[TechAssist] Fw: Toshiba CZ27V51, Dead After Storm, Update, Fix--Sort of
- From: gulftech@xxxxxxxx
- To: techassist@xxxxxxxxxxxxx
- Date: Thu, 12 Aug 2004 09:24:32 -0500
The relay driver ckt consists of two transistors, QB30, 2SC1815, and
Q843, an RN1205 digital. There is supposed to be 4.9 volts on the base
of QB30 to turn on the set. That signal comes from the uP QA01, pin 7
thru RA07, 1K. Problem was that voltage would go low almost immediately.
The relay would click one time, then nothing.
Ed Gadies was kind enough to send a scan of the relay drive ckt, but I
couldn't find the problem. I ordered a new Q843, but had my doubts it
would fix it. It didn't. I also ordered a s/m for the set.
What I found is that power on signal to the base of QB30 also goes to the
collector of Q819. Can't figure out what that transistor is supposed to
do, but when I floated the collector, the set worked. Checked Q819 and
surrounding transistors Q817 and Q818. All checked good.
I had the same problem with Toshiba CF27H50. Again, floating collector,
Q819 "fixed" it as well. Maybe someone can tell me what the circuit
Q817-Q819 does. May be a timing circuit, but the sets both work without
Q819 in the ckt.
Ken Smith
Gulf Technical Services
3034 Gulf Breeze Parkway
Gulf Breeze, FL 32563
850-934-8324 (Voice) 850-932-0819 (Fax)
--------- Forwarded message ----------
From: gulftech@xxxxxxxx
To: techassist@xxxxxxxxxxxxx
Date: Fri, 23 Jul 2004 11:45:14 -0500
Subject: Toshiba CZ27V51, Dead After Storm
This set will click one time and shut down.
I jumpered the relay and the set works fine, except the power light
flashes continuously.
Does anyone have a tip or a schematic of the relay driver ckt. It uses
some transistors I have never heard of. They look and test like
digitals.
Ken Smith
Gulf Technical Services
3034 Gulf Breeze Parkway
Gulf Breeze, FL 32563
850-934-8324 (Voice) 850-932-0819 (Fax)
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