Cambridge Audio A3i repairs and mods

[cucu70]

I bought it damaged and somewhat destroyed. I started to check the BC639/640 and I also checked the zvp3306 and they indicated as in the photo.

 

[cucu70]

If I check irf, 2sk, 2sj type mosfet, it recognizes them.

 

[as_audio]

May be hard to repair if others had their fingers inside.

Useful instructions are by x-pro, the original designer,
mainly at the beginning of this thread and later in post
90 and 93.

"In the case of failure of mosfet Q9 which is unavailable
here I substituted a p-channel j-fet successfully. "

 

[cucu70]

And what type do you recommend?

 

[cucu70]

Do you think BS250?

 

[x-pro]

Which of these do you think is better? BS250
TP0610 VP0610L VP0106N3-G

First three are the same device and either should work just fine in the A3i. Just be careful with the pinout.

Cheers

Alex

 

[cucu70]

I'm going to ride BS250 because I can get it. It's good, no?

 

[as_audio]

If you have it or get it - go for it and use it.
I do not remember which type I used.
Have a look at other weak parts also.
Show us a close up picture.

 

[cucu70]

I have IRFD9110, so as not to wait until the BS250s come. How about?

 

[cucu70]

 

[x-pro]

I have IRFD9110, so as not to wait until the BS250s come. How about?

It is a much larger device, not suitable for this circuit.

Cheers

Alex

 

[cucu70]

Thank you. Then I will wait. All the best.

 

[RS232]

Don't forget to use a inline light bulb limiter it will save you some headaches and some money in new parts this amplifier is not very forgiving to errors.

 

[cucu70]

Hello Sirs. Can't make any modification to use an N channel for T107? 2N700 or BS170 for example.

 

[cucu70]

Thanks RS232, I always use it.

 

[RS232]

Check the "alternative" list that X-pro posted for the improved version of the A3i (check thread from start don't remember post number) but I would recommend to keep it as close to original as possible.
"ZVP3306A is available from Farnell. Possible alternatives are ZVP3310A, ZVP2110, ZVP4105, BSP254."
Check page 5 on this thread post 93 but again recommend read it from the start.

 

[cucu70]

Okay, but in my spare parts store each one costs about 9.50 euros and it takes 15 days to bring it. Seriously, I'm not going to pay almost 20 euros for 2 overpriced transistors..

 

[cucu70]

I better throw the final part and mount there a hybrid amplifier that has been waiting for a case for a long time. Simpler and surely it will sound better.

 

[x-pro]

I'm not sure if I've posted this additional mod previously but here it is. A small change for the output relay return current path will reduce the hum on the output. Two red lines show where to cut a track and the long red line shows a wire to solder.

Cheers

Alex

 

[RS232]

Okay, but in my spare parts store each one costs about 9.50 euros and it takes 15 days to bring it. Seriously, I'm not going to pay almost 20 euros for 2 overpriced transistors..

I'm driving to Portugal in August (I'm Portuguese) and could drop off a few of then for you (depending on location) or I can post 4 (have to buy them here in the UK) for around 5 euro + postage, just let me know