MR80 display ranging

[twiiii]

In my case it was IC, a couple caps and hair line crack on two different circuit board traces. Audio Classics rebuilt the power supply and realigned the tuner and repaired the roaming digital display. The unit has been running close to 3 years and sounds fantastic and works like a charm. Better than new as I remember. We have a lot more stations to day and they are stacked very close together and my favorite stations happen to be very low powered University Stations. And where before I had real reception problems from day one and even more today the tuner now captures the stations and sound fantastic.

 

[Gregory]

In my case it was IC, a couple caps and hair line crack on two different circuit board traces. Audio Classics rebuilt the power supply and realigned the tuner and repaired the roaming digital display. The unit has been running close to 3 years and sounds fantastic and works like a charm. Better than new as I remember. We have a lot more stations today and they are stacked very close together and my favorite stations happen to be very low powered University Stations. And where before I had real reception problems from day one and even more today the tuner now captures the stations and sound fantastic.

Multiple ICs or just a single one? Where were the hairline cracks? what PCBs? One thing I didn't focus on was a thorough solder joint inspection, though all the Control/ Tune interconnects were pulled and reseated. Thinking of it now.. I didn't brush Deoxit 100 on them when re-connecting.

It's not surprising that the old ROE non-pol cap was in bad shape, but it WAS a surprise that the problem wasn't in the Counter module. Now I feel the MR80 has turned into an ongoing project. It still could use a trip to AC.


-Gregory

 

[Gregory]

I'd like to thank everyone for their advise and inputs on the MR80 fixes.. especially MX117.MC7150 (Glenn) who sent a complete photo-copied MR80 Service Manual at his own expense and valuable time. That's what makes the AK/ Mc forum so great. Now we all get to see the MR80 apart and thoroughly inspected... that is short of using professional test gear!

Once you get in there and go over it with fine tooth comb, then you become intimately familiar with the gear. This can be very enjoyable. :yes:


EDIT: will have to go back and edit the thread for correctness.

Also would like to re-post the MR80 Power Supply recap link.


-Gregory

 

[Gregory]

I had the same issue with my MR-80 and it turned out to be a bad IC and multiple bad solder connections and a couple of compromised traces. The guys at Audio Classics got mine running better than new.

I'm resurrecting this thread because the MR80 is still down, and has been in the rack with a cover on it for the last 7 years. Not long after you posted the reply above, I drove out to Los Angeles on a contract job. Fun summer in L.A., went to the beach 5 consecutive weekends! After returning, the project was practically forgotten.

I think Audio Classics is the way to go. As of late last year, Ryan at AC said the cost to update the MR80 would be 200-400 depending on what's needed. It might be a good idea to plan a trip up to NY.

-Greg

 

[kevzep]

I'm resurrecting this thread because the MR80 is still down, and has been in the rack with a cover on it for the last 7 years. Not long after you posted the reply above, I drove out to Los Angeles on a contract job. Fun summer in L.A., went to the beach 5 consecutive weekends! After returning, the project was practically forgotten.

I think Audio Classics is the way to go. As of late last year, Ryan at AC said the cost to update the MR80 would be 200-400 depending on what's needed. It might be a good idea to plan a trip up to NY.

-Greg

Before you do, there is a couple of things to try, my MR80 was doing this as well, during its time on my bench that problem has evaporated.
I'll share that with you later today after I finish a few jobs (repairing some professional ClassD power amps) what I did that may have had an effect on that issue.

 

[twiiii]

The tech at AC didn't clue me in on the details, and I am fine with that. I have dealt with AC for close to or maybe even more than 20 years. I knew Frank Gow when he sold electronic components to the Twin plants in Mexico and came to visit the company I worked for. I miss Frank. Steve and Ryan have taken great care of me since Frank's passing. They are always honest and been there when I needed them. There were some issues with a couple of pieces that had been damaged in shipping, but took care of both post haste. The MR-80 was one of them. Someone had removed the tape from the box and been inside the second box. So it was returned to AC over night repaired and recalibrated and returned to me over night. I bet UPS lost some money on that episode. But she's been running better than new since. I guess some one thought there was an amp or pre-amp in the box they could steal, but found a tuner and. sealed it back up. When I traded my MX 119 for my 151, UPS lost the 119 for 6 weeks. I don't know what condition of the unit was when it arrived, but Steve honored the deal. But there was one listed about the same time as a parts donor.

 

[Gregory]

I have dealt with AC for close to or maybe even more than 20 years. Steve and Ryan have taken great care of me since Frank's passing. They are always honest and been there when I needed them. There were some issues with a couple of pieces that had been damaged in shipping, but took care of both post haste. The MR-80 was one of them. Someone had removed the tape from the box and been inside the second box. ..it was returned to AC over night repaired and recalibrated and returned to me over night.

So you're recommending to have AC go through the tuner? I'd kinda' like to drive up there, see the place and drop it off, maybe have it shipped back. How did someone know there was a McIntosh inside the double box? by the AC address on label?

 

[seacliffe301]

How did someone know there was a McIntosh inside the double box? by the AC address on label?

I'm not sure how the new boxes are adorned, but the older boxes are clearly marked with a large McIntosh script as well as the model number of the particular unit that it originally housed.
Anyone who knew the company clearly knew what freight they were handling (or mishandling).

 

[kevzep]

Multiple ICs or just a single one? Where were the hairline cracks? what PCBs? One thing I didn't focus on was a thorough solder joint inspection, though all the Control/ Tune interconnects were pulled and reseated. Thinking of it now.. I didn't brush Deoxit 100 on them when re-connecting.

In the case if my MR80, I removed and re-seated ALL the IC's on all the boards as I have had issues in the past in other products with intermittent and/or didgy connections through IC sockets.
After simply re-seating all the IC's, the random scrolling issue was gone, its been perfectly fine ever since.

Then the other issue with intermittent problems is in the MPX section with the Separation trimmers, level trimmer and 19khz trimmer, all these seem to just go bad and/or intermittent as well, this can cause imbalance between left and right, and can also cause unreliable and bad FM stereo performance.

There are other things too which are deeper in the IF section, but the above is a good place to start to see where you're at.

 

[Gregory]

In the case if my MR80, I removed and re-seated ALL the IC's on all the boards as I have had issues in the past in other products with intermittent and/or didgy connections through IC sockets.
After simply re-seating all the IC's, the random scrolling issue was gone, its been perfectly fine ever since.

What do you use for a chip puller?


-Greg

 

[kevzep]

What do you use for a chip puller?


-Greg

I have some dental tools which are great for plucking IC's, I don't know the proper name for them, but they slide under the chip and you can gently work the chip loose and then they come out.
Sometimes I use pliers with electrical tape on the jaws depending on how confined the area is.

 

[Gregory]

I can barely remember 45 years ago seeing a 14-pin inline chip puller tool, it was more like a hard-plastic pry-bar. Some of the Intel CPUs had pry-bar tools with sawtooth edge to get between the pins. Just trying to think how best to pull ICs.

What's more, was forward thinking enough ~8 years ago to buy all new Low Noise Op Amps for the C33, and haven't installed them yet.

-Greg

 

[kevzep]

I can barely remember 45 years ago seeing an 8 or 16-pin inline chip puller tool, it was more like a hard-plastic pry-bar. Some of the Intel CPUs had pry-bar tools with sawtooth edge to get between the pins. Just trying to think how best to pull ICs.

What's more, was forward thinking enough ~8 years ago to buy all new Low Noise Op Amps for the C33, and haven't installed them yet.

-Greg

The Dental tool I use is like a Pry-bar, you do one end at a time and kind of "rock" the IC out of the socket, I did most of the MR80 ones like that, there are just a few that I used the pliers on due to surrounding components.

 

[Gregory]

Time to get this thread rolling again


There's no sense having an INOP Mc tuner on the shelf for 8 or 9 years.

I dug out the MR80 Service Manual that AKer Glenn sent in late 2012 at no charge! That was really good – thanks again.


Trying to decide whether to have the manual spiral-bound or keep it loose-leaf.







Had mistakenly told an AKer recently a drafting board was needed to view the D-size schematics, but those were for the C33.



Next step is to get the images restored in this thread.


-Greg

 

[CruzBay]

I can barely remember 45 years ago seeing a 14-pin inline chip puller tool, it was more like a hard-plastic pry-bar. Some of the Intel CPUs had pry-bar tools with sawtooth edge to get between the pins. Just trying to think how best to pull ICs.

What's more, was forward thinking enough ~8 years ago to buy all new Low Noise Op Amps for the C33, and haven't installed them yet.

-Greg

Ought to try those for my C-34v....

 

[Gregory]

Ought to try those for my C-34v....

You mean these?



This is OT.


-Greg

 

[CruzBay]

You mean these?

View attachment 1841352

This is OT.


-Greg

Thread derail-(but it's your thread, so...) Yes, but I'd like to hear what some of the more intelligent folks on here (cough Chris, Patrice, et al) would have to opine on the actual improvements. The C-33, 34v and other pre's of around that time were measuring at about the noise floor of our test equipment at the time, IIRC .003% or so.

Can't think the low-noise IC's could improve that (already well under the threshold of hearing, and maybe measuring) number.

But it's an easy and inexpensive mod.

They have the same gain?

Mike

-edit- I guess you could try it by moving the phono IC's to whatever source you're using most...

@c_dk @clinic-audio

 

[c_dk]

Not in this thread......did use a MCD7005 as a test bed. It is interesting that the Audio mag redo article of a Philips based CD did swap in NE5532n devices for LM series as well as a number of other mods, but like I said for a different thread someday.

 

[Gregory]

Images have been restored in the MR80 power supply recap thread.

https://audiokarma.org/forums/index.php?threads/mr80-power-supply-recap.492147/


-Greg

 

[Gregory]

I'd like to hear what some of the more intelligent folks on here (cough Chris, Patrice, et al) would have to opine on the actual improvements. The C-33, 34v and other pre's of around that time were measuring at about the noise floor of our test equipment at the time, IIRC .003% or so.

Will have to restore the C33 Update Project 2013 images, maybe tomorrow, and you can post the op-amp stuff there, yeah?

https://audiokarma.org/forums/index.php?threads/c33-update-project-2013.494086/

This post for low-noise op-amps.
https://audiokarma.org/forums/index.php?threads/c33-update-project-2013.494086/page-4#post-7359747


-Greg