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etpm@whidbey.com: Aug 01 08:47AM -0700 On Sat, 29 Jul 2017 13:22:30 -0700, Jeff Liebermann <jeffl@cruzio.com> wrote:   >isolation transformer to prevent the oscilloscope case from being at >AC line potential. Or, use a dual trace scope in differential input >mode. After you repair a module, compare voltages and waveforms. Thanks for the reply Jeff. I forwarded your message a few minutes ago to me son and I'll let you know what success or lack of same he has. I'm gonna get some epoxy softener. I didn't even know the stuff was made. I should have too because I use epoxy for lots of fixes. Eric

Phil Allison <pallison49@gmail.com>: Jul 31 11:27PM -0700 Dave M wrote:   ---------------------------     > Are you trying to make a DC power source or an AC source?   ** The OP is making a PSU for a relay the runs from the AC supply with no isolation using a series capacitor.   There is virtually zero chance he is using an AC relay cos they come in 120VAC and 240VAc versions.     > Is the load the relay coil or a load that is being switched by the relay?   ** The OP has told us: " ... the load is a relay ".   Obvious since capacitor fed PSUs have very limited current - but enough for many relays.     > What kind of instrument are you using to measure the current, and how are > you hooking it into the circuit?   ** We need to know what the circuit is first, many possible variations on the theme exist. > Is the relay a DC or AC relay?     ** Forget the AC case.       > If it's a DC relay coil, then just measure the coil resistance, divide that > value into the voltage across the coil and you'll know what the current > should be.   ** Well, that will give you the average value.     > If it's an AC relay coil,     ** You are hooked on that wild card.   BTW:   The OP is clearly a novice and I hope he is aware how dangerous transformerless PSUs are to work on and takes all the precautions needed.   If this is a task set by his electronics instructor, big bad on him or her.     .... Phil

jurb6006@gmail.com: Aug 01 02:09AM -0700 The big problem is there is no isolation.

"pfjw@aol.com" <pfjw@aol.com>: Aug 01 03:25AM -0700 On Tuesday, August 1, 2017 at 2:27:17 AM UTC-4, Phil Allison wrote:   > There is virtually zero chance he is using an AC relay cos they come in 120VAC and 240VAc versions.   Be careful of blanket statements. The boiler in our house uses 24VC relays for various functions. As happens, the 24VAC unregulated, unrectified control voltage switches various 120V pumps, fans and valves. As is the case with many US heating systems.   Similarly on the hot-tub. Also quite common.   Peter Wieck Melrose Park, PA

"fynnashba@yahoo.com" <fynnashba@yahoo.com>: Aug 01 03:47AM -0700 On Tuesday, August 1, 2017 at 6:27:17 AM UTC, Phil Allison wrote:   > The OP is clearly a novice and I hope he is aware how dangerous transformerless PSUs are to work on and takes all the precautions needed.   > If this is a task set by his electronics instructor, big bad on him or her.   > .... Phil   You seem to understand my problem very well. The psu is DC 12volts and the relay is also DC 12v. I am using a 66uF cap a bridge rectifier, a 12v zener diode and a filter cap.I have a 220 ohm resistor in series with the 66uF cap and a 1 meg bleeder resistor across the 66uF cap. In fact the circuit is working as it should but I want to know the amount of power being drawn by the circuit when the relay is off and the power drawn when it is on so that l can compare it to the a similar one using a transformer. I don't know how to post an image of the circuit here else l would have done that so please forgive me. Thanks to you all.

Clifford Heath <no.spam@please.net>: Aug 01 10:50PM +1000 >> If this is a task set by his electronics instructor, big bad on him or her.   >> .... Phil   > You seem to understand my problem very well. The psu is DC 12volts and the relay is also DC 12v. I am using a 66uF cap a bridge rectifier, a 12v zener diode and a filter cap.I have a 220 ohm resistor in series with the 66uF cap and a 1 meg bleeder resistor across the 66uF cap. In fact the circuit is working as it should but I want to know the amount of power being drawn by the circuit when the relay is off and the power drawn when it is on so that l can compare it to the a similar one using a transformer. I don't know how to post an image of the circuit here else l would have done that so please forgive me. Thanks to you all.   So you have a 12v AC load, and a 68uF capacitor feeding it what? 50Hz at 240V it would be in Australia...   That's 5 amps peak, maybe 3A RMS. I don't think your Zener will survive very long dissipating 36W (3*12).   Try again with a 1uF capacitor for maybe 60mA. If your relay needs that much, otherwise smaller. Smaller again if it's 60Hz, but double it for 120VAC in.   Clifford Heath.

Phil Allison <pallison49@gmail.com>: Aug 01 07:03AM -0700 fynn...@yahoo.com wrote:   --------------------------     > > .... Phil   > You seem to understand my problem very well.   ** Fantastic.   Cos it is bloody obvious YOU do not understand it one tiny bit.   Have you realty built this thing ??   I doubt that VERY much.   Maybe you simmed it.   FFS - you have NOT mentioned the AC supply voltage so far.   Slipped your mind ?         .... Phil

Phil Allison <pallison49@gmail.com>: Aug 01 07:13AM -0700 Clifford Heath wrote:   --------------------------     > > You seem to understand my problem very well. The psu is DC 12volts and the relay is also DC 12v. I am using a 66uF cap a bridge rectifier, a 12v zener diode and a filter cap.I have a 220 ohm resistor in series with the 66uF cap and a 1 meg bleeder resistor across the 66uF cap. In fact the circuit is working as it should but I want to know the amount of power being drawn by the circuit when the relay is off and the power drawn when it is on so that l can compare it to the a similar one using a transformer. I don't know how to post an image of the circuit here else l would have done that so please forgive me. Thanks to you all.   > So you have a 12v AC load, and a 68uF capacitor feeding > it what? 50Hz at 240V it would be in Australia...   ** The OP is not making any sense.   66uF implies amps of current and 220 ohms in series implies hundreds of watts of dissipation.   The fool probably means 0.68uF.   Wish he would get one tiny fact RIGHT !!!       .... Phil

Bennett <bjprice@cal.berkeley.edu>: Jul 31 03:09PM -0700 On 7/29/2017 7:26 PM, Tim R wrote: > I run the headphone jack of the PC we use for internet into a Yamaha AV amplifier and a set of stereo speakers. It's not an audiophile system but it's much better than PC speakers.   > It would be really convenient to stand the amp vertically to save desk space. But it has vents top and bottom, none on the front back or sides.   > Can you run these vertically? or do they need the airflow from the bottom to stay cool enough?   How hot does the case get when horizontal? Is it appreciably hotter when vertical? Do you hear any distortion when vertical? If not, you're good to go.

"pfjw@aol.com" <pfjw@aol.com>: Aug 01 03:27AM -0700 Guys and gals, as it may be known here, I have an irrational appreciation of vintage Dynaco products, with specific reference to the ST120 and ST80 (solid-state). They may be run safely in any position but upside down. If that is any help.   Peter Wieck Melrose Park, PA

jurb6006@gmail.com: Aug 01 03:47AM -0700 Why not upside down ?

"Gareth Magennis" <soundserviceleeds@outlook.com>: Jul 31 08:45PM +0100 I'm trying to repair an Onkyo surround sound amplifier with a blown STK 422-730. I wouldn't normally take this on, but it is for a friend who is not very well, or very wealthy.   Well first off, I can't even find a datasheet for this particular STK, let alone find an STK 422-730 I could buy.   (STK's from china don't count as they will be fake and I need to get this working ASAP) The original is a Sanyo package like this, but this is not a Sanyo part: http://www.ebay.co.uk/itm/1PC-STK442-730-Package-SIP-ZIP-IC-/263071290874?hash=item3d404555fa:g:OwwAAOSwXXxZW3rW     So I have been looking at substitutes. There are a whole range of 2 channel STK's with 14 pins, of various amplifier powers. Are all these compatible? If I get something close will it just plug in and play?     There's a whole load of other much cheaper older package STK442-XXX modules available, eg: http://www.ebay.co.uk/itm/Hybrid-IC-STK442-130-Power-Audio-Amp-/311345361915?hash=item487da133fb:g:YywAAOSw53NY~ioe   Not being able to find the datasheet means I don't even know the power, but that is not as important as getting this amp into some semblance of making sounds again.   Might it be worth taking a punt on one of these cheap older packages not from China?       Cheers,     Gareth.

"Gareth Magennis" <soundserviceleeds@outlook.com>: Jul 31 08:49PM +0100 Dammit, my typo.   It's a STK 442-730.       Gareth.

N_Cook <diverse@tcp.co.uk>: Jul 31 09:26PM +0100 On 31/07/2017 20:45, Gareth Magennis wrote:   > Cheers,   > Gareth.     I long ago stopped trying to find exact replacements, settling on 1, or 2 for stereo, easy to find TDA7293. A bit of time working out the pinout of the original . The only hiccup has been , sometimes the mute line needs a simple inverter transistor in line with it/them. None bounced back , is all I cansay on reliability

"Gareth Magennis" <soundserviceleeds@outlook.com>: Jul 31 09:35PM +0100 "N_Cook" wrote in message news:olo3iv$jb4$1@dont-email.me...   On 31/07/2017 20:45, Gareth Magennis wrote:   > Cheers,   > Gareth.     I long ago stopped trying to find exact replacements, settling on 1, or 2 for stereo, easy to find TDA7293. A bit of time working out the pinout of the original . The only hiccup has been , sometimes the mute line needs a simple inverter transistor in line with it/them. None bounced back , is all I cansay on reliability           ***********************************************************     I'm close to liking that idea.       Gareth.

Jeroni Paul <JERONI.PAUL@terra.es>: Jul 31 02:58PM -0700 Gareth Magennis wrote:   > I'm close to liking that idea.   > Gareth.   I did something similar years ago in a Toshiba VCR that had an STK IC in the power supply. A switched 9V output was low with all other outputs fine and the replacement very expensive, I placed a linear voltage regulator with standby control pin to get the missing 9V, worked perfectly.

John-Del <ohger1s@gmail.com>: Jul 31 06:54PM -0700 On Monday, July 31, 2017 at 3:45:44 PM UTC-4, Gareth Magennis wrote:     > (STK's from china don't count as they will be fake and I need to get this > working ASAP)       I was screaming about counterfeit semis back in the 1980s when everyone thought I was full of crap.     But.. not all semis out of China are fakes. I'll bet that if you buy that STK on ebay, it will fix the stereo and it will last.

"tom" <tmiller11147@verizon.net>: Jul 31 10:29PM -0400 "John-Del" <ohger1s@gmail.com> wrote in message news:28fb86db-b929-42cd-b174-ab1c9308429e@googlegroups.com... > thought I was full of crap.   > But.. not all semis out of China are fakes. I'll bet that if you buy that > STK on ebay, it will fix the stereo and it will last.   Not only that but you can easily get your money back if it is fake.

Jeroni Paul <JERONI.PAUL@terra.es>: Jul 31 03:18PM -0700 Googling for pictures my chassis seems to be a 712: http://obsoletetellyemuseum.blogspot.com.es/2011/05/cge-ct3226-tv-26-telecolor-telefunken_07.html   The RGB drive transistors are mounted in an horizontal plug in board above the CHROMA I/II boards unlike the above photos. And the board on the left wall is not there (that is maybe the ultrasonic remote controller).

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