

[txturbo]

According to the manual Q1 should be an MPS U10.

 

[MickP]

According to the manual Q1 should be an MPS U10.

I think these are for Q12 and Q17 please correct me if I’m wrong

 

[sregor]

According to the manual Q1 should be an MPS U10.

that is the 16. The 16A Q1 is a differential pair. I would think a matched pair of high voltage transistors would work - 2n5550 or KSC1845 or 2SC2240, but haven't worked on one, so caveat tech.

 

[sregor]

Oh - welcome to AK.

I would think a matched pair of high voltage transistors would work - 2n5550 or KSC1845 or 2SC2240, but haven't worked on one, so caveat tech.

Closer look at schematic, collector voltages runs (indirectly) off a 10 volt supply, so no restriction on high voltages. So can use lower voltage stuff like BC550, 2n5210, or other good quality NPN transistors. As always, be careful on orientation, and a piece of spaghetti type insulation if you have to twist leads around.

 

[markuus3889]

@MickP Here is some info from one of audiokarma's historical guru's. Be sure to read my follow up post.

https://audiokarma.org/forums/index...c-offset-to-adjust-right.126917/#post-1361278

Good luck,

Mark K.