Please help, I've wrecked my Beresford

[NRG]

It means getting the polarity of the caps the correct way 'round.

The marking on the PCB for the positive cap connection of EC4/5 is incorrect so the cap needs to be fitted opposite to that of the PCB marking.

[StanleyB]

...Because the caps came stuffed the wrong way 'round from the factory?

The mod involves changing the circuit configuration, and that also changes a number of DC voltage levels around the output stage. So those caps need to be reversed in order for them to remain properly biased.

Stan

[kalozois100]

It means getting the polarity of the caps the correct way 'round.

The marking on the PCB for the positive cap connection of EC4/5 is incorrect so the cap needs to be fitted opposite to that of the PCB marking.

Thats just great!! Stan said if we knew why they need to be opposite then he'd have to kill us! Well he can kill us without us knowing cause i now have the hassle of taking it back to the elec. engineer to reverse them and he already wants to kill me! Stan your little secret has caused me alot of grief!!
But in an effort to better myself I can see the funny side of it ......

So to get it right Finally for us electronic dumbos....

I now have to connect the the positive on both caps to the negative on the EC4/5 . is this correct now? And are the top caps okay are there any more surprises?

[NRG]

The mod involves changing the circuit configuration, and that also changes a number of DC voltage levels around the output stage. So those caps need to be reversed in order for them to remain properly biased.

Stan

All I've done is replace the opamp, output caps and EC4 and 5. R11 and 14 are still in place, theres nothing there I can see Stan that would change the DC offset...

[Stratmangler]

Incorrectly marked PCB's are nothing new - I am a telecoms engineer by trade, and one piece of equipment from Panasonic springs to mind.

On the training course for this piece of eqiupment it was pointed out that the jumpers on one of the cards was incorrect. Unfortunately the markings related to molex jumpers which had to be set correctly dependending on how the card was required to function. You had to set the card up to the opposite of the board markings.

The incorrect markings remained on the card for the entire time that the unit was in production.

Chris

[StanleyB]

Incorrectly marked PCB's are nothing new

In this case, the PCB is not incorrectly marked. The MOD21 requires the caps to be swung round. If you look at the PCM1716 datasheet you'll see that the cap and the PCB markings are as per datasheet.

[StanleyB]

All I've done is replace the opamp, output caps and EC4 and 5. R11 and 14 are still in place, theres nothing there I can see Stan that would change the DC offset...

[StanleyB]

I now have to connect the the positive on both caps to the negative on the EC4/5 . is this correct now? And are the top caps okay are there any more surprises?

You got to take them out and rotate them by 180 degrees so that they appear to be incorrectly mounted. But if it sounds good already, why worry?

[kalozois100]

You got to take them out and rotate them by 180 degrees so that they appear to be incorrectly mounted. But if it sounds good already, why worry?

Worry leads to an unpleasent state( and one cannot stay there indefinately), which leads to contemplation, which leads to action, which leads to an improvement( hopefully in practice) to the previous predicament.

Okay Stan the Main Man, i took the tc-7510 to the elec. engineer ( you ve heard so much about him i ll introduce him - he is Mario and he works in the army in communications. In the evenings his second job is fixing mobile phones. I was amazed watching him at work fixing mobile phone using a microscope to see and soldering at the same time!! Any way hes been a saint with all the mods hes done for me.) he said no problem to switch around the caps so off i went LIke a rat in a pied piper pantomine off to seek audio absolution.
After the electrical operation i got home and as Stan says i was blown away with the sound improvement. Most noticeable was the trebles being unbelievably genuine - the cymbals and snares being really clear and defined.
Also yet again a noticable improvement in stage presence and imaging.
The completed mod21 1 & 2 on the tc-7510 sounds very impressive now.........A warm thank you to Stan and all for the valuble help......

[Stratmangler]

In this case, the PCB is not incorrectly marked. The MOD21 requires the caps to be swung round. If you look at the PCM1716 datasheet you'll see that the cap and the PCB markings are as per datasheet.

I hadn't gone through the rest of the thread properly - I see what you mean Stan.

Chris