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A Very Compact Hybrid Amp - Page 60

post #886 of 2203
4/24/09 at 2:55am
Good luck with it, at least you know where D5 lives, I couldn't make out any of it
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post #887 of 2203
4/24/09 at 2:56am
received today
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post #888 of 2203
4/24/09 at 8:30am
Quote:
Originally Posted by zkool448 View Post
I've got most of the board populated and now I have to squeeze in D5H <sigh>
Just wanted to say somewhere that one reason D5H + its leads are so large (3A) is because we sized it to survive a short in the heating circuit.

The smaller, easy-to-fit 1N5818 (1A) works perfectly fine but would be the weak link in case of a short in heater circuit.
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post #889 of 2203
4/24/09 at 9:57am
I ran into a bit of a problem with my CTH and haven't really had the time to diagnose it yet. I powered it up for the first time and after a little bit the e12 switched from red to green and the tube lit up so I figured it must be ok. I turned my back to grab my phones so I could give it a listening test and then, pow! C10P vented itself... I've exploded caps before, but that was because I screwed up and reversed the polarity on the cap. I know that I installed C10P with correct polarity.

Just for fun I tried replacing C10P with another cap I had, and tried a different tube, just in case that had anything to do with it. Same thing happened though, the e12 switched to green, but I was watching C10 closely and I could see the top of the can start to swell so I quickly turned it off.

I haven't had time to really dig into it, the first possibility that came to mind was a reversed diode, but a quick inspection of the board didn't reveal any that were reversed, that is assuming that I'm correct and that the body of the diode goes where the circle is silk screened on the board right?

Any advice on where to start looking for my problem?
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post #890 of 2203
4/24/09 at 10:08am
yes, the body of the diode sits in the circle, and the 'stripe' should be facing upwards.
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post #891 of 2203
4/24/09 at 10:16am
Coreyk78, and everyone building this for that matter, please double-check CTH info from the official site & your installed parts against the BoM, etc.
Especially the *entire* board assembly page before building and esp before powering up your CTH. We're trying to emphasize this whenever & whereever we can.

When proper parts are put in proper places with correct polarity & there are no solder bridges/wire bits around, things work.
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post #892 of 2203
4/24/09 at 10:36am
heres my build so far. just waiting on the bushing, wiring + smoke test!





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post #893 of 2203
4/24/09 at 11:18am
Quote:
Originally Posted by Coreyk78 View Post
Just for fun I tried replacing C10P with another cap I had, and tried a different tube, just in case that had anything to do with it. Same thing happened though, the e12 switched to green, but I was watching C10 closely and I could see the top of the can start to swell so I quickly turned it off.
Are you using a 160V+ rated capacitor to replace it with? C10P is a smoothing capacitor for the ~100V supply.

And am I the only person with working amps
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post #894 of 2203
4/24/09 at 12:41pm
Thread Starter 
Quote:
Originally Posted by Coreyk78 View Post
I ran into a bit of a problem with my CTH and haven't really had the time to diagnose it yet. I powered it up for the first time and after a little bit the e12 switched from red to green and the tube lit up so I figured it must be ok. I turned my back to grab my phones so I could give it a listening test and then, pow! C10P vented itself... I've exploded caps before, but that was because I screwed up and reversed the polarity on the cap. I know that I installed C10P with correct polarity.

Just for fun I tried replacing C10P with another cap I had, and tried a different tube, just in case that had anything to do with it. Same thing happened though, the e12 switched to green, but I was watching C10 closely and I could see the top of the can start to swell so I quickly turned it off.

I haven't had time to really dig into it, the first possibility that came to mind was a reversed diode, but a quick inspection of the board didn't reveal any that were reversed, that is assuming that I'm correct and that the body of the diode goes where the circle is silk screened on the board right?

Any advice on where to start looking for my problem?

Coreyk78, there are only three ways that this can happen:

1. C10P is in backwards. I know you checked for this, but it would be good to verify again using website information

2. C10P is a 100V cap instead of 160V

3. One or more didoes are in upside down or in the wrong places.
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post #895 of 2203
4/24/09 at 12:45pm
Quote:
Originally Posted by nux View Post
And am I the only person with working amps
Not by a longshot Think there are about a dozen or so others working fine (proto + prod PCBs).
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post #896 of 2203
4/24/09 at 1:22pm
Ok, well then the voltage is the problem if it's supposed to be a 160v cap. For some reason I had a 1000uF 50v cap in that position, problem easily solved on my next mouser order.

Also, I look at Adamus' pictures and I see a 1000uF 50v cap at C10P, so are we both wrong?
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post #897 of 2203
4/24/09 at 1:35pm
Yep...looks like both of you have C5P and C10P mixed up

C5P = 1000uF 50V
C10P = 100uF 160V
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post #898 of 2203
4/24/09 at 1:43pm
oops, haha, well at least it should be an easy fix. I have an extra panasonic FM 1000uF 50v cap at home that I coud use for C5P so I wouldn't even have to order anything, but it's probably too fat to fit in the little hammond enclosure since I think it has a 16mm body, I'll have to check it out when I get home.
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post #899 of 2203
4/24/09 at 2:22pm
Quote:
Originally Posted by tacitapproval View Post
cfcubed - I have tried a variety of tubes--it is not tube dependent. Although, different tubes seem to trigger it more or less.

Speaking of which, I was able to watch the offset numbers on a 12bh7, which seems to trigger the problem more than some. It is definitely on the right side. The left is pretty consistently between 2-5mV. The right will swing between positive and negative DC, generally staying low, but sometimes jumping up to as much as 75mV in my brief observation and triggering the e12. This must also confirm the distorted/popping noises I hear in the right side at times. Unfortunately, I changed out Qs4-9R and this has not affected the problem. Any thoughts out there on what to try next?

Bump on this. Anybody?
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post #900 of 2203
4/24/09 at 4:31pm
tacitapproval, sorry to hear about you're ongoing issue with your build. I really hope you get it sorted out soon. I brought mine up and with a bit of luck on my side lately my CTH came to life without any issues.

adamus, that's quite a nice build you got there - congrats!

The only changes I made is I socketed the LED pads, I want to route wires for the E12 LED to go somewhere on the panel. I must've lost the three 100R resistors (R18L, R18R, R9S), so I picked some up from my local electonics shop and used 1/4W metal films instead of 1/8W (it's all they had).

Sadly I'm no expert in giving impressions and pardon my french but, this little guy has some major f*** balls! IMO it holds its own alongside my SOHA II and like the fact that I (no audiophile experience whatsoever) can actually hear the subtle difference in sound as I swap the tubes. Anyway I'll let adamus and other experts share their own comments and impressions.

...time to enjoy and listen to some tunes

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