sci.electronics.repair@googlegroups.com

Google Groups

Clifford Heath <no.spam@please.net>: Aug 02 10:28AM +1000 On 02/08/17 00:13, Phil Allison wrote:   > ** The OP is not making any sense.   > 66uF implies amps of current and 220 ohms in series implies > hundreds of watts of dissipation.   Ugh, yeah, I chose to ignore the 220R. He's probably trying to limit inrush current when switched at the wrong point.   > The fool probably means 0.68uF. > Wish he would get one tiny fact RIGHT !!!   Indeed. It's hard to do electronics without knowing arithmetic.   Clifford Heath.

John Robertson <spam@flippers.com>: Aug 01 06:50PM -0700 >> 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.   Just to get this straight - you are sourcing 12VDC to the 12VDC relay by using a bridge rectifier, filter cap, bleeder resistor, series resistor and a zener. How is the relay hooked to this circuit? Is it simply wired across the 12VDC power so it is always energized when the PSU is on, or is there some sort of switch? Something like below (in simplest form)?   + -\-{--| (12VDC relay) 1 } - (EMF diode) 2 { ^ - ---}--|   (lousy ASCII drawing)   What I am trying to figure out is why you need a bridge rectifier, zener, bleeder, and the 66ufd cap considering that your power supply is already 12VDC - which matches your 12VDC relay. Or are you making it 12VDC by having something around 10VAC connected to your bridge rectifier, then off to the 66ufd cap via the 220R series resistor on the positive line. The 66ufd cap has a bleeder resistor which may be pointless if it is connected directly to the relay.   Put a back EMF diode (1N400X) on the relay coil to protect any solid state devices (diodes, etc.) from reverse discharge when the relay is de-energized.   Is your purpose to have a time delay element for the relay? In other words, when the relay is powered up, do you want it to stay energized for a short period of time after power is removed via the 66ufd cap and resistor? Or is the relay simply switched in/out of the circuit?   John :-#)#   -- (Please post followups or tech inquiries to the USENET newsgroup) John's Jukes Ltd. MOVED to #7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3 (604)872-5757 (Pinballs, Jukes, Video Games) www.flippers.com "Old pinballers never die, they just flip out."

John Robertson <spam@flippers.com>: Aug 01 06:51PM -0700 On 2017/08/01 6:50 PM, John Robertson wrote: > for a short period of time after power is removed via the 66ufd cap and > resistor? Or is the relay simply switched in/out of the circuit?   > John :-#)#   Oh, wait, subject line - transformerless PSU. Sigh, I hope your health insurance is up to date.   John :-#(#   -- (Please post followups or tech inquiries to the USENET newsgroup) John's Jukes Ltd. MOVED to #7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3 (604)872-5757 (Pinballs, Jukes, Video Games) www.flippers.com "Old pinballers never die, they just flip out."

"fynnashba@yahoo.com" <fynnashba@yahoo.com>: Aug 02 03:17AM -0700 On Tuesday, August 1, 2017 at 2:03:26 PM UTC, Phil Allison wrote:   > Slipped your mind ?   > .... Phil   sorry please the cap is 0.66uf and the mains voltage is 220v 50hz.

Phil Allison <pallison49@gmail.com>: Aug 02 06:22AM -0700 fynn...@yahoo.com wrote:   -------------------------------       > sorry please the cap is 0.66uf and the mains voltage is 220v 50hz.   ** The cap is 0.68uF - put your glasses on.   I do hope it is a class X1 or X2 type - rated for mains AC voltage.   It's impedance at 50Hz is 4680 ohms so the average *rectified* current flow is 40mA. Average, full wave, rectified sine wave current = 0.63 times the peak value. Look it up.   The 12V relay must operate reliably at that current, so coil resistance needs to be not more than 300 ohms.   If the relay coil is switched off, there is Zero current flow.   The * HUGE * advantage of using a cap to drop the AC supply voltage to suit the relay is that is dissipates NO power.   A resistor would dissipate nearly 10 watts.       .... Phil

"fynnashba@yahoo.com" <fynnashba@yahoo.com>: Aug 02 07:00AM -0700 On Wednesday, August 2, 2017 at 1:22:32 PM UTC, Phil Allison wrote:   > The * HUGE * advantage of using a cap to drop the AC supply voltage to suit the relay is that is dissipates NO power.   > A resistor would dissipate nearly 10 watts.   > .... Phil   Thanks a lot Phil you were really helpful. All l needed you have provided I also had a lot more info from hackabay.com. But, but l am surprised the high level of respect for members in this group has gone down. Any way all is not lost yet people like Phil are always there to help.

John-Del <ohger1s@gmail.com>: Aug 02 09:19AM -0700 On Wednesday, August 2, 2017 at 10:00:17 AM UTC-4, fynn...@yahoo.com wrote: But, but l am surprised the high level of respect for members in this group has gone down. Any way all is not lost yet people like Phil are always there to help.   LOL...

Adrian Caspersz <email@here.invalid>: Aug 01 07:17PM +0100 > Why not upside down ?   the electrons fall out?   -- Adrian C

rickman <gnuarm@gmail.com>: Aug 01 02:26PM -0400 Tim R wrote on 7/29/2017 10:26 PM: > 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?   If there is no fan, the airflow by convection through the openings will not be a lot. If you have any device on your desk that blows air out you can sit this in front of that airflow and regardless of position it will likely be better than sitting in still air in any position.   --   Rick C

"pfjw@aol.com" <pfjw@aol.com>: Aug 01 02:27PM -0700 > Why not upside down ?   The bottom plate is nearly solid. No air flow.   Peter Wieck Melrose Park, PA

Tim R <timothy42b@aol.com>: Aug 02 07:18AM -0700 > The bottom plate is nearly solid. No air flow.   > Peter Wieck > Melrose Park, PA   But on my Yamaha, there seems to be equal vent space top and bottom.

jethro tull <heavytull@outlook.com>: Aug 01 09:52PM I have a sony walkman, wm-f23, a 1989/90 device I think, which I'm trying to identify a component it uses. This is a SOT23-3 PNP transistor marked "94 F". Actually the "94" is underlined at the left and the "F" is much smaller at the far right. I think the latter is not related to the chip identification but maybe to processing plant or other thing. This transistor is used to preamplify the signal out of the tape head before going to the main audio amplifier which is the sanyo LA4570, an SOIC-16-N chip. Here is the photo : http://cdn.sur.ly/favicon_sur.ly_white_32px.png

jethro tull <heavytull@outlook.com>: Aug 01 09:55PM > preamplify the signal out of the tape head before going to the main audio > amplifier which is the sanyo LA4570, an SOIC-16-N chip. Here is the photo : > http://cdn.sur.ly/favicon_sur.ly_white_32px.png   I forgot, I'm searching for its full reference code.

dansabrservices@yahoo.com: Aug 01 03:00PM -0700 On Tuesday, August 1, 2017 at 5:52:31 PM UTC-4, jethro tull wrote: > the signal out of the tape head before going to the main audio amplifier which > is the sanyo LA4570, an SOIC-16-N chip. Here is the photo : > http://cdn.sur.ly/favicon_sur.ly_white_32px.png   Near as I can tell, this is a DTA114. If I get a chance, I'll look up the service manual and verify.   Dan

N_Cook <diverse@tcp.co.uk>: Aug 02 08:17AM +0100 On 01/08/2017 22:52, jethro tull wrote: > the signal out of the tape head before going to the main audio amplifier which > is the sanyo LA4570, an SOIC-16-N chip. Here is the photo : > http://cdn.sur.ly/favicon_sur.ly_white_32px.png   FWIW the WM F36 uses 1 discrete Q, a 2sd1012 for switching record bias on and off

jethro tull <heavytull@outlook.com>: Aug 02 10:18AM > FWIW the WM F36 uses 1 discrete Q, a 2sd1012 for switching record bias > on and off actually it is WM-BF23

John-Del <ohger1s@gmail.com>: Aug 01 10:34AM -0700 > determine what the 8 pin device is? > Thanks, > Eric   Have you been able to separate in the driver modules from the LED array? The picture shows what looks like 12 "bulbs". Are each of these single large die LEDs or are they made up of many small LED dies in an array?   If you can swap the electronics from the working module to one of the misbehaving LEDs, you can see if it's an LED problem or driver board. From what I've seen over the years, it's more likely the LEDs are crapping out than the driver boards unless the boards are particularly poorly made or designed.   I don't have a lot of faith in high wattage LEDs. Have you contacted the manufacturer?

Jeff Liebermann <jeffl@cruzio.com>: Aug 01 07:16PM -0700 >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   You can also soften some epoxy mixes using acetone and heat or freezing with cooling spray: <http://www.wikihow.com/Remove-Epoxy> See the list of references at the bottom of the page.   The paint section of a hardware store will have some kind of paint stripper that will also work with epoxy. The main active ingredient is methylene chloride. For example: <https://www.lowes.com/pd/Jasco-1-Quart-Semi-Paste-Multi-Surface-Paint-Remover/3586546>       -- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558

Andy Burns <usenet@andyburns.uk>: Aug 02 03:22AM +0100 Jeff Liebermann wrote:   > The paint section of a hardware store will have some kind of paint > stripper that will also work with epoxy. The main active ingredient > is methylene chloride.   Depending where you live ... methylene chloride strippers are banned here apart from for professional use, as a result you might as well use porridge for paint stripper now.

Jeff Liebermann <jeffl@cruzio.com>: Aug 01 08:16PM -0700 On Wed, 2 Aug 2017 03:22:32 +0100, Andy Burns <usenet@andyburns.uk> wrote:     >Depending where you live ... methylene chloride strippers are banned >here apart from for professional use, as a result you might as well use >porridge for paint stripper now.   Thanks. I forgot to mumble something about the VOC ban. Here's a list for various states: <https://www.issa.com/data/moxiestorage/regulatory_education/voc_limits_summary_12-6-16.pdf>   In California: <http://www.dtsc.ca.gov/SCP/Paint_Stripper.cfm> <http://media.mofo.com/files/uploads/Images/140313-Profile-Paint-Stripper.pdf> There seems to be a proposed law banning methylene chloride, but it seem to have NOT been enacted quite yet. I seem to recall that I can still buy the stuff at the local hardware store. I'll check tomorrow.   The EPA and the Trump administration seem to favor not banning it: <https://www.dcreport.org/2017/06/13/epa-may-kill-ban-of-deadly-paint-removing-chemical/>     -- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558

Andy Burns <usenet@andyburns.uk>: Aug 02 09:25AM +0100 Jeff Liebermann wrote:     >> Depending where you live ... methylene chloride strippers are banned >> here apart from for professional use   > Thanks. I forgot to mumble something about the VOC ban.   EU wide ban for household use of DCM   <http://www.paintsquare.com/news/?fuseaction=view&id=7328>   I've never tried to obtain the real stuff in the UK since the ban, but it seems to exist on ebay/amazon so presumably some suppliers are less strict than others about who qualifies as "professional"

"Gareth Magennis" <soundserviceleeds@outlook.com>: Aug 01 08:16PM +0100 "John-Del" wrote in message news:28fb86db-b929-42cd-b174-ab1c9308429e@googlegroups.com...   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.       *****************************************************************************   That may be so, ("fake" I have learnt can be a rather inappropriate term to use), but we don't have the time for the shipping, and expediated shipping is another $35, making this a VERY expensive punt for my friend.     I did a bit more research today and it looks like all the STK's of similar type and pin count seem to use the same pinouts, so I have ordered a way cheaper STK 442-120 from a UK vendor I use when Farnell doesn't have the product, and who I trust not to sell me total crap, and it will get here tomorrow or the day after.     I do have the Service Manual of the Onkyo to confirm the pinouts of the original 442-730, so hopefully this should be a drop in replacement punt with no drama. If the volume levels are different, then that can surely be adjusted in the setup. It's only for domestic TV viewing so it shouldn't be particularly highly stressed.       This is not a commercial repair for financial gain, or I would simply refuse to do it as unviable.       Cheers,     Gareth.

You received this digest because you're subscribed to updates for this group. You can change your settings on the group membership page. To unsubscribe from this group and stop receiving emails from it send an email to sci.electronics.repair+unsubscribe@googlegroups.com.