Rowe AMI jukebox amp

[richfoub]

Hey guys can someone email me some help, i bought a Rowe r-4359a jukebox amp ,i am going to convert it to a home audio amp it uses 7868 tubes, does anyone have a schematic??

cheers

 

[rdf]

Yep, but not at work. Posting so DIYA will remind me when I'm home tonight.

 

[Enzo]

I don't remember that amp specifically , but jukebox amps in general usually have some sort of automatic level control, an AVC. You would likely want to defeat that circuit or remove it.

 

[rdf]

Finally remembered. I'm 95% certain the schematic below is identical to the 4359A but it's been months since last playing with this hardware.

An externally hosted image should be here but it was not working when we last tested it.

 

[dehtak]

rowe ami mm4

Hi,
i search schematics for rowe ami mm4 with 7868 pentode
I have from this amp , outputs transformers.
Thank you.

 

[scooperman]

OK, I give up. How do I get that thumbnail schematic to enlarge, it doesn't work for me. Got a direct link?

 

[kevinkr]

OK, I give up. How do I get that thumbnail schematic to enlarge, it doesn't work for me. Got a direct link?

Nor me...

 

[dehtak]

Hi,
i search schematics for rowe ami mm4 with 7868 pentode
I have from this amp outputs transformers.
Thank you.

I dont no this output (sekundar) kabel from transformers
this color ist:
Black
brown-white
white
yellow
green
green-white
green-yellow

 

[anilkumarbn]

Hi All, I am new to this forum. Please.. can any one help with Rowe r-4359a schematic diagram. Thank you... Anil

 

[aardvarkash10]

go to this website

A goldmine.

Don't try and communicate with Vern - he is somewhat terse.

 

[anilkumarbn]

Hi Aardvarkash10,
Thank you so much..... for your quick response. Indeed link is a goldmine for vintage lovers...
Thanks again and Happy New Year...
Anil

 

[Petjo]

Hallo to All of you, I'm new to this forum.
Please, can any one help with ROWE AMi R-4359A schematic diagram.
I would like to repair this amp.
Thanks a lot

 

[rdf]

Hallo to All of you, I'm new to this forum.
Please, can any one help with ROWE AMi R-4359A schematic diagram.
I would like to repair this amp.
Thanks a lot

My memory of this amp is dimmer than six years ago but I believe this was very close to mine. Due diligence circuit sleuthing recommended.

 

[Petjo]

Hello rti,
Thank you for your quick response, that helps me alot.
Petjo

 

[OldHector]

I also have one of these amps (R-2620).
I was looking at the tertiary winding on the OPT, and saw that some had wondered about using it for CFB. Has this been tried? It has a center tap, and supposedly is for 70v line out. The center tap is linked to the speaker ground tap on the secondary.

 

[rdf]

I recall rumours to the effect Bob Carver used that topology in his rebuilt Rowe amps. Couldn't confirm it.

 

[PRR]

...the tertiary winding on the OPT....wondered about using it for CFB... supposedly is for 70v line out. ....

If it is 70VCT--

The peak voltage across half the winding is 49V. This at the cathode increases the required grid swing.

The stock grid swing is about 18V peak. (The 14V test-point is dragged down by meter loading.)

So we need 18V+49V= 67V peak grid swing. On two grids. From a cathodyne biased at only 56V per side. It can't reach full output.

And what you might gain by a smaller NFB loop, you lose in less NFB in the global loop. As-is, it has very little global NFB. With CFB it has "none" in the global loop. (Unless you change global NFB for much lower gain, forcing a larger input signal and more work for the stage before this.)

Some amps beg for change. IMHO this one doesn't.