Re: 6 v to 12 v for car radio memory

Mystery Component solved!. We were thinking that the 3 wire component was perhaps a miniaturized DC to DC converter to give 12 volts DC to the radio memory from the truck 6 volt battery. Instead, the full power for the booster is connected to the radio and the memory lead on the radio. It seems that when the radio is off, the memory requires very little current, perhaps 8 ma or so and the booster is connnected to the battery at all times and not through the ignition switch. The 3 wire component is just a 6 volt relay so that when the ignition...

My friend has a 1950 Chevrolet pickup truck. He is using a transistor radio powered by a booster module to get 12 volts from the 6 volt battery. To maintain the radio memory there is a wire from the radio that wants to see 12 volts continually. The truck came with the radio and booster and a three wire device that claims to be necessary for the radio memory. As in many restored old cars and trucks, the body and interior work is usually good but you will be surprised at what people do to the electrical system. There is no hook-up data on the three wire mystery component that has a black wire, a...

Re: Bad power supply

paulstef's post #16 on this thread is very instructional and I find that I get more out of it every time I read it. He is obviously a very technically competent person and likely the product of a good school system. This post, in my view, is in the best tradition of this forum. Thanks to paulstef for posting this.
Joe

Re: Problem with start-up Samsung 40LNA550

Thanks for your help on this budm.
Joe

Re: Problem with start-up Samsung 40LNA550

Thanks to CapLeaker and BudM. I will update this thread if his suggestion clears the problem.
Joe

Re: Problem with start-up Samsung 40LNA550

I have taken some photos of the Power Supply and Main Board and will try to attach them here. Where can I get a schematic of the Main Board?
Symptoms sometimes includes sound screeching and negative picture with wrong colors, then shutdown followed by startup.
I am looking at a similar problem on a similar Samsung Main Board and am testing a suggestion by BudM concerning 2 caps on the main board....

Re: Problem with start-up Samsung 40LNA550

I purchased new caps from Badcaps.net store and amother reputable supplier. I will try to post photos.
Joe

I have replaced all the main electrolytics on the power supply board, B44-00197A with Rubycon's. I did not replace the 2 large 100 mfd, 450 volt on the PFC Block, just the 47 mfd, 50 volt on the VCC line. I replaced 7 on the COLD side of the Standby and multi Block. Symptoms are negative picture with wrong colors on start-up. Shuts down and then restarts normally and runs for hours. Seems to be most common on first start up of the day.
I checked voltages while operating with no signal and found 12.82 for 13 volts and 5.1 for 5.3 volts. Standby 5.3 volts reads 5.1 volts when plugged in but...

I read somewhere that recapping with a higher voltage will not always succeed because the new cap may not "form" properly if it is rated much higher than the voltage it sees. Is this true? Can I use a 25 volt electrolytic in place of 10 volt?
Electronicjoe

Re: New Members - please post your introductions here

This is my first post. I go by the name Electronicjoe. I am retired at this time doing some occasional consulting work in the area of nuclear safeguards. I earned a BSEE in 1965 and then an MS and PhD in Applied Mathematics. I always loved electronics and enjoy electronic repair and restoration as a hobby.
I live in Miller Place New York, on the north fork of Long Island. I used to repair color TV's when they had CRT's, with tubes or transistors. I am interested now in learning about the new flat screen LCD and plasma...