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

Maarten · 5th Mar 2015, 6:48 pm

If possible, I would like to see a picture of the ON type transistor or a transcription of any other codes that are on it. It was most likely manufactured by Philips/Mullard on customer spefications, but I have only seen ON-types made (for Philips) by others once, so if it is indeed a TI transistor that would be very interesting. My data collection on ON types and several other exotic Philips types can be found (in Dutch) at http://www.circuitsonline.net/forum/view/113864/

The OEM part numbering was at least partially, but I presume mostly, to prevent "hit or miss" replacements of transistors that were custom selected on one or more parameters (such as hFE) from normal production or even custom made variants on normal transistors.

For example the ON4673 line output transistor pair, consisted of what were basically 2 pieces of BU2508A binned and paired.

Most Sony repair technicians will also remember transistor choice in power supplies and line output stages being very critical sometimes.

5th Mar 2015, 6:48 pm	#11
Maarten Dekatron Join Date: Dec 2007 Location: Haarlem, Netherlands Posts: 4,203	Re: Texas Instruments OEM transistors If possible, I would like to see a picture of the ON type transistor or a transcription of any other codes that are on it. It was most likely manufactured by Philips/Mullard on customer spefications, but I have only seen ON-types made (for Philips) by others once, so if it is indeed a TI transistor that would be very interesting. My data collection on ON types and several other exotic Philips types can be found (in Dutch) at http://www.circuitsonline.net/forum/view/113864/ The OEM part numbering was at least partially, but I presume mostly, to prevent "hit or miss" replacements of transistors that were custom selected on one or more parameters (such as hFE) from normal production or even custom made variants on normal transistors. For example the ON4673 line output transistor pair, consisted of what were basically 2 pieces of BU2508A binned and paired. Most Sony repair technicians will also remember transistor choice in power supplies and line output stages being very critical sometimes. Last edited by Maarten; 5th Mar 2015 at 6:58 pm.