MA Audio HC4002, RSB1 and CSB1 values

[m4ick]

These two components appear to have been clipped out leaving leads sticking out under the board.

The power supply has snubbers on the primary side but these two components appear to be secondary snubbers, tying one leg of each transformers secondary windings to ground. They are RSB1 and CSB2.

The top of the power supply waveform is blurred and I imagine this is the reason.

I will post pics when I find my bluetooth dongle but I'm hoping one of you has pics or the real thing on hand.

Thanks!

[m4ick]

It's right between the rail caps and one of the transformers.

[m4ick]

Anyone with an educated guess what values those might be? They are CSB1 and RSB1, I mistyped them the first time.

[Perry Babin]

I don't have anything on this amp. If they're connected between the secondary windings and the secondary ground, there should be 4 of them. Are all 4 missing?

[m4ick]

The secondary windings and center taps of both of the transformers are soldered together before they go to the rectifiers so they essentially act as one transformer.

One of the two sets of secondary windings is tied to CHASSIS ground via these two components, the other set of secondary windings goes to the rectifiers without anything like this. There is only one set of these two, and they were definitely in there, you can see where they scratched the board cutting them out.

[Perry Babin]

I had to stop using the term chassis ground because it was confusing. Do you mean the ground for the amp chassis or the vehicle chassis?

If you look at the end of these components that are connected to the transformer, is there a rail-rail swing (pre-rectifier) or is it the secondary center-tap?

Are these in series or in parallel?

[m4ick]

Vehicle chassis (negative battery).

Rail to rail swings, definitely not center tap.

Series.

[Perry Babin]

There doesn't seem to be any indication that they burned. Could it be that they made a mistake and removed these parts at the factory? It's not common to have the secondary windings connected in that way to the amp's primary ground.

[m4ick]

Not sure, it looks like someone had desoldered and resoldered some of the primary snubber components as well and they don't appear burned either. My friend bought this amp for $10. It had 1 shorted output, it powers up fine now but it looks like an amateur did a shoddy job clipping out components blindly.

The top of the power supply waveform on the primary side is somewhat blurry but not outrageously so. Would leaving these out make this amp terribly unstable if they were in there originally?

[Perry Babin]

If one end goes to the primary ground and the other end goes to a secondary output winding, I don't think they should be installed. I'm assuming that the secondary center tap (non-bridging speaker terminals) is not connected to the primary ground.