Am I reading this right ?

I pulled a 7A 125V fuse from a G-7000 (F604)

Printed on the board is 7A 120V which I assume to be correct .

Service manual shows 10A 100/120V in it's place



While the schematics shows 7A 120V to back up the board text



As what I have is suspect I would like to replace it with what would be correct .I presume these are fast blow ? Any thoughts ? Any suggestions on best suppliers would be muchly appreciated as well as I don't come up with many searching Google .

Cheers

Voltage is not of concern on fuses. The fuses you find now will be 250V. The amperage rating is what is important. Finding discrepancies between manual and silkscreen is not unusual. I would go with what was in it. A lesser rated fuse is always safer when in doubt.

Note that the type of fuse should definitely not be 'Slo-Blo' - but rather 'quick blow' and even better Quick Acting (= very fast blow).

As KB says providing the voltage rating is at least 125V and the current rating is correct - you are good to go.

Palmer it's interesting we are both working on the same kind of receiver but in different places on earth
Is your G-7000 sick ? Lol

Thanks you all for the replies .

But it appears we have a sick 7000 here . The fuse blew just as I touched the old bias trimpot . I since have replaced the trim pot and installed the new fuse hoping I could just move forward . Not the case ....... Seems when I power the amp up now it goes half power for a sec and smokes from the transformer side :thumbsdn: So Is this an issue with the fuses ? Doubtful but you never know . Did I have more damage when the original fuse blew ? I suspect, but not sure where to start looking . New trimpot tests fine .

As a footnote I see no burn marks on any of the boards and the new fuses are in fact 7A 250V

Any suggestions would be awesome at this point .

Cheers

sansuilove said:

Palmer it's interesting we are both working on the same kind of receiver but in different places on earth
Is your G-7000 sick ? Lol

Click to expand...

Hey sansuilove , where are you located ? Maybe I should send this basket case to you for a boat anchor ? :lmao: :lmao:

palmer67 said:

Thanks you all for the replies .

But it appears we have a sick 7000 here . The fuse blew just as I touched the old bias trimpot . I since have replaced the trim pot and installed the new fuse hoping I could just move forward . Not the case ....... Seems when I power the amp up now it goes half power for a sec and smokes from the transformer side :thumbsdn: So Is this an issue with the fuses ? Doubtful but you never know . Did I have more damage when the original fuse blew ? I suspect, but not sure where to start looking . New trimpot tests fine .

As a footnote I see no burn marks on any of the boards and the new fuses are in fact 7A 250V

Any suggestions would be awesome at this point .

Cheers

Click to expand...

What happened when you touched the 'old bias trimpot' should have told you something! :sigh:

Change the bias trimpots for new ones. - make SURE you set them for minimum bias before turning on.

Well , changed the trip pots to multi turn units , double checked output transistors which show all good. Checked and replace anything needed on the driver board and updated transistors to new .

When I hit the power I get nothing..... no protection rely , nothing .

Where do I start now ?

Fuses test fine . Forgot to mention that ...

Like many of the higher powered units this receiver has a 'soft start' relay (RL602). When you turn the receiver on initially there are 2 x 8.2Ω parallel connected resistors (R601 & R602) in series with the transformer primary winding. This resistance limits the current in the first couple of seconds after switch on so that the surge current is reduced. After that the resistors are shorted by the soft start relay contacts and full power is applied to the receiver. There are other relays that connect the speakers after a longer period - don't confuse the function of these relays.

If you are getting nothing at all power on, the above circuitry needs to be checked. Do not assume anything - double check mains fuse F604 (7A) and F-602 & F-603 (1A) as these provide power to the soft start relay coil to energise it, remember fuses can 'look' fine but actually be blown. :yes:

The fault you describe suggests either F604 is blown, Soft start resistors are open circuit, wiring associated with the transformer is unplugged or disconnected somehow, OR the mains power transformer is open circuit - this last would be very bad - but thankfully is unusual.

You will very likely need to check mains voltages BE CAREFUL !

Thanks for the reply and suggestions John !

I did find one of the 8.2Ohm resistors to be bad . Here's fingers crossed hoping that's as far as the damage has gone .

I've done some searching and not finding suppliers for theses . Any suggestions on where to buy online ?

Thanks again !

This is what you need...

http://uk.mouser.com/ProductDetail/...EpiMZZMsPqMdJzcrNwqvHBJhRX3buCR%2bN%2bQpkyX8=

This is an 8.2Ω, 10 Watt ceramic cased power resistor.

I haven't been able to properly check if these ones are the right physical size - please review the information on the linked (Mouser) page and the link to the data sheet contained therein.

Oh, and change both of them - you never know when the other one might give up.

Thanks again John ! A newbie question here ...... Is it save to replace the 7 Watt resistor with a 10 Watt with the same Ohm value shown via your link ?

Hyperion said:

This is what you need...

http://uk.mouser.com/ProductDetail/...EpiMZZMsPqMdJzcrNwqvHBJhRX3buCR%2bN%2bQpkyX8=

This is an 8.2Ω, 10 Watt ceramic cased power resistor.

I haven't been able to properly check if these ones are the right physical size - please review the information on the linked (Mouser) page and the link to the data sheet contained therein.

Oh, and change both of them - you never know when the other one might give up.

Click to expand...

palmer67 said:

Thanks again John ! A newbie question here ...... Is it save to replace the 7 Watt resistor with a 10 Watt with the same Ohm value shown via your link ?

Click to expand...

Yes it is, 7W or 10W is only a maximum rating, so in this instance, and this particular use of power resistors, it is OK