No it is an assumption. We don’t do those too much do we?
Yes that looks like what 15A can do. How much millimeter between chassis and jumpers? Is the chassis straight or does it nearly touch parts/jumper lead wires? Loose screw or piece of solder around?
Ahem a 50 mA fuse would have saved those tracks. If nothing is done and a simple but destructive error still waits for action then the tracks will be copper filled gas again.
Yes that looks like what 15A can do. How much millimeter between chassis and jumpers? Is the chassis straight or does it nearly touch parts/jumper lead wires? Loose screw or piece of solder around?
Ahem a 50 mA fuse would have saved those tracks. If nothing is done and a simple but destructive error still waits for action then the tracks will be copper filled gas again.
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What if a piece of equipment plugged in the back of the unit - an amp, for example - shorted? Wouldn't that send enough current through the unit to blow up PCB traces before any fuse / breaker has the time to react?
After all, the unit is only designed to handle issues on the line side, so what would happen if there was a hot-neutral or hot-ground jump on the load side?
After all, the unit is only designed to handle issues on the line side, so what would happen if there was a hot-neutral or hot-ground jump on the load side?
Plain wrong understanding of matters, sorry. Too much to explain or either basic electrical knowledge already pointed out in detail. Reread if necessary as my fingertips wear out.
*The jumpers and parts are through hole and go through the PCB. That are little outstanding points of possible contact with exciting results. Same with just one uncut or excess length lead wire. Same with the loose blob of solder on the picture near the burn mark.
Any piece of conducting stuff that comes between a hot one and chassis = bingo! But 19 mm makes that less possible. However that meter circuit has a hard time creating even a small overcurrent. We look for a short or massive overvoltage/overcurrent.
This was enough of my time and I have other stuff to do so bye bye!
*The jumpers and parts are through hole and go through the PCB. That are little outstanding points of possible contact with exciting results. Same with just one uncut or excess length lead wire. Same with the loose blob of solder on the picture near the burn mark.
Any piece of conducting stuff that comes between a hot one and chassis = bingo! But 19 mm makes that less possible. However that meter circuit has a hard time creating even a small overcurrent. We look for a short or massive overvoltage/overcurrent.
This was enough of my time and I have other stuff to do so bye bye!
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Yes. And does the short have to be in the Monster unit itself, or can it be in something that is plugged in the back of it?
Lots to unpack here. I'm on vacation so just now seeing this.
The meter backlight is electrolumenicent panel. Runs on 100+volts at something like 5 KHz.
The meter is incremental which is why the zeners are in the meter circuit.
It does meet UL and that means handling 6KV at 3KA surge. It also means 240V at 250A. That's the series fuse function. The burned traces could be from a mfg failure or some abuse. They are not in a power path so not related to a load. It's possible that someone probing the failed transistors could have done something dumb. Even insert the connector off by a pin. (I'm speaking from painful experiences).
It's unlikely but I may have some documentation somewhere. I won't be home until Aug 17.
The meter backlight is electrolumenicent panel. Runs on 100+volts at something like 5 KHz.
The meter is incremental which is why the zeners are in the meter circuit.
It does meet UL and that means handling 6KV at 3KA surge. It also means 240V at 250A. That's the series fuse function. The burned traces could be from a mfg failure or some abuse. They are not in a power path so not related to a load. It's possible that someone probing the failed transistors could have done something dumb. Even insert the connector off by a pin. (I'm speaking from painful experiences).
It's unlikely but I may have some documentation somewhere. I won't be home until Aug 17.
It would be nice f you would explain this in some more words 🙂
Not easy on a phone but here goes (the auto-uncorrect really helps..)
The incremental voltmeter monitors a limited range and spreads it out so you can see smaller variations. In this circuit the zener diodes don't conduct until then voltage reaches 100V which is the low end of the meter and the series resistor limits the current at 130V to the full deflection of the meter.
I hope this helps. Did the transistors fix the unit?
The incremental voltmeter monitors a limited range and spreads it out so you can see smaller variations. In this circuit the zener diodes don't conduct until then voltage reaches 100V which is the low end of the meter and the series resistor limits the current at 130V to the full deflection of the meter.
I hope this helps. Did the transistors fix the unit?
That is the surge board. It is the primary protection. I don't think it's the direct source of the 12v. I have not looked at one of those in 15? years.
I could be wrong but it seems like it does more than just surge protection, maybe a close up picture will refresh your memory?
That board manages the surge Movs the thermal protection the alarm and I believe there is a relay for the trimode that disconnects the power if any of the Movs overheat or are subjected to major overload. We later upgraded with the delayed turn on and voltage sensing disconnect. I don't know if all that is in your version.
Quick update: Transistors replaced, 12V DC present where expected, all outlets are now getting 120V AC. The voltmeter's electroluminescent panel works fine now, the rotary dimmer adjusts the intensity of the blue glow as it should (very McIntoshish 🙂
Two things I've noticed but need to investigate further:
Two things I've noticed but need to investigate further:
- The pushbuttons that are supposed to turn the switched outlets on or off don't seem to be doing anything, but to be fair I'm not familiar with the way they are supposed to work and that is not immediately intuitive so I'll read the manual first.
- There's a buzzing sound coming from the main board, a bit like an unhappy CFL bulb. I got a length of vinyl tubing in lieu of stethoscope, and traced the buzz to F2 in pic above (post #69). F3 is a little noisy too, but quieter. F4 and F5 seem quiet. No load plugged in, I'll try that tomorrow..
More testing today showed that the "Switched" and "Switched & Timed" receptacles are always on, just like the "Unswitched" ones. Right now they cannot be controlled, if the unit is on they're on.
The two switches (ON and OFF) at the front right of the unit seem inoperative. The OFF switch does not turn off the switched receptacles as one would expect. In fact, depressing either switch appears to have no effect.
The toggle switch on the back of the unit is set to Normal.
On the front panel, the Unswitched, Switched, and Timed LEDs are all lit, which is correct since all receptacles are powered.
Replacing the transistors restored 12V DC (11.6V to be exact), restoring relay operation. The relays are now able to close the AC circuits to the "Switched" and the "Switched & Timed" duplex receptacles, each of which has its own relay.
The ON and OFF switches on the front panel are momentary-action switches - they only close the circuit while pressed. Both test fine. So I assume they are supposed to turn the relays on and off via some logic that I haven't figured yet. It looks like that logic isn't working as it should, however.
As an aside, I wonder why two independent ON and OFF switches are used instead of a single toggle switch? Also, my manual is for the HTS-3500 because the MKII's is nowhere to be found online. The pics that @chrisng shared of his HTS-3500 and my MKII show that they're essentially completely different units internally, with very little in common.
Am I missing something about the expected behavior of the switched receptacles?
If not, any feedback or ideas as to why all the receptacles are always on, the ON and OFF switches don't work, and the Timed functionality does not work either, would be very much appreciated. Thanks in advance!
The two switches (ON and OFF) at the front right of the unit seem inoperative. The OFF switch does not turn off the switched receptacles as one would expect. In fact, depressing either switch appears to have no effect.
The toggle switch on the back of the unit is set to Normal.
On the front panel, the Unswitched, Switched, and Timed LEDs are all lit, which is correct since all receptacles are powered.
Replacing the transistors restored 12V DC (11.6V to be exact), restoring relay operation. The relays are now able to close the AC circuits to the "Switched" and the "Switched & Timed" duplex receptacles, each of which has its own relay.
The ON and OFF switches on the front panel are momentary-action switches - they only close the circuit while pressed. Both test fine. So I assume they are supposed to turn the relays on and off via some logic that I haven't figured yet. It looks like that logic isn't working as it should, however.
As an aside, I wonder why two independent ON and OFF switches are used instead of a single toggle switch? Also, my manual is for the HTS-3500 because the MKII's is nowhere to be found online. The pics that @chrisng shared of his HTS-3500 and my MKII show that they're essentially completely different units internally, with very little in common.
Am I missing something about the expected behavior of the switched receptacles?
If not, any feedback or ideas as to why all the receptacles are always on, the ON and OFF switches don't work, and the Timed functionality does not work either, would be very much appreciated. Thanks in advance!
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@chrisng I checked / replaced all transistors on the main board and on the little user interface board with the 2 pushbuttons and the rotary dimmer.
Out of 9 transistors, 5 were bad.
But new transistors made no difference as far as the remaining issues:
At this point, the only original component left that's capable of any logic is the HA17339 quad comparator. It's getting a correct 12V at Vcc, but input and output voltages show 2 of the 4 cores not behaving as expected. So I guess there's my next focus 🙂
Out of 9 transistors, 5 were bad.
But new transistors made no difference as far as the remaining issues:
- On/off pushbuttons not working
- Inductor buzzing
At this point, the only original component left that's capable of any logic is the HA17339 quad comparator. It's getting a correct 12V at Vcc, but input and output voltages show 2 of the 4 cores not behaving as expected. So I guess there's my next focus 🙂