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Help Needed Fisher MPX100

S

Steve O

Super Member
I've got a Fisher MPX100 I'd like to fix up and align. Problem is, the only info I can find is for the early version with the ECH84 tube among other things. I have the later version w/o the ECH84.

I'm willing to pay for info but all searches point to SAMs or Fisher data for the older model. Any leads out there?

TIA
 
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Thanks for the response. I have a feeling finding the correct schematic for this thing is going to be my biggest tuner challenge yet. :worried:
 
Dadbar said:
Does it use that same basic MPX-65 module that was used in all the Fisher 500B/C and Fisher 400 receivers (with 3 12AX7 tubes...or 2 12AT7 and 1 12AX7?)

http://www.mcmlv.org/Archive/HiFi/Fisher500B.pdf
Click to expand...

Unfortunately, no. I'm sure there are some circuit similarities but there's apparently more going on in this thing than in the MPX-65. This uses 2-12AT7s, 1-12AX7, 1-6AB4, 1-6BL8. Also, what appears to be the 38KHz transformer (where diode bridges tie in) has 6 terminals vs 3 on MPX-65. It's also quite the rat's nest underside so tracing out a schematic from scratch is going to be difficult at best if it comes to that...hopefully not!
 
If you do not find a schematic just write down the values of all components, order them and replace one at a time. I did that with an Ampex model 008 tuner with no problems whatsoever.
 
Tube Radio said:
If you do not find a schematic just write down the values of all components, order them and replace one at a time. I did that with an Ampex model 008 tuner with no problems whatsoever.
Click to expand...

Thanks for suggestion but........the need for the schematic is more to understand the circuit and not so much to replace parts. If I understand the basics of the circuit I can come up with an alignment procedure. This involves things like which transformer is 19KHz vs 38KHz, which is SCA trap, how is relay driver configured etc. Looking at the parts in there now, I expect to have to replace only about 3 signal type electrolytics and the PS can.
 
Mission Accomplished

Good news: I found a source for the correct schematic. Bad news: It cost probably not much less than an MPX100 is worth. Ain't this a great hobby?
 
glad you found what your looking for.as for paying almost as much as the mpx100 been there done that.before the wonderful world wide web came along i frequently paid more for manuals from heathkit than the actual gear.goodluck with the mpx:thmbsp:
 
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