Ultrasonic cleaner...need opinion

[TA7205]

Hi;

A customer brought this Peltsonic T1.9C to me dead.

After taking a close look at the whole thing, the only
problem that I can find are the 2 blown power transistors
(GSTU6030) mounted on heatsinks.

The thing that makes me wonder is that the transducer
mounted under the pan has pieces missing.(found them at the bottom
of the case)

Both wires are firmly attached to it and there is no short,
so the transistors weren't killed by that.
Could the transducer's reduced mass be the problem ?

Thanks in advance,
Rick

 

[Sam Goldwasser]

ta7205@aol.com (TA7205) writes:

Hi;

A customer brought this Peltsonic T1.9C to me dead.

After taking a close look at the whole thing, the only
problem that I can find are the 2 blown power transistors
(GSTU6030) mounted on heatsinks.

The thing that makes me wonder is that the transducer
mounted under the pan has pieces missing.(found them at the bottom
of the case)

Both wires are firmly attached to it and there is no short,
so the transistors weren't killed by that.

Probably were.

Could the transducer's reduced mass be the problem ?

Yep.

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[Dave D]

"TA7205" <ta7205@aol.com> wrote in message
news:20030817145858.06260.00000093@mb-m19.aol.com...

Hi;

A customer brought this Peltsonic T1.9C to me dead.

After taking a close look at the whole thing, the only
problem that I can find are the 2 blown power transistors
(GSTU6030) mounted on heatsinks.

The thing that makes me wonder is that the transducer
mounted under the pan has pieces missing.(found them at the bottom
of the case)

Both wires are firmly attached to it and there is no short,
so the transistors weren't killed by that.
Could the transducer's reduced mass be the problem ?

Thanks in advance,
Rick

The output section in these devices is usually tuned and impedance matched,
when the transducer breaks down its properties change and upset the outputs,
resulting in their demise.

Also, just because the transducer doesn't read as shorted now doesn't mean
it didn't in its final moments. Bear in mind that a piezo is a very high
impedance device, it may not take a 0 ohm short to damage the output
transistor, a few hundred ohgms could do it if the piezo is fed with an
impedance matching transformer.

Dave

 

[TA7205]

Thanks guys for the info.

I surmized it was the piezo that caused
the trouble.

Rick

 

[BillJ]

I think that running it up without a load (eg no fluid in the bath)
could have caused the piezo to crack itself up. That would have
presented the output stage with the wrong load, so the output
transistors would have been next to go.

BillJ, Edinburgh

On 17 Aug 2003 18:58:58 GMT, ta7205@aol.com (TA7205) wrote:

Hi;

A customer brought this Peltsonic T1.9C to me dead.

After taking a close look at the whole thing, the only
problem that I can find are the 2 blown power transistors
(GSTU6030) mounted on heatsinks.

The thing that makes me wonder is that the transducer
mounted under the pan has pieces missing.(found them at the bottom
of the case)

Both wires are firmly attached to it and there is no short,
so the transistors weren't killed by that.
Could the transducer's reduced mass be the problem ?

Thanks in advance,
Rick