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Old 19th January 2002, 09:42 PM   #11
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macka,
i pulled one channel completely out of the case and am starting to go over it even more finely. question, i have a 13.8 dcv power supply. can i hook that up to the negative and pos rail and see if power goes through the system? or, more to the point, is it okay, cuz i did and the power supply sounded like it was straining quite a bit so i turned it off. what do you think?

thanks,
scott
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Old 19th January 2002, 09:54 PM   #12
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question,
i found that one z5 was bad, it was shorted,

A) can this cause problems in both channels, as one channel is fine?

B) i don't have any extra zeners, but z1-4 are okay, can i pull one from there while troubleshooting safely?

thanks
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Old 19th January 2002, 11:18 PM   #13
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OK, Z5 was bad. So the current source will never work.
You will have to replace that, before going further.
If you do not have any zener's left, use one from the other channel, preferably one of Z1..Z4.
Please do hook up only the single "repaired" channel to the PS and start testing things around Q5.
You can soft test your channel using a 15w/220V light bulb in each rail from your power supply. (one bulb for +ve and one for -ve).
If you see some voltage drop between Q5 collector and Q5 emitter (Vce), and no DC (very little) on the output, and no smoke of course, you can take out the bulbs.
Hook up your channel normally to your PS, (don't forget connecting -IN to ground if your going to use an unbalanced i.e. RCA input) and do the measurement around Q5 again.
Vce should be between 3.5 to 5 volts. Check the voltage drop accross drain resistors (R40-R42 and R64-R66) to be 0.5 volts or so.

If this is the case, your channel should be working.

Hope this helps a little more

regards
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Old 19th January 2002, 11:38 PM   #14
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when you say 'don't forget to connect -in to ground for unbalanced' do you mean;

a) to the ground connection on the board

or

b) directly from the -in to chassis ground.

and how will this effect operation of the channel in regards to any voltage readings? won't i still be able to get the correct readings without inputs connected to anything?
thanks,
scott
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Old 20th January 2002, 12:01 AM   #15
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Do not make a permanent connection for -IN to ground during testing. A temporary one will do.

Connecting -IN to a ground in the final setup (i.e. working channel in your chassis) is necessary when you want to drive the ALEPH unbalanced.

Connecting -IN to ground on the board or chassis depends on the grounding scheme you use.
Most of the time you will need to exepriment a bit to find the best result.

Normally connecting -IN to ground will not affect the DC measurements.

Regards
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Old 20th January 2002, 01:28 AM   #16
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well,
i got one channel up and running, but the other can only muster 3.26 vdc across r114???

i get 5 across r11 but q3 doesnt get above 4 vdc, it sits at about 3.8. don't i need at least 4 volts to turn everythin else on? i replaced that mosfet with another but it didn't effect the measured voltage.

and i get only .16 volts across q5??

any thoughts out there?
scott
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Old 20th January 2002, 01:41 AM   #17
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Default aleph 5 project fault

Scott,

I am interested to know what board you are using, as this may be adding to the confusion.

If you continue to have difficulties can I respectfully suggest you check out the boards Mark Finnis used for his Aleph 4.

The reason I say this is that without a board over lay for the location and orientation of all the parts and wiring it is easy to slip up.

Marks site has excellent construction notes also (NB see the diy Gallery @passdiy.com).

The amp is quite simple and should go first pop, provided there are no wiring errors or damaged or wrong part values.


regards

macka
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Old 20th January 2002, 01:49 AM   #18
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Default signal bottleneck

Scott,

Q5 may be damaged, suggest you replace this with new one and perhaps Q4 also may be stuffed.

Check also the insulation washers for the output stage .

regards

macka
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Old 20th January 2002, 02:01 AM   #19
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macka,
these are mark's boards. i replaced q5, but it may be that something's wrong with Q1 or2? because i get really close to 4 volts from q3, so the input mosfets should turn on and give more than 3.26 volts, right? i measured vgs of q1 and q2 and get equally around 3.8 volts.

any thoughts?
thanks,
scott
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Old 20th January 2002, 02:44 AM   #20
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Default signal bottleneck

I may have mis interpret your response,

I have just check my reading (aleph 5) with 35 volt rails ,

across r14 should be between 4-5 volts
across r11 " '" " '
across Q5 emittor - collector 4-5 volts

If you get this plug in the speaker and music should happen.
make certain the signal board ground is connected to 0 volt ground for the power supply.

regards

Ian
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