Re: Troubleshooting FG501A
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If the output transistors are (were?) hot, I would start looking back at the input of that ckt. The bases of Q2101 and Q2113 should be very close to zero. And the bases of Q2013 and Q2321 should be about 1.4V different, and probably centered around zero (+0.7V and -0.7V).
Make sure to check the zener VR2213 also.
If the output transistors blew, you will also probably have blown the 10 ohm resistors (R2122, R2121, R2225, and R2226) on whichever one is bad. If those resistors look like they haven’t overheated, you’re probably okay.
Note that I am not speaking from experience of fixing one of these, I am just looking at the schematic and telling you where I would look.
Best of luck –
From: TekScopes@... [mailto:TekScopes@...] On Behalf Of Dave
Sent: Monday, January 17, 2011 3:49 PM
Subject: [TekScopes] Troubleshooting FG501A
Hi Everyone; Today I tried to start where I left off last week.