JBL EON 515XT No Treble

[ca7922303]

Looks like the frequency showing on the scope is not the same as what the signal generator is putting out.
Does scope say 91.366 Hz, or 91366 khz ?

Scope the signal coming out of your source, get it set up to show a proper sinewave. Then scope the other points with the same time base settings.

91.366 Hz

[ca7922303]

Looks like the frequency showing on the scope is not the same as what the signal generator is putting out.
Does scope say 91.366 Hz, or 91366 khz ?

Scope the signal coming out of your source, get it set up to show a proper sinewave. Then scope the other points with the same time base settings.

Not able to get scope frequency to match signal generator frequency. Also, ch 2 on scope has no frequency reading. It shows a question(?) mark at every adjustment I make.

What does it mean that pin #3 & 14 have the same reading with tweeter connected if perhaps this owon pc based oscilloscope is correct except for the frequency reading?

[g1]

It's possible the signal is not getting to the high amp and the scope is just reading some noise. But it seems to be low frequency and 20V p-p is a lot.

Where is probe for scope Ch.1 connected? Where is scope Ch.2 connected?
If you connect scope directly to sig. gen. it won't show 4Khz waveform?

[ca7922303]

It's possible the signal is not getting to the high amp and the scope is just reading some noise. But it seems to be low frequency and 20V p-p is a lot.

Where is probe for scope Ch.1 connected? Where is scope Ch.2 connected?
If you connect scope directly to sig. gen. it won't show 4Khz waveform?

Ch.1 probe connected directly to signal generator output lead and then ch. 2 connected directly to signal generator output, one at a time to attempt to adjust frequency.

[x-pro]

simple amplifier

[ca7922303]

simple amplifier

I'll be testing this weekend. Everything you've drawn is clear except the writing on the positive probe connections. I get the 4khz on both probes, but can you clarify the other writing on both probes(ch1 & ch. 2). Thanks.

[ca7922303]

It's possible the signal is not getting to the high amp and the scope is just reading some noise. But it seems to be low frequency and 20V p-p is a lot.

Where is probe for scope Ch.1 connected? Where is scope Ch.2 connected?
If you connect scope directly to sig. gen. it won't show 4Khz waveform?

Ch 1 shows incorrect frequency. Ch 2 shows a "?" question mark.

[g1]

Ch 1 shows incorrect frequency. Ch 2 shows a "?" question mark.

If you show a scope shot with both probes connected, you need to say what each probe (channel) is connected to.

[ca7922303]

Probe #1 on pin #3 tda7293
Probe #2 on pin #14 tda 7293

Signal generator 4khz 1v sine

This is without ground leads of probes connected to ground.

[ca7922303]

This is with ground leads connected to PC board attachment screws

[ca7922303]

With tweeter only connected (with probe ground wires connected).

[ca7922303]

Tweeter connected and probe ground wires not connected to ground.

[g1]

So the TDA is putting out over a volt RMS with no load (post #56), but drops to millivolts when you connect the load (post #57). Replace it.

[ca7922303]

So the TDA is putting out over a volt RMS with no load (post #56), but drops to millivolts when you connect the load (post #57). Replace it.

Replaced TDA7293. Checked continuity to all 15 pins. All beep, but no tweeter(treble) function.

[nosaj]

TDA7293 's are very easy to kill (At least in the marshall mode 4's. Draining the filter caps was an important part of the marshall repairs.
nosaj