Electronics Forum / Repair / July 2008

How the hell do they make an LED so damn bright?

Repaired a Technics SU C2000 control amplifier, which is just a preamp. An
LED displays that it is in this VBO mode.
The SU C1000 has a battery back for this, but no battery pack in the C2000
unless it is somehow hidden in the faux (poids for your bucks) heavy metal

But looks more 1970s .
Anyone familiar with strange transistor. capacitor  and these  IC markings
such as
"X2 080" ,"X8 761" ,"TL 761" (not opto) ,"X8 082" ,"X6 081" ,"X6 082" ,

I am trying to repair a pressure alarm unit, the pressure transmitter
will send 4-20 mA to the unit. The unit receives the current and let
it pass through a resistor (178 ohms) to convert to voltage, then it
uses an op amp-amplifier stage to amplify the signal across the

I need your help once again group. This is my first LCD TV to fool
with, but I suspect troubleshooting the power supply is the same. The
set has no standby power, totally dead. I did some initial checking in
the supply, but found nothing wrong. Have good B+ on the switching

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This chip normally puts out square pulses. In the power supply I am
working on (http://www.laserfaq.org/sam/150rcsch.pdf) it is putting
out a sawtooth wave. I am testing it in 'standby mode', in which Q4 is
off and R33 is in control of the duty cycle. Replacing the IC1 has no

I am looking for a small quantity(1 roll will do) of the blue antistatic tape
you see in many electronic devices like ipods and pda's. I am thinking 3/4"
would just about cover all of my bases, wide and varied uses.
I found Botron tape at,

36" sony HDTV tv model:KV-36XBR400,chassis:SCC-S48B-A (Canadian) or
SCC-S47B (USA),chassis: DX-1A,year:Sept 2000,flat screen
crt.Problem:according to customer intermittently the sides of the
picture (left & right) are bowed in (hourglass effect). Anyone have

Anyone repairing these things ?

I have a Yamaha CX-1000 preamp and I just acquired a used Yamaha CD
player that has a digital output (CDX-710).
The CX-1000 preamp has digital inputs on it.  Even though this CD
player sounds fine through the analog outputs, I wanted to hear what

Seemed a neat idea but ...
There is space inside this 1950s dashboard radio for one of those keyfob/
matchbox size FM radios, this one based on a TDA7088T. The original AM radio
works fine, well minimal hash from the buzzer mechanism of the vibrator 12V

Used for fixing otherwise floppy bits to boards.
Is it hygroscopic ? whatever the word is, but pulls dampness out of the air.
Beocenter 4000 from 1985 with the LC7815 (not V reg) electronic 2 pole 4 way
switch, internally locked into Aux only input, so disabling everything else.

In the past year I've exploded to bits my faulty ex-trusty IBM T22
laptop, ruined the original screen by attempting to change the $$ tube
(specifically mangled up the rubber isolation bits over the solder
joins), wasted $$ buying second hand inverter boards, wasted more buying

I have a ~6 year old Sony CRT tv and recently it started giving me
problems.  About a month to two months ago it started to shut off
after a dew seconds of turning on.  I left unplugged for a while and
it worked normally again.  Recently it started to happen again.  This