Pc68xl extremely distorted at 400 hz or less input modulation. Scope shows square wave that looks like an aomeba. Also see herring bone at approx. 160 hz on scope.

You may have channel 1 set to DC input and channel 2 set to AC. If your DC balance is set correctly, as you mentioned, then there is a DC component to the waveform. Having the scope set to DC will show this DC offset, but set to AC, it will not be seen.

I am not an expert but I think there can be little or no modulation of the carrier wave unless there is an audio input to the modulator. Like any audio amplifier a transmitter modulator (amplitude modulation) is quiescent without an input.

If the modulation amplifier and audio pre-amp are working and modulating the carrier wave and the antenna is ok then audio modulated radio frequency must be being transmitted.

It would be an extremely good quality CB that had a modulation meter. Mostly all they have is a meter giving an indication of the rf power being sent to the antenna and that rf (radio frequency) power would be the same whether modulated or unmodulated.
The modulation envelope, incidentally, is traditionally viewed or measured with an oscilloscope.

The indicated rf power could be verified using a field strength meter but the only practical way to discover if a standard CB is transmitting modulated rf is to listen to the transmission on a suitable receiver. If the squelch is turned down it will be obvious if the rf carrier wave is being received as the hiss would be silenced. If no audio is received it can be assumed none is being transmitted.

I suggest you try another microphone and lead and if that doesn't work it is clearly a job for a repair shop.

If its 10 years old boards and or parts will likely not be available--average life on Plasma and LCD sets is 3-5 years.

I would retire it--recycle it and buy a new set.

check for a bad coil, that shows up as a high mark on a scope

bad transformer. A $10 part at most electronic stores. U fried it when you dropped it. Happens all the time.

Many modern gas stoves, ovens, furnaces, and other similar appliances use an electronic ignition rather than a continuously burning pilot flame to ignite the fuel. These are actually simple high voltage pulse generators.

• Where starting is manual (there is a 'start' position on the control(s), a set of switch contacts on the control(s) provides power to the ignition module.
  
  • A problem of no spark with only one control indicates that the fault is with it or its wiring.
    
  • A problem with continuous sparking even with all the controls off or in their normal positions indicates a short - either due to a defective switch in one of the controls or contamination bypassing the switch contacts.
  
  
• Where starting is automatic, an electronic sensor, thermocouple, or bimetal switch provides power to the ignition module as needed.

The Harper-Wyman Model 6520 Kool Lite(tm) module is typical of those found in Jenne-Aire and similar cook-tops. Input is 115 VAC, 4 mA, 50/60 Hz AC. C1 and D1 form a half wave doubler resulting in 60 Hz pulses with a peak of about 300 V and at point A and charges C2 to about 300 V through D2. R2, C3, and DL1 form a relaxation oscillator triggering SCR1 to dump the charge built up on C2 into T1 with a repetition rate of about 2 Hz. C1 A D1 T1 o H o----||----------------+-------|>|-------+-------+ +-----o HVP+ .1 uF D2 1N4007 | 1N4007 | | o ::( 250 V +----|>|----+ | +--+ ::( | | | )::( +---/\/\----+ | #20 )::( 1:35 | R1 1M | C2 _|_ )::( | R2 / 1 uF --- +--+ ::( | 18M \ DL1 400 V | __|__ ::( | / NE-2 | _\_/_ +-----o HVP- | | +--+ | / | | +----|oo|----+---------' | SCR1 | C3 | +--+ | | | S316A | .047 uF _|_ R3 / | | 400 V | 250 V --- 180 \ | | 1 A | | / | | R4 2.7K | | | | | N o---/\/\---+-----------+------------+----+-------+

Since you are able to view the output i'm assuming you are using an oscilloscope and only the positive or negative half of the sine wave is displayed. The output stage will be using a complimentry pair of output transistors, one amplifies the positve half cycle the other the negative. These are driven by a driver stage (phase splitter). One side is not amplifying. First measure the pos' and neg' LT supply rails. If ok check
ouput transistors with analog Ohm meter for base / emitter / collector continuity. If the amp uses an output IC and LT supplies are ok then use scope to view input signal, if input ok but output bad then IC is suspect. Since both channels are affected your problem is most likely a missing LT supply rail.

Specifications Power Output: 100 Watts RMS x 2 channels at 4 Ohms ≤ 1% THD+N Signal-to-Noise Ratio: 80 dBA (reference: 1 W output) Additional Power Output: 200 Watts RMS x 2 channels at 2 Ohms ≤ 1% THD+N
400 Watts RMS x 1 channel bridged at 4 Ohms ≤ 1% THD+N THD+N (Distortion): <0.25% (reference: 1 W output) Frequency Response: 20 Hz to 20 kHz (-3dB) Maximum Input Signal: 5V Maximum Sensitivity: 100mV Dimensions: 14.37 x 9.72 x 2.5 (365mm x 247mm x 63.5mm)

The best way to diagnose is to unplug everything execpt pwr & ant & test & plug one wire in & test and ditto,untill you find the culprit.If this does not work check the pwr supply and any connecting leads in the tv.This way you narrow the possibilitys down(is it the tv or the input device.) regards Chook.