@BakedAlaska,
When having difficulties in dismantling the upper board, you could connect a Cap from outside to R201 and R219 / R202 and R220 at exactly the points where you measured with the shortest possible leads.
Not as elegant, but probably just as effective in solving the problem without having to dismantle.
Hans
When having difficulties in dismantling the upper board, you could connect a Cap from outside to R201 and R219 / R202 and R220 at exactly the points where you measured with the shortest possible leads.
Not as elegant, but probably just as effective in solving the problem without having to dismantle.
Hans
Good, these are vias. Got confused why ML seemed to have soldered it neatly both sides.
Did you mean V_Prereg?
VUnreg (big blue caps 47mF) is 65V (65V noisy ML, 59V silent ML).
V_Prereg, P17 and P19, (smaller blue caps 1900uF) is 90V (93,5V noisy ML, silent ML 85,5V).
Why the difference? Noisy ML has tranformer jumper set to A-E G-H (=220-230V AC mains), silent ML has jumper set to A-F G-H (=230-240V AC mains).
I tried to set jumper to 230-240V for noisy ML, too, but than the relais doesn't click. I suspect they saved on the extra winding. Still weird. The marking (red dot) on the backplate is identical to both MLs.
BR
Did you mean V_Prereg?
VUnreg (big blue caps 47mF) is 65V (65V noisy ML, 59V silent ML).
V_Prereg, P17 and P19, (smaller blue caps 1900uF) is 90V (93,5V noisy ML, silent ML 85,5V).
Why the difference? Noisy ML has tranformer jumper set to A-E G-H (=220-230V AC mains), silent ML has jumper set to A-F G-H (=230-240V AC mains).
I tried to set jumper to 230-240V for noisy ML, too, but than the relais doesn't click. I suspect they saved on the extra winding. Still weird. The marking (red dot) on the backplate is identical to both MLs.
BR
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That is indeed weird.
It is almost as if this additional winding between E F was destroyed by some short circuit.
And if this would be the case, it could be that more components on the primary side are damaged such as the DC blocking circuitry.
ML specifies +/- 94V on Vprereg and +/- 64V on Vunreg, so your noisy amp is quite close and the silent amp is a bit low, probably because your mains is not 240V.
Hans
It is almost as if this additional winding between E F was destroyed by some short circuit.
And if this would be the case, it could be that more components on the primary side are damaged such as the DC blocking circuitry.
ML specifies +/- 94V on Vprereg and +/- 64V on Vunreg, so your noisy amp is quite close and the silent amp is a bit low, probably because your mains is not 240V.
Hans
Ahh, the Bourns are the 4 trim pots, now I get it.
Your amp is now operational, I take it?
BR
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Sorry to keep you waiting, was blocked from working on the amp.
Hans, you are a genius. C201 C202 are the problem. I bypassed them with caps from outside, and the noise is gone.
Thank you very very much for your help!
I made a new measurement for P1 P4 for the right channel, and VReg +- looks so much better now.
BR
Hans, you are a genius. C201 C202 are the problem. I bypassed them with caps from outside, and the noise is gone.
Thank you very very much for your help!
I made a new measurement for P1 P4 for the right channel, and VReg +- looks so much better now.
BR
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Yes, this selection is from Harman.
Yes, these roe disgusting capacitors! I set myself a nichicon muse kz 22uf 100v. Harman recommends another nippon kmg 22uf 100v.
Don't be lazy and restore it completely! He deserves whatever you give him attention 🙂
@M.L.
My Russian is a bit rusty, but I'll figure it out, thanks
(off-topic)
I'm so happy that my problem was fixed, here's a little anecdote: I had some bad experiences with Roe caps before. They are used in the power supplies of east german computers from the 80s (people collect these). They often leak and explode, and we call them 'fish cans', because when you put them in a box, it smells of fish for leaking electrolyte. The assumption is that these bad caps had been supplied to east germany, but apparently the problem is not limited to socialism. US (Madrigal) got framed with this stuff as well ;-)
BR
My Russian is a bit rusty, but I'll figure it out, thanks
(off-topic)
I'm so happy that my problem was fixed, here's a little anecdote: I had some bad experiences with Roe caps before. They are used in the power supplies of east german computers from the 80s (people collect these). They often leak and explode, and we call them 'fish cans', because when you put them in a box, it smells of fish for leaking electrolyte. The assumption is that these bad caps had been supplied to east germany, but apparently the problem is not limited to socialism. US (Madrigal) got framed with this stuff as well ;-)
BR