Electronics Forum / Repair / May 2004

I keep one funny battery for 20 years ago, it was a size AA, 1.5 volt.
The reason was this battery'polarity was invert when you measure,
untill to day I
don't understand why ? Can any person know what is going on. Thanks

please help to identify:
written to smd:
M43AB
0438-8078

I have a 14" colour television here at home,its a ZX-Series (some shop's own
brand here in irland) and when i turn it on all i get is a horizontal line
on the across the middle of the screen, its was working fine and then it
just went like this,it was dropped or damaged in any way. ...

I use a Videonics MX1 digital video mixer's composite video output
ahead of my VCR so that I can watch and distribute my DVD player's
output throughout my house. Without the MX1 the picture is of course
unwatchable. I am told that it is the TBC function of the MX1 that is

I have a twelve year old Sony Trinitron that has suddenly developed a color
problem.  The colors all of a sudden changed to mainly green and pink.  No
adjustment brings it back to normal.  A friend told me a color gun failed.
Might this be so?  Another friend told me it might be the ...

I have just been given a computer monitor. The problem is the screen is
rather dark.
I have the settings of brightness and contrast up to 100, which is the
highest it can go.

Hey all,
I've got an old MTC 28" tv that I'm working on.  (model MTV-2800C)
The flyback is a KFS60490A which crosses to a HR 8562
Anyhow, the set has a HV shut down problem.  You can hear a tiny arc, zapping once in a

I picked up an EE Tools TopMax universal device programmer at the flea
market recently.  It appears to be in fine shape, but it fails the
hardware test in the Windows software.  Some functions seem to work OK
(e.g. the 74xx logic test/identifier), but I haven't been able to

I  got in a RCA 13" 1993 E13320se with a vertical jitter.
This has a separate tuner in a can and not on the PC board.
I looked for a chassis number, but there was none inside.
All the caps around the vertical chip seem to ESR ok.

Hi all... If someone has this transistor (known good), I would greatly
appreciate its DMM readings (ie. +/-B-E mV, +/-B-C ohms & +/-C-E mV).
TIA, Obone.

I am gathering information about how to build a class-C power amp for
SSTV operation on 20 m.
Some interesting designs have been published using inexpensive MOSFETs.
Grounded-gate triodes are a long-time classic. I never saw MOSFETs being

Hello everyone. I have a pile of schematics here. Mostly from the
early to mid 90's and some earlier.
There are a few copies from assorted vcr manuals and then I have a
pile of Profax schematics which I haven't looked too hard at but

To all who want to try to repair their broken Modem 3COM US ROBOTICS
56K INT ISA-Slot Type 0613 themselves a tip that may help: I got a
broken one for free, which could be installed as usual with driver
from http://www.driversguide.com.

 I bought a Sony 43 inch projection TV about a month ago.  It still
runs great, but has developed a quirk over the last week or so.  When
I switch it off, a red dot appears in the middle of the screen and
then rapidly travels down the screen and disappears.

I have a Proscan PS34190 with chassis CTC172ATA that has
developed a problem: when I press the ON button, it takes
two, three, four or more hours for it to turn on!
I took the back off, and I can see the fan twitching, and hear