Mark Levinson 333 in bad condition need your advice

[Mark levinson]

Hello everyone I bought an ML 333 and it sounded bad, I opened it, they already tried to restore it...
Put a lot of bad capacitors put samwha gt 8 * 22000uf and other cheap Chinese capacitors. The sound is disgusting....
My ml5805 sounds many times better.
Here I think to put it in order, but it's expensive ...
Are there those who restored the 3rd line in perfect technical condition? Has the sound improved much?
Do you have a photo of the disassembled amplifier? If there is, please send it. I need to see how it was before the repair.

 

[Mark levinson]

Здравствуйте. Мне все еще нужна твоя помощь. Может быть, у кого-то есть полная схема 333? Кто может сказать, за что отвечают конденсаторы 22 мкФ 100 В c111 c100 c104 c115 470 мкФ 10 В c23 c6 c8, на какие из них лучше их заменить?

 

[Hans Polak]

Before doing drastic things, it would be wise to start measuring a number of things, see some specs below:

1) what is the bias current through the end stage transistors
2) what is the total current drawn per amp
3) what is the distortion per amp at 1kHz@10Watt in 8R
4) what is the -3dB frequency range from low to high

This will give you at least an indication where to look.

Hans

 

[Mark levinson]

Good evening, Hans! The amplifier was working, but it was in terrible technical condition. I disassembled it completely... They tried to restore it very cheaply... Now I'm choosing new spare parts...

 

[Mark levinson]

I wrote to Harman about what they put in return, but they did not respond this time 😰

 

[Mark levinson]

It's a miracle that nothing burned down. I washed the black viscous rubber

 

[Hans Polak]

Good luck in restoring this maltreated amp.

Hans

 

[adason]

Mark, you're the man.

 

[Mark levinson]

Всем привет, я наконец-то восстановил большую часть усилителя, осталось восстановить только каналы. Пожалуйста, скажите мне, могу ли я включаться без каналов?

 

[Mark levinson]

Удачи в восстановлении этого поврежденного усилителя.

Ганс

Ганс, добрый день! Не могли бы вы помочь мне каким-нибудь советом? Как заменить микросхему u1 на плате vsmb на lt1097cn8? Микросхема u1 имеет 16 ножек, а микросхема lt1097cn8 - 8.

 

[Hans Polak]

Could you please write in English.

Hans

 

[Mark levinson]

Ханс, мне очень жаль! Я не обращал внимания! Необходима замена платы усиления по напряжению 🥲

 

[AllenB]

Hans, I'm so sorry! I didn't pay attention! Need to replace voltage booster board

Mark levinson, many of your posts are not in English although we are an English language forum.

You are a well known member here and I expect there must be a simple explanation. We see some other members having problems with Google automatic translate and it's difficult from their end to see and know what has happened directly on the forum, so if you're using that service you might consider stopping, or reconfiguring it.

 

[Hans Polak]

So you want to replace U1 with a LT1097.
This one or the OPA227 is the chip that should be used for U1 on the voltage gain board.
I have no idea what this 16 pin opamp may be, are you sure you are looking at the right PCB ?

Hans

 

[Marionks]

The IL2Q is an quad Optocoupler.

 

[astouffer]

Late to the party but those Rifa caps are ticking time bombs. The epoxy absorbs moisture from the air until they become conductive enough and go up in a cloud of smoke. They’re a plague in the vintage computing world too.

 

[rayma]

I can confirm that, so do not use them.

 

[Mark levinson]

So you want to replace U1 with a LT1097.
This one or the OPA227 is the chip that should be used for U1 on the voltage gain board.
I have no idea what this 16 pin opamp may be, are you sure you are looking at the right PCB ?

Hans

Hans, I mixed up the boards) I figured out where to replace the lt1097. Hans, can I turn on the amplifier without connected channels? I want to check if I did everything correctly in the power supply.

 

[Mark levinson]

Mark levinson, many of your posts are not in English although we are an English language forum.

You are a well known member here and I expect there must be a simple explanation. We see some other members having problems with Google automatic translate and it's difficult from their end to see and know what has happened directly on the forum, so if you're using that service you might consider stopping, or reconfiguring it.

I'm sorry, the translator translated this into Russian automatically, but I wrote in English 🥲

 

[Hans Polak]

Hans, I mixed up the boards) I figured out where to replace the lt1097. Hans, can I turn on the amplifier without connected channels? I want to check if I did everything correctly in the power supply.

I really have no idea, but why don’t you try ?
It could be that some supervising circuitry prevents the switching on, but just try it, I don’t see what harm it could do.

Hans