700B blew one Right channel 5A supply fuse

Ok, drop all 4- 5 amp rail fuses, turn it back on , all the way, then check each post in the rectifier...ac fot the ac of course and DC for the DC...
 
NavLinear said:
The collector should be isolated from ground by the mica isolator / Sil-Pad.
Click to expand...

62vauxhall said:
Good point, did not think of that.
Click to expand...

I think what Nav is getting at is you shouldn't have a short from the case of the 410's to ground. Is that with the rail fuses pulled? If it is, pull it and then measure from the socket's collector lead to ground... if you still have a short at that point, then it could be any of the outputs having a failure on their insulator. Pull them one at a time until the zero ohm to ground goes away.

But again all depends on if you had the rail fuses in or not. With the rail fuses in, your "short" could very well be residual voltage coming from the PS caps.
 
laatsch55 said:
Ok, drop all 4- 5 amp rail fuses, turn it back on , all the way, then check each post in the rectifier...ac fot the ac of course and DC for the DC...
Click to expand...

Fuses are out - variac at 120 volts.

Did I understand right - determine which are AC and which are DC posts on the rectifier?

DC: 142.4 volts
AD: 107.0 volts
 
Yes, but reference ground at the bus bar and check all 4 posts, also was the ground check result on the 410 case zero ohms or OL?
 
Check the rectifier posts one at a time, then power down again, with rail fuses out you should have OL on the meter when referenced to ground with the red lead on the 410's case....
 
laatsch55 said:
You did have the grey sil-pads under the 410's????????
Click to expand...

They've been used more than once and that may be a problem - aka the condom syndrome.

I'm thinking that for trouble shooting it's ok to use the Sil-Pads multiple times but I've never done that so it's something to look into.

Jer has a good point - we'll need to wait and see what Gary says. I think he is bleeding the reservoir caps with a 10 ohm resistor.
 
laatsch55 said:
Yes, but reference ground at the bus bar and check all 4 posts, also was the ground check result on the 410 case zero ohms or OL?
Click to expand...

Ground to bus bar - variac at 117 volts - fuses out.

DC post voltage 83 volts
AC post voltage 62.3 volts

410 case check was ZERO ohms and fuses were in then.
 
No minus volts on one of those posts ?? Check that 410 case now with no fuses in....
 
jbeckva said:
Pull fuses.. recheck. If you still have zero, insulator breakdown... or those 4uF caps that go between the tie points (the pos and neg rails) and ground. Or a cat whisker wire ya can't see yet... :)
Click to expand...

Fuses are out still get zero OHMS.

4uF capacitors????

tomorrow durung the day I can fire up my air compressor and blow out any debris. I live in a second floor condo and think running an air compressor after 7PM contravenes some strata rule.
 
Jer is referring to the caps on the back wall wher those pesky diodes are, yours are .33uf I believe...
 
OK, the 410 short is a very bad thing, is it on the right channel?
 
62vauxhall said:
Fuses are out still get zero OHMS.

4uF capacitors????

tomorrow durung the day I can fire up my air compressor and blow out any debris. I live in a second floor condo and think running an air compressor after 7PM contravenes some strata rule.
Click to expand...

Pull the 410 where you are getting the zero from, then measure between it's collector lead (or where the screws normally go) and ground.

These caps here ... the orange guys. Also those diodes that go between the leftmost and rightmost tiepoints on the center terminal blocks.

IMG_9871.jpg
 
laatsch55 said:
Jer is referring to the caps on the back wall wher those pesky diodes are, yours are .33uf I believe...
Click to expand...

Do you mean the 4 capacitors I attached to the rectifier posts? I can't tell what value they are.

If not, the only other capacitors (not on the board) are one between the AC leads to the rectifier and those in the area of the input jacks.
 
You must log in or register to reply here.
Back
Top