Gould 4072 / 4074 Power Supply - please help - UK Vintage Radio Repair and Restoration Discussion Forum

Lee Gulland · 21st Apr 2019, 9:20 pm

Hi all

Thanks to the car boot earlier today, I am now the proud? Owner of a Gould 4072. It was sold as dead, but I couldn't resist it for a fiver !

First of all thanks to everyone who has contributed to previous post about these scopes, they have saved me so much time ( particularly the person who uploaded the PSU schematic, and the valuable tip about tantalum capacitors going short - not something I've come across before.

I have now found out my PSU has the 33R feed resistor to Q11 is O/C along with D17 and D18 which are S/C. I suspect this was caused when the tantalum C16 ( I think) went short.

Does anyone know what type D17 and D18 are ? I'm guessing fast low current rectifiers but would like to fit the correct parts.

Many thanks,

Lee

Noopy2014 · 22nd Apr 2019, 7:29 am

Hello Lee,

the service manual calls the diodes IS923.
Some people suggest that it hast to be a 1S923.
Indeed you can find a datasheet for both names. Comparing the specifications leads to the assumption that the two diodes are the same.

Greetings,

Richard

Lee Gulland · 22nd Apr 2019, 10:25 am

Thanks Richard, that's a great help.

I think you are right - 1S923 and IS923 are they same part, but the 1 gets confused for an I

Where did you get your service manual ? I've searched online but found nothing complete so far.

Thanks again

Lee

Noopy2014 · 22nd Apr 2019, 1:18 pm

You are welcome!
WME_Bill has a quite good scan of the service manual. Just write him a message!

Richard

21st Apr 2019, 9:20 pm	#1
Lee Gulland Retired Dormant Member Join Date: Oct 2017 Location: Cornwall, UK. Posts: 2	Gould 4072 / 4074 Power Supply - please help Hi all Thanks to the car boot earlier today, I am now the proud? Owner of a Gould 4072. It was sold as dead, but I couldn't resist it for a fiver ! First of all thanks to everyone who has contributed to previous post about these scopes, they have saved me so much time ( particularly the person who uploaded the PSU schematic, and the valuable tip about tantalum capacitors going short - not something I've come across before. I have now found out my PSU has the 33R feed resistor to Q11 is O/C along with D17 and D18 which are S/C. I suspect this was caused when the tantalum C16 ( I think) went short. Does anyone know what type D17 and D18 are ? I'm guessing fast low current rectifiers but would like to fit the correct parts. Many thanks, Lee

22nd Apr 2019, 7:29 am	#2
Noopy2014 Tetrode Join Date: May 2014 Location: Eichstätt, Germany Posts: 88	Re: Gould 4072 / 4074 Power Supply - please help Hello Lee, the service manual calls the diodes IS923. Some people suggest that it hast to be a 1S923. Indeed you can find a datasheet for both names. Comparing the specifications leads to the assumption that the two diodes are the same. Greetings, Richard

22nd Apr 2019, 10:25 am	#3
Lee Gulland Retired Dormant Member Join Date: Oct 2017 Location: Cornwall, UK. Posts: 2	Re: Gould 4072 / 4074 Power Supply - please help Thanks Richard, that's a great help. I think you are right - 1S923 and IS923 are they same part, but the 1 gets confused for an I Where did you get your service manual ? I've searched online but found nothing complete so far. Thanks again Lee

22nd Apr 2019, 1:18 pm	#4
Noopy2014 Tetrode Join Date: May 2014 Location: Eichstätt, Germany Posts: 88	Re: Gould 4072 / 4074 Power Supply - please help You are welcome! WME_Bill has a quite good scan of the service manual. Just write him a message! Richard