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SAE Mark III / Mark Three meters fixable?

redondo2018

redondo2018

Active Member
So I recently got a one-previous-owner silver Mark III (with 2 meters and 4 knobs on the front) that cosmetically and audibly is pretty much as good as can be (all original), with the main issue that the meters seem to be completely dead (obviously any 50 year old piece of gear needs a recap / bias check, but I'm a bit of a if-it-ain't-broke kind of guy). The meter knobs on the front don't do anything to help. Been trying to find something online to see if the meters are fixable but haven't found anything... (running my also recently acquired all-original SAE 2300 while I figure this out - and the "meters" work on that one ;-)).

I'm ok at cleaning / swapping out parts, but that's about my limit. I'm in the PDX area. Any thoughts appreciated!
 
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You can try cleaning and exercising the meter switch. The next step would to make sure the signal is getting to the meter board. If the armature of the meter is open there's not much you can do except find new meters.

Craig
 
llwhtt said:
You can try cleaning and exercising the meter switch. The next step would to make sure the signal is getting to the meter board. If the armature of the meter is open there's not much you can do except find new meters.

Craig
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thanks - my guess is that they are fried, but I'll try those steps
 
A quick way to check the meters themselves.. Switch off the machine, set your multimeter to resistance (ohms) in the smales setting. Then tap the contacts of the meter with the leads of your multimeter (like you where measuring resistance over the meter). If it's working at all, it will slam right to the end of the scale.
 
I thought the meters were dead in my Mark 1M preamp, but it turned out they had just become unplugged from the board. I happily discovered this while recapping it.
Sometimes it's the simple thing!
 
llwhtt said:
Also the meter level trim pot may be bad/oxidized, been there done that.
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so good news - both meters jumped to the right when I touched the contacts! thanks for tip. Images are what I see when I open up the bottom cover. Other than blow dust out and replace the meter bulbs with blue LEDs (which BTW is useless because the tinted meter glass makes it impossible to see the meters, so those are going to have to be replaced again with bright white unless someone has any other color ideas...). I'm guessing that red goop is old glue (it's not really sticky anymore, it's hardened) - is that something I need to be concerned about? I'm going to DeOxit the meter pots next and see if that does anything.

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The "red stuff" you are talking about is on the transformers and wires? If so that's varnish left over the manufacturing of the transformers, no concern. So your meters seem to be OK, clean/replace the trimmer on the circuit boards.
 
llwhtt said:
The "red stuff" you are talking about is on the transformers and wires? If so that's varnish left over the manufacturing of the transformers, no concern. So your meters seem to be OK, clean/replace the trimmer on the circuit boards.
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Ok, varnish, makes sense. Are the trimmers the kind of "rabbit-looking" metal part on the board? Looks like the connection from the post that connects the white wire from the meters goes there. Would I DeOxit that?
 
The trimmers are on the edge in the middle next to the red/gray wires, yep squirt them with Deoxit and then exercise.
 
Np!

Yes you can treat the trimmers like that, but only if you are able to recalibrate the machine after. "Setting them back" by sight is not likely to bring optimal results.

And are those light blue capacitors Philips'es by any chance? In that case you would really want to replace them.
 
Okke 70s said:
Np!

Yes you can treat the trimmers like that, but only if you are able to recalibrate the machine after. "Setting them back" by sight is not likely to bring optimal results.

And are those light blue capacitors Philips'es by any chance? In that case you would really want to replace them.
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they say "Holland" so yeah, guess so. if I can get the meters working, I think it's worth getting this recapped, it's in great shape otherwise (even the original wood case is in great shape)
 
Have to really crank it because my Cerwin Vegas are so sensitive, but we have movement! I sprayed the trimmers but didn't exercise them, so not sure what did it

 
What were the original bulbs? Can you get those? These with the smoked glass in front of the meters are pretty cool with the original look. But if the bulbs aren't available, there should be something bright enough to be able to have something between subtle and wake the dead lighting on those meters. Hopefully you get something you like. Be sure to post what it looks like and what you used when you get that task done
 
For the work required to get the boards in position to replace parts I would replace all of the electrolytic capacitors and carbon comp resistors. The capacitor next to the carbon comp resistor is usually very discolored for some reason, it's the only one passing an audio signal so maybe that's the reason, who knows? Make sure the meter trimmer is working or maybe just replace it.

The lamps are just good old #47s kludged into place on top of the meters with RTV. I don't think the meters were designed to be illuminated so the results are so-so.
 
..and if those are the small bleu ITT zenders, those as well. Yes it always goes this way (with me anyway) .
 
llwhtt said:
For the work required to get the boards in position to replace parts I would replace all of the electrolytic capacitors and carbon comp resistors. The capacitor next to the carbon comp resistor is usually very discolored for some reason, it's the only one passing an audio signal so maybe that's the reason, who knows? Make sure the meter trimmer is working or maybe just replace it.

The lamps are just good old #47s kludged into place on top of the meters with RTV. I don't think the meters were designed to be illuminated so the results are so-so.
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Yeah, it doesn't seem like they were meant to be lit up which is a bit strange - I'll try other colors, but blue certainly doesn't do anything other than make a blue glow without being able to see the meters
 
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