Look guys I am new to this portion of electronic repair but I need a little help identifying a component it looks like a bipolar transistor of some kind numbers are G4BC30U IR 342F also on the part 7A 3D.
I have looked it up in several places and can only find part numbers that are close. Have no idea if a regular diode test will work. And will probably replace if I can find what it is and where I can get one.
This is an older ultrasonic and I am also replacing the amplifier transistors that seem to be on one power rail.
It currently keeps blowing slo blo 250v 2a fuses.
Also having trouble identifying a diode labled PK MR 0217.
Have tested all parts in circuit some are iffy. Will take out of circuit if necessary to check.
Any help would be great. Thanks

 

A few photos would be really helpful, particularly close-ups of those parts.

 

A few photos would be really helpful, particularly close-ups of those parts.

 

None of those sound like standard part numbers. They could be "in house" custom markings for parts that are unique to the particular device. Under those circumstances your chance of finding a replacement part, at any price, is exceedingly remote. Among a large segment of the population there is a peculiar belief that companies are "obligated" to design devices with standard and commonly available parts. It is further believed that they are supposed to provide readily accessible documentation that would allow people to repair broken devices. I am here to tell you that NOTHING could be further from the truth. Just look at the fate of "right to repair" legislation in the bought and paid for state legislatures.

 

None of those sound like standard part numbers. They could be "in house" custom markings for parts that are unique to the particular device. Under those circumstances your chance of finding a replacement part, at any price, is exceedingly remote. Among a large segment of the population there is a peculiar belief that companies are "obligated" to design devices with standard and commonly available parts. It is further believed that they are supposed to provide readily accessible documentation that would allow people to repair broken devices. I am here to tell you that NOTHING could be further from the truth. Just look at the fate of "right to repair" legislation in the bought and paid for state legislatures.

You make a good point.

 

To let you know I called Crest and of course they told me to pound sand when I asked for a schematic. That was expected but during the call I got insight into my problem. Seems to be transistor problems, and since there are only 4 on the board I have done my best to order the three amplifier transistors and the fourth (pictured) from an ebay seller in Germany.
All in all it cost about 25 bucks so we shall see what happens.
I am quite familiar with the right to repair legislation and have listened to Louis Rossman's views. I look at it both ways with understanding of corporate intellectual property rights and of course as an end user who just wants to be able to fix his broken crap.
My leaning is still up in the air.

 

I can deal with either. What I'd like is more disclosure about the item you're buying. A certifying agency that could score an item for user-repairability would let consumers know how to make informed purchases.

Back when I was a kid, I can remember that my dad would never buy an appliance, lawn mower, etc that didn't come with a parts diagram and list. It usually cost a little more but before the Internet, if your item failed and you had no parts list, that was the end of the road. Paying a little more for the potential of future DIY repairs was a no-brainer.

 

Ir342 could be the international relations rectifier number.

 

[Good catch it is, that is how I tracked it down I believe it is a mosfet and I have two on the way. I do believe I will have to tune the coil someway after replacing transistors. I think it involves adding or removing coil wires... not sure though.

 

Good news and bad got it working replaced one amp transistor and mosfet worked for about 30 min then blew fuse and now mosfet tests bad. Head scratcher.

 

Another item that cost loads of cash and the company don't care about the brand name enough to even help you out with a Replacement part. I mean I am one that I understand if it is under warranty that it would be best to be repaired by their Repair center. However if it is out of warranty why make it so the items can't be repaired. The Company that Only will say Starts with A has just changed the idea that all items that are turned in should now be destroyed rather then fall into the hands of others that may be able to repair and have someone use it. You take it into the Auth Repair center and only thing you get from them is can't repair it here and you need to pay to replace it at an inflated price seeing the one your buying is a already repaired unit that in most cases wasn't repaired the right way by their own Repair center and brakes down again anyway. Just seen one last week that was repaired after it was a replacement a few months back. All over a headphone jack they said they couldn't repair and told them they would need to pay 400 to replace. After opening it up it was clear it was a Repaired before unit. There are signs. After 25 minutes and a CHINA replacement part installed the unit was back in working order. I think people should be able to buy legit parts from the company rather then tracking down parts that may or may not even work.

So yes I Support the Right to Repair.

 

Another item that cost loads of cash and the company don't care about the brand name enough to even help you out with a Replacement part. I mean I am one that I understand if it is under warranty that it would be best to be repaired by their Repair center. However if it is out of warranty why make it so the items can't be repaired. The Company that Only will say Starts with A has just changed the idea that all items that are turned in should now be destroyed rather then fall into the hands of others that may be able to repair and have someone use it. You take it into the Auth Repair center and only thing you get from them is can't repair it here and you need to pay to replace it at an inflated price seeing the one your buying is a already repaired unit that in most cases wasn't repaired the right way by their own Repair center and brakes down again anyway. Just seen one last week that was repaired after it was a replacement a few months back. All over a headphone jack they said they couldn't repair and told them they would need to pay 400 to replace. After opening it up it was clear it was a Repaired before unit. There are signs. After 25 minutes and a CHINA replacement part installed the unit was back in working order. I think people should be able to buy legit parts from the company rather then tracking down parts that may or may not even work.

So yes I Support the Right to Repair.

I completely agree out of warranty stuff should be repairable by end user and parts to do so should be available without having to search all over check to find.
Companies like Crest who produce a good product are protecting their intellectual property I get that, I however am not interested in making copies of their product just fixing the one I have.
So I guess I lean to repair.

 

Well it seems to be working with German mosfet and three new amp transistors.
Cleaned a couple of water damaged phone boards so we will see. I'm sure it needs to be tuned all I could do is turn down the pot a little, don't have oscilloscope.
These cleaners get good reviews they are pricey but some help with repairing them would be nice by the manufacturer. Like parts. I guess you could compare them to the A company. No schematics either.
If these things are throw away I need a cheaper alternative.
Thanks for the help.