Zen and the Art of Hi-Fi Repair

[Binkman]

I'm not specifically opposed to blanket re-caps and I've done them myself but I don't believe its the first thing that ought to be done to a malfunctioning device unless its obvious that it is a capacitor problem. Often folks seem to have some glitch and the "time to re-cap" suggestion is trotted out before any diagnostics are done.

Absolutely! "cap happy".. many many results are by amateurs who can't solder worth a crap and damage boards.
Just posted today.
http://audiokarma.org/forums/index.php?threads/recapping-first-do-no-harm.858137/#post-12461327

plug it in and see if it works?? is very very foolish without inspection testing.. probably why we read many transistor replacement Q threads..

 

[birchoak]

There are different failure modes of capacitors. Leakage is when voltage bleeds from one side to the other. Pretty simple concept. ESR equivalent series resistance) is a little different. It acts like there is a resistor in series with the capacitor, so it limits the amount of current the capacitor can deliver. This is more of a problem in power supply circuits. When used as an audio coupling / DC blocking cap it generally doesn't matter all that much since the capacitor isn't dealing with much current to speak of.

and then of course there is physical leakage which rots nearby component leads along with foil traces on double sided boards.

I'm not specifically opposed to blanket re-caps and I've done them myself but I don't believe its the first thing that ought to be done to a malfunctioning device unless its obvious that it is a capacitor problem. Often folks seem to have some glitch and the "time to re-cap" suggestion is trotted out before any diagnostics are done. Caps may or may not fix the problem, but it definitely adds a whole bunch of new variables to the troubleshooting process. I only like to re-cap things when I'm confident that the thing is basically working correctly already, that way I at least have somewhere to start with the troubleshooting process. Obviously if visual inspection shows leakage or other physical failure, then there isn't a lot of need to proceed further before changing the clearly defective parts.

The last two times I expected a re-cap situation to fix my ailment it was noisy transistors. They did get a re-cap after I figured out the problem and fixed it though.

Absolutely. If you're clever enough to diagnose the problem, fix the actual problem before recapping (hoping that recapping will put the healing on).

 

[birchoak]

Update to "Zen" approach:

Well, it was a nice idea.

Although my work methods have improved and I'm certainly in a calmer state of mind when I do this stuff, I recently worked on a JVC VR-5551, a hulking beast compared to its little brothers, the 5010 and the VR-5521. I recapped the entire PRE board (it's a plug-in board) and the entire power amp (also a plug-in board). I recapped the main filter and coupling caps with Nichicon Gold Tunes. I sucked out as much bad solder as I could on several boards and put on fresh solder. I went nuts on the thing, no question. Maybe not so Zen.

It sounded good but kind of tame compared to the smaller JVCs. I realized that the 5551 may have simply been designed/voiced this way, being a more powerful receiver (50 watts, vs. 16 & 22 watts), but, hey, since I'd gone this far...only one of the original Sanken 2SC1115 output devices remained; the rest were all different brands. At some point in this receiver's history it had been ridden hard and put away wet, so hard that two of the speaker terminals over the TO-3s had melted. "Let's see if we can find those Sankens," I said. Well, Sanken 2SC1115s are no longer made....or are they? This is the first time I've done this: I ordered 4 reproduction Sanken 2SC1115's from China, $20 shipped. I figured 60/40 counterfeit/good and crossed my fingers. Well, they came and I could find little difference between the new ones and the remaining survivor. They tested pretty much the same, and after I installed them they sounded...exactly the same as the mismatched band they replaced. No difference. But they seem to work fine.

I have since recapped virtually everything on the Sherwood and yes, it still works. Like a champ.

 

[birchoak]

Update to update on "Zen" approach to hi-fi repair:

Work was very slow last week, so slow that birchoak had an entire week with which to amuse himself. Not always a good thing when self-employed, but I decided to put it to good use, and I literally spent 50-60 hours working on receiver after vintage receiver. I do feel like I'm getting better, turning a corner maybe, starting to actually get a feel for this. It is one of the most fascinating hobbies I've ever known, right up there with chess, reading sci-fi, camping, working on old Saabs, and rowing. But I have to get in there and try stuff and make mistakes and sometimes make bad mistakes and blow outputs or drivers. I do the learning on things that are not working or close to it, or of little value to anyone except me.

 

[birchoak]

Have done nothing but deoxit and this one sounds great for a under $10 thrift find. It was nothing but static prior to the deoxit. May open it again one day and replace dead lights and possibly a few caps. It does have a little transistor noise but its intermittent and a very low amount. Have resisted doing anything thus far. Its been on my desk for at least 8 yrs now.
It is powered on 24/7 so the switch will not go bad.

So simple. So humble. And because there's no vents in the top, you can stack all kinds of stuff on top of it, like that secret diary!

 

[VYNULADIKT]

The "secret diary" is actually a very good read. I highly recommend it.
.

And this was a great camping trip with a group of 14 youth for a week in July.

 

[VYNULADIKT]

There WERE a few ZEN moments up there.

 

[VYNULADIKT]

i

What is that Sherwood like? Bet it sounds awesome. It seems the late 60's/very early 70's are the true Golden Age of Audio (the stuff just didn't look as impressive as the mid-70's and later).

It is a very rich, maybe tube like sound. Impressive for the low power rating. One of my younger coworkers that is into having the latest AV equipment was listening to it and admiring its sound. I'm driving some great ESS speakers with it. I asked him if he thought it was worth the seven fifty I gave for it. He looked at me a bit and then replied. " I probably wouldn't have spent more than a couple hundred for it, but it sure does sound good". He about crapped himself when I explained that it was $7.50.

 

[birchoak]

The "secret diary" is actually a very good read. I highly recommend it.
.View attachment 1462374

And this was a great camping trip with a group of 14 youth for a week in July.

View attachment 1462375

I've seen few books with true leather covers! Is it about hunting? Looks beautiful where you were---

 

[VYNULADIKT]

I've seen few books with true leather covers! Is it about hunting? Looks beautiful where you were---

It is a daily devotional written by an avid hunter. He relates anecdotal stories of his life experiences hunting to his and others' spiritual journeys. Contains some very enlightening viewpoints.
The camping trip was up to a small lake below Could Peak in the Bighorn mountains Wyoming. A 12 mile hike up Ten Sleep creek packing in al the gear for 4 days and nights. We camped at just under 10,000ft in a protected wilderness area. No ground fires, no latrine, "everything" brought in got carried out. Bear country, so food had to be kept away from the tents and buried in rocks in scent protection bags. Groups had to be kept below 10 people to minimize impact, so we actually camped and travelled as two groups but mingled back and forth. Breath taking and not just due to the elevation.

 

[birchoak]

It is a daily devotional written by an avid hunter. He relates anecdotal stories of his life experiences hunting to his and others' spiritual journeys. Contains some very enlightening viewpoints.
The camping trip was up to a small lake below Could Peak in the Bighorn mountains Wyoming. A 12 mile hike up Ten Sleep creek packing in al the gear for 4 days and nights. We camped at just under 10,000ft in a protected wilderness area. No ground fires, no latrine, "everything" brought in got carried out. Bear country, so food had to be kept away from the tents and buried in rocks in scent protection bags. Groups had to be kept below 10 people to minimize impact, so we actually camped and travelled as two groups but mingled back and forth. Breath taking and not just due to the elevation.

I did more of that before we had a kid! Good for you; I'm getting tired just reading about all the hiking and carrying!

 

[VYNULADIKT]

I want to do it a few more times while I can. I'm 57 and a 40 lb pack gets pretty challenging at times.

 

[RobinTW]

"Let's see if we can find those Sankens," I said. Well, Sanken 2SC1115s are no longer made....or are they? This is the first time I've done this: I ordered 4 reproduction Sanken 2SC1115's from China, $20 shipped.

Could you post some pictures of the stock and newly purchased 2SC1115's?

I am glad to know the newly purchased ones work the same as the stock ones.

 

[birchoak]

Could you post some pictures of the stock and newly purchased 2SC1115's?

I am glad to know the newly purchased ones work the same as the stock ones.

Let me see what I can do--the "stock" ones had been mostly swapped out, leaving only one original Sanken 2SC1115---I thought swapping out the four mismatched output transistors with four new ones would improve the sound, but I honestly can't hear any difference! The JVC is at the bottom of a recording stack on my desk right now so it's hard to access at the moment.

In general, I don't recommend what I did (buying supposedly "new" TO-3s from China) but I thought, what the hell?

 

[Adam Zapple]

Hi. I own a Sherwood RD -7405HD receiver and use it for my TV sound system. I have the manual (too big a file to upload) but it is all based on changing things using the remote control. I don't have the original remote. Working with the on-panel controls it's VERY confusing how to change for example the Compression. Can someone please just list the sequence of steps to do that, using the panel buttons?