Ebay cheap TDA7498 boards

[zek]

Put switch between + on DC input jack on the back panel and + on the amp board, it may help.

 

[jopereira]

Are you sure your power supply doesn't go into protect mode?

 

[Mark2727]

Zek,

OK, will definitely try that. Putting a switch on the positive line.

Don't know why, but I've always switched the negative line. And have never had a problem until this amp.

It's really puzzling me. It's working since I pulled it, tested it, and re-installed (with the capacitor) yesterday. But, like I indicated in the last post sometimes this will work OK for weeks and then the thing doesn't want to switch off.

It's this intermittent stuff that drives you nuts. And I'm not an electrical engineer or anything so much of this is over my head. I'm just a "intermediate rookie"....Ha!

Thanks Zek,
Mark

 

[Mark2727]

??? Not sure

Are you sure your power supply doesn't go into protect mode?

How would I know if this was the case?

To clarify, I'm not switching the power supply. That remains on, but I'm just switching the amp on/off.

All I know is the amp won't turn off. The power supply is a 30VDC one with as I recall plenty of amps. I got it with a Winsome Mouse amp and it's never given me any problems.

I could try the 7498 with one of my 24VDC Meanwell clone power supplies I suppose.

Mark

 

[jopereira]

That with be easy, just see if the power supply still produces 30v.
Low ESR capacitors can require a huge, instant, demand of current that some SMPS don't take easily (their protection system could be more sensitive, not necessarily a bad thing per si).

 

[den_hr]

Zek,

OK, will definitely try that. Putting a switch on the positive line.

One of those amp boards I had behaved just like this - I had to put both positive and negative lines trough the switch in order for it to work (you'll need a "double pole" switch, not a "single pole" as usual, so that you switch *both* positive and negative leads).

I think this may be the problem, not the power supply...

 

[jopereira]

Then, a ground loop must be the problem... I don't see how switching positive or negative causes a problem like this.
(It's easy to have a leak somewhere in the system)

 

[Mark2727]

DPST?

One of those amp boards I had behaved just like this - I had to put both positive and negative lines trough the switch in order for it to work (you'll need a "double pole" switch, not a "single pole" as usual, so that you switch *both* positive and negative leads).

I think this may be the problem, not the power supply...

So, I should obtain a DPST switch?

Not quite sure how to wire that. I might need help, will research,it if that's what I need.

Thanks everyone for the replies so far,
Mark

 

[Mark2727]

More information:

Everyone,

I can tell you fellows this. On the amp board: underneath where the stock DC input jack is attached --- well, I did a simple continuity test to determine where to solder my negative and positive wires. As I recall there were two points which made negative continuity. I now have my wire attached to one of them. I think originally I had jumped a wire across both the negative board points. It seems to me as if the DC jack is grounded at its mounting point and at the internal point where the male connector would make contact as well. Is that correct?

Also, on MY DC input jack (located on the back panel with the rest of the connections) it's pretty much the same thing. That one has two points (lugs) for negative also. And one for the positive.

Not sure why this is done, but here again, I soldered my wire to one point.

I'm not sure if this information is helpful, but I thought I'd offer it up. I'm sure you already know this.

Mark

 

[easp]

Some barrel jacks are switched. When a plug is inserted, they open the switch between the two ground points (while connecting one to the plug ground). What, if anything, the PCB or device designer does with that fact probably varies with the design.

I'm not sure I follow what you are doing, but it sounds like you might not be taking the nature of these jacks into consideration.

 

[Mark2727]

easp,

So, I should re-check both my jack and the jack on the amp board with a male connector inserted in order to establish the points I need to solder to?

To explain, I'm not using the board's DC input jack. I'm soldering wires to a DC input jack I placed on the back of my test board. That also has RCA's, and a switch, and binding posts.

I should do a sketch or photo I suppose.

Mark

 

[afterlife2]

I wanna use this as a PC setup for music what do you guys think? Also where can I get a cheap case for it?
TDA7498 Dual Channel Class D 2X100W Audio Stereo Amplifier Board Component Power | eBay

 

[easp]

easp,

So, I should re-check both my jack and the jack on the amp board with a male connector inserted in order to establish the points I need to solder to?

To explain, I'm not using the board's DC input jack. I'm soldering wires to a DC input jack I placed on the back of my test board. That also has RCA's, and a switch, and binding posts.

I should do a sketch or photo I suppose.

Mark

A photo or sketch would probably help.

My thinking is that the board might have its own way of using the fact that the switch between the two negative pins is closed when there is nothing plugged into the jack (like maybe it drains caps through a resistor), and that might explain why you are having a problem if you've just soldered to one (or both) of those points and left the jack in place. F

 

[Buehgemeiste]

The number of cheap class d amps has become uncountable.
I wonder if there really is a market for all that stuff.

One new implementation of the 7498 popped up and caught my attention.
It seems to have same layout as my favorite sounding 7498-board, but has through hole power caps on it.
Super nice low ESR caps and better stuff on the signal input and output are possible modifications on this unit:

Freies verschiffen XH M510 TDA7498 Class d High power digitalverstrker board 2*100 watt Auto verstrker DC 14 34 v in Beschreibungen: 100% nagelneu und hohe Qualitt TDA7498 ist eine 100 Watt + 100 W aus Verstrker auf AliExpress.com | Alibaba Group

I'm not sure if it is worth the effort, because its blue sanwu-equivalent sounds great in stock form.
But it could be fun for somebody in search for nice little project....

 

[afterlife2]

The number of cheap class d amps has become uncountable.
I wonder if there really is a market for all that stuff.

One new implementation of the 7498 popped up and caught my attention.
It seems to have same layout as my favorite sounding 7498-board, but has through hole power caps on it.
Super nice low ESR caps and better stuff on the signal input and output are possible modifications on this unit:

Freies verschiffen XH M510 TDA7498 Class d High power digitalverstrker board 2*100 watt Auto verstrker DC 14 34 v in Beschreibungen: 100% nagelneu und hohe Qualitt TDA7498 ist eine 100 Watt + 100 W aus Verstrker auf AliExpress.com | Alibaba Group

I'm not sure if it is worth the effort, because its blue sanwu-equivalent sounds great in stock form.
But it could be fun for somebody in search for nice little project....

Yeah I was asking about that amp no reply yet. Which ones in that price range would you recommend?

 

[doctormord]

Please don't do full quotes, thank you.

 

[chienmort]

Why not doctormod? If the reply is to something way back in the thread is is annoying going way back. Without the full quote we may lose some of the meaning or context of quoted text and the subsequent response.

 

[Buehgemeiste]

Yeah I was asking about that amp no reply yet. Which ones in that price range would you recommend?

It depends on your application.

 

[easp]

The number of cheap class d amps has become uncountable.
I wonder if there really is a market for all that stuff.

I'd guess there are maybe a dozen original sources of these cheap Class D boards, some of which then get knocked off -- probably by someone(s) with a tight relationship with their (former?) PCB supplier.

As for whether there really is a market for all of it. There is right now, more or less, and it's anyone in the world who wants to work with audio modules for fun or profit. I think most of these board makers are very lean and opportunistic. They enter the market because they see an opportunity. They stay as long as they can turn a marginal profit on the boards they've designed (or copied).

From what I can tell, many have other lines of business (Sanwu, for example, seems to do stuff for LED lighting and overpowered laser pointers), so no one is making amp boards because they can't think of anything better to do. At some point, if another line of business demands too much of their time and has the profits, and the amp boards are still profitable. they'll probably find someone else to worry about the amp boards -- at least until they run out of in-laws and nieces/nephews or other people they can trust. At some point, rising costs and ambitions will probably drive consolidation, but that isn't happening tomorrow.

One new implementation of the 7498 popped up and caught my attention.
It seems to have same layout as my favorite sounding 7498-board, but has through hole power caps on it.
Super nice low ESR caps and better stuff on the signal input and output are possible modifications on this unit:

Freies verschiffen XH M510 TDA7498 Class d High power digitalverstrker board 2*100 watt Auto verstrker DC 14 34 v in Beschreibungen: 100% nagelneu und hohe Qualitt TDA7498 ist eine 100 Watt + 100 W aus Verstrker auf AliExpress.com | Alibaba Group

I think this is the maker's TaoBao listing for that board. It looks like they are also responsible for some of the cheap red-PCB single and dual chip TPA3116 boards.

 

[Buehgemeiste]

I recognized that manufacturer (XH) before.
Their stuff is noticeably similar to sanwu stuff.
There is another one with similar designed products (umsong):
TAS5630 2X300 watt stereo/dual channel/Leistungsklasse D/digitale verstrkerplatine in    bord eingelassene art wie folgt:klasse TAS5630 D verstrker in der lage fahren 4 ohm in unter DC48V, k aus Verstrker auf AliExpress.com | Alibab
I have an eye on their TAS5630 module.
It excludes a lot of the wannabe-fancy stuff others have on their 5630-boards.
Only the heatsink is giving me a bit of a headache.