Panasonic SU-HTB18 dead power supply (unidentified transistor)

[Dannyx]

Good day folks. I had a look at this soundbar from Panasonic today and it seemed like an easy enough fix, but then I got stuck.

Have a look at that fried primary. I reckon the transistor popped and took out the current sense resistors with it before the fuse could open to cut the power. I thought I'd have a hard time figuring out what values those are, as it usually happens when SMD resistors go up in smoke, but thankfully I was able to clean them enough to read 1r60 on there, which is 1.6ohms, so that was sorted - we need 8 of those.

On to the transistor: it's one of those mystery parts that no one's heard of. 14SL70....what could this be ? Ironically, it has a little logo there too, but all searches come out empty. I tried everything, including sourcing a service manual, but that didn't yield any results either....I'm tempted to just dig through my parts bin and pick one out semi-randomly. I'm hoping the control IC survived, because the small passives around it are fine, so I'm hoping something from the FQPF series will work in place of the original one. It claims to be a 120w amp, in case someone wants to suggest something based on past experience, enough to be in the ballpark. As always, thanks for any help. Cheers.

[zen]

Hi

Regards the F E T , you can probably match up another . By the numbering seems to be rated at 14 amp , 700 volt . I don't recognise the manufacturer logo either .

I would replace the drive chip also . Doubt it would have survived .


Regards Zen

[Dannyx]

The driver IC is also tough to find info on. I don't have the board in front of me right now, since it's at the office, but we can just about make out the part number in this pic....

I'd say it's MIP034c and below 714c4? (C or 0) - we won't know for sure until I look at it up close, but it doesn't matter because I tried every combination and nothing came up - HATE it when manufacturers do this and somehow manage to source the most obscure parts on the planet

[zens electronics]

Makes thrings very difficult for us , i know .

No schematics ?

[Dannyx]

No, no schematics.....of course

I tried searching for SU-HTB and indeed found a service manual, but the schematic isn't even close - that one has a separate STBY power supply, even some relays and sh!t. It's for a HTB500.

Turns out there IS such a thing as "MIP" series IC, since on page 92 you've got IC5799 which is a mip2f20 which DOES at least return some results on google, as do other searches for "panasonic MIP IC". Meanwhile mine gets nothing...

I'll try the transistor+resistors first and if it goes bang again, that's it - tough luck - it's going in the bin....

[sam_sam_sam]

Dannyx

Try this website to see if you can match the device manufacturer

https://how-to.fandom.com/wiki/How_t...heir_logos/P-T

I do not recognize this manufacturers logo

There are no hits on this part number which is very strange most of time you would get something even if it is the wrong device ( but nothing at all weird ) unless it is a house part number

Can you determine what the output voltage is by any chance————>

I do not know if this will help you or not

[Dannyx]

Originally Posted by sam_sam_sam

Can you determine what the output voltage is by any chance————>

The closest I can get to doing this is by assuming the part number on the transistor stands for 700v, 14A as zen suggested. Like I said - I'll dig through my parts bin and go with the highest spec'd I can find and just YOLO it...

The output of the supply itself to the amp section could be anywhere between 30v and 60v based on my limited past experience with amps.

The amp claims it's 120w...not sure if this is reflected by the transistor's ratings in any way, since it's a SMPS...

[Dannyx]

I ran a search on Aliexpress and it does actually throw some transistors in there, like 2n60f, so I'm actually curious if they're regarded as equivalents....

There IS such a thing as SL701, but that's a different part entirely....

[Dannyx]

Ok, I made some more progress on this thing: I actually managed to find the IC: it's a MIP004, when I thought all along the second 0 is a 6, so there IS an official Panasonic datasheet for it here. It's probably dead (Jim ), since the two 47ohm SMD resistors next to it are open-circuit, so I'm not risking firing it up like this.

For the FET, I dug through my drawer of transistors and after comparing and contrasting several types, I think I'll go with the P14NK50ZFP.

[Dannyx]

Ok, I took a shot at powering it up today. I couldn't source a MIP004 anywhere, much less so in SMD form, so I just replaced those resistors and tried it with a lightbulb in series. Ironically, nothing explosive happened: the bulb went dim, but it also produced no output. Measuring the VCC pin of the IC, I can see it jumping between 0 and 19v repeatedly, so this makes me think it's dead and doesn't drive the output....I'm now hoping to be able to replace it with a "FAN" IC by comparing datasheets as much as I can....