RCA Sub Rebuild

[notmy...@3web.net]

I have an older RCA subwoofer model SP2099AW that the amplifier
section croaked on me. I have no intention of repairing the amp but
wanted to use some of the junk I have collected over the years to
retofit into the box and make it go boom-boom again. The control
circuit is in working order and is connected to the amp circuit with a
plug. I want to keep the control circuit and built the necessary power
supply to run it. It required a + and - 15 volt supply, a standby
supply of about 1.5 volts ( to turn the standby led on). In return it
supplys a mute line and a variable audio output, filtered and phase
matched. So far so good. I mated this to a Sony audio output stage
from a KV27EXR??? (K board). It uses 2 TDA2009's for the output stage
and will work good enough for me. The TDA's are bridgeable and I
succeded in bridging both outputs into 1. The question I have goes
back to the power supply. I had this circuit all breadboarded up and
it worked perfectly, or so I thought. I had only made the amp work
independantly of the mute and input sense circuits, using only the +
and - supplies of the power supply I made with the 3 terminal
regulators. The transformer I used has a center tapped secondary. The
split supply uses the center tap as the reference. This follows the
original RCA design of the power supply for the amp circuit. Problem
is I get one heck of a 60 Hz hum on the audio output. All grounds are
referenced to the center tap. I want to reinforce the point that all
the circuits work great, when they are tested independantly. But when
connected together the bugger only knows 1 song(60Hz). Am I missing
something silly?? I apoligize for the rather long post.

DAvid K.

[Sofie]

notmyemail:
Hook up your oscilloscope to the outputs of the 3-terminal regulators and
make sure they are indeed regulating at the correct voltage and that the B+
and B- are free from AC ripple...........with your DMM also check that your
bridge (or rectifier diodes) are OK and not shorted or open and if you have
an ESR meter also check your filter capacitors right after the bridge
rectifier...before the 3-terminal regulators. There is not much more to go
wrong here so if there is any doubt about the components, just replace them.
If you verify with your oscilloscope that there is no AC ripple on the
regulated DC then you may want to start looking at the amplifier......... a
thought, make sure that your signal ground is good and that the shielded
cord with RCA plugs is OK and does not have an open ground.
Best Regards,
Dan Sofie
Electronics Supply & Repair
==============================================

<notmy...@3web.net> wrote in message
news:39fe539e...@news.3web.net...

[Mr. Spork]

You say the transformer in the RCA sub is center tapped eh? What would the
number on the top of the transformer be?

Matt

<notmy...@3web.net> wrote in message
news:39fe539e...@news.3web.net...

[Dav...@home.net]

On Tue, 31 Oct 2000 12:17:54 -0600, "Mr. Spork" <spo...@iand.net>
wrote:

>You say the transformer in the RCA sub is center tapped eh? What would the
>number on the top of the transformer be?
>
>Matt

>The original transformer used in the sub amp circuit has the following #'s on it

HK86H-103 C
TTJ1201-001 C
BUILT IN THERMAL FUSE
9748

I suppose I should mention here that I am not using the original
tranfomer in my hookup. The amp circuit from the Sony only uses a +22V
supply for the output stage,so I used a transformer from something
else to run this thing. I can't see all the numbers on it but it has a
healthy 24V AC center tap I used.

[m...@here.now]

Thanks for the advice. The first thing I did was to measure for ripple
on the supplies, it was negligible. To me this sounds more like an
open ground. It is a super hum, not just some noise in the background.
I just haven't had anymore spare time to fiddle with it yet. Hopefully
this weekend. The only other thing I can think of is if I reversed the
polarity of the windings from the standby circuit to the main power
supply. Would that have an effect?

David K

[011ser...@gmail.com]

I want To hook a car amp and use car woofer can I run it thermal fuse

[John-Del]

On Tuesday, February 23, 2016 at 2:19:01 AM UTC-5, 011ser...@gmail.com wrote:
> I want To hook a car amp and use car woofer can I run it thermal fuse

I would use two of them..

[Adrian Caspersz]

On 23/02/16 07:18, 011ser...@gmail.com wrote:
> I want To hook a car amp and use car woofer can I run it thermal fuse
>

To detonate?

--
Adrian C

[jurb...@gmail.com]

On Tuesday, February 23, 2016 at 2:19:01 AM UTC-5, 011ser...@gmail.com wrote:

> I want To hook a car amp and use car woofer can I run it thermal fuse

You have replied to a 16 year old thread.