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John-Del <ohger1s@gmail.com>: Sep 10 10:43AM -0700 I have a hand held HDMI generator in to repair, and I need a boost/buck converter IC. I drew out the circuit but can't find an exact match. I'm pretty sure I need a 5V output as the reg feeds the HDMI DC output.   Since this is battery operated and assuming it should run with weak batteries, this should maintain a consistent 5V output whether the battery pack (4 X AA) is at 6V or below 5V   The IC is an SOT-23-6 case. Pin 6 is the DC VIN in, pin 5 is the out. Pin 1 is the SW pin (connected to the VIN pin via a 6uh inductor) and pin 2 is ground. The rest I'm not completely sure of, but it looks like pin 3 is the feedback and pin 4 is the enable (it's connected to the VIN by a 1 meg resistor).   The pin 5 feeds the anode of a Schottkey diode, the cathode presumably being the DC output as the cathode of this diode feeds a fuse near the HDMI connectors and there is continuity between that fuse and one of the pins of both of the HDMI connectors.   This IC looks a lot like the circuit I drew out: http://www.ti.com/lit/ds/symlink/tlv61046a.pdf   The problem is that the max voltage allowed for that IC is 6V and four fresh alkalines at 1.6 each would exceed this or certainly push it to the absolute limit. I can probably add a diode to drop the input by 0.6 but I'd love to find the original. Plus, the voltage selection equation would require a change of resistors on the FB pin and I'd have to eliminate the Schottkey diode.   Because the case blistered a bit, the print is hard to read, but it looks like VZVAC The Z could be a 7. The only letters I'm fairly sure of is the last three "VAC". In any case, I can't find anything searching on any combination of those letters/numbers.   I know it's a long shot but if anyone can point me in the right direction I'd appreciate it. It's kind of tight in the case but as a last resort I can probably stuff a 5V fixed regulator inside.

tabbypurr@gmail.com: Sep 10 12:33PM -0700 On Monday, 10 September 2018 18:43:09 UTC+1, John-Del wrote:     > The problem is that the max voltage allowed for that IC is 6V and four fresh alkalines at 1.6 each would exceed this or certainly push it to the absolute limit. I can probably add a diode to drop the input by 0.6 but I'd love to find the original. Plus, the voltage selection equation would require a change of resistors on the FB pin and I'd have to eliminate the Schottkey diode.   > Because the case blistered a bit, the print is hard to read, but it looks like VZVAC The Z could be a 7. The only letters I'm fairly sure of is the last three "VAC". In any case, I can't find anything searching on any combination of those letters/numbers.   > I know it's a long shot but if anyone can point me in the right direction I'd appreciate it. It's kind of tight in the case but as a last resort I can probably stuff a 5V fixed regulator inside.   6.2v on a 6v IC is usually a goer.     NT

dansabrservices@yahoo.com: Sep 10 01:58PM -0700 On Monday, September 10, 2018 at 1:43:09 PM UTC-4, John-Del wrote:   > The problem is that the max voltage allowed for that IC is 6V and four fresh alkalines at 1.6 each would exceed this or certainly push it to the absolute limit. I can probably add a diode to drop the input by 0.6 but I'd love to find the original. Plus, the voltage selection equation would require a change of resistors on the FB pin and I'd have to eliminate the Schottkey diode.   > Because the case blistered a bit, the print is hard to read, but it looks like VZVAC The Z could be a 7. The only letters I'm fairly sure of is the last three "VAC". In any case, I can't find anything searching on any combination of those letters/numbers.   > I know it's a long shot but if anyone can point me in the right direction I'd appreciate it. It's kind of tight in the case but as a last resort I can probably stuff a 5V fixed regulator inside.   What is the make and model of the generator? Perhaps someone has one that can open it up and get the part number for you.

John-Del <ohger1s@gmail.com>: Sep 11 06:42AM -0700 > > Because the case blistered a bit, the print is hard to read, but it looks like VZVAC The Z could be a 7. The only letters I'm fairly sure of is the last three "VAC". In any case, I can't find anything searching on any combination of those letters/numbers.   > > I know it's a long shot but if anyone can point me in the right direction I'd appreciate it. It's kind of tight in the case but as a last resort I can probably stuff a 5V fixed regulator inside.   > What is the make and model of the generator? Perhaps someone has one that can open it up and get the part number for you.     It's an Atlona HD-800 and the location is IC1 - an SOT23-6 device at the bottom left edge of the board (with the HDMI jacks facing up). If anyone wants to take theirs apart they have to remove the silver buttons before sliding the board out.   I've fixed a few Atlona items and they seem to be bottom end. The commercial account I have that uses them has had a lot of problems with them. Every time I contact Atlona, they are no help.   I talked to the owner of the generator yesterday, and I think they're going to order another generator from different company as they've had enough of Atlona products. They'll either use this as a backup or just donate it to me. Either way I'd like to get it going.

Chuck <ch@dejanews.net>: Sep 11 10:36AM -0500 On Tue, 11 Sep 2018 06:42:20 -0700 (PDT), John-Del <ohger1s@gmail.com> wrote:     >It's an Atlona HD-800 and the location is IC1 - an SOT23-6 device at the bottom left edge of the board (with the HDMI jacks facing up). If anyone wants to take theirs apart they have to remove the silver buttons before sliding the board out.   >I've fixed a few Atlona items and they seem to be bottom end. The commercial account I have that uses them has had a lot of problems with them. Every time I contact Atlona, they are no help.   >I talked to the owner of the generator yesterday, and I think they're going to order another generator from different company as they've had enough of Atlona products. They'll either use this as a backup or just donate it to me. Either way I'd like to get it going. We tried using their Hdmi to Cat6 extender using shielded Cat6. A university wap, a few feet away, caused the extenders to malfuntion. We tried a different brand which worked perfectly.

"pfjw@aol.com" <peterwieck33@gmail.com>: Sep 11 05:29AM -0700 It is just about time to annoy you with announcements for Kutztown XXXIX - a very large 2.5-day vintage radio/equipment meet in Kutztown, Adams County, PA.     http://www.dvhrc.com/kutztown.html   Set-up for vendors and club members is Thursday, the meet starts in earnest very early Friday morning, and is more-or-less wrapped up by 1:00 pm Saturday.   Watch this space for my usual list of freebies and such. I am culling the herd, and this is your opportunity to take advantage.   Peter Wieck Melrose Park, PA

thekmanrocks@gmail.com: Sep 11 06:41AM -0700 Vintage 'boom boxes'?

"pfjw@aol.com" <peterwieck33@gmail.com>: Sep 11 07:50AM -0700 > Vintage 'boom boxes'?   More than a few. Look in the pictures on the DVHRC website.   Peter Wieck Melrose Park, PA

David Farber <farberbear.unspam@aol.com>: Sep 10 11:06AM -0700 I am servicing an Orascoptic Zeon Discovery controller/power pack. A description of the device can be found here:   https://www.dentalcompare.com/4591-Operator-Lights-for-Dental-Loupes/42352-Zeon-Discovery-Portable-LED/   I was neither given the charger nor the headlamp that it powers to test it however a quick check showed that the power led would not illuminate and the rechargeable 7.4 volt battery pack measured 0.2 volts. I charged the nearly dead battery with my bench supply and the voltage came up successfully though initially there were some current spikes that kept triggering my bench supply's overload circuit. I would like to replace the battery but the company that makes the device, Orascoptic, told me it's a discontinued model. Instead I was told that if I send the battery pack to them, they will refurbish it with new cells and a new protector PC board for a cost of $325 +$25 shipping. That seems a bit steep for a battery pack.   The writing on the battery says:   Electrochem www.electrochemsolutions.com SDS Kerr 931549 S10001-140 7.4 VDC 17.76 WH Lithium Ion Battery Pack ROHS compliant HG should contain less than 0.0005% CD should contain less than 0.002%   The closest product match I could find on the internet (which came from North America) was this: https://www.onlybatteries.com/showitem.asp?ItemId=14569 It's 7.4 volt @2600mah battery pack (which converts to 19.24 WH) My main hesitation in purchasing this item is that I have no idea how trustworthy this aftermarket battery is. It's supposedly made by Samsung.   This website also shows what seems to be a good fit and it even matches the product's application but it's from Australia and I was hoping for something local that could be purchased with a couple of clicks. https://www.master-instruments.com.au/products/64245/MB987.html   Thanks in advance for your suggestions.   -- David Farber Los Osos, CA

"jfeng@my-deja.com" <jfeng@my-deja.com>: Sep 10 11:35AM -0700 It looks like a pair of 18650 batteries held together with heat shrink tubing. You can get these batteries from several sources for under US$10 each. If you are going to build your own, get the ones with solder tabs already welded on such as https://www.sparkfun.com/products/13189 (disclaimer: I have no relation to this company, and only found them in a google search on 18650 batteries).   If you are billing a customer (as opposed to doing this for a hobby or a favor), then get one already built up and charge your usual retail markup. They seem pretty common if you search on "18650 battery pack".

David Farber <farberbear.unspam@aol.com>: Sep 10 12:42PM -0700 > It looks like a pair of 18650 batteries held together with heat shrink tubing. You can get these batteries from several sources for under US$10 each. If you are going to build your own, get the ones with solder tabs already welded on such as https://www.sparkfun.com/products/13189 (disclaimer: I have no relation to this company, and only found them in a google search on 18650 batteries).   > If you are billing a customer (as opposed to doing this for a hobby or a favor), then get one already built up and charge your usual retail markup. They seem pretty common if you search on "18650 battery pack".   According to the sparkfun product description, it's good for ~300 charges. That seems a bit on the low side. Also, would I just reuse the original protection PC board?   Thanks for your reply.   -- David Farber Los Osos, CA

mike <ham789@netzero.net>: Sep 10 03:27PM -0700 On 9/10/2018 11:06 AM, David Farber wrote:   > -- > David Farber > Los Osos, CA   How much is your business worth? Medical equipment!! Lithium Battery!! You've found a battery that's DESIGNED and approved for use in that device. Doesn't say how much it costs, but cutting corners on safety to save someone else a few bucks is RISKY.   If you jury-rig a battery and anything ever happens, you're gonna get sucked into the legal fight even if you did nothing wrong. Is it worth the risk?

"jfeng@my-deja.com" <jfeng@my-deja.com>: Sep 10 04:13PM -0700 On Monday, September 10, 2018 at 3:28:17 PM UTC-7, mike wrote: > How much is your business worth? > Medical equipment!! Lithium Battery!!   I had not considered the liability issues, only the costs of fixing the battery at a labor rate of $50-$100 per hour.   I did an ebay search on "led dental headlight" and got lots that look the the original for $10 to $30, with matching charger and the letters "FDA" in the title. So, maybe about $50 from your full-price medical supplier. Given these prices and the potential legal exposure, I would junk the old one and offer it to some hobbyist to cannibalize.

John-Del <ohger1s@gmail.com>: Sep 10 04:19PM -0700 On Monday, September 10, 2018 at 6:28:17 PM UTC-4, mike wrote:   > If you jury-rig a battery and anything ever happens, you're gonna get > sucked into the legal fight even if you did nothing wrong. > Is it worth the risk?     It's a fancy flashlight for dentists...   Really bright, optimized for color temp and for not curing compounds.

The Real Bev <bashley101@gmail.com>: Sep 10 02:07PM -0700 On 09/05/2018 11:37 AM, John-Del wrote: > Heating the brick or power supply a bit with a hair dryer may get it > to start. If so, recap the power supply. Other than that you'd > probably need a schematic at least.   We bought our son a Moog (I think) keyboard at a church rummage sale. The pastor swore it worked. It didn't, but Son replaced the power supply with one from a computer and it worked fine thereafter.   Maybe this is karma...   -- Cheers, Bev

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