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Velodyne fsr-15 sub amplifier questions. Stk4040ii
Velodyne fsr-15 sub amplifier questions. Stk4040ii
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Old 8th November 2019, 02:38 AM   #1
Richard_James is offline Richard_James
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Default Velodyne fsr-15 sub amplifier questions. Stk4040ii

So I got this 15" subwoofer. It works now. But when worms up there is some high pitched noise here and there. It's not the same pattern.
Random low volume noises around 1000hz frequency.

I repaired subs before. But usually it was filter caps and it was 60hz back groundnoise.

The sub plays nice. Hits pretty low.

Want to keep it. Doing some preventative maintenance.
I removed the amp to source capacitors. Notice one transistor is running hot. See pics.

Velodyne customer service phone clerks get very combatative and almost wants to get into fist fight when you ask for service manuals. So I could not find service manual for this amp. But will call velodyne tomorrow to double check.


Attached are some pics.

Transistor that is running hot says "malasya TIP29C" it's labeled q1 on the board. Looks dull brown grey instead of black. It's connected to one of the filter caps

There is another transistor labeled q2, which looks different. Says "8823 TIP30B"


So I'll recap the amp.

Questions
1) is it possible to say what could cause q1 transistor to run hot

2) do these all in one power amplifiers (stk4040ii ) go bad like capacitors. Are they wearable components
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Old 8th November 2019, 04:46 AM   #2
Richard_James is offline Richard_James
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Does the transistor pair
Tip29c + tip30b need to be a matching pair like output transistors on amplifiers.

Any ways to replace these with something more heat durable
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Old 8th November 2019, 05:42 AM   #3
NMOS is offline NMOS  Germany
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replace with todays Class D plate amps and problem solved

Sanyo Semi conductor is sold 10 years ago to onsemi

STK Series, and rest of 90 % of ex Sanyo semiconductors are obsolete.
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Old 8th November 2019, 05:47 AM   #4
wiseoldtech is online now wiseoldtech  United States
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What's it using for a power supply?
One of those SMPS jobs?
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Old 8th November 2019, 02:41 PM   #5
Richard_James is offline Richard_James
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Quote:
Originally Posted by wiseoldtech View Post
What's it using for a power supply?
One of those SMPS jobs?
Inelco b3 transformer.


The shape of the amp is a little odd. Well the amp works. Sub is 22 years old.
All capacitors, q1 and q2 transistors cost me around 46$ shipped

Maybe a resistor r1 connected to q1 is not powerful enough?
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Old 8th November 2019, 05:06 PM   #6
wiseoldtech is online now wiseoldtech  United States
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My first suggestion would be to clean those charred/overheated areas of the PC board.
and all those overheated parts likely have compromised soldering now, which needs re-doing at least.
Those transistors may be weakened from overheating, new ones with a small heatsink fitted would be a good idea.
The diodes D!, D12, small transistors should also be checked, as well as the small caps in that overheated area.
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Old 8th November 2019, 05:18 PM   #7
Richard_James is offline Richard_James
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I've read on some threads that
Tip29c and tip30b could be replaced with tip40 tip41
Are there any transistors that i can replace tip29c tip30b with?
I ordered original 29 and 30 from mouser. Will put some heat sinks.
Basically amp works fine. Only after it runs few hours at 9 o'clock volume you can hear weird inconsistent noises
When close to the sub. Not very loud
I'll replace all electrolytic capacitors
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Old 15th November 2019, 08:06 PM   #8
Richard_James is offline Richard_James
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Well I replaced all capacitors. Some isues still there . Unfortunately velodyne does not provide schematics..
Too much time to swap things around. Like NMOS suggested better to buy another amp and be done with it.
Sub sound good just hissing noise during first 10mkn of operation.
But the high pitched noise disappeared.

Dc voltage values jump from -400 to + 400mv(measured at subwoofer driver terminals)

When out of the box woofer shows motorboating. Floats sat around 10hz frequency. When the box is sealed you don't notice motorboating.

Probably those stk4040ii power amplifier.i don't know much about these all in one amps. But usually see them on cheap gear. Half of which does not work or about to fail.

Seems like purposeful design to fail right after warranty runs out.
Not sure what I will do now. Probably use some external amplifier.

Last edited by Richard_James; 15th November 2019 at 08:29 PM.
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