Prev: Revox B225 Service/User Info
Next: Fuse or fusible resistor?
From: William R. Walsh on 28 Jun 2010 10:19
Hello all...

Thanks to everyone for the replies...

The new cap is installed properly. I made careful notes of how the old
one had been installed and the schematic is in agreement with my
notes.

I do believe the "E0" indication is some kind of error. But what it
means is a mystery, and the service manual does not help. I'm going to
ask TEAC, although so far they have not been helpful at all. The
output of the amplifier does not appear to be blocked--it is
amplifying this humming sound. It's not outputting DC to the speaker
connections.

Outside of the burned area, no traces on the board were ruined.

If I knew what E0 meant, I suppose it might be very helpful.

I may try pulling the cap (since the original was completely open
circuit, I doubt it can hurt) and seeing how the behavior changes.

William
From: Geo on 28 Jun 2010 14:32
On Sat, 26 Jun 2010 19:57:31 -0500, "William R. Walsh"
<newsgroups1(a)idontwantjunqueemail.walshcomptech.com> wrote:


>I kept on looking and found a capacitor at location 7C27 (220uF, 16V) that
>had blown out the rubber plug at the bottom. So I replaced that. Now nothing
>works. I know the new cap to be good.

Is it a double-sided (or worse - multilayer) pcb?
If the pcb designer used one or both of the capacitor pins as vias then you
could possibly have removed sufficient of the hole plating to lose e.g a power
or ground through connection.

--
Geo
From: Arfa Daily on 28 Jun 2010 20:12


"William R. Walsh" <wm_walsh(a)hotmail.com> wrote in message
news:016c0e5e-f07c-4ecb-81be-4af0611b1632(a)r27g2000yqb.googlegroups.com...
> Hello all...
>
> Thanks to everyone for the replies...
>
> The new cap is installed properly. I made careful notes of how the old
> one had been installed and the schematic is in agreement with my
> notes.
>
> I do believe the "E0" indication is some kind of error. But what it
> means is a mystery, and the service manual does not help. I'm going to
> ask TEAC, although so far they have not been helpful at all. The
> output of the amplifier does not appear to be blocked--it is
> amplifying this humming sound. It's not outputting DC to the speaker
> connections.
>
> Outside of the burned area, no traces on the board were ruined.
>
> If I knew what E0 meant, I suppose it might be very helpful.
>
> I may try pulling the cap (since the original was completely open
> circuit, I doubt it can hurt) and seeing how the behavior changes.
>
> William

So what does the cap do in the circuit ? Is it a big secret, or something ?

Arfa

From: William R. Walsh on 29 Jun 2010 09:59
Hi!

> So what does the cap do in the circuit ? Is it a big secret, or
> something ?

No, should it be? :-)

I don't know for certain what it does. I haven't explored it that
closely. I only noticed it being bloated out of the corner of my eye,
so I said "that should be replaced".

I've put it aside for now. Maybe another day.

TEAC has been no help. Although they did respond to my request asking
for more information, they recommended "shotgunning" the unit. (Yeah,
really.)

William
From: William R. Walsh on 29 Jun 2010 12:26
Hi!

> Is it a double-sided (or worse - multilayer) pcb?

No, it appears to be a simple PCB with one layer on one side.

I would not call this receiver the greatest design I have seen.
Compared to the Sherwood and Sony receivers that I have been working
on, it strikes me as being unnecessarily complex. The main PCB is
littered with all sorts of components where the others are much
cleaner and simpler.

William
First  |  Prev  |  Next  |  Last
Pages: 1 2 3 4 5
Prev: Revox B225 Service/User Info
Next: Fuse or fusible resistor?