Thanks Mark, I replaced R1020 although it was not bad. The troubleshooting
for that circuit using a power supply says the switch should activate from
20 to 25 volts. Mine latches at 17.5 volts. I don't think it is significant.
I replaced C1024 with no change.
The RIFAs look good so I did not change any. They don't fit with the
symptoms.
I don't know if C1051 would cause my problems. I won't discount it.
CR1110 would show in the current sensing if it was shorting. There is no
evidence of a problem after T1060.
I don't think the doublers would cause my symptoms but I may change them. I
have the ones recommended.
I'm thinking that something in the U1030 circuit is acting up.Maybe U1040
feedback optocoupler? I need to see what its supposed to do.
I have good 'scope pictures of the signals but cannot post them. They show
the drive signals suddenly stopping after running from 1 to 5 seconds. The
recovery to working happens when the interval DECREASES. It seems that
there is something like overvoltage that needs to drift down to a control
range.
Peter
On Wed, Mar 6, 2024 at 8:15?PM Mark Vincent <orangeglowaudio@...>
wrote:
Peter,
R1020 is known to go bad. That should be 2W. Make sure to get a resistor
that is about 15mm long. Some 2W resistors are 3.68 x 8.72mm which is
smaller than a 1/2W. C1034 is originally a tantalum. I replaced the three
on that board with 50V film types to ensure low ESR. C1055 and a few others
are the clear amber tinted RIFAs that are known troublemakers. I used 630V
film types to replace them. C1051 is another condenser that is a RIFA type.
Look to see if those were replaced. CR1110 is known to go bad. It is a
Schottky rectifier. I replaced mine with a Si type and it worked with the
proper voltage out. Mine is 200V, I think, because I have some in stock. If
you decide to replace the doubler condensers, I suggest using Nichicon LGR
types. I put in 390mfd in mine. Make sure the diameter is small enough to
fit where the originals are. Add wires from the lugs/pins of the LGR type
to the board.
Mark
