A PCB pic of the A3I
Hi All,
Happy New Year to all of you and your families!!
A very interesting and useful thread!!!
I got an A3I about a month ago, with a funny fault, of course, Q8 was dead, also Q7, Q1 and 2, their 100 Ohm resistors were gone
All replaced. LEDs too. All this on the RIGHT channel.
Left channel OK.
Now, what happens is that R11 gets hot in 2-3 secs after POWER on, 28,5 Volts
on it, and normally it is 4,99 - 5,01 V
All semiconductors checked, replaced. LED 1 and LED 2 checked.
Replaced.
On the same channel, RIGHT, LED 2 illuminates normally, LED 1 is somewhat dimmed, not bright enough.
Does somebody have a good clean copy or pic of the PCB, solder side, as I am beginning to suspect a wrong, broken, or shorted PCB trace on the RIGHT channel?
If you have a pic or a copy of the PCB (solder side), you can send it directly to radko71@abv.bg
Thanks a lot in advance!!!
Best regards,
Radko
Hi All,
Happy New Year to all of you and your families!!
A very interesting and useful thread!!!
I got an A3I about a month ago, with a funny fault, of course, Q8 was dead, also Q7, Q1 and 2, their 100 Ohm resistors were gone
All replaced. LEDs too. All this on the RIGHT channel.
Left channel OK.
Now, what happens is that R11 gets hot in 2-3 secs after POWER on, 28,5 Volts
on it, and normally it is 4,99 - 5,01 V
All semiconductors checked, replaced. LED 1 and LED 2 checked.
Replaced.
On the same channel, RIGHT, LED 2 illuminates normally, LED 1 is somewhat dimmed, not bright enough.
Does somebody have a good clean copy or pic of the PCB, solder side, as I am beginning to suspect a wrong, broken, or shorted PCB trace on the RIGHT channel?
If you have a pic or a copy of the PCB (solder side), you can send it directly to radko71@abv.bg
Thanks a lot in advance!!!
Best regards,
Radko
Attachments
New to the forum seeking advice. Its a great thread by the way.
Could anyone advise me on what the problem could be on my A3i amp that I've owned with no problem for about 10 years. When I connect my record deck or a CD player and then put the AMP on I get complete silence, than after about 90 seconds or so the AMP suddenly comes to life and then I can hear what's playing via the speakers as normal. Seems strange to me, and its not a problem I've had before.
Could anyone advise me on what the problem could be on my A3i amp that I've owned with no problem for about 10 years. When I connect my record deck or a CD player and then put the AMP on I get complete silence, than after about 90 seconds or so the AMP suddenly comes to life and then I can hear what's playing via the speakers as normal. Seems strange to me, and its not a problem I've had before.
A3i Schematics
Hi,
First time posting on here. I've just had my A3i amp profesionally repaired and it sounds as good as ever ( it had failed with usual LED failures ) having had the output circuit rebuilt.
This has whetted my for an electronics project, to that end I've purchased a faulty A3i amp from eBay for £4.20, on investgation the amp is functional but has a faulty CD input which is heavily disorted. I want to have a go at rebuilding this amp using the mods / upgrades suggested by X-Pro, to help with this does anyone have the schematics and any suggestions or tips for a novice.
Thanks in advance
Steve
Hi,
First time posting on here. I've just had my A3i amp profesionally repaired and it sounds as good as ever ( it had failed with usual LED failures ) having had the output circuit rebuilt.
This has whetted my for an electronics project, to that end I've purchased a faulty A3i amp from eBay for £4.20, on investgation the amp is functional but has a faulty CD input which is heavily disorted. I want to have a go at rebuilding this amp using the mods / upgrades suggested by X-Pro, to help with this does anyone have the schematics and any suggestions or tips for a novice.
Thanks in advance
Steve
If it's just the CD input, then quite likely it is bad contacts in the input source selection switch.
Thanks for the reply. I've started stripping amp down ready for its rebuild / upgrade. I'll have a look at the input select switch and try some contact cleaner to start with.
Any schematics or service manuals would be appreciated.
Thanks
Steve.
Any schematics or service manuals would be appreciated.
Thanks
Steve.
Can any UK members recommend a suitable vendor for my parts shopping list ?
MJE243 quantity 2
MJE253 quantity 2
green LED ( 5mm high temp ) quantity 4
10ohm 1 watt 1% resistor - quanitity 4
2.2k ohm 1 watt 1% resistor - quantity 2
33k ohm 1watt 2% resistor - quantity 4.
Thanks in advance
Steve
MJE243 quantity 2
MJE253 quantity 2
green LED ( 5mm high temp ) quantity 4
10ohm 1 watt 1% resistor - quanitity 4
2.2k ohm 1 watt 1% resistor - quantity 2
33k ohm 1watt 2% resistor - quantity 4.
Thanks in advance
Steve
You really could do your own searching on RS, Farnell etc.
None of those parts are in any way exotic!
None of those parts are in any way exotic!
Thanks Cliffforrest and Jaycee for the quick replies, I'll check them out.
Thanks Jaycee for the service manual link
I'll post up the results of the rebuild when complete.
Cheers
Steve
Thanks Jaycee for the service manual link
I'll post up the results of the rebuild when complete.
Cheers
Steve
Just discovered this thread after my 18-yo A3i (literally) went pop and died on both channels. No fuses blown and LEDs still glowing.
Read through thread carefully and traced as best I could and appeared to have same problem as others. Replaced components as suggested by x-pro in #93 and it's now been working fine for 3-4 hours and sounding as good as it ever did.
There's a definite heat problem though - my PCB had a 50mm diameter darkened area around the trouble spot. Under one of the LEDs the track had lifted too so not sure how many more years this amp will keep going, but for £15 of components (sourced from Farnell/element14) it's far cheaper than shelling out for a new amp right now!
Many thanks to x-pro for taking the time to post and being helpful and open with information.
Read through thread carefully and traced as best I could and appeared to have same problem as others. Replaced components as suggested by x-pro in #93 and it's now been working fine for 3-4 hours and sounding as good as it ever did.
There's a definite heat problem though - my PCB had a 50mm diameter darkened area around the trouble spot. Under one of the LEDs the track had lifted too so not sure how many more years this amp will keep going, but for £15 of components (sourced from Farnell/element14) it's far cheaper than shelling out for a new amp right now!
Many thanks to x-pro for taking the time to post and being helpful and open with information.
Hello Alex,
My name is Radu and I have also a CA A3i Amplifier. I like very much how it sounds. Unfortunately, recently has started to have the following symptoms:
- after 5-10 seconds it is switched on, a scratchy noise comes from the left channel (for about some seconds). After that it is going into protection mode and no sound can be heard into the speakers.
I have not enough knowledge to repair it by myself. Still, I saw that the Q8, Q7 and Q108 are overheating while the amplifier is on. The LEDs are on (all 4).
Can you help with an advice and also send me the full schematicsof this amp?
My email: mogos.radu@gmail.com
Thank you very much,
Radu M.
My name is Radu and I have also a CA A3i Amplifier. I like very much how it sounds. Unfortunately, recently has started to have the following symptoms:
- after 5-10 seconds it is switched on, a scratchy noise comes from the left channel (for about some seconds). After that it is going into protection mode and no sound can be heard into the speakers.
I have not enough knowledge to repair it by myself. Still, I saw that the Q8, Q7 and Q108 are overheating while the amplifier is on. The LEDs are on (all 4).
Can you help with an advice and also send me the full schematicsof this amp?
My email: mogos.radu@gmail.com
Thank you very much,
Radu M.
Last edited:
Are the A3i amplifier getting reliable or were they all recycled ?
Almost 1 year without posts...
Almost 1 year without posts...
Am I right? I see much noise and distortion on the measurement sheet at first page. Goes up to -90dB! Is it really quality? I doubt.
I have one of these on the bench and have got it partially working. It works fine on "direct" position but is much quieter on normal i.e. with tone controls engaged and of course even quieter on -20db. any ideas? thanks.
Hi everybody. I know this is a very old post, I've read it all, looking for info, hopefully from X-Pro.
Just bought a Cambridge Audio Atac 3, after reading that is a project from the same engineer.
Can anyone explain wich was the market placement of this amp? Seems to be in the middle between A1 and A3i. Am I wrong?
It is an old amp, but seems to work perfectly.... to date
Is it useful to check if the bias is correct? Other maintenance or testing?
The power transistors are 2N3055 and his complement, MJ2955.
Thanks in advance
Giuseppe, Italy
Just bought a Cambridge Audio Atac 3, after reading that is a project from the same engineer.
Can anyone explain wich was the market placement of this amp? Seems to be in the middle between A1 and A3i. Am I wrong?
It is an old amp, but seems to work perfectly.... to date
Is it useful to check if the bias is correct? Other maintenance or testing?
The power transistors are 2N3055 and his complement, MJ2955.
Thanks in advance
Giuseppe, Italy
Using those BJT power transistors for just 30W/channel, I believe it is a low cost version of A3 by Michael Creek. Even so, it is said to be one the best sounding budget designs of the 1990s period.
Without the service manual and test specifications, there is no point in testing anything, so long as it is working OK and is quiet with no signal. I doubt it will require maintenance other than cleaning of switches or replacing control pots if they are noisy or erratic and it should not yet require new power supply electrolytic capacitors.
After a careful inspection for possible signs of damage, just close it up and enjoy - bearing in mind it is not a powerful amp and won't deliver large amounts of bass power.
Without the service manual and test specifications, there is no point in testing anything, so long as it is working OK and is quiet with no signal. I doubt it will require maintenance other than cleaning of switches or replacing control pots if they are noisy or erratic and it should not yet require new power supply electrolytic capacitors.
After a careful inspection for possible signs of damage, just close it up and enjoy - bearing in mind it is not a powerful amp and won't deliver large amounts of bass power.
Thanks, I enjoy it a lot.
...and, as I have a pair of Klipsch KG4, don't need many watts for reacing house-shaking sound pressures 🙂.
...and, as I have a pair of Klipsch KG4, don't need many watts for reacing house-shaking sound pressures 🙂.