Electrohome HVIN-RR75-1 Mains transformer help please

[zen]

Hi all

Customer bought a retro stereo unit from Canada & didn't realise it was a 120V unit.

Need I say more?

Primary winding blown quite badly, therefore trying to work out the secondary AC supplies, of which there are two.

AC2 which are the thicker BLUE wires go through a rectifier, then to a 25V cap, which narrows things down slightly.

AC1 the yellow wires, after rectification go to regulator IC6, which may also be fried.

The appliance is an Electrohome HVIN-RR75-1

[zen]

Re: Mains transformer help please

AC2 after rectification arrives at the audio out chip STA540SAN.

Pulled up datasheet for chip & supply voltage stated as a maximum of 22V

[zen]

Re: Mains transformer help please

AC1 as mentioned after rectifier seems to arrive at IC6, which is a Microne ME6118A33B3G adjustable regulator.

This one might be slightly trickier to pin down.

[stj]

Re: Mains transformer help please

Electrohome used to produce great service manuals - did you search?

[zen]

Re: Mains transformer help please

Connected a Variac to the AC2 terminals on PCB & increase supply gradually.

An AC input of around 12V will result in DC 15V on audio chip supply pins 3 & 13. Will play it safe & start with that.


AC1 I'm not quite sure about.

[stj]

Re: Mains transformer help please

so i just tried to look up that UL code on the transformer.
it seems the UL has sold out and is just another "kosher" mark now.
just go to the website and buy a few, but you cant check one without an account!!
so no use anyway if they cant be verified as real by non-gangsters - i mean non-members

[zen]

Re: Mains transformer help please

Hi STJ no didn't even think to check. Will have a search.

[stj]

Re: Mains transformer help please

AC1 is probably 7v
AC2 is probably 15v

7v is common for driving a regulator for logic circuits.

[zen]

Re: Mains transformer help please

Thanks , i wasn't too far off then

Managed to dig out a transformer I had stripped out of an Onkyo AV system years ago, which has load of outputs.

12V to AC2

10V to AC1

Unit then powered with radio and turntable working, but no CD play.

Started scratching my head thinking supply not correct, or surge has damaged it.

Turned out to be bad contacts on CD turntable motor & a quick spray with some cleaner restored operation.

Result finally after a whole day on this beast.

[zen]

Re: Mains transformer help please

Can't believe this unit.

Meant to be new, fully working, but CD turntable motor lazy.

The turntable motor has no marking to indicate type, therefore modified board to take a physically larger motor, but that didn't work.

As a last resort, I have immersed original motor in WD40 & will leave it overnight, which I'm hoping might restore full operation.

[stj]

Re: Mains transformer help please

wd40 is moisture remover,
you should use 3-in-1 oil instead.

[zen]

Re: Mains transformer help please

Thanks STJ, worth a try.

[zen]

Re: Mains transformer help please

Well tried it all, including injecting very fine watchmaker oil into the motor bearings.

This improved the functionality, but not reliable enough.

I then started searching for CD mechs that use same reader, which is a Sanyo SF-P101N

Found a generic one at ASWO that looked same, except for the spindle & sled motors which were physically larger.

Took a chance, as it was cheap enough.

Fitted & now working on test.