Hello everyone I want to tell you about the maintenance of Mark levinson 26 & Mark Levinson 27.5.
First I bought an amp and used it as a pre-amp for the Cantata music centre.
The sound was good, but lacked depth and volume. So I bought a Mark levinson 26. the Sound was amazing, I couldn't believe my ears! But one channel rustled in the silence. Since it is already 30 years old, I decided to remove the lid and see what condition it is in. The former owner replaced most of the capacitors.
I also noticed that the four resistors were very hot cracked and burned.
I ordered new original dale 1w 20om 1% and raised them from the Board by 5mm, the temperature dropped to 70c. I also ordered the new expensive original sprague 672; nichicon muse kz. the Sound is even deeper and richer! But the rustling didn't go away... I checked the Board for microcracks and cold soldering, there were no problems with this. I started looking at all possible information and found harman's service sheets with the restoration work done. All 26 people were replaced with tuning resistors. I picked up a pencil and tapped on them, the rustling responding to the tapping! I ordered new Bourns resistors, new rifa RME 271y capacitors in the power supply, since the old ones are all cracked and it's not safe.
I also became interested in the condition of Mark levinson no 27.5 capacitors. I bought mastech MS5308 and made a dianostic for all electrolytic capacitors.
All large and medium capacitors were as new! Hurray! I thought) but the small capacitors were not suitable.. Esr 61 om...
And I started work on restoring 27.5 to its new state. I found the harman service sheets and also studied all possible information on replacements typical for 27.5.
1. Replaced the rifa RME 271y in the protective Board with new ones.
2. Replaced the cracked ROE 10uf 63v capacitor
3. Replaced the axial roe 100uf 50v
First I bought an amp and used it as a pre-amp for the Cantata music centre.
The sound was good, but lacked depth and volume. So I bought a Mark levinson 26. the Sound was amazing, I couldn't believe my ears! But one channel rustled in the silence. Since it is already 30 years old, I decided to remove the lid and see what condition it is in. The former owner replaced most of the capacitors.
I also noticed that the four resistors were very hot cracked and burned.
I ordered new original dale 1w 20om 1% and raised them from the Board by 5mm, the temperature dropped to 70c. I also ordered the new expensive original sprague 672; nichicon muse kz. the Sound is even deeper and richer! But the rustling didn't go away... I checked the Board for microcracks and cold soldering, there were no problems with this. I started looking at all possible information and found harman's service sheets with the restoration work done. All 26 people were replaced with tuning resistors. I picked up a pencil and tapped on them, the rustling responding to the tapping! I ordered new Bourns resistors, new rifa RME 271y capacitors in the power supply, since the old ones are all cracked and it's not safe.
I also became interested in the condition of Mark levinson no 27.5 capacitors. I bought mastech MS5308 and made a dianostic for all electrolytic capacitors.
All large and medium capacitors were as new! Hurray! I thought) but the small capacitors were not suitable.. Esr 61 om...
And I started work on restoring 27.5 to its new state. I found the harman service sheets and also studied all possible information on replacements typical for 27.5.
1. Replaced the rifa RME 271y in the protective Board with new ones.
2. Replaced the cracked ROE 10uf 63v capacitor
3. Replaced the axial roe 100uf 50v
Attachments
So, after studying the typical 27.5 repairs, I took the harman repair sheet as a lead.
Having dismantled one channel, I proceeded to a slow disassembly. On the first Board, I found a broken cr160 diode.
Also on the first Board there was a cold soldering. From the first payment:
1. 10uf 50v capacitor is Soldered
2. Soldered 2 capacitors 68uf 25v
3. Vipan diode cr160
4. Soldered 2 capacitors 0.01 uf 160v
5. Tuning resistor spectrol
From the bottom Board :
1. 2 ROE ekz 22uf 63v capacitors
2. 1 10uf 50v capacitor
3. 10 yellow capacitors 0.01 uf 160v
Cold soldering was also present on the lower Board.
So to replace the upper and lower Board I purchased in mouser electronics
1. 2 nichicon uka 100uf 50v capacitors
2. 2 nichicon Muse KZ 22uf 100v capacitors
3. 2 sprague 517d 10uf 100v capacitors
4. 4 Bourns resistors
5. 12 capacitors orange drop 716P10354JA3
6. the cr160 Diode was hard to find, found only in Italy. I ordered it the day before yesterday, I'm waiting for my arrival.
6. Full soldering on the boards has been restored.
Now I have a question for you, what do you think about cr160 whether there are fakes? Because the new one looks different from the one that burned down.
What do you think about the selected replacement parts?
A photo of the harman sheet is attached.
Having dismantled one channel, I proceeded to a slow disassembly. On the first Board, I found a broken cr160 diode.
Also on the first Board there was a cold soldering. From the first payment:
1. 10uf 50v capacitor is Soldered
2. Soldered 2 capacitors 68uf 25v
3. Vipan diode cr160
4. Soldered 2 capacitors 0.01 uf 160v
5. Tuning resistor spectrol
From the bottom Board :
1. 2 ROE ekz 22uf 63v capacitors
2. 1 10uf 50v capacitor
3. 10 yellow capacitors 0.01 uf 160v
Cold soldering was also present on the lower Board.
So to replace the upper and lower Board I purchased in mouser electronics
1. 2 nichicon uka 100uf 50v capacitors
2. 2 nichicon Muse KZ 22uf 100v capacitors
3. 2 sprague 517d 10uf 100v capacitors
4. 4 Bourns resistors
5. 12 capacitors orange drop 716P10354JA3
6. the cr160 Diode was hard to find, found only in Italy. I ordered it the day before yesterday, I'm waiting for my arrival.
6. Full soldering on the boards has been restored.
Now I have a question for you, what do you think about cr160 whether there are fakes? Because the new one looks different from the one that burned down.
What do you think about the selected replacement parts?
A photo of the harman sheet is attached.
Attachments
Looking forward to hearing if there are any improvements to the sound of 27.5 after you're done with changes. Wish I could help with your questions but Im not that savvy. Best of luck!
Also...that invoice from that site that cannot be translated...I see it says 27.5 on it.
Do they have like upgrade kit for 27.5 or what. How did you get to buying that ?
Thanks. Also what other refresh/upgrades would you suggest for it?
Do they have like upgrade kit for 27.5 or what. How did you get to buying that ?
Thanks. Also what other refresh/upgrades would you suggest for it?
I’ve already restored the preamplifier, it sounds just fine! Do not compare with what it was. And I had to tinker with the amplifier. Two months waiting for the diode cr160. Now in this channel two diodes 1N4936 are not working. I ordered a wait. At the expense of your question: this is not an upgrade. This is just a recovery. At the expense of replacements, I checked everything for a very long time and also wrote in madrigal. They change yellow film capacitors to all amplifiers 27, 27.5 23, 23.5 20.5 20.6 since they are old and they often break through before a fire. They also change all small electrolytic capacitors that have already lost their condition. That's all. That is, I did what is necessary to restore the amplifier and preamp to its original technical form.
Hello everyone I waited for the cr160 diode. Diode 1N4936.
The amplifier was assembled, the small capacitors were replaced, the film capacitors were replaced, and the tuning resistors were replaced. Assembled, turn on and there is no sound, on the acoustic terminals 30 and 300 milliamer.
Maybe who knows what the problem might be?
Previously, the speakers twitched when turned on, but now they don't.
The capacitors have the same voltage on both sides.
The amplifier was assembled, the small capacitors were replaced, the film capacitors were replaced, and the tuning resistors were replaced. Assembled, turn on and there is no sound, on the acoustic terminals 30 and 300 milliamer.
Maybe who knows what the problem might be?
Previously, the speakers twitched when turned on, but now they don't.
The capacitors have the same voltage on both sides.
So, when I understand this correctly: Madrigal (Harman) recommends to change the yellow film caps (that always look cracked) and all electrolytics leaking or not up to spec, plus the German Roederstein caps, that's all?
BR
BR
I stopped repairing the amplifier for a while. But recently returned. For some reason, the amplifier is working, but the trasistors are sleeping. There is no sound in the speakers. Need a complete scheme 27.5. On the Internet, it is unfortunately not complete...
Hello,
I recently bought an ML 26 with phono boards, do you have a calibration procedure? There are a lot of trimpots inside
I recently bought an ML 26 with phono boards, do you have a calibration procedure? There are a lot of trimpots inside