Thanks. I realized I would have to get to the underside of the board and have already lifted the board off the chassis to see if there any obvious short. I didn¡¯t see anything that looked burnt. Based on your last note regarding that there shouldn¡¯t be any AC voltage at the transistors, I¡¯ve decided to not proceed any further. Thank you for your assistance and advice.?
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On Dec 8, 2024, at 3:44 AM, Chris Clifton via groups.io <clifton.christopher@...> wrote:
?
At some point in the repair process you would have to get to the
back of the amplifier board in order to unsolder a faulty
component. That's not particularly easy on the T-series. Whether
you lift the chassis off the pedal board, (my preferred method) or
lift the circuit board off the chassis. There are a lot of wires
connected to that board. It is possible to work on the board
without disconnecting any wires, but if one accidentally gets
disconnected, then you have a new fault to trace.
On 07/12/2024 22:38, Ned Lucas via
groups.io wrote:
Haha, yeah, I¡¯m thinking the same thing. I¡¯ve kept my B3, C3 (x2)
and A100 running for 20 years but solid state stuff is new to me.
I¡¯d hate to junk this but that may be the play here. I¡¯be taken
the Leslie unit out to access the boards. The Leslie was
functioning alright ie it was firing up and spinning properly so I
guess someone will probably want it.?
?
Pin 17 and the collector of Q604 should be 25 volts DC (not
AC!) when measured with the negative lead of the meter to
ground (any point on the chassis) and positive to the point
where you're measuring. It should never be an AC voltage,
and certainly not 60 volts. Voltages around all the
transistors should in the first instance be measured as DC
voltages.
To be honest, I'm beginning to wonder if you've bitten off
more than you can chew with this. From your comments, you
appear to have no understanding of what we are trying to do
here. I can't teach you all you need to know by email.
On 07/12/2024 17:56, Ned Lucas
via groups.io wrote:
Well, just looking at the voltages at Q604 (the transistor
with the heat sink),?
Pin #17 (which should be the Collector voltage of
+25vac) I¡¯m reading +60vac. ?When I put the positive probe
on the C leg and the negative probe on the chassis I read
0 vac.?
On the Base and Emittor, I¡¯m reading 0 vac.?
On Dec 7, 2024, at 9:05 AM, Ned
Lucas via groups.io <nedlucas@...>
wrote:
?
Thank you so much!
On Dec 7, 2024, at 4:31 AM,
Christoph via groups.io <kuku@...>
wrote:
?
Oh, typos:
unfortunately. I just wanted
Am 07.12.2024 um 10:22 schrieb
Christoph via
<
kuku@...>:
Ned,
did you check the power supply
voltages ??
Funnily, the other day I was
able to download?
the T-500 Service manual from?.
Unfotunately I forgot to
download part II, which contains most of
the circuit diagrams. I kusted wanted to
lookup the points where to measure the
15 and 35V.
unfortunately. I just wanted ... ?15 and 25V
When I try to dowload it now
I¡®m getting
?Item not available due to
issues with theitem¡®s content¡° Anyone
knowing an alternate source?
¡ª
Christoph?
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