RMI 300A Eletra Piano output transformer?

[matthewdfisher]

Hello all, trying to get my RMI 300A Electra-Piano back to where it should be, but it is really, really quiet. I don't think its leakage, just really low output. I have some service notes that indicate the "impedance matching transformer," part W1713, is likely at fault. The note suggests replacing with part #222-1037. Mine has part #222-1037, so it was either replaced or made after RMI switched parts. This part is the last component before the output cable. However, the schematics contain no specifications for this part, and my googling has turned up nothing on either part number. Anybody have any info, or (yeah, right!) a spare sitting around? Or perhaps any other suggestions? Could I just try to swap in another output transformer? Thanks in advance!

Matt

[Enzo]

Schematic?

Exactly why do we think it is the transformer. They do fail now and then, but are the most reliable parts in an amplifier.

[matthewdfisher]

Schematic?

Exactly why do we think it is the transformer. They do fail now and then, but are the most reliable parts in an amplifier.

Well, I bought the schematic from Music Parts and they don't seem to be freely available on the internet, so I didn't want to just post it.. Don't want to step on toes!

The only reason I thought that it's the transformer is because of the service note.

[Enzo]

Since you have the drawing, look back before the transformer and see if signal levels in the circuit are strong or are they also diminished there?

[matthewdfisher]

Will do tonight and report back.

[matthewdfisher]

Well, I didn't get a chance to look at the instrument last night, but Allen Organ themselves sent me the following, so I feel comfortable posting it here.

Analog Matching Transformer Details.pdf
RMI 300A Schematics.pdf

[g1]

From the info about the transformer, it sounds like you can just bypass it to test.

[matthewdfisher]

Well, I did bypass the transformer and essentially got no audible signal at all, so it seems like it is working. Any suggestions on what I might look at next would be most welcome...

[g1]

Start with the most basic, it must be something common to all 61 oscillator sections. Do you have a good 25VDC coming out of that connector shown as 'A' on the schematic?

[matthewdfisher]

Solid 24.7

[matthewdfisher]

Well, I decided to go ahead and build the impedance matching circuit, but I don't see where to get the 12v B+. Can I tap into the 25v and halve it with a two resistor voltage reduction mod?