Hi
I rebuilt my gainclones a few months ago. Now I had to order some new LM1875s because I only had 1 left. So the new ones look slightly different from the older ones but I didn't think much of it.
So I rebuilt them and the right channel gainclone was giving a horrible DISASTER noise! The right channel uses the new LM1875 that looks slightly different from the older one. Eventually I added a Zobel and it started to work again. So I thought the right channel is closer to the power leads so maybe that was why it needed a Zobel network.
I know that manufacturers can make changes to the production line or maybe even subcontract out to someone else, but should the actual chips look identical?
Yesterday, the right channel gainclone has suddenly stopped working! I was not listening at high volumes. It wasn't even hot. I have isolated the problem to the right channel gainclone. The resistors are OK. Power supply voltage is OK.
I am seriously starting to think that the right channel LM1875 was a fake!? It has two slight circles indented on the front, lower left and top right corner. These two circle indents have B1 and 2 embossed inside them. On the other side, the metal part is a very slight wedge, the two sides are not parallel. Also, on the front, the plastic composite is slightly chamfered. The left channel LM1875 does not have any of these features.
On balance, do you think the right channel LM1875 was a fake???
I rebuilt my gainclones a few months ago. Now I had to order some new LM1875s because I only had 1 left. So the new ones look slightly different from the older ones but I didn't think much of it.
So I rebuilt them and the right channel gainclone was giving a horrible DISASTER noise! The right channel uses the new LM1875 that looks slightly different from the older one. Eventually I added a Zobel and it started to work again. So I thought the right channel is closer to the power leads so maybe that was why it needed a Zobel network.
I know that manufacturers can make changes to the production line or maybe even subcontract out to someone else, but should the actual chips look identical?
Yesterday, the right channel gainclone has suddenly stopped working! I was not listening at high volumes. It wasn't even hot. I have isolated the problem to the right channel gainclone. The resistors are OK. Power supply voltage is OK.
I am seriously starting to think that the right channel LM1875 was a fake!? It has two slight circles indented on the front, lower left and top right corner. These two circle indents have B1 and 2 embossed inside them. On the other side, the metal part is a very slight wedge, the two sides are not parallel. Also, on the front, the plastic composite is slightly chamfered. The left channel LM1875 does not have any of these features.
On balance, do you think the right channel LM1875 was a fake???
