OC303 transistor - UK Vintage Radio Repair and Restoration Discussion Forum

glitteringprize · 24th Oct 2014, 6:16 pm

Hi guys,what can I use to replace the 0C303 transistor. There are 3 on the board. Do they fail like caps or does age not really bother them. I'm repairing a sound board from a very old pinball. I think it was the first ever and very unique to have solid state sound.

robjkmannering · 24th Oct 2014, 6:42 pm

OC71? Lower voltage rating but not sure of supply ratings in your circuit. These tend to be fairly reliable, are all of yours open/short circuit?
Rob

Ed_Dinning · 24th Oct 2014, 7:20 pm

Hi Gents, is this a Ge type or Si, from memory the OC200 series were industrial Si types, of which I have a fair few.

Ed

Restoration73 · 24th Oct 2014, 7:32 pm

Think these were made by Mistral, Italy. AC125, AC128, 2N406 pnp germanium should work.

glitteringprize · 24th Oct 2014, 7:34 pm

i dont have the pinball here just the sound board.I do believe they are something to do with the amp or pre amp.I have replaced all the caps and the main output tranny which is an oval metal body.I have no idea of the voltage it works on.Most of the caps are rated at 25 or 35 volt

paulsherwin · 24th Oct 2014, 7:53 pm

They seem to be a general purpose small signal Ge transistor. Any Ge transistor scavenged from a scrap late 50s / early 60s transistor radio is likely to work.

There is no reason to think that the originals will be bad.

HamishBoxer · 24th Oct 2014, 8:30 pm

OC70 OC71 are both listed in my book plus dozens of others.

24th Oct 2014, 6:16 pm	#1
glitteringprize Triode Join Date: Nov 2013 Location: Mansfield, Notts, UK. Posts: 49	OC303 transistor Hi guys,what can I use to replace the 0C303 transistor. There are 3 on the board. Do they fail like caps or does age not really bother them. I'm repairing a sound board from a very old pinball. I think it was the first ever and very unique to have solid state sound.

24th Oct 2014, 6:42 pm	#2
robjkmannering Retired Dormant Member Join Date: May 2009 Location: Norwich, Norfolk, UK. Posts: 717	Re: oc 303 transistor OC71? Lower voltage rating but not sure of supply ratings in your circuit. These tend to be fairly reliable, are all of yours open/short circuit? Rob

24th Oct 2014, 7:20 pm	#3
Ed_Dinning Dekatron Join Date: Jan 2004 Location: Newcastle upon Tyne, Tyne & Wear, UK. Posts: 8,194	Re: OC303 transistor Hi Gents, is this a Ge type or Si, from memory the OC200 series were industrial Si types, of which I have a fair few. Ed

24th Oct 2014, 7:32 pm	#4
Restoration73 Nonode Join Date: Jun 2013 Location: Surbiton, SW London, UK. Posts: 2,801	Re: OC303 transistor Think these were made by Mistral, Italy. AC125, AC128, 2N406 pnp germanium should work.

24th Oct 2014, 7:34 pm	#5
glitteringprize Triode Join Date: Nov 2013 Location: Mansfield, Notts, UK. Posts: 49	Re: OC303 transistor i dont have the pinball here just the sound board.I do believe they are something to do with the amp or pre amp.I have replaced all the caps and the main output tranny which is an oval metal body.I have no idea of the voltage it works on.Most of the caps are rated at 25 or 35 volt

24th Oct 2014, 7:53 pm	#6
paulsherwin Moderator Join Date: Jun 2003 Location: Oxford, UK Posts: 27,943	Re: OC303 transistor They seem to be a general purpose small signal Ge transistor. Any Ge transistor scavenged from a scrap late 50s / early 60s transistor radio is likely to work. There is no reason to think that the originals will be bad.

24th Oct 2014, 8:30 pm	#7
HamishBoxer Dekatron Join Date: Aug 2007 Location: W.Butterwick, near Doncaster UK. Posts: 8,932	Re: OC303 transistor OC70 OC71 are both listed in my book plus dozens of others. __________________ G8JET BVWS Archivist and Member V.M.A.R.S