Replacement Board for Event Electronics Tuned Reference Monitor TR-5?

[Paul[_13_]]

Where can I get a replacement Board for an Event Electronics Tuned
Reference Monitor TR-5?

One of my TR5s went bad, with very low volume, so I cracked it open
(after swapping speakers, to make sure that was not the problem).

Unfortunately, I was not able to find a schematic online.

At first I thought maybe the LM3886TF audio ICs went bad, but after
doing some signal tracing, it appears the input signal isn't making
it to differential input pins 9 and 10, on either of the ICs. Or
at least, the signal is much attenuated from the input level.

Also, the heat sink that the LM3886TFs are bolted to, is getting a
little bit warm, and the +/-24 Volt rails are at pins 1 and 4. So this
makes me think maybe the LM3886 chips are NOT the culprit here (they
also do not look melted, damaged, or cracked).

Perhaps there is a bad passive component in the cross-over circuitry?
Or maybe the TL072C Opamp is bad? 

At any rate, does anyone know where I can get a replacement board? Does
Event still support this older model? Could they replace, or at least
troubleshoot this board?

Or does someone have a schematic? I'm lost in the forest without one!

:(



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[geoff]

On 12/10/2018 3:21 PM, Paul wrote:
> Where can I get a replacement Board for an Event Electronics Tuned
> Reference Monitor TR-5?
>
> One of my TR5s went bad, with very low volume, so I cracked it open
> (after swapping speakers, to make sure that was not the problem).
>
> Unfortunately, I was not able to find a schematic online.
>
> At first I thought maybe the LM3886TF audio ICs went bad, but after
> doing some signal tracing, it appears the input signal isn't making
> it to differential input pins 9 and 10, on either of the ICs.Â* Or
> at least, the signal is much attenuated from the input level.
>
> Also, the heat sink that the LM3886TFs are bolted to, is getting a
> little bit warm, and the +/-24 Volt rails are at pins 1 and 4. So this
> makes me think maybe the LM3886 chips are NOT the culprit here (they
> also do not look melted, damaged, or cracked).
>
> Perhaps there is a bad passive component in the cross-over circuitry? Or
> maybe the TL072C Opamp is bad? 
>
> At any rate, does anyone know where I can get a replacement board?Â* Does
> Event still support this older model?Â* Could they replace, or at least
> troubleshoot this board?
>
> Or does someone have a schematic?Â* I'm lost in the forest without one!
>
> :(
>
>
>
> ---
> This email has been checked for viruses by Avast antivirus software.
> https://www.avast.com/antivirus
>

If no or very low signal to the power amp chip inputs, then look further
back. Sure, change the TL072 might be first option, that is after
checking for fractures at input socket connections to PCB and thereabouts.

You could maybe try www.eventelectronics.com for spare parts or service
info.

geoff

[Paul[_13_]]

On 10/11/2018 8:41 PM, geoff wrote:
> On 12/10/2018 3:21 PM, Paul wrote:
>> Where can I get a replacement Board for an Event Electronics Tuned
>> Reference Monitor TR-5?
>>
>> One of my TR5s went bad, with very low volume, so I cracked it open
>> (after swapping speakers, to make sure that was not the problem).
>>
>> Unfortunately, I was not able to find a schematic online.
>>
>> At first I thought maybe the LM3886TF audio ICs went bad, but after
>> doing some signal tracing, it appears the input signal isn't making
>> it to differential input pins 9 and 10, on either of the ICs.Â* Or
>> at least, the signal is much attenuated from the input level.
>>
>> Also, the heat sink that the LM3886TFs are bolted to, is getting a
>> little bit warm, and the +/-24 Volt rails are at pins 1 and 4. So this
>> makes me think maybe the LM3886 chips are NOT the culprit here (they
>> also do not look melted, damaged, or cracked).
>>
>> Perhaps there is a bad passive component in the cross-over circuitry?
>> Or maybe the TL072C Opamp is bad? 
>>
>> At any rate, does anyone know where I can get a replacement board?Â* Does
>> Event still support this older model?Â* Could they replace, or at least
>> troubleshoot this board?
>>
>> Or does someone have a schematic?Â* I'm lost in the forest without one!
>>
>> :(
>>
>>
>>
>> ---
>> This email has been checked for viruses by Avast antivirus software.
>> https://www.avast.com/antivirus
>>
>
> If no or very low signal to the power amp chip inputs, then look further
> back. Sure, change the TL072 might be first option, that is after
> checking for fractures at input socket connections to PCB and thereabouts.
>
> You could maybe try www.eventelectronics.com for spare parts or service
> info.
>

Ok, never-mind everyone. I'm 99.9% sure I found the problem!

The sensitivity/gain pot had the center wiper lifted, so it was
an open! When I shorted the center lead to the high gain lead, my
sig gen was loud and clear! And I could hear the crossover working,
as the sound went from woofer to tweeter as I increased the frequency.

I believe this is a linear taper (not log) pot, 2KB.

I hope my electronics place has one with similar physical
dimensions, when I go there tomorrow morning.

Hurray!

:)

[Scott Dorsey]

In article >, Paul > wrote:
>
>At first I thought maybe the LM3886TF audio ICs went bad, but after
>doing some signal tracing, it appears the input signal isn't making
>it to differential input pins 9 and 10, on either of the ICs. Or
>at least, the signal is much attenuated from the input level.
>
>Also, the heat sink that the LM3886TFs are bolted to, is getting a
>little bit warm, and the +/-24 Volt rails are at pins 1 and 4. So this
>makes me think maybe the LM3886 chips are NOT the culprit here (they
>also do not look melted, damaged, or cracked).

So, start tracing signal from the input connector into the LM3886 chip,
paying very special attention to coupling capacitors. If you have an ESR
tester, just put it on all the electrolytic coupling caps and see.

You have the advantage of having two identical speakers. One works, and one
doesn't, so your goal is to find out what the difference between the two are,
and you might be able to find that just with static power-off measurements.

>Perhaps there is a bad passive component in the cross-over circuitry?
>Or maybe the TL072C Opamp is bad? 

If the TL072 is bad then a DMM set to diode test will indicate different
readings on the chip than on that of a good speaker.

The passive components likely don't fail. But measure resistance at the
output of the amp, compare with the good speaker. If they are the same,
the crossover is good enough to pass low frequencies at least.

>At any rate, does anyone know where I can get a replacement board? Does
>Event still support this older model? Could they replace, or at least
>troubleshoot this board?

Call Event and ask. They might support it, although it would seem to me
to be easier to just do component-level repair. Find a good tech, this
should not be that hard to fix.

>Or does someone have a schematic? I'm lost in the forest without one!

Get paper and draw out what you find as you poke around at it. Likely the
output stage will be identical to the diagram in the LM3886 datasheet.

But on equipment like this, 90% of what goes wrong are connectors and switches,
and coupling capacitors. The other 10% are mostly RoHS solder joints.
Check switches and pots very carefully. Check all coupling electrolytics.
Use cramolin liberally.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Scott Dorsey]

In article >, Paul > wrote:
> The sensitivity/gain pot had the center wiper lifted, so it was
>an open! When I shorted the center lead to the high gain lead, my
>sig gen was loud and clear! And I could hear the crossover working,
>as the sound went from woofer to tweeter as I increased the frequency.
>
> I believe this is a linear taper (not log) pot, 2KB.
>
> I hope my electronics place has one with similar physical
>dimensions, when I go there tomorrow morning.

Pump it full of Cramolin or Calube or FaderLube or whatever today's
popular version of Quietrole is. It'll be fine.

If you replace it, replace it on both speakers so you -know- the taper is
the same.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Paul[_13_]]

On 10/12/2018 6:49 AM, Scott Dorsey wrote:
> In article >, Paul > wrote:
>> The sensitivity/gain pot had the center wiper lifted, so it was
>> an open! When I shorted the center lead to the high gain lead, my
>> sig gen was loud and clear! And I could hear the crossover working,
>> as the sound went from woofer to tweeter as I increased the frequency.
>>
>> I believe this is a linear taper (not log) pot, 2KB.
>>
>> I hope my electronics place has one with similar physical
>> dimensions, when I go there tomorrow morning.
>
> Pump it full of Cramolin or Calube or FaderLube or whatever today's
> popular version of Quietrole is. It'll be fine.
>
> If you replace it, replace it on both speakers so you -know- the taper is
> the same.
> --scott
>

Thanks for the advice.

Replacing both pots sounds like a good idea, but isn't the linear
taper going to be decently similar, even between different manufacturers?

It's not easy getting these little reference speakers apart: the
cabinets seem to be glued somewhat permanently together (no screws, just
glue).

[Scott Dorsey]

In article >, Paul > wrote:
>
> Replacing both pots sounds like a good idea, but isn't the linear
>taper going to be decently similar, even between different manufacturers?

Hopefully, if it really IS linear. I'll say that a lot of Chinese pots
that are supposed to be linear aren't. Rather than fiddle with making
everything match, I'd first see if the old one cleans up with cleaning.

> It's not easy getting these little reference speakers apart: the
>cabinets seem to be glued somewhat permanently together (no screws, just
>glue).

Yes, they are not intended to be maintained.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Paul[_13_]]

On 10/12/2018 11:43 AM, Scott Dorsey wrote:
> In article >, Paul > wrote:
>>
>> Replacing both pots sounds like a good idea, but isn't the linear
>> taper going to be decently similar, even between different manufacturers?
>
> Hopefully, if it really IS linear. I'll say that a lot of Chinese pots
> that are supposed to be linear aren't. Rather than fiddle with making
> everything match, I'd first see if the old one cleans up with cleaning.
>

Will do.

>> It's not easy getting these little reference speakers apart: the
>> cabinets seem to be glued somewhat permanently together (no screws, just
>> glue).
>
> Yes, they are not intended to be maintained.
> --scott
>

And therein lies the "throw away" mentality of the world's
corporations. They make more money if people just junk their
old equipment, and buy brand new models. One good reason why
Event doesn't support this model anymore.

Crony capitalism is nasty.

[Paul[_13_]]

On 10/12/2018 6:47 AM, Scott Dorsey wrote:
> In article >, Paul > wrote:
>>
>> At first I thought maybe the LM3886TF audio ICs went bad, but after
>> doing some signal tracing, it appears the input signal isn't making
>> it to differential input pins 9 and 10, on either of the ICs. Or
>> at least, the signal is much attenuated from the input level.
>>
>> Also, the heat sink that the LM3886TFs are bolted to, is getting a
>> little bit warm, and the +/-24 Volt rails are at pins 1 and 4. So this
>> makes me think maybe the LM3886 chips are NOT the culprit here (they
>> also do not look melted, damaged, or cracked).
>
> So, start tracing signal from the input connector into the LM3886 chip,
> paying very special attention to coupling capacitors. If you have an ESR
> tester, just put it on all the electrolytic coupling caps and see.

Yes, I have an ESR meter, and the electrolytics were fine.

>
> You have the advantage of having two identical speakers. One works, and one
> doesn't, so your goal is to find out what the difference between the two are,
> and you might be able to find that just with static power-off measurements.
>
>> Perhaps there is a bad passive component in the cross-over circuitry?
>> Or maybe the TL072C Opamp is bad? 
>
> If the TL072 is bad then a DMM set to diode test will indicate different
> readings on the chip than on that of a good speaker.
>

Ok, the TR5 is similar to the TR8 on the front end, with the
TL072 Opamp configured as an inverting, unity-gain buffer amp.

So it's normal to NOT see any signal on the input differential
pins 2 and 3, right? I remember reading about the virtual ground on the
input pins of this topology.


> The passive components likely don't fail. But measure resistance at the
> output of the amp, compare with the good speaker. If they are the same,
> the crossover is good enough to pass low frequencies at least.
>
>> At any rate, does anyone know where I can get a replacement board? Does
>> Event still support this older model? Could they replace, or at least
>> troubleshoot this board?
>
> Call Event and ask. They might support it, although it would seem to me
> to be easier to just do component-level repair. Find a good tech, this
> should not be that hard to fix.

They don't support this model anymore, although I did ask for the
schematic, so we'll see if they come up with it, for my future use.


>
>> Or does someone have a schematic? I'm lost in the forest without one!
>
> Get paper and draw out what you find as you poke around at it. Likely the
> output stage will be identical to the diagram in the LM3886 datasheet.
>
> But on equipment like this, 90% of what goes wrong are connectors and switches,
> and coupling capacitors. The other 10% are mostly RoHS solder joints.
> Check switches and pots very carefully. Check all coupling electrolytics.
> Use cramolin liberally.
> --scott
>

[Mike Rivers[_2_]]

On 10/12/2018 11:35 AM, Paul wrote:
> Â*Â* It's not easy getting these little reference speakers apart: the
> cabinets seem to be glued somewhat permanently together (no screws, just
> glue).

I haven't seen those so I don't know if this applies, but is the woofer
attached to the front of the cabinet with screws? If so, you can
probably get to the inside workings by removing the woofer and working
through the big hole that leaves. That's how I got into my KEF speakers
to make some repairs on the crossovers. Leaky electrolytics etched
through a copper trace - same problem with the same capacitor in both
speakers, just that one ate all the way through the trace before the
other did, prompting the repair, and taking a look at the other one.

--

For a good time, call http://mikeriversaudio.wordpress.com

[Paul[_13_]]

On 10/12/2018 12:24 PM, Mike Rivers wrote:
> On 10/12/2018 11:35 AM, Paul wrote:
>> Â*Â*Â* It's not easy getting these little reference speakers apart: the
>> cabinets seem to be glued somewhat permanently together (no screws,
>> just glue).
>
> I haven't seen those so I don't know if this applies, but is the woofer
> attached to the front of the cabinet with screws? If so, you can
> probably get to the inside workings by removing the woofer and working
> through the big hole that leaves. That's how I got into my KEF speakers
> to make some repairs on the crossovers. Leaky electrolytics etched
> through a copper trace - same problem with the same capacitor in both
> speakers, just that one ate all the way through the trace before the
> other did, prompting the repair, and taking a look at the other one.
>

Yes, I took off the screwed-in woofer, which was the only
way to access the board inside. And you have to unscrew the
transformer as well, to fully remove the board.

As opposed to my HS 80Ms, that have a screwed on plate
on the back, for easy access. But granted, they are much larger
speakers.

[geoff]

On 13/10/2018 2:49 AM, Scott Dorsey wrote:
> In article >, Paul > wrote:
>> The sensitivity/gain pot had the center wiper lifted, so it was
>> an open! When I shorted the center lead to the high gain lead, my
>> sig gen was loud and clear! And I could hear the crossover working,
>> as the sound went from woofer to tweeter as I increased the frequency.
>>
>> I believe this is a linear taper (not log) pot, 2KB.
>>
>> I hope my electronics place has one with similar physical
>> dimensions, when I go there tomorrow morning.
>
> Pump it full of Cramolin or Calube or FaderLube or whatever today's
> popular version of Quietrole is. It'll be fine.
>

Unless it has had an inwards whack.

geoff

[geoff]

On 13/10/2018 7:43 AM, Scott Dorsey wrote:
> In article >, Paul > wrote:
>>
>> Replacing both pots sounds like a good idea, but isn't the linear
>> taper going to be decently similar, even between different manufacturers?
>
> Hopefully, if it really IS linear. I'll say that a lot of Chinese pots
> that are supposed to be linear aren't. Rather than fiddle with making
> everything match, I'd first see if the old one cleans up with cleaning.
>
>> It's not easy getting these little reference speakers apart: the
>> cabinets seem to be glued somewhat permanently together (no screws, just
>> glue).
>
> Yes, they are not intended to be maintained.
> --scott
>


If the amp panel is not removable from behind, then try taking the
woofer out and the board may be removable through there. I can't imagine
they would install the electronics then glue the cabinet together.

geoff

[geoff]

On 13/10/2018 8:24 AM, Mike Rivers wrote:
> of the cabinet with screws? If so, you can probably get to the inside
> workings by r

Hey Mike - what are your KEFs ? I have R107s in my lounge. Who needs a
sub ?!!!

geoff

[geoff]

On 13/10/2018 8:04 AM, Paul wrote:

> Â*Â*Â*Â* They don't support this model anymore, although I did ask for the
> schematic, so we'll see if they come up with it, for my future use.

If you get a copy, do submit it to elektrotanya.com - a valuable (and
free) resource.

geoff

[Mike Rivers[_2_]]

On 10/12/2018 7:43 PM, geoff wrote:
> Hey Mike - what are your KEFs ?

103.2

I've been using them for more than 30 years, long before anyone invented
the term "reference monitor." They were recommended to me by a couple of
folks in town who recorded a lot of classical music and jazz from the
period (1980s). That was about the time that manufacturers came out with
products for the home/project studio, and most of the small studio
monitors on the market at the time were more rock-oriented.

KEF was kind of a new name over here, and the only place you could find
them were the high end HiFi shops of the day. I was looking at some
Fostex speakers which I arranged to borrow for a couple of days, took
them to a HiFi shop that sold KEF, and compared them side-by-side with
some recordings of mine and some commercial recordings of the same sort
of music that I was recording. There were things that I liked about each
one, but decided on the KEF because it made rock music sound less hard,
and the Fostex made string band music sound too bright and pushy.


--

For a good time, call http://mikeriversaudio.wordpress.com