NAD 4155 Tuner - UK Vintage Radio Repair and Restoration Discussion Forum

kkyahoo · 20th Jun 2019, 1:40 pm

The display on this tuner does not work until the unit has been switched on for some time. (5-10mins). Any idea what the fault is?

Thanks

Kevin

orbanp1 · 21st Jun 2019, 12:21 pm

Hi Kevin,

The tuner has the service manual available on the hifiengine web-site:
https://www.hifiengine.com/manual_li...nad/4155.shtml

It looks like the tuner uses a vacuum-fluorescent display.
Do check the filament voltage with a scope, as well as the other control signals to the display.

Here are some articles on how to drive in general vacuum-fluorescent displays:
http://www.kerrywong.com/2013/06/05/...ver-using-555/
http://www.kerrywong.com/2013/06/13/...isplay-driver/
https://www.instructables.com/id/A-S...-VFD-Displays/

The above should get you going.

Regards, Peter

turretslug · 21st Jun 2019, 6:31 pm

Check the VFD's connections to the PCB- they often seem to be something like sparingly-tinned springy mild steel and love to go dry-jointed over time. Particularly the one or two at each end- these are very frequently the filament pins.

kkyahoo · 21st Jun 2019, 10:38 pm

Thanks for the responses chaps. I think it might be one or more dry joints too. One thing I noticed is that the display starts off blank before reading properly.

Kevin

kkyahoo · 21st Jun 2019, 11:14 pm

Just to clarify my last post, the display, on f.m, now reads 00.0 at first then 93.5 for example after it warms up. Used to be blank at first.

Kevin

Biggles · 21st Jun 2019, 11:21 pm

Does the tuner still receive ok while the display is off/reading 00.0?
Alan.

kkyahoo · 22nd Jun 2019, 3:33 am

Yes

Jonster · 22nd Jun 2019, 2:50 pm

These are an excellent sounding FM tuner and well worth the effort of repairing.

20th Jun 2019, 1:40 pm	#1
kkyahoo Tetrode Join Date: Apr 2014 Location: Essex, UK. Posts: 70	NAD 4155 Tuner The display on this tuner does not work until the unit has been switched on for some time. (5-10mins). Any idea what the fault is? Thanks Kevin

21st Jun 2019, 12:21 pm	#2
orbanp1 Heptode Join Date: Nov 2009 Location: London, Ontario, Canada Posts: 675	Re: NAD 4155 Tuner Hi Kevin, The tuner has the service manual available on the hifiengine web-site: https://www.hifiengine.com/manual_li...nad/4155.shtml It looks like the tuner uses a vacuum-fluorescent display. Do check the filament voltage with a scope, as well as the other control signals to the display. Here are some articles on how to drive in general vacuum-fluorescent displays: http://www.kerrywong.com/2013/06/05/...ver-using-555/ http://www.kerrywong.com/2013/06/13/...isplay-driver/ https://www.instructables.com/id/A-S...-VFD-Displays/ The above should get you going. Regards, Peter

21st Jun 2019, 6:31 pm	#3
turretslug Dekatron Join Date: Nov 2011 Location: Surrey, UK. Posts: 4,394	Re: NAD 4155 Tuner Check the VFD's connections to the PCB- they often seem to be something like sparingly-tinned springy mild steel and love to go dry-jointed over time. Particularly the one or two at each end- these are very frequently the filament pins.

21st Jun 2019, 10:38 pm	#4
kkyahoo Tetrode Join Date: Apr 2014 Location: Essex, UK. Posts: 70	Re: NAD 4155 Tuner Thanks for the responses chaps. I think it might be one or more dry joints too. One thing I noticed is that the display starts off blank before reading properly. Kevin

21st Jun 2019, 11:14 pm	#5
kkyahoo Tetrode Join Date: Apr 2014 Location: Essex, UK. Posts: 70	Re: NAD 4155 Tuner Just to clarify my last post, the display, on f.m, now reads 00.0 at first then 93.5 for example after it warms up. Used to be blank at first. Kevin

21st Jun 2019, 11:21 pm	#6
Biggles Rest in Peace Join Date: Feb 2004 Location: Hexham, Northumberland, UK. Posts: 2,234	Re: NAD 4155 Tuner Does the tuner still receive ok while the display is off/reading 00.0? Alan.

22nd Jun 2019, 3:33 am	#7
kkyahoo Tetrode Join Date: Apr 2014 Location: Essex, UK. Posts: 70	Re: NAD 4155 Tuner Yes

22nd Jun 2019, 2:50 pm	#8
Jonster Heptode Join Date: Apr 2008 Location: Eastbourne, East Sussex, UK. Posts: 671	Re: NAD 4155 Tuner These are an excellent sounding FM tuner and well worth the effort of repairing.