Tweet
Hi all. A friend brought in for repair a Coin Magnum VLF Descriminator detector, advising that he tried for the first time a pair of headphones, and this caused the audio to fail. A puff of smoke came through the speaker grille, and no more sound!
Sure enough, there was a burned pinhole through the speaker cone, but the damage didn't stop there! A small transistor which appears to be the audio output transistor, has its jacket split, the flat side which has the part number, though still present, is lucky to be still attached by a thread. But the number cannot be read anymore.
I need to replace the transistor but to do that I need to know the type. I have downloaded schematics for other models, and observed the variations, none quite the same as this one in the sound output part of the circuit. Rather than just guessing, I'm hoping that someone has either a schematic or a unit the same so that the transistor can be replaced by something at least remotely similar.
There are a lot of plastic bits glued to the metal cabinet which have come adrift, that I am in the process of regluing. A replacement speaker wasn't a problem, a common pocket transistor radio speaker from an earlier era was almost identical.
The hole for the wires to the remote pushbutton could've been a size larger, that would've allowed the plug to pull through so that the cabinet could've been put aside, making servicing a little easier. But otherwise it's a neat unit.
There's a possibility that whatever drives that transistor may also have been damaged, I haven't traced that out yet. But a circuit diagram would make that so much easier.
Does anyone have one, or a suitable link? I've recently changed email addresses so can't presently use Paypal, so a free link would be best.
Thanks,
Technomaniac.
Sure enough, there was a burned pinhole through the speaker cone, but the damage didn't stop there! A small transistor which appears to be the audio output transistor, has its jacket split, the flat side which has the part number, though still present, is lucky to be still attached by a thread. But the number cannot be read anymore.
I need to replace the transistor but to do that I need to know the type. I have downloaded schematics for other models, and observed the variations, none quite the same as this one in the sound output part of the circuit. Rather than just guessing, I'm hoping that someone has either a schematic or a unit the same so that the transistor can be replaced by something at least remotely similar.
There are a lot of plastic bits glued to the metal cabinet which have come adrift, that I am in the process of regluing. A replacement speaker wasn't a problem, a common pocket transistor radio speaker from an earlier era was almost identical.
The hole for the wires to the remote pushbutton could've been a size larger, that would've allowed the plug to pull through so that the cabinet could've been put aside, making servicing a little easier. But otherwise it's a neat unit.
There's a possibility that whatever drives that transistor may also have been damaged, I haven't traced that out yet. But a circuit diagram would make that so much easier.
Does anyone have one, or a suitable link? I've recently changed email addresses so can't presently use Paypal, so a free link would be best.
Thanks,
Technomaniac.
Comment