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Lambda MM-1 Modulation Scope Info Wanted




 
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Author Topic: Lambda MM-1 Modulation Scope Info Wanted  (Read 2278 times)
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Chuck WB3LGG
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« on: October 24, 2009, 07:40:49 PM »

I have this Lambda MM-1 scope and it recently quit. I'm looking for a schematic and anything else to help me to repair this item. It is very small (1 1/2 Inch display)and sits on top of my 32V2.
I did look inside and found a split capacitor and low emission on the 6C4 which I believe is being used as the HV rectifier. After replacing both these items, I now have a very faint trace.
I see that this has been worked on before and don't know what others have done in the past..
Any help or information is appreciated...
Thanks,
Chuck   WB3LGG
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WB6NVH
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« Reply #1 on: October 26, 2009, 04:24:05 PM »

I have a Lambda MM-2 and the documentation for it, would that be of any help?  The MM-2 was a kit consisting of a small 902 CRT with a 6C4 as the rectifier/sweep section, the grid of the 6C4 being used to produce a "sort-of" 60 Hz sawtooth wave as well as a retrace blanking function.

In mine, I found that all of the capacitors were bad, and wasn't surprised when I found they were branded "Micamold."  I suspect you will need to replace all the capacitors in this unit and also check the resistors for accuracy. The highest voltage is approx. 650 Volts.
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Geoff Fors
Monterey, California
Chuck WB3LGG
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« Reply #2 on: November 12, 2009, 12:33:07 PM »

Thanks for your reply, Sadly I'm just catching up with it..  Someone had told me about the MM-2 and I went on a search.  I talked to Pete (Manualman) and he looked into the MM-2 which he does have on hand and it uses the same CRT and 6C4. He told me that it was a kit which explains the poor workmanship! I did order a manual from him and also picked up a spare CRT on ebay which I'm waiting to arrive.  Thank you for your offer,  73,  Chuck
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Patrick J. / KD5OEI
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« Reply #3 on: November 12, 2009, 09:44:22 PM »

wow. There's a NOS 902 for $9.99 on the bay. I figured they'd cost more. There is also a $40 one.

Well please post pics of the scope, maybe before and after!! - and if permitted the schematic would be interesting.
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