Yamaha C-6 Intermittant Power on Relay issue

[thelonerider]

Hi,
Has anyone experienced issues with the powering on of vintage Yamaha equipment with the large square illuminated button? I have a C-6 Preamp that sometimes doesn not activate the power relay. The unit lights up, but no sound. I turn it off and on again, this time I hear the faint click of the power relay (or is it the protection circuit againts power up transients) and the unit has sound.
Is this a corrosion/lubrication of the relay issue in that the relay is sticking?
Any Help?

Here is a pic of my system.

 

[avionic]

Power on mute delay circuit. Most likely have a dried up electrolytic cap in the mute relay circuit/power supply. I'm not at home at the present -so my schematics is not accessible. Check the solder connections on the two heatsink mounted regulator transistors.

 

[avionic]

Nice little pre-amp. I have two of them. BTW welcome to AK..

 

[avionic]

Looked over the schematic. Have a close look at/ or swap out C470 & C472 and see it it improves the relay "set" issue. ( couple small caps near the relay thats closest to the rear panel.)

 

[bob06]

Nice little pre-amp. I have two of them. BTW welcome to AK..

There goes the price on the C-6.

 

[avionic]

There goes the price on the C-6.

Perhaps.

 

[junkaudio]

got one too it s great :thmbsp:
buy them while they are hot

 

[thelonerider]

Looked over the schematic. Have a close look at/ or swap out C470 & C472 and see it it improves the relay "set" issue. ( couple small caps near the relay thats closest to the rear panel.)

Mucho Thanks for the heads up... I'll take a look at those parts. As an interm and less intrusive test...
Originally I was powering the C-6 and the M-4 right after... I'm testing to see if, by powering up the M-4, there is an instant drain on the electric circuit when there is no surge supressor in the loop. The theory is that the drop on the line makes the C-6 stumble. So far, giving the C-6 a few seconds to wake up before firing up the M-Beast.. Uh... M-4 has proven to 3 flawless startups.
... Lets see where this "wait until you can't take it anymore" solution leads to...
Thanks for the warm welcome,
I have always been a fan of Yamaha receivers and amp/Pre-amps for their looks as well as their sound. The memories date back to a small shop on Mountain st. in Montreal where they had Yamaha as well as McIntosh audio hooked to Advent/B&W as well as other similar speakers, Altecs I believe.
Once I got the Advents, I was hooked... I had to put the M-4 to work. I'm the second owner and it has been in a box for 8 to 10 years after being used to power a pair of Advent 3001 which are out of commission at the moment. I cleaned and ajusted the M-4 but I just couldn't bring myself to use a Hafler DH-100 with only one phono input.
The original owner of the M-4 is a lifetime buddy of mine; he still had the pairing C-4 to the set but was unwilling to sell it after he also hooked up his vintage system.
The C-4s I found "did not want to ship to Canada" and I just couldn't get my hands on one north of the Border. I managed to finally come across a place in New Jersey that shipped me this C-6 for $265+$17 duty tax. Thanks to them, I'm SMILING...
Oh, and the vinyl is out, too...

 

[avionic]

I just bought a C-6 for less than what you paid for "duty" on yours..Only thing wrong with it was a couple lamps and some dirty controls.:scratch2:
http://www.audiokarma.org/forums/showpost.php?p=5464679&postcount=1

 

[avionic]

The theory is that the drop on the line makes the C-6 stumble.

Wasting your time:yes:..Know issues with these pre-amps ie. C-4/C-6. Power supply/ muting circuit caps or relay driver transistors.Cracked solder connections on the regulator transistors - dried glue/corrosion from glue -dirty switches and controls.

 

[thelonerider]

Wasting your time:yes:..Know issues with these pre-amps ie. C-4/C-6. Power supply/ muting circuit caps or relay driver transistors.Cracked solder connections on the regulator transistors - dried glue/corrosion from glue -dirty switches and controls.

Kind of figured as much... but on the plus side... today make 4 good startups without having to take the unit apart.
Sounds like I will need to do some serious upgrades to the Pre once I've had enough of listening to it.

Man, a C-6 for $15 bucks turned my smile to a frown... great deal!!!:thmbsp:

 

[thelonerider]

Finally got around to swapping out the C470 & 472 caps... problem still exists. Seems the longer the unit is off, the more chances it doesn't "click in" upon start up.
Can someone send me a pic and part list of the other issues with these pre-amps (i.e. relay driver transistors, cracked solder connections on the regulator transistors) ?
Turning it off then back on works all the time.

 

[charles 1973]

Nice system BTY. I'm a fan of Yamaha Amps, Dual TT and Advent Speakers.

I had a C6 Preamp many years ago. I Traded it for A NAD Preamp/Tuner because it had a Remote. The NAD sounded good with my Realistic Mach One's, Hardly the most refinded speaker of it's day, and is a fine preamp in it's own right, But I think my Energy Pro-22 Monitor's would have benifitted form the Yamaha. I really like the Tone Controls/EQ set-up and it's Phono Stage.

Sorry I can't help you with the Problem, I'd bring it to a local Tec and pay them to fix it like I did my Reciever, or use it as is if you can get it to work and it's SQ doesn't suffer

 

[avionic]

Going to need this sooner or later..
Norman has kick ass scans...:thmbsp:

http://www.analogalley.com/osccart/product_info.php/products_id/284

 

[bob06]

Finally got around to swapping out the C470 & 472 caps... problem still exists. Seems the longer the unit is off, the more chances it doesn't "click in" upon start up.
Can someone send me a pic and part list of the other issues with these pre-amps (i.e. relay driver transistors, cracked solder connections on the regulator transistors) ?
Turning it off then back on works all the time.

WOW! And I thought I was a slow worker. Did you try dexoit on the on/off switch? :scratch2:

 

[avionic]

TR420 (2SB646)---- http://www.mouser.com/ProductDetail...GAEpiMZZMsTKkj12KWLXuW5oDYpP%2bzxONEQZbQU7fA=
TR419 (2SC2320)---- http://www.mouser.com/ProductDetail...GAEpiMZZMsTKkj12KWLXuW5oDYpP%2bzxhZRZX67sGN8=

D411 (RD6.2EB2) 6 volt zener/500mw http://www.mouser.com/ProductDetail...=sGAEpiMZZMsnCtsnHQqDld7R4Wy5GrRLYzrMzRWlzGg=

D412 (WZ120) 12 volt zener / 500mw http://www.mouser.com/ProductDetail...=sGAEpiMZZMsnCtsnHQqDlT6/b8fSyzVF/gOerrxjzK4=

Check R507 (330Ω 1/4 watt) http://www.mouser.com/ProductDetail...GAEpiMZZMu61qfTUdNhG3bgRPzbhC1w48MRsWb%2bEjQ=

 

[thelonerider]

WOW! And I thought I was a slow worker. Did you try dexoit on the on/off switch? :scratch2:

LOL... Yea... I'd rather be listening than repairing... plus, as you can see by the pictures in the first post... disconnecting and reconnecting in the tight area is such a pain...
As for the power switch, Yup, it got sprayed.

 

[thelonerider]

TR420 (2SB646)---- http://www.mouser.com/ProductDetail...GAEpiMZZMsTKkj12KWLXuW5oDYpP%2bzxONEQZbQU7fA=
TR419 (2SC2320)---- http://www.mouser.com/ProductDetail...GAEpiMZZMsTKkj12KWLXuW5oDYpP%2bzxhZRZX67sGN8=

D411 (RD6.2EB2) 6 volt zener/500mw http://www.mouser.com/ProductDetail...=sGAEpiMZZMsnCtsnHQqDld7R4Wy5GrRLYzrMzRWlzGg=

D412 (WZ120) 12 volt zener / 500mw http://www.mouser.com/ProductDetail...=sGAEpiMZZMsnCtsnHQqDlT6/b8fSyzVF/gOerrxjzK4=

Check R507 (330Ω 1/4 watt) http://www.mouser.com/ProductDetail...GAEpiMZZMu61qfTUdNhG3bgRPzbhC1w48MRsWb%2bEjQ=

OK, will check these out next time I take things apart, as mentioned above, not the quickest to repair things.
As for the Service Manual, I downloaded a scanned version of the service manual but the scan seems to be a fax scan and the circuit board/ part location diagram images are dark and are very poor quality. Is the link you posted much better (@$14 a copy) ?

 

[avionic]

OK, will check these out next time I take things apart, as mentioned above, not the quickest to repair things.
As for the Service Manual, I downloaded a scanned version of the service manual but the scan seems to be a fax scan and the circuit board/ part location diagram images are dark and are very poor quality. Is the link you posted much better (@$14 a copy) ?

You got what you paid for....:scratch2:

Is the link you posted much better (@$14 a copy)

Like having and original service manual--color and all..:thmbsp:

 

[avionic]

... disconnecting and reconnecting in the tight area is such a pain...

About that tight area..Not much ventilation for the M-4 or the C-6. C-6 runs hot with the two pass transistors in the power supply.Which is normal for the C-6.