Identifying Part from Schematic

[paulstef]

Re: Identifying Part from Schematic

tested the filter caps and they seem fine, kinda of torn the transformer apart now !! well just the outer layers to see if there was a short up top.

Well another lesson for the future, ill see if I can put it back together later and tried without connecting to switch. Erm would I just wire directly to the socket bypassing the voltage selector?

I would probably disconnect the transformer completely and measure resistance of primary first before continuing to blow up fuses...

But from what you describe it really seems to be your transformer. I think I never had a faulty low frequency transformer

[stj]

Re: Identifying Part from Schematic

you could just put a 200v 25a rectifier in knowing it's over-rated.
got a foto of the one you have for size comparison?

btw, shit design - it needs a couple of fuses on the outputs from the rectifier or caps.
as it is, if you have a shorted output transistor it will overload everything until the mains fuse blows - or something else does!

[paulstef]

Re: Identifying Part from Schematic

you could just put a 200v 25a rectifier in knowing it's over-rated.
got a foto of the one you have for size comparison?

btw, shit design - it needs a couple of fuses on the outputs from the rectifier or caps.
as it is, if you have a shorted output transistor it will overload everything until the mains fuse blows - or something else does!

I thought he had the secondary disconnected from the board...

[mikay786]

Re: Identifying Part from Schematic

Yep disconnected output side so just transformer on its own

[mikay786]

Re: Identifying Part from Schematic

you could just put a 200v 25a rectifier in knowing it's over-rated.
got a foto of the one you have for size comparison?

btw, shit design - it needs a couple of fuses on the outputs from the rectifier or caps.
as it is, if you have a shorted output transistor it will overload everything until the mains fuse blows - or something else does!

I put in a 400v 25a rectifier, then found out I have a dead transformer. Lesson is always test transformer before worrying about and spending money on things further down the line.

[mikay786]

Re: Identifying Part from Schematic

I would probably disconnect the transformer completely and measure resistance of primary first before continuing to blow up fuses...

But from what you describe it really seems to be your transformer. I think I never had a faulty low frequency transformer

This is my 2nd in a month!

[stj]

Re: Identifying Part from Schematic

good, based on statistics the rest of us wont see one for a year!

[budm]

Re: Identifying Part from Schematic

If you disconnect the primary winding from the circuit and then check the resistance between the terminals where the primary winding wires of the transformer were connected to, the resistance should show infinite resistance, but more likely you have bad transformer with shorted turn.

[mikay786]

Re: Identifying Part from Schematic

Have done, on the AC socket it's 0.L on all points. On voltage selector is 0.L on points, aside from 2 which depending on position of switch, so that seems fine.

The primary windings on transformer all have resistance with one another.

Any idea on a replacement transformer? I'm guessing it's difficult due to dual different output voltages, 55ac and 12vc?

Would it be possible to use two seperate transformers? I have plenty of room and can mount another inside chassis.

[paulstef]

Re: Identifying Part from Schematic

The primary windings on transformer all have resistance with one another.

Would it be possible to use two seperate transformers? I have plenty of room and can mount another inside chassis.

Just out of curiosity, what resistance do you measure? And what fuse did you use?

I'd say it's not impossible to use separate transformers, you'd need to find the right wattage...

[mikay786]

Re: Identifying Part from Schematic

I'll check for you tommorrow Paul.

What options do I have for this transformer, I'm willing to put £100 towards a transformer.

Is a repair feasible, professional rewind?

[budm]

Re: Identifying Part from Schematic

The smaller transformer 12-0-12 (24V center tap) 2 A will be fine.
The larger one 40-0-40, 7~8A will be OK. 40V will give DCV on the filter cap about 56VDC (40V * 1.414), in case if the line Voltage goes up by 20%, the Voltage on the cap will be about 67V (48V *1.414) , the filter cap is rated at 80V so you will still have some head room left.

[mikay786]

Re: Identifying Part from Schematic

So will that be for two seperate transformers?

[budm]

Re: Identifying Part from Schematic

Yes. But you should try to locate the original one first, I will not use two transformers in customer set or sell it using two transformers.

[mikay786]

Re: Identifying Part from Schematic

So just spoke to a few transformer places and one saying roughly around £150 for a rewind on a laminated unit.

The 2nd place I called (http://www.jmstransformers.co.uk/pages/rewinds.php) are saying they can build a new 600va one for around £90 and a rewind wouldn't be much cheaper than a new one. I'm ok to spend upto a £100 so that sounds ok to me?

He wants me to send over specs and photos

600VA Shielded Transformer

Dual Primary (4 cables (1 split with thermal fuse) (115-230v)

6 Output Cables
2 x 55ac (8A)
2 x 12vc (2A)
2 x GND

Is that ok for specs, or anything I'm missing that they would require?

[budm]

Re: Identifying Part from Schematic

https://www.badcaps.net/forum/showpo...56&postcount=9

I still have doubt that it should be 55V, and 55V*8A*2 will be much higher than 600VA.
BTW, what is the output rating of this sub woofer?

[mikay786]

Re: Identifying Part from Schematic

360w RMS

Uses 2 x 12" Drivers, class A-B Amplifer

Will it being overpowered be harmful, or can we just class it as having room to spare?

[budm]

Re: Identifying Part from Schematic

@55V there is not much room for error, especially if the line Voltage goes up, caps are only rated at 80VDC (55V *1.414 = about 78Vdc) so the circuit probably not designed for Voltage that high.
I would use 40V-0-40V.

[mikay786]

Re: Identifying Part from Schematic

I told them what you said so they had me send in the old transformer and they reverse engineered it to original spec. I've got the replacement in a couple of days ago so will get it fitted as soon as I get time. Will need some help when reinstalling as the colours don't match on new transformer!

[mikay786]

Re: Identifying Part from Schematic

Quick question, is this a regular film cap or a suppression film cap?




Looking to buy this to replace - http://uk.farnell.com/epcos/b32912a3...rad/dp/2469104 which is a suppression one.