• These commercial threads are for private transactions. diyAudio.com provides these forums for the convenience of our members, but makes no warranty nor assumes any responsibility. We do not vet any members, use of this facility is at your own risk. Customers can post any issues in those threads as long as it is done in a civil manner. All diyAudio rules about conduct apply and will be enforced.

GB for TPA3116/8 PBTL bare pcb

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Jump to Latest
DUG

DUG

Member
Joined 2003
A snubber is (usually) a series R and C that present a resistive load at higher frequency (or rise time) signals.

A snubber circuit can aid in reducing high frequency ringing that results from circuit L and C components.

Anything with length has an inductance.

Anything with area has capacitance. (relative to another thing with area)

There will be a certain amount of L (trace length, etc) and C that will have some sort of resonance frequency.

If there is not enough circuit loading (R portion) on this LC combination there can be unwanted ringing in either (or both ) the current in the inductance or the voltage on the capacitance. (This can also cause RF interference)

A snubber is place to damp (or transform) this energy into heat or to provide a non-reactive load at higher frequencies.

On a lot of TPA311X boards snubbers are used on the output of the chip itself as well as in the output filter.

Some say that the snubber on the output of the IC affects the sound.

It was in the demo board notes but not in the original (SLOS708 –FEBRUARY 2012) or revised (SLOS708B –APRIL 2012–REVISED MAY 2012) data sheet.

See also https://en.wikipedia.org/wiki/Zobel_network for more on this sort of thing.
 
A

ambiance

Member
Joined 2013
DUG said:
Measure the snubber R and R of RC in output filter to check for value shift.

Then try to check for capacitor shorts on the output side of the board.

Are you using two separate supplies?
Click to expand...

Dug,

My multi-meter (Fluke 75-3) does not have a feature for measuring capacitance (in circuit or off circuit) but can measure ohms and continuity.

R1 and R2 (of both boards) has 3.2 ohms, but NO continuity. On circuit R1-C16-C18, I think R1 is bad. The same for circuit R2-C17-C21, R2 is bad.

Visually, all capacitors seems OK, but cannot measure. I had my brother-in-law to visually inspect.

Since it will cost me more money to buy a meter that can measure capacitance (which I may have not need in the future), it may be more prudent for me to buy the parts to replace R1 and R2 and keep the capacitors. Or replace all the capacitors also?

Any further advice?
Thanks!

BTW, I use only one power supply (with two leads) when it was still working.
 
A

ambiance

Member
Joined 2013
I miss the SQ on this board, so I will attempt to repair it by process of elimination since I do not know which component is defective. I'll replace the first output circuit, starting from J3, and if it does not solve the problem, I'll replace the chip itself. I will test the SQ after replacing the components of each individual circuit before proceeding with the next. Is this seem like a logical approach?

Since I have a Nichicon cap (2200 uF 50V) laying around, is it OK to replace the original cap (1500uF 35V) with this one?

Thanks for any help!
 
I

irribeo

Member
Joined 2013
The ampboard doesn't need the electrolytics, it functions without. The ampboard does not need any outputfilter part, it functions without. So replacing can be just removing some parts and trying without. Electrolytics are not likely to fail in popping way, during overvoltage is only time I heard popping electrolytics, and those where solid electrolytics, not wet ones.
 
A

ambiance

Member
Joined 2013
irribeo said:
The ampboard doesn't need the electrolytics, it functions without. The ampboard does not need any outputfilter part, it functions without. So replacing can be just removing some parts and trying without. Electrolytics are not likely to fail in popping way, during overvoltage is only time I heard popping electrolytics, and those where solid electrolytics, not wet ones.
Click to expand...

Thanks for the response Irribeo.

If the board is functioning and just suddenly makes clicking sound without a warning, is it more likely the problem is the chip? Such is the case on my boards. No sound is coming out, just clicking noise.
 
I

irribeo

Member
Joined 2013
Trying to start up, sharp pop, protection, restart attempt, sharp pop, protection, restart attempt, that sequence would give no music.
Could be a lot of capacitors. One of them might be underrated by mistake, if BOM contained same value different voltages for example, that could be for the AVCC ceramic.

The AVCC/PVCC RCsplit is by itself not a good implementation of tpa3116, as TI keeps answering. But I would remove parts and look for external failure.
 
I

irribeo

Member
Joined 2013
Two ampboards failed as described, not at same moment, but shortly after each other. That must have external to ampboard cause. So use different powersupply and connect nothing to inputside, when testing. The external fault must be serious to kill these chips.
DO connect speaker
 
A

ambiance

Member
Joined 2013
irribeo said:
Two ampboards failed as described, not at same moment, but shortly after each other. That must have external to ampboard cause. So use different powersupply and connect nothing to inputside, when testing. The external fault must be serious to kill these chips.
DO connect speaker
Click to expand...

Thanks for the response, I am learning.

One thing I forgot: I have been using Little Dot MK3 (headphone amp with preamp) as a preamp. As a precaution, I always turn on the preamp first and wait for 2 minutes before turning on the board. From what I read, this procedure stabilized the preamp prior to use. I did not have any problem using this procedure, until one day.

Question: How do I test the board without connecting the input? I do hope that it is not the chip. Desoldering and soldering the chip will be a challenged for me. Thanks again!
 
A

ambiance

Member
Joined 2013
irribeo said:
If the ampboard pops it may pop without anything on inputside, just speaker and "a" psu.
Little Dot has burnt amplifier chips before, but that doen't mean it happened to you.
Click to expand...

It is very possible that the Little Dot is the caused of the problem. If so, do you think replacing the chip is more prudent? If it got fried, are the caps usually the first one to be fried or both? Does it usually affect other parts as well? I am wondering if it is better to replace only certain caps or start from scratch.
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Top Bottom