ADA microtube 200 power amp - Weird Gear Problems and Solutions

Started by chrish, January 06, 2017, 10:14:55 AM

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chrish

I own an old ADA microtube 200 power amp that has seen years of good service, but now it will not power up and stays in protect mode.

A web search offered up with the solution to my particular issue.

Appariently the brighness of neon protect light is somehow tied to under current detection and that under current keeps the machine in protect mode.

Over time, that neon light gets dimmer.

The solution is to buy a 75 cent neon light, pay the 5 dollar shipping fee, and solder it in. Simple or...

do what one guy on the web did. Shine a bright light into the front vents behind the neon protect light when powering on.

I tried it and to my surprise, it works.

Any other simple fixes to quirky machines out there?

Elantric

QuoteI own an old ADA microtube 200 power amp that has seen years of good service, but now it will not power up and stays in protect mode.

http://adadepot.com/index.php?topic=148.0
Microtube 200 (MT-200) Schematics
ADA Microtube 200 Audio Board Loading Chart.pdf
ADA Microtube 200 Burn In Procedure.pdf
ADA Microtube 200 Power Supply.pdf
ADA Microtube 200 Chassis Assembly Drawing.pdf
ADA Microtube 200 Primary AC Wiring.pdf
ADA Microtube 200 Audio Channel A.pdf
ADA Microtube 200 Audio Channel B.pdf
ADA Microtube 200 Pots & Jacks Board.pdf
ADA Microtube 200 Pots & Jacks Board Wiring.pdf
ADA Microtube 200 Wiring Harness.pdf
ADA Microtube 200 Power Supply Unit (PSU) Assembly Drawing.pdf
ADA Microtube 200 Power Supply Unit (PSU) Loading Chart.pdf


http://adadepot.com/mods/mt200/ADA-Microtube-200-power-supply.pdf
Schematic

"NE1" is a common NE-2H Neon Bulb
"T2" is a 287022 Photo sensitive switch
QuoteAny other simple fixes to quirky machines out there?

get a new NE-2H Neon Bulb here
http://www.jameco.com/z/NE-2H-C2A-Lamp-C2ANe-2H-Neon-65-120VAC-1-90-mA_210315.html?CID=GOOG&gclid=Cj0KEQiAnb3DBRCX2ZnSnMyO9dIBEiQAOcXYH5TOeZVElp44ZhwguWmJjKcUdDKSh4V990KZy1hL0psaAlKP8P8HAQ



QuoteOver time, that neon light gets dimmer.

same issue exists for old Fender "Tremolo bugs" - over time, often the glass Neon bulb may leak NEON and diminish its Light intensity output 

chrish

That's a great resource site for us ADA owners. Besides the ADA power amp, i have the ADA MP-2 preamp, which also has many analog fx.

Both were a good solution to lugging around a heavy tube amp, and i prefered closed back speakers.

Thanks for posting that link.

chrish

Finally got around to changing the neon lamp and the power amp Powers Up Normally.

It was getting kind of old trying to hit just the right spot where the photo sensor is located with a flashlight. :)