Pioneer SX-580 problem...

[Alan Maier]

I am puzzled! I have been working on a Pioneer SX-580 receiver - a personal
restoration project, and it's giving me trouble passing a signal through the
tape monitor when set for "source". Here are a few details...

Tuner, tape and phono can be heard at very low level at full volume control
setting - as though it is simply bleeding through.
Tape monitor input works normally.
Tape output works normally.... indeed the selected input is routed at normal
level to the tape output, and yes I can do a in/out loop - press the tape
monitor button and have normal audio.
All other controls work normally.
Both channels are affected the same.

Since there is an audible mute delay when pressing the tape monitor button,
I assumed the tape monitor switch might activate another source select
control such as a preamp IC - and there is an IC in the preamp stage as
found in microprocessor controlled receivers. I replaced that IC with one
from a parts donor SX-680 (near twin - 50% more power and a second monitor
is all I can find different) to no avail. I should add that the controls
are clean and static free. Pressing the tape monitor switch without a jumper
cable yields a momentary mute - then the same volume low level returns. So
it seems all I can getting is bleed-through via the ribbon cable used for
the tape loop.

So help me, it seems like the source function of the tape monitor switch is
simply open... but it's not.

Any thoughts? These hobbies are supposed to be fun - this one has me
stumped.

Alan

[TIM SCHWARTZ]

Alan,
Though it has been a while since I've worked on an SX-580, I'm quite
sure that this minimal audio 'leakage' is normal, and not a fault in
your unit. It is quite common on many products.

Regards,
Tim Schwartz
Bristol Electronics

[russell hall]

How did you determine that the switch was good?

Maybe measuring something in the wrong way.

When things make no sense I usually find I've missed something or there is
actually a bizarre problem

I've got a manual if you need some layout info on the switch circuit

Russell
"Alan Maier" <alan.l...@worldnet.att.net> wrote in message
news:%Y3L5.10862$UL.6...@bgtnsc07-news.ops.worldnet.att.net...

[Alan Maier]

Russell,

Thanks for your input. I have been searching into this receiver more this
evening... I bought it with this problem, and see someone else has tried
their hand on it. Now I am on a mission from God!

The switch is fine. It's not a simple DPDT monitor switch and the tape
signal and source signal are separated, I am expecting to find a pair of
failed transistors (or caps) in the source side which are fine at the tape
monitor side of the circuit (assuming the tape out is buffered and working,
and the tape input is passive to the rest of the preamp stage). So far,
every transistor is checking out fine. I have not traced the signal from
point to point... that's next.

This is a project I am going to fix out of determination. The used market is
full of 20 year old, 20w/ch receivers with silver faces - it's principle!!!

Best regards,

Alan

"russell hall" <db...@bellsouth.net> wrote in message
news:FWoL5.3184$Fs1....@news2.atl...
: How did you determine that the switch was good?

: >
: >
:
:

[russell hall]

went and got the manual out

wouldn't you know that in even a small rcvr Pioneer did something more than
just a switch

this has a muting circuit that comes into play during function select, but
is defeated when the tape monitor

is used.

Send you some details later

Russell
"Alan Maier" <alan.l...@worldnet.att.net> wrote in message

news:ShML5.16359$xJ4.7...@bgtnsc06-news.ops.worldnet.att.net...

[Alan Maier]

Russell,

Thanks for checking into this for me. I have a SX-680 manual (fisch) and
it's not the same in this area as it's two tape loops are simple switches -
with the momentary mute feature of course. Built to last, even at the entry
level.

Reasons like this is why I put so much effort into these older units.

Alan

"russell hall" <db...@bellsouth.net> wrote in message

news:C9%L5.7075$Fs1....@news2.atl...
: went and got the manual out

: > :
: > :
: >
: >
:
:

[beauc...@gmail.com]

I am having the same problem. Sound is great on tape monitor, but got hardly anything on radio or aux.

Do you have those files you sent to the other guy who had this problem

[Trevor Wilson]

On 13/08/2014 6:46 AM, beauc...@gmail.com wrote:
> I am having the same problem. Sound is great on tape monitor, but got hardly anything on radio or aux.
>
> Do you have those files you sent to the other guy who had this problem
>

**Connect your tape deck correctly. Refer to your instruction manual.
You have probably transposed your inputs and outputs.

--
Trevor Wilson www.rageaudio.com.au

[William Sommerwerck]

wrote in message news:9935c89e-9ed4-4fac...@googlegroups.com...

> Sound is great on tape monitor, but got hardly anything on radio or aux.

Sounds like a busted tape monitor switch, that isn't passing the non-tape
inputs.

Try hooking another amp to the Tape Rec outputs, and see whether they play.