HA13001 sound amp - sound goes in, none comes out

I

IronGiant

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Currently trying to fix an old Capcom Section Z boardset - there's no sound. Amp itself is fine as swapped it with a known good one. Can see sound going into it on pin 3 with a scope (and hear the correct sounds playing using a crystal earpiece).

Decided to swap out all the electrolytics in the sound section - still nothing.

Next step is to swap out the ceramics I guess.

Can't think what else to try if that fails, seeing as there are no schems for this boardset.

Any ideas please anyone?

Thanks
 
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IronGiant

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Thanks. I do hate the shotgun approach, but in cases like this I guess there's no choice. Have to order myself the right ceramics first though as I don't seem to have some of the values that the sound amp circuit is using.
 
ttooddddyy

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Alternatively check the resistance between 7 and 12. You should see the speakers resistance. If not this is a continuety issue, maybe a broken track somewhere.
 
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ttooddddyy said:
Alternatively check the resistance between 7 and 12. You should see the speakers resistance. If not this is a continuety issue, maybe a broken track somewhere.
Click to expand...

Thanks. Checked that and all is well. Must be the caps then .......... or a broken track somewhere (hard to tell as you can't see the tracks on these old Capcom boards, and there are no schems ............ ).
 
ttooddddyy

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It is not the ceramics imho (unless you have one short circuit) the circuit will work without them.
 
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Oh, well that's a pain. In that case I'm utterly stumped!

Amp = okay
Electrolytics = okay
Ceramics - don't know, no obvious shorts, but you say it'll work without them which is fine by me
Resistors = apparently all okay, checked in circuit though

Sound is going into the amp but not out

Unless there is a cracked or corroded track then I don't now what else it can be.

And I have two Section Z's with exactly the same fault.
 
Xian Xi

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If they both have the same fault then it's most likely a part that failed unless they both have the same corroded trace.
 
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IronGiant

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If only I had some schematics ............. damn Capcom and their covered up traces on these early boards!
 
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Sorry to say that was the first thing I checked on both boards and that's fine. Also tried shorting out the wiper to the other legs and still no sound.
 
ttooddddyy

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IronGiant said:
Sound is going into the amp but not out
Click to expand...

What sort of level going in. If you inject a signal at the input what happens (the scope probe should be enough to test this).
Can you hear anything at all from the speaker - the slightest low level noise, hum or buzz ??

Edit- regarding input level, just remembered you said you could hear via a earpiece - that should be plenty.
 
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Nothing at all comes out, irrespective of the level going in. Even doing the old 'finger rub' test on the solder side of the board on all the components does nothing whatsoever, not even a very faint buzz.
 
ttooddddyy

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Is the device getting warm

Check none of the via holes are open circuit around that stage.

A dc voltage measurement on each pin may help figure this out.
 
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IronGiant

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No, doesn't seem toeven be slightly warm.

This is a pain - I've fixed many boards in my time and this has been the worst in terms of some obscure sound fault.
 
channelmaniac

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Are you SURE you replaced all the caps?

Post a pic and show us which caps you replaced.

How are you determining that there is no signal coming from the output of the IC chip? There's a DC component to the signal coming out from the IC. Make sure your scope is set right to view or the trace will be off the screen.

There's a big cap on the output of the IC chip that sits inline with the speaker. Have you replaced it yet? It's the DC blocking cap that blocks that DC component from going to the speaker.
 
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channelmaniac said:
Are you SURE you replaced all the caps?
Click to expand...

All the electrolytics in the sound section, yes. Not all the ceramics though, but apparently their failure (if any have failed) won't stop the amp from outputting sound (unless any have shorted, which they haven't).

Post a pic and show us which caps you replaced.
Click to expand...

Will take one after typing this and post it .

How are you determining that there is no signal coming from the output of the IC chip? There's a DC component to the signal coming out from the IC. Make sure your scope is set right to view or the trace will be off the screen.
Click to expand...

Thanks. Yup, used the scope accordingly. Also used a crystal earpiece with a small cap attached which is very useful when tracking sound through a circuit and of course of of an amp. I can hear with the earpiece (and see via the scope) the normal sounds for the game going into the amp on pin 3, but nothing elsewhere. There's just nothing coming out of the amp. Even rubbing my finger on the solder side of the PCB under the sound circuitry doesn't do anything - no crackles, buzzes, hisses, etc as you would expect. I've fixed many sound circuits in my time, but this one is a real swine.
 
MKL

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IronGiant said:
If only I had some schematics
Click to expand...

You do have them: the HA13001 datasheet. The only thing that may be different is the output: in the datasheet there is a direct connection between pins 7, 12 and the speaker and in fact some Capcom boards are like that: on a GnG board pins 7 and 12 are connected directly to the edge connector. In your case there seem to be in-line electrolytic caps (as on MVS boards) but then again you said you replaced them all...

*If* what you said is true (audio input to the amp OK, amp IC OK, all electrolytic caps replaced) then it can only be a broken trace but with the datasheet it should be a piece of cake to find out even if the traces are hidden.
 
DewmanSNK

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You are operating that Ha13001 without a heat-sink and its not even warm? Mine get noticeably warm even after about a minute of use. Then again it is driving speakers. Did you check pin 10 to make sure its getting power?

Was this board stereo or mono?

From the datasheet - it looks like there are in-line caps used on pins 7,12 if this chip is used in a stereo and no caps if it is used in mono.
 
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Section Z boards don't use a heat sink for the amp.

Yup, pin 10 is getting power.

It's mono.
 
MKL

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After looking more carefully at the pic you posted I realized you replaced caps that have nothing to do with the amplifier. When set to mono the HA13001 has only 6 electrolytic caps (plus the big 2200u axial one as filter for +12v) that I tentatively marked in this pic:



Have you replaced those caps too?

Am I correct in thinking pins 7 and 12 of the amp go straight to pins b and 24 of the edge connector?

Is the Capcom-to-Jamma adapter you're using 100% reliable?
 
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