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repair, does this estimate look accurate?

VQLT

VQLT

Active Member
I took my yamaha C-80 preamp and M-80 amp in for service. both units are 20 years old so i thought it might be time for service and bring both back to spec.
for the M-80 the tech wants to clean off old glue, replace all lamps (preventive) & solder PCB
for the C-80 replace a loose pin jack, solder PCB, clean all controls.
do these procedures appear correct for routine servicing?
 
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i'd have him upgrade your caps, or at least check them. the rest is entirely reasonable, but i'm no expert. ask EW or Punker-X.
Tyler
 
only things i remembered to tell the tech were check DC offset (thanks echowars) & check the caps. Tech said all the caps look fine. just some dried up glue at the base of a few caps, etc.
I figure the tech knows about DC offset so I wont pester him to much on that subject.
not sure what solder PCB means?
 
Labor and parts can add up if you replace the caps. If this is something your going to hold onto for a long time then you should think long and hard about replacing all the electrolytics. As far as the dried glue, it isn't hurting anything. it was to hold the cap in place during assembly. I wouldn't pay someone to clean it off.

X
 
vortego said:
not sure what solder PCB means?
Click to expand...

Older units used solder and fluxes that could corrode over time. This will result in a resistive, or open connections. Just as input jacks corrode, in certain circumstances so will solder connections. The wire used was likely copper, or aluminum and solder of that vintage was usually a lead/tim mix. Anytime dissimilar metals are in contact, corrosion can occur. Proper application of heat and flux will "renew" and clean the connections and make the signal paths cleaner.

Regards,
Joe
 
All looks reasonable. Joe described the soldering very well, except I'd like to add that sometimes the reason for touching up the solder connections has more to do with the fact that the solder reflow process used at the factory was not very good in the first place, resulting in poor, grainy solder joints. I have seen many units older than yours where the solder joints are perfect. I have seen many pieces from the 1980's that have poor solder joints throughout, and this is when they were new!
Don't waste money on getting the caps replaced, they can last for a very long time. Replace them if they are bad. Don't fix it if it ain't broke.
 
Don't fix it if it ain't broke.
Click to expand...

Couldn't agree more - i'd also avoid having the glue cleaned off and the lamps replaced unless they're actually broken.

Sometimes changing something "as a preventative maintenance precaution" can cause more problems than it solves.
 
Beobloke said:
Sometimes changing something "as a preventative maintenance precaution" can cause more problems than it solves.
Click to expand...

I agree w/ that 100%. Besides, what is the cost for him to replace all the lamps when you can buy them for a pittance at Parts Express and install them yourself (unless they require soldering). Have a tech do the things that you CANNOT do - it saves bench time ($$$, in English!).

I would also throw "cleaning the controls" in with the things you can do yourself. It may take time and some out of pocket expense for some DeOxit/ProGold, but time is money for the tech. There have been a number of threads instructing how to properly clean all the pots/controls.

If I were you (or anyone considering handing a unit over to a non-AK tech), I would open her up, clean her out as best as I could, clean all the controls, replace the lamps, and THEN hand it to him, letting him know what you have done. That way he can't overcharge you for time/money for something as simple as a burnt-out lamp. Would you call your electrician to replace a light bulb? :no:

Good luck!!
 
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Luxman glue ages to a dark brown and becomes conductive with age causing noise and other problems, have seen it conuct between two traces and burn a hole in the board, Yes cleaning off the old glue is reccomended.
 
dewickt said:
Luxman glue ages to a dark brown and becomes conductive with age causing noise and other problems, have seen it conuct between two traces and burn a hole in the board, Yes cleaning off the old glue is reccomended.
Click to expand...
I second that. Sansui glue does the same thing and also becomes corrosive! I've seen it eat through wires! Let him take the glue off. He's doing the lamps for the same reason I do, he doesn't want you to get the unit back and have a lamp go out in a month. Now you have to yank it out of the system and get the lamp replaced or live with the dark spot on the dial. If you can't solder, let him do the lamps too. :thmbsp:
 
I was charged $120 at Inner Sound in Portland to refurbish my M-80, which included reflowing the solder and replacing a broken rca input connector. I wish that I'd thought of having them replace the speaker terminals. Tiffany connectors would have been nice too.
 
I often resoldered PC boards, as it is common for the solder joints to start cracking. And if you find a few bad solder joints, more are on the way! Sometimes I see a board that looks fine, even when thirty years old. And some new stuff starts cracking loose before it gets out of the box (RCA has a lot of this trouble with their TVs). On my own stuff, or on someone else's stuff when they'll pay for it, I expect to resolder boards & replace caps if it's vintage gear. Usually it doesn't take much time to clean controls (except for SX-1980) & change lamps once the unit is already apart, so that won't add much labor cost. Old glue is always suspect, as I have seen it go bad as others have described. I also replace heat-sink grease routinely on older gear. Sometimes that is labor intensive, but when the old silicone grease dries out it won't conduct heat nearly as well. Best to keep those outputs as cool as possible.

If someone wants it just "fixed", and as cheaply as possible, then I do so, but I won't be able to vouch for the long-term prospects for the amp. Even then I can usually throw in a control cleaning without extra cost, and touch-up any obvious broken solder joints.
 
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