Digest for sci.electronics.repair@googlegroups.com - 8 updates in 3 topics

8:58 AM Penedão
"pfjw@aol.com" <pfjw@aol.com>: Feb 06 03:59PM -0800

First, the Stuff:
 
Pioneer SX780 Receiver: Turns on and tunes for perhaps 20 seconds, not all the time and passes no sound. Complete, cosmetics are fair, no visible damage. My SWAG is power-supply issues, but I do not 'do' Pacific Rim stuff.
Pioneer TX8100 Tuner: Excellent condition with original box, works very well, clean and complete. A nice basic tuner for those in need of such. No presets.
Dynaco FM5 Solid-State Tuner: Good cosmetics, tunes, and meter works. Output is a variable-with-volume HUMmmmm. It would be my fourth if working, so I am investing nothing and would rather give it to someone who might do something with it.
Sherwood Mono Tube Tuner (3000): Works after the fashion of these things, all complete, expected cosmetics, but, again, complete.
 
Catch #1: No cherry picking. Take all, or take none.
Catch #2: I ain't nohow packing or shipping, so you must come here or arrange to have it picked up.
 
This offer lasts until 5:00pm, Sunday, February 7, 2016 (tomorrow) whereupon it becomes a Craig's List Curb Alert. If someone needs a reasonable period of time from tomorrow to come get it, that I can work with. Reasonable = less than a week.
 
There will be other actual radio-related stuff as well, also free, but NOT subject to #1, optional to take if wanted.
 
We are in Melrose Park, PA. Jenkintown is immediately to our north, and Philadelphia is immediately to our south for location.
 
E-mail me here or off-group and I will send along my cell number.
 
First come first served. I will check the time-stamp of a reply if I actually get any!
 
Enjoy!
 
Peter Wieck
Melrose Park, PA
John-Del <ohger1s@aol.com>: Feb 07 05:26AM -0800


> Enjoy!
 
> Peter Wieck
> Melrose Park, PA
 
A generous offer Peter, but I'm surprised you don't just put them on Craigs for $250 which someone will snap up in an hour.
 
I don't care for those Pioneers either, but recently sold units on ebay went for $100 to 350. The whole package will go quickly unless you don't like dealing with people from Craigs (which I understand).
"pfjw@aol.com" <pfjw@aol.com>: Feb 07 06:18AM -0800

On Sunday, February 7, 2016 at 8:26:14 AM UTC-5, John-Del wrote:
 
>>SNIP<<
 
The two Pioneer units came to me as porch-puppies - left on my back porch without provenance of any sort (even though there is an address on the 8100 box). The Sherwood was a $1 BIN at Kutztown, and I got it working by cleaning the controls and loosening the on/off switch. The Dynaco is waiting for a 'round tuit' and hasn't achieved one in two (2) years, so it goes.
 
I figure I can get rid of them and make someone else happy all at the same time, and they cost me very, very little. It never crossed my mind to try and sell them.
 
Peter Wieck
Melrose Park, PA
"Ralph Mowery" <rmowery28146@earthlink.net>: Feb 07 10:16AM -0500

<pfjw@aol.com> wrote in message
news:45c56180-d2ac-4741-abf3-5a1f7efef8c3@googlegroups.com...
>I figure I can get rid of them and make someone else happy all at the same
> >time, and they cost me very, very little. It never crossed my mind to try
>and >sell them.
 
Sometimes you can sell stuff at a bargin price that you can not give away.
Especially if you have one good item and sell it all as a lot with the junk
you wnt to get rid of.
Fred McKenzie <fmmck@aol.com>: Feb 06 12:22PM -0500

In article <n92ett$17g$1@dont-email.me>,
> get them to fire if I keep bending them, but not always.
 
> Any help for these 283's or time for something else? I'd hate to lose
> all 3 of them, but none of them seem to want to work properly.
 
Bill-
 
It was my understanding that the flash is turned off when it reaches a
critical brightness, determined by light reflected to a photocell. Some
models react to the camera's metering system to determine when the
correct amount of light reached the film. Your modification probably
bypasses the automatic circuitry and stops the flash at 1/16th power.
 
That said, I don't see how your modification affects firing of the flash
in the first place. I believe that is done by dumping a capacitor's
charge into the primary of a small ferrite-core ignition transformer.
The high voltage secondary of the transformer is connected to the
outside surface of the glass flash tube. The voltage pulse is
capacitively coupled through the glass to the Xenon gas, causing it to
ionize.
 
The problem you describe suggests that the ignition transformer or its
firing capacitor is leaking. It might be caused by bad contacts in the
camera, but I think you have ruled that out.
 
You may be able to replace the capacitor with a commonly available part,
but I don't know where you would get a replacement for the ignition
transformer. Perhaps leakage was caused by absorption of moisture from
the air, and could be reversed by baking at a low temperature, or using
a dehumidifier.
 
Fred
whit3rd <whit3rd@gmail.com>: Feb 06 01:16PM -0800

On Friday, February 5, 2016 at 7:28:44 AM UTC-8, Bill Baxter wrote:
> ... even if I push the
> ready light button on the 283's, they won't fire. Sometimes the ready
> light is flashing, sometimes steady but doesn't seem to matter.
 
It's possible that the discharge tubes have gone gassy; that would
cause the breakdown voltage to rise (and make triggering hard).
Some diagnostics are possible, if there's a neon sign
shop in your neighborhood... or if you have a Tesla coil
in your toolbox.
John-Del <ohger1s@aol.com>: Feb 06 12:57PM -0800

On Saturday, February 6, 2016 at 7:40:45 AM UTC-5, Tim Schwartz wrote:
I'm not a huge fan of tantalum caps in power supplies, they
> reverse voltages.
 
> Regards,
> Tim Schwartz
 
So true. They actually make a fair zener if a one shot crowbar is needed..
"pfjw@aol.com" <pfjw@aol.com>: Feb 06 01:13PM -0800

On Saturday, February 6, 2016 at 3:57:48 PM UTC-5, John-Del wrote:
 
> > Regards,
> > Tim Schwartz
 
> So true. They actually make a fair zener if a one shot crowbar is needed..
 
As I noted to Tim directly, I observed no tantalum-type caps visible anywhere in this unit. The B251 is about a generation newer than the B750, so I expect this might be the reason. I don't like them much either, but I am using some lately doing TIP mods on a series of Dynaco 120 amps that I tripped over. Three original configuration unit right down to the original 3055 outputs... That one of them actually works on both channels is remarkable. Anyway, at a finished cost of less than $50/unit, all in including first-cost, they come out as not bad at all, and pretty rugged. Nothing like OEM in other words.
 
Peter Wieck
Melrose Park, PA
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