anglil22

Hello,
My HK amp has a fried capacitor and I can't seem to find a match to replace. I have attached photos, hoping someone could give me some guidance. Thank you in advance.

CaliBenzDriver

A: Power Amps B: caps

Take a good picture of the parts marking you are interested in replacing... or let's just say both A + B.This will help identify what parts were used.

anglil22

Thanks for the reply. Based on your markings its A. I have attached another pic showing the fried circuit area with an arrow.

CaliBenzDriver

I see... one of the power amp chip took out part of its circuit traces

overheated traces (not yet 100% cooked)

Do you want fix that? 70% this can be done successfully because these amps are all similar... you can compare reference measurements with nearby circuit .
See the 2 little "ceramic caps" are like a signature next to this chip: likely Spk. outputs (not a power feed) because there are repeated pattern.

Beside one or more TDA chips + caps.

For everyone... this is why you don't want to push this OEM amplifier enclosed in the trunk left side with restricted air circulation.

anglil22

Thanks, I would be interested in fixing this.

CaliBenzDriver

clean up the chip markings


> Time vs. Money:
Are you a quick learner?
Can solder micro-electronic right?

> Plan B:
Whats your budget to buy a donor amp

anglil22

Yes, I am pretty good with a soldiering iron and can pick up things pretty quickly

anglil22

I have replaced this amp, don't want to spend too much since it would essentially be a spare. I figured I would give it a shot to repair myself if possible.

CaliBenzDriver

Read the markings off of your very own chip.

my HKL7 chip as sample (MY'14... Mfd'13)
It uses a different layout, so likely a different reference.

CaliBenzDriver

What did you replace it with: Identical or aftermarket?

What was wrong with bad channel: SPK shorted near zero from overheated coil insulation? This forced the amp to drive power into a shorted load maximum current + heat

anglil22

Easier said than done...LOL mine are not as clearly marked as yours.... I have attached a photo. Even with my readers on it is tough to make out the numbers. Yes, speaker shorted out. I replace it with identical since I upgraded my sound system and had to use the stock amp to integrate with an aftermarket.

CaliBenzDriver

this is the designation marking

Do you read... "77B88ES" ?
You need to be sure!

anglil22

Yes, that is what I read...

CaliBenzDriver

that's the part you have to buy.

I dont find matches, double check markings with a magnifying lens

anglil22

Thanks, yes I tried a quick search and came up empty. I'll zero in on the markings and take it from there. I appreciate all your help! I'll chime in if I find it.

RWagz

I found a working one on ebay for $240. It might be difficult to find the integrated circuit being sold anywhere. You will likely need to get one from a dead donor.

Maybe you'll get lucky and find someone selling a dead one on ebay.

anglil22

I saw that one. I'll keep poking around, as mentioned no rush. I was able to decipher the chip, picture attached. Unfortunately, haven't found one so far. Thanks again for your help!

CaliBenzDriver

that reference number looks like a short straw until a genius stops by with directions to the land of plenty...

Senecat

ebay.

Left Coast Geek

that ST logo on the lower left of the last smallish picture is ST Microelectronics, https://www.st.com/content/st_com/en.html

that said, none of those numbers, with all sorts of variants, match any search, so its quite possible these are proprietary parts for Harman-Becker.

btw, surface mount soldering of chips like these is a lot trickier than regular soldering.

BenzV12

I didn't know those things could be burnt out

CaliBenzDriver

specs say chips are foolproof

These chips being hard to toast, the circuit board Vias got overheated in the process

Baltistyle

Smd repair is a nice skill to pick up. I recently picked up a nice hot air rework station and tools for my pinball machines. This can not be fixed with just a soldering iron. You need hot air, iron with a needle tip and magnifying lamp and a flux pen.

Chips are in short supply for everything, not just new items. Some for my pinballs are not scheduled to be made for 12 months.

Make sure to try mouser or digikey. Digikey will have a reference if it’s available anywhere.

the cost of the smd rework station and you time and the chip make this not an economic winner. I only repair expensive or out of production items and it made the station worthwhile.

good luck. That little cap is easy to find and the numbers are on them. but the chip will require a deep dive….alibaba if no others found. If they have it, that’s all there is.

Quint22

Pointy iron and mag glass is what I used to repair smaller ones on a couple tablets. No hot air or flux pen. Granted I am not an electrician and if doing a bunch better ways but it is doable. I found some good instruction videos on doing it.

This is the soldering iron I picked up for doing the jobs It has performed pretty good for the random repairs I need it for.

Edit to add obviously good lighting, flux wick, tweezers, flux, basic soldering stuff required.

anglil22

I have checked Moser and DigiKey and came up empty. Hopefully when chips become more readily available I will have some luck. Fortunately, not in a rush here.

Thanks to everyone for their help!