Hi
Just sitting at work, and having lots of spare time offshore.
So I'll might plan and order caps to do this job.
Plan to use it with a 218 THX, that's also might need some service...
So maybe someone sitting on a cap list and might share it.
Also it's challenging to find a decent service manual with good quality.
The one i got from net, is so so.
Challenging to read some values on it.
Had to fix the motorized volume potmeter. Somehow stuck motor.
I will install a simple BT receiver in it as well.
Did that mod on 2 of my 3400's, with good result.
Just sitting at work, and having lots of spare time offshore.
So I'll might plan and order caps to do this job.
Plan to use it with a 218 THX, that's also might need some service...
So maybe someone sitting on a cap list and might share it.
Also it's challenging to find a decent service manual with good quality.
The one i got from net, is so so.
Challenging to read some values on it.
Had to fix the motorized volume potmeter. Somehow stuck motor.
I will install a simple BT receiver in it as well.
Did that mod on 2 of my 3400's, with good result.
I just got one Today. There is only one sourcesfor the service manual that i can see., Same one available in countless been sites. Letters are very small. The pdf is malformed and i had to take and print screen captures and print them out. The unit has a lot of capacitors , so i will start by replacing the ones that are bad, c505,504 1000 uf 50V that are all puffed out. I've already removed the plastic goo and cleaned / lubes the connector and pots
I look at the manual, in paper i cannot read them but in a 32" monitor, no problem. I have to change c504,c505 as they are damaged; they are the power supply caps on the tone board. Even with that it was hard to read some values.
Reconsider.
Most recap jobs are completely unnecessary for starters. Secondly you have to bend the leads of the new capacitors without stressing the rubber seal (99.9% of people jam them in wrecking the seal). That's if you don't damage the PCB or lift pads.
Unless an electrolytic cap is actually bad, you will not improve sound quality. Sorry, that's the truth of the matter.
Want to do something useful? Follow the service manual directions carefully and check / correct bias currents and DC offsets. But to accurately measure in the mV rang, you must show at least two LSD after the decimal point on the mV scale. That means you need a (for real) good meter. Those are over $200 folks. If you do not have a meter at least that good, do not touch any adjustments.
I've been practicing for over 45 years now, I do test components and have the equipment to do so. I am pretty tired of repairing damage to equipment, but do what you want. The truth in electronics is not reflected in internet reports and people who "improve" equipment testing by ear. I and others like me get real results, and we test before and after changes are made. News flash, what they talk about on the internet does not lead to improvements.
All I can do is tell you the truth and hope you use common sense and think about things before you do anything.
-Chris
Most recap jobs are completely unnecessary for starters. Secondly you have to bend the leads of the new capacitors without stressing the rubber seal (99.9% of people jam them in wrecking the seal). That's if you don't damage the PCB or lift pads.
Unless an electrolytic cap is actually bad, you will not improve sound quality. Sorry, that's the truth of the matter.
Want to do something useful? Follow the service manual directions carefully and check / correct bias currents and DC offsets. But to accurately measure in the mV rang, you must show at least two LSD after the decimal point on the mV scale. That means you need a (for real) good meter. Those are over $200 folks. If you do not have a meter at least that good, do not touch any adjustments.
I've been practicing for over 45 years now, I do test components and have the equipment to do so. I am pretty tired of repairing damage to equipment, but do what you want. The truth in electronics is not reflected in internet reports and people who "improve" equipment testing by ear. I and others like me get real results, and we test before and after changes are made. News flash, what they talk about on the internet does not lead to improvements.
All I can do is tell you the truth and hope you use common sense and think about things before you do anything.
-Chris
anatech, thank for the info. this is my second job bringing back old equipment. on the prior, two sl1200km2, i cleaned them, open them, inspected for problems, clean the contacts, clean and lube the spindle, change the defective signal and ground cable and followed the service manual specs for adjustment. and you are right, i lifted the track of the signal rca cable and i ended up applying some epoxy to glue it back. i have done a lot of rework in pcs, mostly caps and connectors, and it is never fun for me. i consider myself a beginner when it comes to rework / fix.
doing something similar with my nad 1600. clean the box, plastics, deox-it the connectors inside the boards and the rca connectors. a youtube video also recommended removing the rubber gunk on the caps as it tends to become conductive. i went head and did that.
upon inspection, most caps look good with no obvious signs of damage,. only two caps seem damaged with the tops all bloated, a couple of the 1000 uF, the power supply caps in the tone board ( also power supply board). those are probably going to be exchanged.
the only issue that i am aware in my nad1600 has is a channel imbalance. but that may be fixable with the adjustment procedure as stated in the service manual.
what about clearing the boards? the unit came from a smoker house.,
some people in another post recommends upgrading the op-amps (probably a waste of time IMHO), or changing all the resistors and capacitors in the opamps. anatech, I would like your opinion about this.
photos of the two caps with the bloated top (blue, could not get a good pic of them), a diode bridge with the rubber type gunk all around and another cap with the gunk (it is claimed that it get conductive with age) over several components and unit after initial opening.
PD: I think is time for me to get a new meter.
doing something similar with my nad 1600. clean the box, plastics, deox-it the connectors inside the boards and the rca connectors. a youtube video also recommended removing the rubber gunk on the caps as it tends to become conductive. i went head and did that.
upon inspection, most caps look good with no obvious signs of damage,. only two caps seem damaged with the tops all bloated, a couple of the 1000 uF, the power supply caps in the tone board ( also power supply board). those are probably going to be exchanged.
the only issue that i am aware in my nad1600 has is a channel imbalance. but that may be fixable with the adjustment procedure as stated in the service manual.
what about clearing the boards? the unit came from a smoker house.,
some people in another post recommends upgrading the op-amps (probably a waste of time IMHO), or changing all the resistors and capacitors in the opamps. anatech, I would like your opinion about this.
photos of the two caps with the bloated top (blue, could not get a good pic of them), a diode bridge with the rubber type gunk all around and another cap with the gunk (it is claimed that it get conductive with age) over several components and unit after initial opening.
PD: I think is time for me to get a new meter.
Attachments
I found another interesting video. It is a repair video from a prior NAD, preamp model, NAD 1155 with some commonality. The repair tech recommends to swap many of the capacitors, and when the old ones were tested, all of them were within range after more than 30 years. This proves what anatech said before "Most recap jobs are completely unnecessary for starters."
Video has been cued to 2:48
Video has been cued to 2:48
Hi Frabor,
If the metal is convex (pushed outward), then replace the capacitors. Often only the plastic has distorted and that is not unusual. Sometimes I will replace filter capacitors, but that's after I look at the ripple waveform with an oscilloscope. You can tell when they start to get tired.
Yes, get that glue off the boards near other connections and components. It can go conductive and it is corrosive. Cleaning the PCBs with IPA isn't a bad idea either.
Op Amps. Some, like the TL072 sounded great in their day but better ones exist. The NE5532 and NE5534 are difficult to beat in a practical sense unless you have a very good performing piece of equipment. I wouldn't worry about it in yours simply because there are other limiting factors. Sometimes specific resistors and capacitors can matter, but I study the schematic and look at what is in there before replacing anything. If you have a channel imbalance, something has gone bad for sure. If that unit has speaker relays, you might want to replace those or that.
Your meter, that is the critical piece of equipment because you rely on the reading. You will own it for many years, which means the ability for it to hold the calibration is critical. This is a characteristic that doesn't really have an easy to understand specification. It depends on the construction of the meter. That means it depends on the brand and position in the model lineup. This is one thing you do not want to go very cheap on!
Okay, so I would recommend either a Fluke or Keysight meter. Something over $200 for sure, and watch the specs carefully. I have a few HP 974A meters that are spec'd at 0.05% basic DC accuracy. They are very old, but guess what? They are still in tolerance! That is a very tight specification by the way, the same as my new Keysight U1273A. So those are top end meters and not cheap. But they have paid for themselves and I can trust them absolutely. The new meters have a DC reference that is in an oven. You don't need something that accurate, but you do need something with the ranges these have (look at the lowest range for DC volts, you need at least two LSD behind the decimal to set bias). Also look at the AC frequency response, 100 KHz I think. Many meters cannot measure at 1 KHz accurately. Both Fluke and Keysight make meters that fit the bill. It is doubtful other meters will hold their calibration nearly as well. Keysight is the T&M division of HP in case you were wondering.
I would recommend a dual channel, 100 MHz analogue scope, not a digital one. These are less expensive anyway. You should have one.
-Chris
If the metal is convex (pushed outward), then replace the capacitors. Often only the plastic has distorted and that is not unusual. Sometimes I will replace filter capacitors, but that's after I look at the ripple waveform with an oscilloscope. You can tell when they start to get tired.
Yes, get that glue off the boards near other connections and components. It can go conductive and it is corrosive. Cleaning the PCBs with IPA isn't a bad idea either.
Op Amps. Some, like the TL072 sounded great in their day but better ones exist. The NE5532 and NE5534 are difficult to beat in a practical sense unless you have a very good performing piece of equipment. I wouldn't worry about it in yours simply because there are other limiting factors. Sometimes specific resistors and capacitors can matter, but I study the schematic and look at what is in there before replacing anything. If you have a channel imbalance, something has gone bad for sure. If that unit has speaker relays, you might want to replace those or that.
Your meter, that is the critical piece of equipment because you rely on the reading. You will own it for many years, which means the ability for it to hold the calibration is critical. This is a characteristic that doesn't really have an easy to understand specification. It depends on the construction of the meter. That means it depends on the brand and position in the model lineup. This is one thing you do not want to go very cheap on!
Okay, so I would recommend either a Fluke or Keysight meter. Something over $200 for sure, and watch the specs carefully. I have a few HP 974A meters that are spec'd at 0.05% basic DC accuracy. They are very old, but guess what? They are still in tolerance! That is a very tight specification by the way, the same as my new Keysight U1273A. So those are top end meters and not cheap. But they have paid for themselves and I can trust them absolutely. The new meters have a DC reference that is in an oven. You don't need something that accurate, but you do need something with the ranges these have (look at the lowest range for DC volts, you need at least two LSD behind the decimal to set bias). Also look at the AC frequency response, 100 KHz I think. Many meters cannot measure at 1 KHz accurately. Both Fluke and Keysight make meters that fit the bill. It is doubtful other meters will hold their calibration nearly as well. Keysight is the T&M division of HP in case you were wondering.
I would recommend a dual channel, 100 MHz analogue scope, not a digital one. These are less expensive anyway. You should have one.
-Chris
Will look for both a tested and a scope. I have a USB hanger 29 MHz, noisy as crap that i use for digital basic i/0 measuring for my Arduino micros. Definitely it does not cut it for analog audio. Thanks for the great advice, will keep positing here about the nad 1600
The board were all covered with nicotine tar residue. I go some 91 isopropyl to clean. Tried with qtips but the area was too big. The brush worked very well, getting some brown residue an eventually going clean. I found out that the motorized pot does not work.
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Those little USB 'Scopes or inexpensive digital ones are okay for experimenting with microcontrollers as you've noted. One huge problem is aliasing and the less expensive the product, the greater the problem is. In order to do passible analogue stuff, I had to get into a 1 GHz, 12 bit Keysight 3000x series 'scope, and those are gastly expensive. My Philips PM3365A does a much better job with eye patterns and cost a fraction of what the Keysight did new. These days you can pick up a Philips PM3070 or 3365A for peanuts.
If you get a chance to grab a bench meter, an HP 34401A is about the best, period. The new 3446x series are great meters, but be careful measuring resistance in some situations as they can lie to you. However the new series meters are truly the best on the market. Of course a Keysight handheld is another classic. THe upper Fluke products are also excellent. I wouldn't buy any other brand than Fluke or Keysight.
For your pot, measure the DC voltage across the motor contacts. Operate the remote. You can also disconnect the motor and use an external power supply to check it, but it only takes a couple volts to operate the motor. I normally use some resistance (<10 ohms) in series to control current in case something goes wrong. Never apply power tothe motor contacts while it is connected to the circuit.
-Chris
If you get a chance to grab a bench meter, an HP 34401A is about the best, period. The new 3446x series are great meters, but be careful measuring resistance in some situations as they can lie to you. However the new series meters are truly the best on the market. Of course a Keysight handheld is another classic. THe upper Fluke products are also excellent. I wouldn't buy any other brand than Fluke or Keysight.
For your pot, measure the DC voltage across the motor contacts. Operate the remote. You can also disconnect the motor and use an external power supply to check it, but it only takes a couple volts to operate the motor. I normally use some resistance (<10 ohms) in series to control current in case something goes wrong. Never apply power tothe motor contacts while it is connected to the circuit.
-Chris
Following anatech (Chris) advice, i went for a minimal first stage refurbishing. Unit came from a heavy somoker home and it needes an extended clean up of the PCB ( bottom with alcohol and top just brushed), other than vacuum shaking, dust removal. As much as the b.rown goop as i could was replaced, and rtv electronics grade was applied to all the ribbon ( i accidentally broke and had to resolder one. Also, i accidentally broke the search button but found a replacement in ebay. All button and volume/ balance/ tone control were cleaned with contact cleaner. Also, after shaking all kinds of crap came out. I have not done many refurbishing with Audil, but in computers, dust , hair and nicotine can make the computer very unstable.
I decided to hold in the two bad caps, as they are only used for the 12 volt relay colis.
The results are nice. Good balance between channels ( there was a level difference before removal of the brown goop), no noise when using balance or tone, no aparent dtorsion when pushed all the way up, phono works good radio does not seem to be able to get any stations but i have a have a metal roof and i have not tried with a proper antenna.
Next step will be to get a scope and feed test
Sinwewaves in both channels and see how they look. Also, will give a try to the motorized pot repair. Some of the chanels of the remote are nor Responsive, don't know yet if this is the reciver or transmis
Pics of the unit after the cleanup and after the Brown goop removal and
I decided to hold in the two bad caps, as they are only used for the 12 volt relay colis.
The results are nice. Good balance between channels ( there was a level difference before removal of the brown goop), no noise when using balance or tone, no aparent dtorsion when pushed all the way up, phono works good radio does not seem to be able to get any stations but i have a have a metal roof and i have not tried with a proper antenna.
Next step will be to get a scope and feed test
Sinwewaves in both channels and see how they look. Also, will give a try to the motorized pot repair. Some of the chanels of the remote are nor Responsive, don't know yet if this is the reciver or transmis
Pics of the unit after the cleanup and after the Brown goop removal and
Attachments
Yes, you can also use an oscilloscope to look at the output pin of the IR detector. However since some buttons on the remote do work, I can guarantee that some of the rubber pads are not making contact to the board properly in that remote.
The fix would be to scrub the remote PCB contacts with 99% IPA, or methyl Hydrate using wood or paper Q-Tips (not plastic sticks!!!). Then, very lightly clean the carbon pads on the back of the buttons. Do not scrub these! They do make repair kits havinga conductive paste, I have used foil glued onto he button, but sometimes the foil can detach if the button is pressed hard. Use flexible adhesive. Conductive ink or paint would probably work, but not for as long as the original coating. Last resort, www.remotes.com or a similar outfit. I just ought one for a Luxman pre-tuner. I also just replaced my remote key fobs for my car. Programming the car was much more than the remotes, but the GM price was over $200 each! Amazon for $35 - ish a pair in Canada.
Good luck with the remote cleaning.
The fix would be to scrub the remote PCB contacts with 99% IPA, or methyl Hydrate using wood or paper Q-Tips (not plastic sticks!!!). Then, very lightly clean the carbon pads on the back of the buttons. Do not scrub these! They do make repair kits havinga conductive paste, I have used foil glued onto he button, but sometimes the foil can detach if the button is pressed hard. Use flexible adhesive. Conductive ink or paint would probably work, but not for as long as the original coating. Last resort, www.remotes.com or a similar outfit. I just ought one for a Luxman pre-tuner. I also just replaced my remote key fobs for my car. Programming the car was much more than the remotes, but the GM price was over $200 each! Amazon for $35 - ish a pair in Canada.
Good luck with the remote cleaning.
I don't understand what you are trying to get tell me. Some of the remote buttons are non responsive. Till i get an aftermarket remote will not know if the remote is bad or the receiver if chip is bad. I don't see how the camera can be used to diagnose this. Please elaborate, thanks.
Ah, I didn't understand that, I understood that you didn't know if it was the sender or the receiver of the remote control that was causing the problem.
if certain functions do not work it is certainly that the remote control needs a good cleaning as Anatech said.
if certain functions do not work it is certainly that the remote control needs a good cleaning as Anatech said.
I took the remote apart, cleaned the plastic case, dip in water soap the membrane and wipped the PCB with IPA, qtips and brush, reassamble and out fresh batteries. Still, after than some of the buttons Are off. Will reclean and or go to remotes..com
oggioffshore, the manual of the 7100 in hifi engine is a very good scan with almost perfect text. The preamp board of the 1600 and the 7100 is the same, up to the component numbers. That is the best readable list of caps for the preamp section. In ebay there is a kit for sale with all the caps, but with no list.
How did you fix the pot? Mine seems to be stuck, the volume up of the remote blinks but the motorized pot does not move.
How did you fix the pot? Mine seems to be stuck, the volume up of the remote blinks but the motorized pot does not move.