AidanLunn wrote:Have ordered the N-types, the machine had the F-types.
I was thinking if the voltages turn out to be OK but the machine still has the fault, would it be random hash on the rails? For obvious reasons a multimeter wouldn't be able to pick up on this, if present.
Red to black wrote:Okay,
Cp802 = ICP F/N 25
Cp803 = ICP F/N 38
CP804 = ICP F/N 25
F/N - F or N type
AidanLunn wrote:ignoring the AC lines, all measured within 5V of the values printed in the FV33H service manual.
Red to black wrote:The un-regulated ones, particularly the higher ones will vary a bit.
The important one is the one used to set the PSU, with the machine switched on @ 15.3 V at Test Point CN-1 pin 1 to ground, assuming the machine can be turned on. If this supply is not fully loaded due abnormal conditions it may well be slightly higher.
The regulated ones, post-regulator should be close to their specified voltage, within say 10% of the value of that rail.
CN1 pin 1 seems to be erratic. I measured it once, correctly, and it was measured at 33V. After half an hour of being unplugged, I measured it again, and it turned out at 17.2V. It seems to be steady after that.
Red to black wrote:CN1 pin 1 seems to be erratic. I measured it once, correctly, and it was measured at 33V. After half an hour of being unplugged, I measured it again, and it turned out at 17.2V. It seems to be steady after that.
That is quite a variation Aidan, although the output of the chopper transformer is classed (named in the manual) as unregulated it is still actually regulated via the primary side of the SMPSU, albeit maybe not as tightly as the secondary regulated supplies via the fixed regulator on the secondary side.
I would not expect to see such large variations, first off are you sure your multimeter is okay ?
If you are sure your multimeter is definitely okay then you might have a problem in either the STR 1006 chopper IC itself or a problem in the feedback loop.
I will have a closer look at the circuit later on.
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