It's time for surgery on some gear

Guys, I need your advice.

Over the past little while, I've been working around two issues with my equipment:

1. The Dual needs the motor control capacitors replaced. When I put it back into service in 2005, the platter would occasionally start spinning backwards on powerup. That's stopped, but now the platter will occasionally need a push from my finger to spin. (I lubed the platter and motor in December 2006) I've been told that replacing the capacitors on the PC board beneath will fix this.

2. The Yamaha needs a new speaker protection relay. Cleaning the contacts or giving the relay a sharp rap with a screwdriver are only temporary measures when a channel goes dead, and cranking up the volume fixes this, only to have it happen again.

I've got all the parts, some desoldering braid, strong lights, tools, close-up reading glasses, service manuals, my soldering skills, and a desk that doubles as my workbench. Anything I need to watch out for here? Any advice to give me? Because if I bork this up (especially the Yamaha), Alvaro and Jorge will be able to hear my screams from across the Atlantic, never mind the rest of you in the States!

This post has been edited by OvenMaster on September 14, 2007 08:37 am

Tom,

You´re a hero, from my point of view.

The only caps I´ve managed to bring myself to mingle with have been speaker passive crossover ones. I´m terrified of touching caps on charged boards for fear of electrecution.

If you are sure they are discharged beforehand, then I figure it´s only a question of getting your polarities correct and your solder joints properly done.

Jorge

The motor capacitors are really very small: .01μF, .33μF, and .068μF, and they're polyester metal film type; you could hold about 50 in your hand easily. They're too small to get a shock from. The largest one is only maybe 3cm long, 1cm tall... the pic shown is bigger than actual size. I'm afraid to touch the beer can sized ones in the Yamaha for the same reasons you mention! I got a shock once from a much smaller one on a camera's electronic flash unit. Fully charged, I accidentally touched the terminals.

That, my friend, is painful.

My main concern is the removal of the speaker relay on the circuit board. I really really really do not want to mess this up by damaging the PC board.

This post has been edited by OvenMaster on September 14, 2007 10:13 am

Attached Image

Like you says, the Dual needs the motor control capacitors replaced.

So, fire your soldering iron up and allow it to reach full temperature. Once its hot it's time to remove the damaged caps. Imho the best way to do this is to "grab" the cap you're desoldering with one hand whilst applying heat to its pads with the other. Pull them out with a rocking motion as soon the solder starts to melt on the pad, you'll find they pop out pretty easily once you get the knack of this.

Once you have removed all of the caps you'll now have to mop up the excess solder from the pads in order to expose the hole for the new caps to fit into. This can either be achieved with a desoldering pump or you can mop the excess solder up using desoldering braid and heat applied from your soldering iron. The objective here is to expose all of the holes under the excess solder, don't hold the iron on too long or you run the risk of lifting a pad...if in doubt practice desoldering on an old board (poach one out of a dustbin if necessary) or visit http://www.epemag.wimborne.co.uk/solderfaq.htm which gives you some good advice.

Now it's time to fit the new caps! Solder all the caps into the right position - again it may be woth visiting the site mentioned above before doing this) - and finish off by cleaning the pad side of the PCB with a toothbrush and some isopropyl alcohol to ensure there are no loose blocks of solder.

I whish you a good job, and enjoy the music.

in regards to the Yamaha, i'd go right to the master and ask Merrylander for pointers.

About the Yamaha output problem, why do think the problem comes from the relay ? I don't have the schematic...but, i have to ask you these simple questions:
Did you measure or verify the output line before the relay ? Did you have a stable reading rate ? Maybe that relay is doing its job and the problem comes from a bad transistor...?
Sorry about all this questions, but sometimes the answer lies in a question...
BTW, do you have the same problem in both outputs?

This post has been edited by clint e. on September 14, 2007 05:12 pm

...one more thing you should try about that relay.
You can prove that the relay is the issue (and that my "repair" worked) by playing a quiet, steady tone while listening through headphones. Gently tap the relay with an insulated rod. If the relay needs cleaning, you'll hear the sound cut out or briefly become distorted.
With a healthy relay you'll be able to smack the relay very hard, almost to the point of breaking the case without an audible consequence...

Enjoy.

I gave the relay a "love tap" with a screwdriver handle last summer, and that repair lasted for almost a year! I didn't do anything else. A couple of weeks ago I started hearing distortion again, but I could not get the cover off... very tight quarters. So I used a Dremel to cut the cover. Spraying contact cleaner in there fixed the problem again. But some have told me that if I have to keep doing this, it's time to replace the relay because of burned or pitted contacts. I would figure that after 30 years of daily use, it's time to replace it.

I didn't measure anything, Alvaro. I have a service manual, but my strengths are in mechanical repairs like cleaning, replacement, etc. not electronic stuff. I never was able to get the hang of it.

Almost forgot: when I hear distortion, it's always in the Left channel. Turning up the volume to 10 o'clock or higher when playing music fixes it for a few minutes.

I think I'll tackle the turntable first. The caps are very easy to get at... but first I need to get a hold of a digital camera so I can take "before" and "after" pictures, as well as pictures of what I did to the platter and my home brew "guide white" repair.

I saved the pages and pictures from the soldering site, Alvaro. Perfect... because I was unsure of how to use the desoldering braid!

30 years of daily use... that's incredible! They don't do things like that anymore.
...and yes, it's about time to replace not one but both relays.
Glad you like the site.
Could you put some pix when you do the job also in the Dual ?

I will be happy to take and post before and after pix of everything, Alvaro. I hope to start with the turntable this week.
"Both" relays? I'm not that brave! I don't switch back and forth from Class A to Normal but maybe three times a year. I'll stick with the speaker relay this time out!

Okay!
I finally got my hands on a digital camera and tackled the capacitor replacement on the Dual this afternoon!
1. Before:



2. After:



It's amazing how much smaller the new caps are; the old ones were quite heavy, and also cracked and broken. After I put in the new ones, I powered up the TT and it took five seconds before the platter started spinning. Now I notice that the strobe bars stay rock steady when the platter spins.
I was NOT up to tackling the speaker relay on the Yamaha today. I'm not sure when I'll get to it, and taking pix would be kinda boring; all there'd be is a new relay box that looks just like the old one!

This post has been edited by OvenMaster on September 22, 2007 08:03 pm

thats some good work and good news Tom. did the cap replacement on the tt do anything for the sound?

Thanks, Scott. Listening closely, I can't tell any difference or improvement in sound. But at least the steadier strobe bars mean less wow and flutter, so that does mean something's improved!

must have at least stopped a break down in the near future.

Cool.
Good job and very nice pix.
When comes to sound everything maters...if your TT motor have a more steady and uniform playing, certanly have some impact sound wise. Sometimes we can not listen or hear but we in fact we can feel it with our body... The groove, the beat, a more easy listening and following the tune kind of feeling in a more relaxed way...
IMHo Sound Thinking kind of feeling, everything counts...