The BOM has 512-bc550cta listed for q3, q4. I got those a couple weeks ago from mouser, they had plenty.
I posted this problem in power supply forum but since it is about an Aleph J build maybe this is a better place. In that forum I posted:
"I completed and tested the diy universal power supply in february and it tested fine (dual mono blocks). Shelved it until last month while waiting for the Aleph J boards to become avaialble. Built the Aleph J boards but having issue with one of them. Want to rule out the PSU...."
I subsequently found the post on testing the power supply thanks to AllInMyHead. When I re-tested them (dual monoblocks). The dim bulb tester seems to indicate things are fine: bright them dims some. I get these results with the multimeter:
Right 8.7 volts. This side has the amp board connected..
Left 6.6 volts. The amp board is not connected.
I've checked and rechecked the wiring, checked connections for tightness, blew out the chassis with compressed air in case there were loose bits of wire or solder causing trouble. I tried testing using several different grounding points. I'm stumped especially since it tested fine at one point. Here's a picture. Maybe someone sees something I don't.
"I completed and tested the diy universal power supply in february and it tested fine (dual mono blocks). Shelved it until last month while waiting for the Aleph J boards to become avaialble. Built the Aleph J boards but having issue with one of them. Want to rule out the PSU...."
I subsequently found the post on testing the power supply thanks to AllInMyHead. When I re-tested them (dual monoblocks). The dim bulb tester seems to indicate things are fine: bright them dims some. I get these results with the multimeter:
Right 8.7 volts. This side has the amp board connected..
Left 6.6 volts. The amp board is not connected.
I've checked and rechecked the wiring, checked connections for tightness, blew out the chassis with compressed air in case there were loose bits of wire or solder causing trouble. I tried testing using several different grounding points. I'm stumped especially since it tested fine at one point. Here's a picture. Maybe someone sees something I don't.
hold your horses
starting solely with PSU - what voltages you have on output of each cap board, without amp pcbs conected?
starting solely with PSU - what voltages you have on output of each cap board, without amp pcbs conected?
A few questions for clarity.
When you tested the PSU by itself using the process laid out in the guide, was everything correct?
Where are you measuring current voltages?
Is the DBT still connected?
When you tested the PSU by itself using the process laid out in the guide, was everything correct?
Where are you measuring current voltages?
Is the DBT still connected?
My horses are trying to hold. Had the DBM connected. Without it I get 24 volts for both input and output on the left (amp board connected) and 26.4 volts Input and output on the right no amp board connected. Maybe everything in the psu is OK?
know difference between AC and DC, measuring and writing down?
"input" is AC at Donut secondaries
"output" is DC on end of cap pcbs
do you know how many rails you have, and their polarity?
"input" is AC at Donut secondaries
"output" is DC on end of cap pcbs
do you know how many rails you have, and their polarity?
know difference between AC and DC: YES measuring and writing down?: I think that's what I did.
"input" is AC at Donut secondaries: Yes but isn't output from rectifiers DC? I measured voltage after the rectifiers not at the donuts.
"output" is DC on end of cap pcbs: I knew that.
do you know how many rails you have, and their polarity? Don't know the terminology "rails" but I know what polarity is.
Further update.
I'm assuming that the voltages I got were close enough to 26 to be usable. I may be wrong about this. I wired up the right side amp to the power supply and was able to adjust the bias to 350mv. This is after I replaced Q4 and the R27 pot and did the other things recommended by Zen Mod.
Is there something else to check other than giving it a 30 minute warmup then resetting the bias and offset? Or am I still floundering in the deep end of the pool when I should be holding the horses?
"input" is AC at Donut secondaries: Yes but isn't output from rectifiers DC? I measured voltage after the rectifiers not at the donuts.
"output" is DC on end of cap pcbs: I knew that.
do you know how many rails you have, and their polarity? Don't know the terminology "rails" but I know what polarity is.
Further update.
I'm assuming that the voltages I got were close enough to 26 to be usable. I may be wrong about this. I wired up the right side amp to the power supply and was able to adjust the bias to 350mv. This is after I replaced Q4 and the R27 pot and did the other things recommended by Zen Mod.
Is there something else to check other than giving it a 30 minute warmup then resetting the bias and offset? Or am I still floundering in the deep end of the pool when I should be holding the horses?
precision is what is welcome when speaking of measurements/presenting measured data
now, why AC - because you're saying to us what your secondaries are
now, why DC - with unloaded rails ( no amp pcbs connected) it is pretty much irrelevant where you put your probe - on first or on last cap , before or after R in CRC; that's the reason why "input" is AC, before bridges, because after bridges everything is "output", as long there is no load
now, number of rails - because maybe you know what you are thinking and what you are writing, but I'm confused/puzzled - can't decipher do you know what is needed to know - it wouldn't be first time that Greedy Boy is not aware that Aleph J is asking for dual rails (call it bipolar PSU if you like)
and nothing wrong with that - that's why we are here, to help with anything needing help (just imagine me cooking, go figure ........ no Forum enough existing for that scenario)
so, I was asking jut fro precision i writing , nothing else
main reason being that you did mention:
I don't understand where 8V7 and 6V6
now, why AC - because you're saying to us what your secondaries are
now, why DC - with unloaded rails ( no amp pcbs connected) it is pretty much irrelevant where you put your probe - on first or on last cap , before or after R in CRC; that's the reason why "input" is AC, before bridges, because after bridges everything is "output", as long there is no load
now, number of rails - because maybe you know what you are thinking and what you are writing, but I'm confused/puzzled - can't decipher do you know what is needed to know - it wouldn't be first time that Greedy Boy is not aware that Aleph J is asking for dual rails (call it bipolar PSU if you like)
and nothing wrong with that - that's why we are here, to help with anything needing help (just imagine me cooking, go figure ........ no Forum enough existing for that scenario)
so, I was asking jut fro precision i writing , nothing else
main reason being that you did mention:
I don't understand where 8V7 and 6V6
I have a bunch of left over Panasonic 3watt .47 resistors from the power supply build. Are those acceptable to use for R16 through R23? The part number is slightly different.
PS resister part number: erx-3sjr47
alephj part number: erx-3fjr47
PS resister part number: erx-3sjr47
alephj part number: erx-3fjr47
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It would be best to assume that I don't know what is needed to know. (That's what I assume!) I still don't know what dual rails are, their purpose,or their location but there are lots of references to them all over the site.
Are you needing to know the ac output of the transformer secondaries?
These were taken on the PSU just after the rectifiers. However, I took these measurements originally with the dim bulb tester connected so they were in error. Checking voltages in the same spot (amps connected) with the dim bulb tester disconnected I got 25 and 26 volts.
What should I be looking at? Or what could I do that would be most effective for you? (Again assuming that my electronics knowledge is limited.)
I am most appreciative of your help!
I might go with the vishays I got. They are smaller and might make it easier fitting them in.
for any help, you must follow directions, and go in steps, ensuring that we are on same page
now, study both schematic of PSU and stare at pcbs ( and goats, if you like/must) to realize that you have PLUS Rail and MINUS Rail, on your cap bank pcbs, and these two rails is what is feeding your amp pcbs
now, when you confirm that you have PLUS and MINUS Rails operative, you can proceed further, formulating any (if) problem you have
sure way to confirm rails on cap bank pcbs is to clip black probe to GND wire/point/whatever you find adequate with GND marking
power PSU ( with bulb tester preferably; after few initial seconds it'll stop glowing and you'll have full voltages everywhere)
then connect/lean on/touch Red probe to one rail (dunno these pcbs, hope/logical that one) output pad is marked "+" ; for unloaded you can expect something as +26Vdc , give or take V, doesn't matter
then connect/lean on/touch Red probe to second rail (dunno these pcbs, hope/logical that one) output pad is marked "-" ; forunloaded you can expect something as -26Vdc , give or take V, doesn't matter
get back here when you do that
Rails: 26.88 volts +/- on both left and right rails; amp boards both disconnected
dim bulb test light comes on then fades out after a few seconds.
now, connect just one amp board to correspondent PSU, (+ rail, - rail, GND)
no bulb tester, no load on output, shorted inputs to GND
one DVM between output posts, set to Vdc, to observe DC offset
second DVM (set to Vdc) across one of 0R47 output source resistors, to observe Iq
try to set both Iq and DC offset to prescribed values
inform here
no bulb tester, no load on output, shorted inputs to GND
one DVM between output posts, set to Vdc, to observe DC offset
second DVM (set to Vdc) across one of 0R47 output source resistors, to observe Iq
try to set both Iq and DC offset to prescribed values
inform here
Before I turn this on just want to double check. Picture shows how I shorted inputs to ground (green wire loop on euroblock). This is that what you meant?
I only have one VOM so I'll have to go back forth on settings.
you have +Input and -Input on Aleph J
short both to GND, in whichever way you manage
that probably means two shorting wires on euro block
or - if you already shorted (soldered) neg input pad to gnd, planning to use just + Input for RCA, you can plug RCA shorting plug in connector at back
shorting plug is cheapest RCA you have, thin wire soldered between GND and Hot contacts
short both to GND, in whichever way you manage
that probably means two shorting wires on euro block
or - if you already shorted (soldered) neg input pad to gnd, planning to use just + Input for RCA, you can plug RCA shorting plug in connector at back
shorting plug is cheapest RCA you have, thin wire soldered between GND and Hot contacts