UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post

space_charged · 11th Jul 2019, 1:04 am

Nop, haven't tried a BU806. Looks similar to the BU931T I'm getting some results from.
To make it work I've had to put a 1K pot in series with the base and tweek that for good waveform and reasonable current. The BU931 gets too hot and shows signs of runaway as in increasing current. The base waveforms from the working original 2SD625 and the BU931 attached. The YELLOW trace is the BU931, the purple is the original Sony 2SD625.

I'm thinking that assuming it is getting saturated (turned on fully) then excess heating could be due to rise/turnoff time being too long so maybe my BU931 doesn't have the speed needed. A BU806 sounds like a line output transistor. My BU931 is aimed at automotive ignition switching - I think.

Thanks for your suggestion which I will try and also for consulting your books tomorrow.

C

11th Jul 2019, 1:04 am	#3
space_charged Hexode Join Date: Dec 2014 Location: West Midlands, UK. Posts: 315	Re: Sony 2SD625 line output transistor Nop, haven't tried a BU806. Looks similar to the BU931T I'm getting some results from. To make it work I've had to put a 1K pot in series with the base and tweek that for good waveform and reasonable current. The BU931 gets too hot and shows signs of runaway as in increasing current. The base waveforms from the working original 2SD625 and the BU931 attached. The YELLOW trace is the BU931, the purple is the original Sony 2SD625. I'm thinking that assuming it is getting saturated (turned on fully) then excess heating could be due to rise/turnoff time being too long so maybe my BU931 doesn't have the speed needed. A BU806 sounds like a line output transistor. My BU931 is aimed at automotive ignition switching - I think. Thanks for your suggestion which I will try and also for consulting your books tomorrow. C Attached Thumbnails Last edited by space_charged; 11th Jul 2019 at 1:09 am.