Yamaha CR 450 tuner amp - UK Vintage Radio Repair and Restoration Discussion Forum

Apusapus · 3rd Nov 2019, 10:36 am

Hello, I am wondering if anyone might have any suggestions regarding a vintage Yamaha CR450 amp/tuner I have recently obtained.
The issue with it is, it powers up and lights up, however there is not any sound or volume, im wondering if there might be some internal fuse that may be the cause, before I start searching for something more sinister?
Thanks

Herald1360 · 3rd Nov 2019, 11:07 am

Might it have "missing links" between preamp and main amp? Some systems had these so you could add things like graphic equalisers.

edit: There are internal fuses, quite a few. You can get the service data (after a bit of faffing about) from eservicedata.com. Google "yamaha cr 450 schema" and it's there a few hits down.

Goldie99 · 3rd Nov 2019, 12:27 pm

The service manual is also free on the hifiengine.com site - you need to join to download, but the site's 'clean', simple, and no problem at all.

I don't see any pre-out / main-in links, but there are indeed internal fuses on the transformer primary, and the main amp power rails. There's also a protection relay on the speaker outputs, which should 'click' in a few seconds after the unit is turned on - do you hear the 'click' ?

Alan

ajgriff · 3rd Nov 2019, 12:27 pm

Hi-Fi Engine has the instruction and service manuals available for free download. Simple registration required.

Alan

PS Crossed with previous post.

ajgriff · 3rd Nov 2019, 12:45 pm

Yamaha designers were very fond of output protection relays back in the day and they often give problems due to dirty contacts especially after long periods of hibernation. However, it's more usual for them to operate intermittently on one channel or the other. If fuses have blown it's important to try to establish the cause, which can come down to expensive and difficult to isolate component failure, or may be something very simple. Fingers crossed.

Alan

Goldie99 · 3rd Nov 2019, 12:49 pm

I was wondering more if the output relay was just doing it's job - and interrupting the outputs due to a fault.

Alan

ajgriff · 3rd Nov 2019, 1:02 pm

Yes, I see what you mean.

Alan

paulsherwin · 3rd Nov 2019, 1:26 pm

If both channels are completely silent then that does point towards either the output protection circuitry or the power supply. Most stereo amp faults don't knock out both channels.

Don't neglect the obvious stuff though - clean all the switch contacts carefully, particularly any speaker/headphone switching.

It's certainly worth checking any internal fuses, and replacing them once if there are no obvious signs of distress. Fuses do sometimes fail through simple old age. If the fuse fails again then you will need to investigate the underlying cause.

Kentode · 3rd Nov 2019, 4:32 pm

Apusapus, what speakers are you using?

3rd Nov 2019, 10:36 am	#1
Apusapus Triode Join Date: Mar 2018 Location: Oxford, Oxfordshire, UK. Posts: 10	Yamaha CR 450 tuner amp Hello, I am wondering if anyone might have any suggestions regarding a vintage Yamaha CR450 amp/tuner I have recently obtained. The issue with it is, it powers up and lights up, however there is not any sound or volume, im wondering if there might be some internal fuse that may be the cause, before I start searching for something more sinister? Thanks

3rd Nov 2019, 11:07 am	#2
Herald1360 Dekatron Join Date: Feb 2007 Location: Leominster, Herefordshire, UK. Posts: 16,536	Re: Yamaha CR 450 tuner amp Might it have "missing links" between preamp and main amp? Some systems had these so you could add things like graphic equalisers. edit: There are internal fuses, quite a few. You can get the service data (after a bit of faffing about) from eservicedata.com. Google "yamaha cr 450 schema" and it's there a few hits down. __________________ ....__________ ....\|____\|\|__\|__\_____ .=.\| _---\__\|__\|_---_\|. .........O..Chris....O Last edited by Herald1360; 3rd Nov 2019 at 11:21 am.

3rd Nov 2019, 12:27 pm	#3
Goldie99 Heptode Join Date: Jul 2014 Location: Boston, Lincolnshire, UK. Posts: 995	Re: Yamaha CR 450 tuner amp The service manual is also free on the hifiengine.com site - you need to join to download, but the site's 'clean', simple, and no problem at all. I don't see any pre-out / main-in links, but there are indeed internal fuses on the transformer primary, and the main amp power rails. There's also a protection relay on the speaker outputs, which should 'click' in a few seconds after the unit is turned on - do you hear the 'click' ? Alan

3rd Nov 2019, 12:27 pm	#4
ajgriff Nonode Join Date: May 2004 Location: Halifax, West Yorkshire, UK. Posts: 2,587	Re: Yamaha CR 450 tuner amp Hi-Fi Engine has the instruction and service manuals available for free download. Simple registration required. Alan PS Crossed with previous post.

3rd Nov 2019, 12:45 pm	#5
ajgriff Nonode Join Date: May 2004 Location: Halifax, West Yorkshire, UK. Posts: 2,587	Re: Yamaha CR 450 tuner amp Yamaha designers were very fond of output protection relays back in the day and they often give problems due to dirty contacts especially after long periods of hibernation. However, it's more usual for them to operate intermittently on one channel or the other. If fuses have blown it's important to try to establish the cause, which can come down to expensive and difficult to isolate component failure, or may be something very simple. Fingers crossed. Alan

3rd Nov 2019, 12:49 pm	#6
Goldie99 Heptode Join Date: Jul 2014 Location: Boston, Lincolnshire, UK. Posts: 995	Re: Yamaha CR 450 tuner amp I was wondering more if the output relay was just doing it's job - and interrupting the outputs due to a fault. Alan

3rd Nov 2019, 1:02 pm	#7
ajgriff Nonode Join Date: May 2004 Location: Halifax, West Yorkshire, UK. Posts: 2,587	Re: Yamaha CR 450 tuner amp Yes, I see what you mean. Alan

3rd Nov 2019, 1:26 pm	#8
paulsherwin Moderator Join Date: Jun 2003 Location: Oxford, UK Posts: 27,998	Re: Yamaha CR 450 tuner amp If both channels are completely silent then that does point towards either the output protection circuitry or the power supply. Most stereo amp faults don't knock out both channels. Don't neglect the obvious stuff though - clean all the switch contacts carefully, particularly any speaker/headphone switching. It's certainly worth checking any internal fuses, and replacing them once if there are no obvious signs of distress. Fuses do sometimes fail through simple old age. If the fuse fails again then you will need to investigate the underlying cause.

3rd Nov 2019, 4:32 pm	#9
Kentode Octode Join Date: Mar 2015 Location: Yorkshire, England. Posts: 1,303	Re: Yamaha CR 450 tuner amp Apusapus, what speakers are you using? __________________ Regards, Ken. BVWS member