Hafler DH-120 intermittent issue

[podbaydoors]

I recently acquired a Hafler DH-120 to compliment the Phase Linear 2000 I have posted about separately.
I connected the unit to speakers after doing the usual disaster prevention procedures / checks.
Unit was working fine with about 25MV on one side and 32 on the other after about fifteen minutes.
Sounds great as-is but after after a few days of occasional test bench usage the left channel was suddenly very garbled.
I removed the cover and it was gone.
Left the cover off and began using it again.
After a few days i turned it on to find it doing it again.
Tried running CD player directly in to bypass the preamp and it was still doing it.
Nothing amiss at the outputs. Fuses OK.
Just <touched> the left channel board and voila, it is fine again.

I HATE intermittent issues that are seemingly due to a poor connection and not obvious where.

Anyone else ever had this problem with this amp?

Best,

Lou

 

[cademan]

Not with that amp particularly, but it does happen often enough. If sound comes back to normal after pressing where you did then that is the area I would be looking at. Probably a bad ground or cold solder joint somewhere on that left channel board.

 

[podbaydoors]

Yep.
The dates on the PS caps suggest that it was made in 1989.
I can't imagine it'll be reliable for much longer.
With it being as short as it is I need to stick to the 2 5/8" cap length.
Just ordered two from Kemet 6800uf screw termination from Mouser.
Everything else like the smaller electrolytics and beefier rectifier are in the parts box.
I'll just reflow all the solder joints while I have the boards out.

 

[podbaydoors]

An update;

All caps replaced in November.
No further issues.
Those were really odd sized power supply caps, had to order from Mouser.
Amp now in workshop system, might move to living room system.