Who can help me, Eric foster maybe?

[draco]

Hi guys, my GS 5 stopped working. It had been out the day before and the next morning when I went to turn it on, the battery meter went all the way up and started to smell burnt.
I quickly unplugged it and the transistor below was very hot. Not that this could happen.
Can somebody help me? Or I would like to know who can fix ...
Thanks

[kt315]

not a transistor. it's a stabilizer of negative voltage of power supply.

[Carl-NC]

The LM337 provides -10V for the audio circuit. Maybe the headphones got shorted. The -10V also drives a -5V regulator for the rest of the circuitry but I would think the -5V reg would burn up long before the LM337.

[surfdetector]

Hi guys, my GS 5 stopped working. It had been out the day before and the next morning when I went to turn it on, the battery meter went all the way up and started to smell burnt.
I quickly unplugged it and the transistor below was very hot. Not that this could happen.
Can somebody help me? Or I would like to know who can fix ...
Thanks

[ATTACH]56380[/ATTACH]

Why is there an IC missing from the Dip8 socket?

[eclipse]

There's probably another issue with the board.
The regulator there is probably overloaded with high current caused by short, maybe even damaged mosfet transistor not willing to switch on/off or mosfet timing circuit malfunction.

If you have knowledge in testing do the following:
1) Disconnect the coil
2) measure the coil resistance must be over 2 ohms to be sure coil is not shorted
3) Measure voltages +5V, -5V, -BAT to LM337 output
4) Measure the gate pin on the mosfet, you must have about ~3Khz frequency there with oscilloscope

All Eric Foster machines can be repaired because there's no chips deleted, white paint etc crap.

[draco]

True. Voltage stabilizer

[draco]

Why is there an IC missing from the Dip8 socket?

It has always been like this. The reason I do not know

[draco]

There's probably another issue with the board.
The regulator there is probably overloaded with high current caused by short, maybe even damaged mosfet transistor not willing to switch on/off or mosfet timing circuit malfunction.

If you have knowledge in testing do the following:
1) Disconnect the coil
2) measure the coil resistance must be over 2 ohms to be sure coil is not shorted
3) Measure voltages +5V, -5V, -BAT to LM337 output
4) Measure the gate pin on the mosfet, you must have about ~3Khz frequency there with oscilloscope

All Eric Foster machines can be repaired because there's no chips deleted, white paint etc crap.

Although I have cloned some detectors, I have no knowledge of electronics. I wouldn't put my hand on something as precious as the GS5

[draco]

The LM337 provides -10V for the audio circuit. Maybe the headphones got shorted. The -10V also drives a -5V regulator for the rest of the circuitry but I would think the -5V reg would burn up long before the LM337.

Thanks Carl. The headphones, I'm a Gray ghost. They seem to work perfectly on other detectors

[Ferric Toes]

Hi guys, my GS 5 stopped working. It had been out the day before and the next morning when I went to turn it on, the battery meter went all the way up and started to smell burnt.
I quickly unplugged it and the transistor below was very hot. Not that this could happen.
Can somebody help me? Or I would like to know who can fix ...
Thanks

[ATTACH]56380[/ATTACH]

Hi Draco,

Something puzzles me about this board. The missing IC is a Cmos 555 used to generate a square wave of about 60kHz to drive a diode pump type inverter for the +5V rail used in the receiver. The link of black wire to the 4538 IC looks to be a substitute for the 555. This is not original. If it works, then the result is that the inverter is synchronised to the TX pulse rate, thereby eliminating a potential source of interference.
Over the next few days, I will get a board and see if this, or a different fault, could cause the 337 regulator to run hot. The green capacitor is also a foreigner.

Eric.

[Skippy]

The green tantalum bead capacitor does look to be 106 = 10 uF, and it's fitted the correct way round, so maybe the original died, but the replacement is OK ?
The dark blue preset pot looks non-original, too, to me.
If the 555 pin 3 was used to drive a charge-pump & its load, then there would've been a significant current drawn from that output. No problem for a plain bipolar NE555, or even a LinCMOS TLC555, but hopeless for a 4000-series monostable timer IC, surely ?

[draco]

Everything is original. Nothing has ever been touched except a capacitor that was replaced at the time.
Eric, if I remember correctly, you reviewed this device and updated it to the latest version, before I bought it.
Thanks for your help

Ps: I will look for the documentation that you sent with the device

[draco]

Eric, I post a photo of the update you made to my GS5 below. I bought it from the person to whom you address the following message.
Thanks

[ivconic]

I have hesitated to say this before; but it seemed to me that I had seen that signature before:

[Vadim18]

I have hesitated to say this before; but it seemed to me that I had seen that signature before:
[ATTACH]56477[/ATTACH]

Nice vision memory! Ivconic, are you ex tax worker in the past?)