Vintage Asylum

Classic gear from yesteryear; vintage audio standing the test of time.

Return to Vintage Asylum


Message Sort: Post Order or Asylum Reverse Threaded

Mistakes were made... Yamaha CR-1000

47.208.65.165

Posted on June 29, 2020 at 20:00:52
So I installed the power caps backwards... (I know...) In the old Yamaha the forum helped me find TO-3's for a while back.

There is a protection circuit listed in the repair manual.

It flips on amp boards get power but won't bias. Lights out at the front, but maybe someone home? No difference switched or unswitched. The headphones aren't putting out audio and the preamp and radio are dead. Feeling really stupid about this one...

Does anyone have any thoughts where to check. I looked at the fusable resistors and the old diodes, but they test the same on both amp boards, and test ok on the power board.

A little stumped.

 

Hide full thread outline!
    ...
Is there a fusible link in the power transformer?, posted on June 30, 2020 at 07:29:51
mhardy6647
Audiophile

Posts: 13851
Location: New England
Joined: October 12, 1999
Contributor
  Since:
October 23, 2016


That's all I can think of.

Any damage done would've (should've) been between the filters installed backwards and the where the power cord plugs into the wall. ;)
That should narrow things down considerably, I would think.
Indeed, usually the caps pop and that's that -- replace the sacrifical caps and life goes on.
I have a CR-1000, but I bought it rehabbed so I don't really know much about the guts.

You probably have the SM already, but, in case you don't, there's a good looking copy at the link below.

EDIT: The schematic is very clean; the P/S is complicated, I am attaching a screen shot showing the 'back side' of the P/S for various territories; looks like a smattering of "real" fuses therein(?).

Good luck!


all the best,
mrh

 

Tube bridge thing - what is it called?, posted on June 30, 2020 at 18:12:13
That is much appreciated... but crap... In some ways I would prefer a straight up change out.

It is producing some voltage, and the 50V at the power caps from the transformer. The 15-17V off the powerboards is definitely not there, and there is nothing at headphone in (which goes to the powerboard near the power caps). Getting around 8V at the speakers - not consistent across all posts like 8V-8V-8V-8V. More like: 5.6V-7V-6.1V-8V - which seems wrong (this is without tone).

Is it though?

I also can't find any obviously dead resistors or diodes...

Seems like maybe half the windings are good and half not - so the internal fuse in the transformer has gone?

 

RE: Tube bridge thing - what is it called?, posted on July 2, 2020 at 18:53:12
JURB
Audiophile

Posts: 1730
Location: North Ohio
Joined: May 29, 2016
The internal "fuse" is on the primary and is a thermal cutout, unfortunately usually non-resetting.

 

RE: Mistakes were made... Yamaha CR-1000, posted on July 6, 2020 at 22:02:20
Does anyone know which Tamura transformer in production is the right one? I hate to make an educated guess based on specs...

 

Yamaha CR-1000 Transformer, posted on July 9, 2020 at 12:01:36
Yeah - it was already making an intermittent buzzing like maybe that fuse was going. Anyone have any ideas about where to find a drop in transformer?

 

Page processed in 0.027 seconds.