vintagejim59
New Member
i have recapped and replaced transistors on marantz model 1070 now the dc offset will not adjust down to 0mv why thanks for any advice
Marantz model 1070 dc offset
- Thread starter vintagejim59
- Start date
Register to hide this ad
List the parts you replaced and what you used to replace them with.
Post a couple good close up pics of the top and bottom of the board so they can be checked.
You didn't say whether it was working before you started replacing parts. Did Bias set ok? What was the offset before you started on it?
Curious as to how low you can adjust the offset. 10mV?? or 30V or...
Lavane
Lunatic Member
That would be good info to know.
To the OP, have you read through the service manual? I've never owned a 1070, but not all manufacturers state in there service manuals to set the DC offset to 0. Anything up to 30mv isn't bad.
Those trimmers Marantz used in the 70's didn't age well. I've run across enough of them that wouldn't hold bias or DC offset when adjusted to spec.
They would slowly drift out of spec. I just replaced them on sight with either single or multi turn Bourns trim pots.
Lavane
Lunatic Member
So +/- 5mv is where it should be set then. It's been ten years or so since I worked on any Marantz gear. I didn't think it was 0mv.
I used to restore and collect earlier Marantz equipment through '74.
flatwound
Active Member
Is there any significance in the specification mentioning the use of a VTVM vs. a voltmeter ? I seem to remember (from long ago) that a VTVM usage has an affect on the reading (?) .
Use of a VTVM was because at the time, measuring low voltages (like 10 mV) was nearly impossible and not accurate with a regular meter. DMM and modern equipment has changed all that. VTVM should have no affect on the reading. My 2 nickels.
