Yamaha CR800 poor bass performance

[damiangt3]

I finally got around to getting a few of the older items of Hi-Fi I have out of storage, one of these being a Yamaha CR800 receiver.

It's in very good condition with blown lights but completely untouched so with a little trepidation I connected it up to some cheap speakers and it still worked, all the pots were silent, the tuner worked well, no smells, no smoke and very little bass.

Thinking that some of the caps were all dried out I set about replacing the older electrolytics, the main Nippon-Chemicon 6800uf were not functioning, I've replaced many of the others (90%, I'm waiting on three 220uf/25v) on the power supply board, the 100% on the coupler board and the 100% the main board. Yet still after all of this the bass is light.

With these old receivers the main-out can be used, bypassing all the tone controls etc, even using this method the same problem exists.

Any further suggestions before I go down the transistor route?

 

[llwhtt]

There are two 47uf/16v capacitors, one per channel, in the feedback path. They are connected to the base of TR703/704. It's hard to read the schematic, could be C709/710. If those are bad you'll have weak bass.

Craig

 

[JonSnell Electronic]

It will not be a semiconductor. They either work or not.

 

[damiangt3]

There are two 47uf/16v capacitos, one per channel, in the feedback path. They are connected to the base of TR703/704. It's hard to read the schematic, could be C709/710. If those are bad you'll have weak bass.

Craig

Thanks Craig, I'll have a look but I'm pretty sure I replaced those pair with some new Nichicon ES BPs.

It will not be a semiconductor. They either work or not.

Thank you Jon.

I've read that the 'Natural Sound' Yamaha's can be a little troublesome when matching with speakers but I thought my pair of Neat Petite 3s would be fine, they certainly are with my Marantz 2238BL!

 

[damiangt3]

Checked and I did replace the following:

C703/704 with Wima MKP 2.2uf (replacing an electrolytic with a poly)
C708/709 with Nichicon ES 47uf
C713/714 with Nichicon Muse 220uf
C715/716 with Nichicon FW 100uf
C729/730 with Nichicon ES

The amp's idle and midpoint adjust to exact specs.

What else could I look at?

 

[llwhtt]

Test equipment?

Craig

 

[damiangt3]

Test equipment?

Craig

Multimeter, separate pre-amp to isolate any possible issues with the receiver's preamp circuitry.

 

[sreten]

Hi, Cheap speakers generally have weak bass, due to no BSC (search), rgds, sreten.

 

[llwhtt]

This would be a 5 minute problem with a signal generator and an o'scope, otherwise it's all a guessing game.

Craig

 

[damiangt3]

This would be a 5 minute problem with a signal generator and an o'scope, otherwise it's all a guessing game.

Craig

Hi Craig,

That's more than likely going to be a future purchase for me.

I can signal generate and feed it back into the amp but then I'm reliant on my ears and the psycho-acoustic nature of the different frequencies!

Thanks,

Damian