Pioneer A-717 popping noise

[vldr]

Hello

I'm a happy owner of a second hand PIONEER A-717 amplifier. Old but gold they say. Nice combo with my Sonus Faber Minuetto speakers in my opinion!

I bought it last year but it had some small problems.

1. Speaker terminal relay wasn't switching anymore. Replaced it, problem solved.

2. Every now and then I had a loud popping noise on my right speaker.
--> Switched speakers, problem didn't move to other side. So no problem with my speakers.
--> Heard this could have something to do with elco's discharging..
While the amp was open, I found some leaky elco's in the power supply assembly.

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

Schematics power assy:

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

I replaced those and reassembled the beast of 19 kg.
For a while I thought it was fixed but now it's coming back...
It's a heavy amp and a hard one to open up so if I open it up again I want to be sure it's gonna be the last time...
Can you guys assist me where to look for the problem?

I uploaded the schematics of the pioneer here:
Smallpdf.com

Thanks for the feedback!

Willem D.


Update: some more pics from the amp when it was opened up:

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

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

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

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

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

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

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

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

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

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

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

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

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

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

 

[vldr]

Some extra pics from the amp when it was open:

https://ibb.co/pLR8Nzw[IMG]
[IMG]https://ibb.co/LpLgSjf[IMG]
[IMG]https://ibb.co/WzVNVjm[IMG]
[IMG]https://ibb.co/TtvcnLH[IMG]
[IMG]https://ibb.co/V28GqBB[IMG]
[IMG]https://ibb.co/W6tjqz7[IMG]
[IMG]https://ibb.co/9g0Pr7B[IMG]
[IMG]https://ibb.co/hc4KDPn[IMG]
[IMG]https://ibb.co/KzV6CK9[IMG]
[IMG]https://ibb.co/wCns4ZX[IMG]
[IMG]https://ibb.co/Fbtr4Wy[IMG]
[IMG]https://ibb.co/tDRqBZh[IMG]
[IMG]https://ibb.co/hftbpYW[IMG]
[IMGDEAD]https://ibb.co/HBG55XM[/IMGDEAD]

 

[duncan2]

"Speaker terminal relay wasn't switching-replaced----problem solved ".


There is more than one relay .
It still sounds like a fault in the relay relating to the channel or a bad soldered joint .


Question --does this happen during use or just switch on ?


If during use then it could be a capacitor problem but it could be something else.

 

[vldr]

Hi Duncan

Thank you for your reply. It happens on both occasions.
I think the soldering is well done.

What other relays are you thinking of?

Gr W

 

[duncan2]

RY901/2/3 in the =speaker term.assembly board ,they all run back to the relay driver section they are worth checking out .


By the way thanks for the very easy access to your schematic diagram one of the easiest to access , no logging in, a bit of tracking but that's par for the coarse no worse than some and much better than others.

 

[vldr]

Hi Duncan

Thanks. Will check these relays out.
My pleasure to give you easy access to the schematics! Gr W

 

[vldr]

Hello there

I finally found some time to open up my Pioneer.
Seems the relays you're talking about is in fact one REED relay.
See pictures as attachment.

Can you tell me something more about reed relays used in amplifiers? My knowledge of these relays is industrial.. I know you use them for detecting nearby ferro materials but I have no idea why this is used in amplifiers..

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

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

Ps.: In the meantime I'm using my old dual cv5670 amp again and i kinda really like this one also!! Any thoughts on this one?

Greetz!

 

[Mooly]

Try attaching your images like this:
How to attach images to your posts.



My first thought would be hard to spot dry joints, particularly on hot running parts/semiconductors and semiconductors fixed to heatsinks where the solder can crack as the board flexes.

 

[vldr]

Hi Mooly

Thanks for the tip, will also check this. It started indeed after reassembling the amp after an earlier intervention. Could be the board was somewhat under tension assembled..

You don't believe in the reed relay?

Thanks for tip on attaching images. Didn't know you could do this. Pics attached as you asked.

Gr

W

 

[Mooly]

Your original fault description suggested something more than just a relay was at fault. If a relay isn't 'switching' it's more likely because it is being deliberately held in an off state rather than a problem with the relay itself. The act of disturbing it all to replace the relay could indicate a dry somewhere and the popping sound also points to something like that.

Dries can be hard to spot and typically look like this.

Another possibility is an intermittent failure of a semiconductor, usually a transistor that runs hot.