Green AVT-8710 broken, replacement part number?

[sheeshyall]

Hello,
I have a Green AVT-8710 that does not seem to work at all. Upon opening up the case, there is what looks to be a linear regulator (total guess) that has blown up.

I know there is something tricky about the barrel jack polarization being opposite to most other devices, so I'm guessing this had something to do with it.

My hope, is that one of you have a 8710 you could take a picture of for me to see the full part number of the blown part. I attached a photo of the main board showing the blown part. You can see a 594 (but I doubt its a shift register), and 3JD. I expect there are some more characters that are missing before the 3JD.

Crossing my fingers that is the only part busted, and that everything downstream is still working.

Thank you all for any help here.

[lordsmurf]

There are multiple variations of the green AVT-8710. However, this is close to your exact revision:

AVT-8710_request_NK8_6906.jpg

https://www.semicon.sanken-ele.co.jp...duct=SI-8033JD

[timtape]

Yes the 12v socket's polarity is the much less common centre negative. This is compounded by the fact that nowhere on the TBC is there any markings stating this fact. Not even the usual small international symbol next to the power input socket.

A reversed input polarity will likely instantly overheat and damage the regulator.

The part no is 8033JD. Here is a link to a Chinese site from which I bought some.

https://www.ebay.com.au/itm/303854695247

I'm a service technician.These regulators are not simple to replace as the heat sink contact area must be soldered to the PCB contact area, not bolted or held by a metal compression clip, so of necessity the solder between the reg and the PCB cannot be viewed to confirm conductivity right across the contact area. It's tricky. There is also the risk of the soldering process overheating the new regulator. This is not a job for a novice IMO.

In the AVT-8710 unit I repaired, fortunately no other parts were damaged but I guess YMMV.

Tim.

[radiokom]

Quote:

Originally Posted by timtape

Yes the 12v socket's polarity is the much less common centre negative. This is compounded by the fact that nowhere on the TBC is there any markings stating this fact. Not even the usual small international symbol next to the power input socket.

Yes, AVT-8710 has marking only on power supply. My 2 Cypress has center negative symbol near power input. I use that kind of adapter - simply match +and- on plug and you have center negative. Or get plug and solder as center negative.

20251013_213255[1].jpg

[sheeshyall]

Thank you for all the help! I will keep you updated with the repair.

[lordsmurf]

Those cheap "selectable tip" type PSU (AC adapters) almost always spew noise in the signal. (At least in North America, 110-120V. I know PSUs can react a but different to Europe 220-240V.) Same for those "adjustable output" models with the dial, like Belkin.

Better is to acquire a name branded PSU, like Honor or APD, then use a polarity reversal cable. Those cables are common in the music industry, for guitars, amps, etc. But that's not 100% flawless either, just 90%+ of the time. I have seen 2 units to date that only worked properly with a 12V or 15V negative adapter (and preferably the Cypress/OEM "OEM brand").

I've never seen a DIY soldered cable that didn't suck. I've gotten some in the past, and I immediately threw those in the trash. I refuse to give out subpar gear, even mere PSUs.

Did this come from eBay? There was a specific known-non-working green unit that had been passed around several times, what some of us were (in private) calling "the hooker TBC". It last sold for about $900, and the shady seller referred to it as "untested" and sold for parts/repair. (to avoid refunds). That seller cross his T's, dotted his I's, and somebody was going to get screwed. Serial last 4 = 0113. Newbies should not be buying TBCs from eBay! We've been waiting to see if/when that person would show up around here.

[radiokom]

Quote:

Originally Posted by lordsmurf

Those cheap "selectable tip" type PSU (AC adapters) almost always spew noise in the signal. (At least in North America, 110-120V. I know PSUs can react a but different to Europe 220-240V.) Same for those "adjustable output" models with the dial, like Belkin.

Of course they should be tested and bought from trusted source. My are OK. But you can get, for example, WD HD power supply, cut wires and reverse, and you are done. Those power supply are OK if they are up to specs, and TBC input has filter stage anyway.

[timtape]

I suspect the easiest and most common way to fry the TBC's internal regulator is using a reversed polarity PSU. We dont get a second chance.

The polarity reversing lead is fine so long as the owner is aware that it must never be removed from that PSU when used on the unit. If I was a seller I would make damn sure the buyer was aware of this in writing, to cover both the buyer and myself.

I would also make sure the polarity reversing lead could not be unplugged from the PSU lead. I'd glue it to the PSU lead with strong glue, and/or fit a length of plastic heatshrink tubing over the plug and socket.

Either that or I'd cut off the plug and socket, solder the leads together, and apply heatshrink tubing over the joint. Anything short of that I would regard as negligent.