Hitachi DV-PF4E VCR/DVD Combo - no power

[Markie76]

Hi,

I have a Hitachi DV-PF4E VCR/DVD Combo unit which is dead - no power.

Last used and working ok about a year ago.

Then it has stood unused in the tv cabinet unplugged from the mains.

I went to use it this week, plugged it in and nothing happens, no display/lights, no response when pressing standby button.

Opened to check and fuse ok, ac supply ok, caps all look ok, other components & pcb look ok with no trauma visible.

Any cause for it to just go 'bad' by not being used for a year?

Thanks,

Mark

[stj]

Re: Hitachi DV-PF4E VCR/DVD Combo - no power

startup capacitor in the psu is dead
it will be small - 10uf > 47uf usually
post a foto

[Markie76]

Re: Hitachi DV-PF4E VCR/DVD Combo - no power

startup capacitor in the psu is dead
it will be small - 10uf > 47uf usually
post a foto

Hello,

Thank you for your reply.

There are three which fit the range;
10uF 50v
22uF 50v
10uF 16v

See 3rd attached pic with capacitor values shown.

Thanks,

Mark

[vinceroger69]

Re: Hitachi DV-PF4E VCR/DVD Combo - no power

no 3 picture top right cap have you checked or changed that

[Markie76]

Re: Hitachi DV-PF4E VCR/DVD Combo - no power

no 3 picture top right cap have you checked or changed that

Hi,

Thank you for your reply.

No I haven't done anything except for an AC & visual check.

What is the best way to check/test it?

Thanks,

Mark

[R_J]

Re: Hitachi DV-PF4E VCR/DVD Combo - no power

Your power supply is slightly different than the one in the service manual, I'm not sure if the designations are the same as yours.

Look for C1032, Likely the (10µf/16v), replace it, then check the two resistors R1011 (1.3Ω/1w) off the source pin of the mosfet and R1043 (2.7Ω/1w) between the + of the 100µf/400v cap. and the transformer, if the resistors are ok, it is likely the power supply is just not starting up.
Also check if you have any voltages on the two plugs, CL051A and CL052A, There is also a zener diodes (D017) in the secondary, check that it is not shorted.

[stj]

Re: Hitachi DV-PF4E VCR/DVD Combo - no power

probably the 10uf cap next to the big 400v one,
i cant see a chip - got any underside photo's ?

[Markie76]

Re: Hitachi DV-PF4E VCR/DVD Combo - no power

Your power supply is slightly different than the one in the service manual, I'm not sure if the designations are the same as yours.

Look for C1032, Likely the (10µf/16v), replace it, then check the two resistors R1011 (1.3Ω/1w) off the source pin of the mosfet and R1043 (2.7Ω/1w) between the + of the 100µf/400v cap. and the transformer, if the resistors are ok, it is likely the power supply is just not starting up.
Also check if you have any voltages on the two plugs, CL051A and CL052A, There is also a zener diodes (D017) in the secondary, check that it is not shorted.

A number on the pcb which looks like a P/N: BH951 0F01 02

C1032 is the small cap in top right as mentioned by vinceroger69 & stj - it is 10uF 16v.

I'll try to test it out later or tomorrow.

probably the 10uf cap next to the big 400v one,
i cant see a chip - got any underside photo's ?

Yes the small cap next to the 400v one is the 10uF 16v one.
No chips on it just transistors, large mosfets (?) and a 4 pin rectangular thing - see pics.

Thanks.

[lotas]

Re: Hitachi DV-PF4E VCR/DVD Combo - no power

Diagram of your power supply page 38

[Markie76]

Re: Hitachi DV-PF4E VCR/DVD Combo - no power

I've finally done some testing.

Capacitor C1032 - top right - 10uF 16v removed and in my multimeter;
Starts at 8.88 and reduces settling at 8.68uF;



Resistor R1011 (brown|orange|gold|gold) shows a changing value in the 2000k range - 1557k, 1605k...



Resistor R1043 (red|purple|gold|gold) shows 02.7 ohms.



Diode D017 shows .155 one way and OL the other way;

[vinceroger69]

Re: Hitachi DV-PF4E VCR/DVD Combo - no power

the capacitor could of failed esr wise the resistor r1011 are you sure of the colours as the calculator here says 1.3 ohms
https://www.digikey.co.uk/en/resourc...tor-color-code

[Markie76]

Re: Hitachi DV-PF4E VCR/DVD Combo - no power

the capacitor could of failed esr wise the resistor r1011 are you sure of the colours as the calculator here says 1.3 ohms
https://www.digikey.co.uk/en/resourc...tor-color-code

Yes, close up pics below.

R1011: brown - orange - gold - gold = 1.3


R1043: red - purple - gold - gold = 2.7


It has what looks like a couple of cracks on the body;

[vinceroger69]

Re: Hitachi DV-PF4E VCR/DVD Combo - no power

in post 10 you say Resistor R1011 (brown|orange|gold|gold) shows a changing value in the 2000k range - 1557k, 1605k...it should be 1.3 ohms

[Markie76]

Re: Hitachi DV-PF4E VCR/DVD Combo - no power

.

[Markie76]

Re: Hitachi DV-PF4E VCR/DVD Combo - no power

in post 10 you say Resistor R1011 (brown|orange|gold|gold) shows a changing value in the 2000k range - 1557k, 1605k...it should be 1.3 ohms

Sorry my mistake I mixed them up!

I've probed them again and getting yet different readings

I'm going to remove them from the pcb to test.

[vinceroger69]

Re: Hitachi DV-PF4E VCR/DVD Combo - no power

Sorry my mistake I mixed them up!

I've probed them again and getting yet different readings

I'm going to remove them from the pcb to test.

for odd readings i just the part best way really if they all test ok put all parts back in heat the psu up with a hair dryer and see if the player now works (some times heating bad capacitors up lowers the esr tempory and allows it too work)

[R_J]

Re: Hitachi DV-PF4E VCR/DVD Combo - no power

It looks like R1011 is open, So I suspect Q1001 (2sk3566) is shorted, if it is shorted, Q1003 is likely bad as and likely more components in that circuit
R1043 (2.7Ω) is ok. C1032 is BAD
With the circuit not working, the main filter cap can remain charged to around 300vdc, this capacitor should be discharged (using a resistor or incandescent lamp can work) If it is not discharged, resistance readings in the rest of the circuit can be effected, not to mention getting a shock or the risk of damaging the power supply

These power supplies are difficult to repair at the best of times, if any component is out of tolerance the circuit won't oscillate

[Markie76]

Re: Hitachi DV-PF4E VCR/DVD Combo - no power

for odd readings i just the part best way really if they all test ok put all parts back in heat the psu up with a hair dryer and see if the player now works (some times heating bad capacitors up lowers the esr tempory and allows it too work)

Thanks for the tip. I tried it but didn't make any difference.

It looks like R1011 is open, So I suspect Q1001 (2sk3566) is shorted, if it is shorted, Q1003 is likely bad as and likely more components in that circuit
R1043 (2.7Ω) is ok. C1032 is BAD
With the circuit not working, the main filter cap can remain charged to around 300vdc, this capacitor should be discharged (using a resistor or incandescent lamp can work) If it is not discharged, resistance readings in the rest of the circuit can be effected, not to mention getting a shock or the risk of damaging the power supply

These power supplies are difficult to repair at the best of times, if any component is out of tolerance the circuit won't oscillate

Oh, doesn't sound encouraging.

BTW when I tried the hairdryer I measured the big 400v cap and plugged in it was only reading 209/210v.
When unplugged it wasn't holding a residual charge - just showed up as 90-100ma 20 seconds after unplugging it. Does that mean it's dried up/bad?

[Markie76]

Re: Hitachi DV-PF4E VCR/DVD Combo - no power

Diagram of your power supply page 38

Thank you - I will have a look.

[vinceroger69]

Re: Hitachi DV-PF4E VCR/DVD Combo - no power

i would do as rj suggests first, replace thet small capacitor remove and re test r1011