Help with Delta 1010 PSU regs/diodes - diyAudio
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Old 14th July 2015, 02:13 PM   #1
grantos is offline grantos  United States
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Default Help with Delta 1010 PSU regs/diodes

Hi all, please forgive me once again for my noobiness, I just want what's best for my audio interface . Mostly I'm trying to mitigate overheating.

Several posts have indicated that a change to LDO regulators would be beneficial to this PSU, but there's conflicting advice.

Also, it looks like many change the four in4001 diodes at the top (D1-D4) to schottky type. Question: since many people seem to automatically change all PSU diodes to schottky types, why not change D5 and D12 as well?

Can anyone confirm or dispute these recommendations? Thank you!

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Last edited by grantos; 14th July 2015 at 07:29 PM.
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Old 14th July 2015, 07:07 PM   #2
Mooly is offline Mooly  United Kingdom
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Shottkys might give a slight efficiency advantage due to slightly lower forward junction voltage.

For a 9vac input and given the 470uf coupling cap values, the current that can be drawn is very limited before it would start to impinge on the 78xx regs drop out voltage. Anything much over 100ma will cause problems. Unless the current is way below that figure then increasing the 470uf to say 1000uf would be the (my) first thought.

Without knowing the actual current draw on each rail its hard to say... it could all be fine, or it could be very marginal.
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Old 14th July 2015, 07:16 PM   #3
grantos is offline grantos  United States
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Quote:
Originally Posted by Mooly View Post
For a 9vac input and given the 470uf coupling cap values, the current that can be drawn is very limited before it would start to impinge on the 78xx regs drop out voltage. Anything much over 100ma will cause problems.
This is a reason to switch to LDO's (LM2990T and LM2940CT), right?

Quote:
Originally Posted by Mooly View Post
Unless the current is way below that figure then increasing the 470uf to say 1000uf would be the (my) first thought.
Not enough space for that.. in fact all of these cap values are appear to be maxed out in terms of space.
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Old 14th July 2015, 07:18 PM   #4
SY is offline SY  United States
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What's the specific problem with the 1010 you're trying to solve?
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Old 14th July 2015, 07:20 PM   #5
grantos is offline grantos  United States
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The caps tend to overheat and blow on this thing (two of mine were blown when I looked), so I'm mainly trying to take care of heat, I guess, and cleaning up the supply voltage would be a good bonus, too.
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Old 14th July 2015, 07:39 PM   #6
SY is offline SY  United States
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Why not just replace the caps with 105°C rated ones of the same size and from a reputable supplier?
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Old 14th July 2015, 07:41 PM   #7
grantos is offline grantos  United States
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Why not just replace the caps with 105°C rated ones of the same size and from a reputable supplier?
I already did but they still get very hot just being powered on.
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Old 14th July 2015, 07:43 PM   #8
SY is offline SY  United States
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Can you put your finger on them?
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Old 14th July 2015, 07:46 PM   #9
grantos is offline grantos  United States
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Quote:
Originally Posted by SY View Post
Can you put your finger on them?
Not for over a second.. They're around 100C I'd say. Here is the advice I'm going by... is it good or no?

"I used to build industrial control equipment and one of my pet hates is under engineered power supplies in audio gear. You could get a big improvement just by replacing the +/- 15V regulators with low dropout types like the LM2940CT-15 and LM2990T-15. Also replace the rectifier diodes (the four 1N4001s next to each other near the 9Vac input connector) with Schottky types like the MBR1100, for a lower voltage drop. You'll get a cleaner supply without the extra heat that bigger booster caps would cause."
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Old 15th July 2015, 06:30 AM   #10
Mooly is offline Mooly  United Kingdom
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Quote:
Originally Posted by grantos View Post
I already did but they still get very hot just being powered on.
New good quality caps shouldn't get hot. You need to check whether it really is the cap heating on its own or whether it is heat from the regs affecting the cap.

Also measure the 'DC' voltage across them and check they are fitted correctly as per measured results, not board markings.
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