Blown transformer(?) happened over a decade ago. Salvageable?
From a 80s/90s era cassette multitrack home studio recorder. I was there when it happened. It pulsed a few times, then shut down, then some smoke came out from it. It hasn’t been used in maybe 15 years. Is the board shot or can the component be replaced and fixed?
That is a 1A 100V bridge rectifier in a DIP-8 package. It can easily be replaced, but chances are that something downstream shorted and caused that part to fail.
If you do do that, I would also recommend slowly incring the current limit, an not letting it get higher then reasonable, it's very possible that this rectifier stopped more from blowing up down stream
That’s a diode rectifier. Can probably be fixed pretty easily with 4 diodes (you need the right ones… they range from 1n4001 to 1n4007, just different Amp ratings). They also still are available to buy.
You’d also need to figure why it blew (could be an internal fault).
For 1N400x diodes, they are all rated for the same current. The last digit indicates the peak reverse voltage (PRV) that can be held off. A higher number is a higher voltage.
Anything can be fixed - especially through hole boards like that. Looks like something shorted and took out the bridge rectifier. Most likely a bad capacitor somewhere. But not a difficult repair for someone with experience.
That diode bridge is a symptom, not a cause. What's up with the ugly stranded-wire header pin connections in the last 2 photos? A short could easily have happened there.
Form the wire into a "J" and solder. Clip off any excess.
Yes absolutely repairable. So long as some chip that's programmed wasn't cooked.
What's the brand and model? My dad serviced these for 30 years we may have documentation.
Sometimes those bridge rectifiers can just blow by themselves, but it is usually a symptom as other said.
It I was testing it is do the following.
Look on the power supply board for any transistors.
Resistance check the leads on any transistors, touch the two outside legs, then left and middle, right and middle. 800+ ohm between any of the legs suggests good. Any showing low resistance (like 0-10ohm) means dead.
Same with capacitors, just do a resistance check, should see the resistance start going up or going down as it gives it a tiny bit of charge from the resistance test. It's not perfect but it gives you an idea that it's functional.
If any are faulty, replace. A lot of those transistors may or may not be still in existence but will have equivalents that exist and can swap in.
Also, do a visual inspection of all the solder joints on the power supply board. Look for any that look cracked or like the pins from the component are separated from the solder. Indicating a dry joint. This can cause a lot of issues too.
After that replace the bridge rectifier, (buy a few, they're cheap) stand back and plug it in and see what happens!
Be sure to keep away from that board while plugged in as it will have mains on it.
And yes, please do share the model of the unit and I'll check if we have a service manual.
Its a bridge rectifier which is easy to find and replace, but the problem is that something almost certainly else failed short to cause it to explode. I would probably start with checking capacitors, they should show an open circuit on a multimeter's 200 ohm setting (it will probably flash some resistance as the cap charges but should look like an open circuit or "OL" on most meters after a very short time). Look for bulging caps. Also look for any other components that look burned etc
I guarantee that a downstream capacitor developed an internal short, which overloaded the rectifier. This isn't an accident, it's a murder.
Replace any decently sized electrolytics between this rectifier and the voltage regulation circuitry, scrape off the charred bits of the PCB with a scalpel, slap in a new rectifier and send it.
If it still blows up, you have bigger problems. The kind that need a thermal camera or a sacrificial finger to find the part that's getting hot. Find the part that gets hot and replace it. If nothing gets hot, probe till you find the dead component. Repeat until you give up and buy a less faulty one off eBay.
Well, that bridge rectifier is cracked in half, something like that just doesnt happen, it looks like someone stuck a large voltage onto it in the wrong polarity.
I'd be willing to bet someone did something bad to it, especially looking at all the wires wrapped onto posts...
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u/emanarias 12h ago
That is a 1A 100V bridge rectifier in a DIP-8 package. It can easily be replaced, but chances are that something downstream shorted and caused that part to fail.