when you talk about lower and upper halves of the output stage, what exactly do you mean. are you basing that on the schematic? i'm a little confused.
thanks for the input, i did do the same thing with my 9610's. i'll remove the sinks for trouble-shooting and re-read.
scott
thanks for the input, i did do the same thing with my 9610's. i'll remove the sinks for trouble-shooting and re-read.
scott
i'm also seeing ~34 volts at the jumper from Q3 to Q1???? and no voltage at Q5????
i'm running out of ideas
i'm running out of ideas
dave.
i'm using kapton insulators with grease on each side. can anyone help as far as grounding goes? i've been to numerous sites, threads, etc. but am a little foggy when it comes to actually installing the ground scheme in my amp. i've already posted in this thread what my current grounding scheme is.
i've checked all the resistors they all check out except r6 which is 9k but supposed to be 100k. how much will that effect the operation?
all the caps are oriented correctly.
no burning smells or smoke when it is on.
the gate to -Vcc of lower output mosfets is high, 6 and 9 for the left and right channel.
no voltage across Q5
ps is working fine ~34 vdc at the rails.
i think it may be with the grounding of signal but am not sure how to check or remedy this.
i'm dead in the water with no paddle!!!!
scott
i'm using kapton insulators with grease on each side. can anyone help as far as grounding goes? i've been to numerous sites, threads, etc. but am a little foggy when it comes to actually installing the ground scheme in my amp. i've already posted in this thread what my current grounding scheme is.
i've checked all the resistors they all check out except r6 which is 9k but supposed to be 100k. how much will that effect the operation?
all the caps are oriented correctly.
no burning smells or smoke when it is on.
the gate to -Vcc of lower output mosfets is high, 6 and 9 for the left and right channel.
no voltage across Q5
ps is working fine ~34 vdc at the rails.
i think it may be with the grounding of signal but am not sure how to check or remedy this.
i'm dead in the water with no paddle!!!!
scott
uhhh,
i measured it at the outputs and got positive at the right channel and negative at the left. a little of each, how nice. one thing that concerns me is the 34 volts at the jumper between q3 and q1/q2. it should read ~ 4 volts.
thanks,
scott
i measured it at the outputs and got positive at the right channel and negative at the left. a little of each, how nice. one thing that concerns me is the 34 volts at the jumper between q3 and q1/q2. it should read ~ 4 volts.
thanks,
scott
Scott,
Your measured resistance for R6 of 9K vs 100K is fine. R6 is in parallel with R4, so what you are measuring is their parallel resistance. 10K in parallel with 100K gives a resistance of about 9.1K, so everything's normal.
In terms of upper land lower halves of the output stage: if you look at the Aleph 5 schematic, you'll notice there are two dashed-line boxes. I call the box around Q6-8 the upper half of the output stage (its connected to the +ve rail), and the box around Q18-20 the lower half of the output stage (its connected to the -ve rail).
The reason I'm describing them like this is: if your circuit is turning Q6-8 on and not Q18-20, for example, your output voltage will be close to the +ve rail voltage. But, without any load resistance (or a high load resistance), virtually no current will flow since Q18-20 are not conducting. A similar situation arises if Q18-20 are on and Q6-8 are off - the output will be at the -ve rail.
You've said you have 6-9V across R14 but nothing across Q4. The collector of Q4 should be connected directly to R14, so I think this warrants closer investigation. Carefully check your connections and tracks.
In terms of Q5, the Aleph 5 schematic is easy to misread in this area. Check that R19 connects to the base of Q5, not the collector. What voltage do you measure between the base and emitter of Q5?
Which city do you live in, Scott? If you're in Perth, Australia, I'd be happy to drop over and look at it in person.
Your measured resistance for R6 of 9K vs 100K is fine. R6 is in parallel with R4, so what you are measuring is their parallel resistance. 10K in parallel with 100K gives a resistance of about 9.1K, so everything's normal.
In terms of upper land lower halves of the output stage: if you look at the Aleph 5 schematic, you'll notice there are two dashed-line boxes. I call the box around Q6-8 the upper half of the output stage (its connected to the +ve rail), and the box around Q18-20 the lower half of the output stage (its connected to the -ve rail).
The reason I'm describing them like this is: if your circuit is turning Q6-8 on and not Q18-20, for example, your output voltage will be close to the +ve rail voltage. But, without any load resistance (or a high load resistance), virtually no current will flow since Q18-20 are not conducting. A similar situation arises if Q18-20 are on and Q6-8 are off - the output will be at the -ve rail.
You've said you have 6-9V across R14 but nothing across Q4. The collector of Q4 should be connected directly to R14, so I think this warrants closer investigation. Carefully check your connections and tracks.
In terms of Q5, the Aleph 5 schematic is easy to misread in this area. Check that R19 connects to the base of Q5, not the collector. What voltage do you measure between the base and emitter of Q5?
Which city do you live in, Scott? If you're in Perth, Australia, I'd be happy to drop over and look at it in person.
okay,
i see your lableling and it makes sence. so i should be checking to see if one set of hexfets is not being turned on. that would explain the fact that i'm seeing amost 30 vdc at the outputs right?
i looked at the schematics and am not sure that r19 should be connected directly to q5 at all. in the artwork that i used for my pcb's r19 goes from the + side of c10 over to meet up with +c9, r18 and then onto r17. my stuffing diagram shows that r19 doesn't hook directly to q5 at all. r20 goes from the base of q5 over to sense of upper hexfet set. maybe my stuffing diagram is incorrect.?
i checked my board vs stuffing diagram over and over and everything agrees. i'm really at a loss as to what the problem may be.
i've never seen mosfets fail. is it noticeable? because, so far, aside from that "new amp" smell, all the devices appear normal, i.e. no blackened legs, no smoke, heck not even hot devices.
thanks,
of all things to not work, i thought for sure it'd be over-heating not no sound at all!
cheers,
scott
from seattle, washington area, which makes debugging all the more difficult.
i see your lableling and it makes sence. so i should be checking to see if one set of hexfets is not being turned on. that would explain the fact that i'm seeing amost 30 vdc at the outputs right?
i looked at the schematics and am not sure that r19 should be connected directly to q5 at all. in the artwork that i used for my pcb's r19 goes from the + side of c10 over to meet up with +c9, r18 and then onto r17. my stuffing diagram shows that r19 doesn't hook directly to q5 at all. r20 goes from the base of q5 over to sense of upper hexfet set. maybe my stuffing diagram is incorrect.?
i checked my board vs stuffing diagram over and over and everything agrees. i'm really at a loss as to what the problem may be.
i've never seen mosfets fail. is it noticeable? because, so far, aside from that "new amp" smell, all the devices appear normal, i.e. no blackened legs, no smoke, heck not even hot devices.
thanks,
of all things to not work, i thought for sure it'd be over-heating not no sound at all!
cheers,
scott
from seattle, washington area, which makes debugging all the more difficult.
Ah-ha! Progress.
Where R19 connects to the positive end of C10 should connect to the base of Q5. R17, R19 and R20 form a voltage divider which provides a part of the bias to turn Q5 on. Looking at the schematic, there's 0.5V across R40. But, the turn on voltage of most transistors is around 0.7V. The extra 0.2V is supplied by the R17, R19 and R20 voltage divider. Make this connection!
If you want to check, have a look at the circuit for the Aleph 30 or 60 available from www.volksamp.com - it's the same circuit topology, but the schematic is drawn more clearly and shows what I've described above.
Seattle is kinda far to drive from Australia... you'll have to send me pics one they're working 🙂
Keep at it, we're making progress. The heart-ache is worth it, believe me.
Oh, and keep testing without your speakers connected until you're happy you have 0V DV offset at the output.
Where R19 connects to the positive end of C10 should connect to the base of Q5. R17, R19 and R20 form a voltage divider which provides a part of the bias to turn Q5 on. Looking at the schematic, there's 0.5V across R40. But, the turn on voltage of most transistors is around 0.7V. The extra 0.2V is supplied by the R17, R19 and R20 voltage divider. Make this connection!
If you want to check, have a look at the circuit for the Aleph 30 or 60 available from www.volksamp.com - it's the same circuit topology, but the schematic is drawn more clearly and shows what I've described above.
Seattle is kinda far to drive from Australia... you'll have to send me pics one they're working 🙂
Keep at it, we're making progress. The heart-ache is worth it, believe me.
Oh, and keep testing without your speakers connected until you're happy you have 0V DV offset at the output.
okay,
so it looks like r20, + end of c10, and r19 all connect to the base of Q5, does that make sense? if it does, that's a problem, cuz on my stuffing diagram it doesnt. just r20.
thanks,
i won't be able to get back to you til tomorrow about this time or a little earlier, but would really appreciate any help.
that's why this is so frustrating, because i'm sure it's worth it and i'm really anxious to get this running.
thanks,
scott
here's the link to the site that i got the artwork from. the aleph 4 is listed but the area we're looking at is the same, just labeled c9 or something like that. see what you think
http://members.ozemail.com.au/~dfinnis/passlabs/files/aleph_pcbs.pdf
so it looks like r20, + end of c10, and r19 all connect to the base of Q5, does that make sense? if it does, that's a problem, cuz on my stuffing diagram it doesnt. just r20.
thanks,
i won't be able to get back to you til tomorrow about this time or a little earlier, but would really appreciate any help.
that's why this is so frustrating, because i'm sure it's worth it and i'm really anxious to get this running.
thanks,
scott
here's the link to the site that i got the artwork from. the aleph 4 is listed but the area we're looking at is the same, just labeled c9 or something like that. see what you think
http://members.ozemail.com.au/~dfinnis/passlabs/files/aleph_pcbs.pdf
> so it looks like r20, + end of c10, and r19
> all connect to the base of Q5, does that make sense?
That's correct.
I looked at the link, and the good news is that the stuffing diagram and circuit in the pdf looks ok to me:
To avoid confusion in the next paragraph, I'll refer to part numbers on the stuffing diagram in the pdf you linked, and add the equivalent Aleph 5 part in brackets. Eg Q3 (Q5) denotes that Q3 in the stuffing diagram is the same as Q5 in the Aleph 5 schematic.
Q3 in the stuffing diagram is actually the same as Q5 in the Aleph 5 🙂. The base of Q3 is the middle pad, looking top to bottom. There's a track leading off to the right of the base pad (as you look at it on screen) that goes under C7 (also C7 on the A5). The track then branches in two - it heads "up" where it leads to R26 (R19) and to the positive end of C9 (C10). The other branch keeps going left, where it leads to R28 (R20).
(Back to Aleph 5 component references). If the boards you have etched/made do not have this track, simply solder a short piece of wire between the base of your Q5 and the joint between R19 and C10.
Note that the stuffing diagram is shown looking through the PCB to the copper track, but the artwork is shown looking at the copper track side, so they are vertical mirror images of each other.
> all connect to the base of Q5, does that make sense?
That's correct.
I looked at the link, and the good news is that the stuffing diagram and circuit in the pdf looks ok to me:
To avoid confusion in the next paragraph, I'll refer to part numbers on the stuffing diagram in the pdf you linked, and add the equivalent Aleph 5 part in brackets. Eg Q3 (Q5) denotes that Q3 in the stuffing diagram is the same as Q5 in the Aleph 5 schematic.
Q3 in the stuffing diagram is actually the same as Q5 in the Aleph 5 🙂. The base of Q3 is the middle pad, looking top to bottom. There's a track leading off to the right of the base pad (as you look at it on screen) that goes under C7 (also C7 on the A5). The track then branches in two - it heads "up" where it leads to R26 (R19) and to the positive end of C9 (C10). The other branch keeps going left, where it leads to R28 (R20).
(Back to Aleph 5 component references). If the boards you have etched/made do not have this track, simply solder a short piece of wire between the base of your Q5 and the joint between R19 and C10.
Note that the stuffing diagram is shown looking through the PCB to the copper track, but the artwork is shown looking at the copper track side, so they are vertical mirror images of each other.
sud,
i e-mailed the fellow who sent me the artwork and he said that that was an older set that omitted the connection and so i'll do that, but he also said that that's not the cause of my problem, as he did the same and his amp ran fine, it was just a fine-tuning addition.
after work today, i'm going to go through the schematic with a fine-toothed comb. all resisitors check, caps are oriented right, the only problems i can see are failed mosfets Q1-3, or mis-wiring.
if you can think of anything else, please forward it.
question, in unbalanced mode, do i need to ground the pcb, i.e. signal to anything or should i leave them floating? i currently have the tranny/cap, and power cord earthed to the chassis at different points.
thanks so much,
scott
i e-mailed the fellow who sent me the artwork and he said that that was an older set that omitted the connection and so i'll do that, but he also said that that's not the cause of my problem, as he did the same and his amp ran fine, it was just a fine-tuning addition.
after work today, i'm going to go through the schematic with a fine-toothed comb. all resisitors check, caps are oriented right, the only problems i can see are failed mosfets Q1-3, or mis-wiring.
if you can think of anything else, please forward it.
question, in unbalanced mode, do i need to ground the pcb, i.e. signal to anything or should i leave them floating? i currently have the tranny/cap, and power cord earthed to the chassis at different points.
thanks so much,
scott
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