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Old 11-09-2019, 12:37 PM   #21
jinu_j
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Default Re: Shredder very slow to start

Voltage across C1 is 3.31 V.

The violet and grey are from the Photodiode (Paper detection sensor). Marked as C and D in the last image. The voltage across them is 2.25V
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Old 11-09-2019, 12:38 PM   #22
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Default Re: Shredder very slow to start

What's the voltage at the anode of D6 when a sheet of paper is inserted?

Ah now we're getting more critical information. Too many wires going everywhere, no idea where they go...

2.5 volts across the phototransistor is fairly low when paper is inserted IMHO, though it should be just barely enough.

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Old 11-09-2019, 12:41 PM   #23
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Default Re: Shredder very slow to start

voltage at the anode of D6 = 2.23V. Most of the wires are going to the motor. The key wires are the ones going to the IR transmitter marked as A and B and the ones coming from the IR receiver (photodiode) marked as C and D

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Old 11-09-2019, 12:43 PM   #24
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Default Re: Shredder very slow to start

The voltage across C1 is too low, Check R3, R11 & R10. ZD1 will set the voltage across C1, What is the number on ZD1
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Old 11-09-2019, 12:52 PM   #25
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Default Re: Shredder very slow to start

R3 is 48 Ohms. R11 and R10 are 380KOhms. ZD1 is 4742A
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Old 11-09-2019, 12:55 PM   #26
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Default Re: Shredder very slow to start

ZD1 is a 12volt zener, You should have 12 volts across C1. That yellow capacitor across R11/R10 could be open.
Check the a/c voltage between ground/neutral and each side of that yellow cap

Last edited by R_J; 11-09-2019 at 01:03 PM..
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Old 11-09-2019, 12:58 PM   #27
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Default Re: Shredder very slow to start

if D3, D4 are good, as well as ZD1, I hope it's not that yellow capacitor next to R3...
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Old 11-09-2019, 01:02 PM   #28
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Default Re: Shredder very slow to start

Thats a X2 104k 275v Capacitor.
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Old 11-09-2019, 01:06 PM   #29
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Default Re: Shredder very slow to start

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Originally Posted by R_J View Post
ZD1 is a 12volt zener, You should have 12 volts across C1. That yellow capacitor across R11/R10 could be open.
Check the a/c voltage between ground/neutral and each side of that yellow cap
Its 249V on one side and 2.25 V on the other side of the yellow capacitor
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Old 11-09-2019, 01:11 PM   #30
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Default Re: Shredder very slow to start

I suspect the cap is open.
That cap is used to couple the a/c to the diodes, if it is bad/open, you will not get enough a/c voltage to get the 12v needed to operate the circuit. the only a/c getting to the diodes will be through the two 470k resistors. thats is why you only get a couple volts across C1
2.25v a/c feeding the diodes would result in only about 3vdc across C1

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Old 11-09-2019, 01:13 PM   #31
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Default Re: Shredder very slow to start

Ok will replace this cap and then update. Thanks a lot for your help so far.
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Old 11-09-2019, 01:20 PM   #32
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Default Re: Shredder very slow to start

If the other yellow cap is the same or close to the same value, you could swap them to see if the 12 volts comes up. That other yellow cap is for suppling the 24 volts to the relay, so if you do swap the caps you would not get the 24 volts for the relay but should get the 12 volts across C1 This would confirm the cap is bad and the zener etc. are ok.

I would replace both caps if one is bad.
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Old 11-09-2019, 01:22 PM   #33
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Default Re: Shredder very slow to start

can i replace the the X2 104 K capacitor with X2 224 K as i have that in stock, the 104 I will have to order
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Old 11-09-2019, 03:14 PM   #34
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Default Re: Shredder very slow to start

I think in this situation it would be ok to use the higher capacity cap, it is not that critcal a circuit for the capacity of the cap as long as the voltage is high enough

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Old 11-09-2019, 07:35 PM   #35
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Default Re: Shredder very slow to start

IMHO it's ok to use the 224 temporarily as a test though long term it may not be a good idea. Make sure the diodes are good before buying anything, though the capacitor seems most suspicious.
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Old 11-10-2019, 08:54 AM   #36
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Default Re: Shredder very slow to start

Good news. Replacing the capacitor solved the problem. Now shredder is back to full function. I checked the 224 and found that even though it says 224 the actual capacitance was only 104nf. So i guess that is also on its way of failing. So ordered new capacitors to replace both the AC caps.

Thanks a lot for your help
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Old 11-10-2019, 05:10 PM   #37
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Default Re: Shredder very slow to start

Quote:
Originally Posted by jinu_j View Post
Thanks. This is a new shredder and not used much so no issue with gears. I have ordered the replacement CAPS. will replace those and update once done. Thanks folks
That is pretty bad to have new unit with failed dropper cap already.
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