Meyer Sound 833 problem

I have a Meyer Sound 833 control unit on my bench. It has a weird fault
that appears to centre around a 15kHz oscillation that affects one
channel, directly, but is bleeding through to the other channel.
Meyer Sound refuses to supply a schematic. They will repair it for a set
charge of US$592.50 (nice round figure). That's a bitter pill to
swallow, but it gets worse. I (and my customer) are here in Australia
and I figure on the freight charges to blow that figure out to around
US$1,000.00 or so.
I am hopeful that someone has some experience with this product. Maybe
even schematics.
TIA
Trevor Wilson
Reply to
Trevor Wilson
Loading thread data ...
Will they supply parts? Even buying the complete guts can't cost as much as their charge plus freight. I think I know the answer to that.
In Connecticut U.S., we had a law years ago that required any company that sold electronics in our state to supply schematics to a licensed repair facility and free of charge as well (I guess to cut off any attempt to sell schematics for $500 each). When I informed a company (can't recall which one) that they had to supply me a schematic by state law, they essentially told me to pound sand.
We definitely need "right to repair" laws with teeth in them.
Reply to
ohg...
=====================
** The unit is nearly 40 years old. Consists of one PCB in a box.
FYI TW is an agent for an audio product with the exact same policy.
Karma ??
..... Phil
Reply to
Phil Allison
Fair enough, but if they offered to "repair" the unit, they must either have parts or a substitute board I would imagine, unless the repair cost is actually an exchange cost with a later model.
Reply to
ohg...
not familiar with the amp and not an audio guy but: 15Khz sounds like switching supply noise? Bad caps on power rails? JC
Reply to
JC
I thought of and then dismissed that assuming both channels shared a common supply, but I guess there could indeed be a separate converter for each channel. One thing I've found consistent in consumer electronics is that that lazy electros generally respond to heat and cold. Warm it up with a heat gun. Noise gone? Good chance an electro bypass is the cause.
Reply to
ohg...
**Not power supply noise. The power supply is as clean as a whistle.
All electros have been replaced with high quality (Panasonic and Nichicon) components.
The unit is pure analogue. NO digital stuff to be seen.
There are 25 dual OP amps (5532), a handful of bipolar transistors, 2 X dual gate MOSFETs, four Vactrol opto-isolators and here's the big one: 27 preset pots. Every single one has been moved from factory settings by a previous tech. Without access to factory service data, I have no chance of restoring this thing to anything resembling normal operation.
I have been able to stabilise one channel (though I still have a low level 2MHz oscillation to deal with). I was able to measure the frequency response curve and fell confident that I can duplicate the curve using a a 32 band, digital parametric EQ. I won't have the ability to use the speaker feedback section, but that should be a concern, give that the system is designed for sound reinforcement use, but will be used in a domestic application. The speaker feedback system is designed to protect the HF drivers under very high power operation. MY solution should work well and will cost my client much less cash.
Reply to
Trevor Wilson
"... but that should be a concern,...."
Should read: "...but that should NOT be a concern,...."
Reply to
Trevor Wilson
===================
** Errr - no it ain't.
formatting link
And this section is dead funny for all the wrong reasons.
formatting link
...... Phil
Reply to
Phil Allison

ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.