When ok isn't really ok...
I had a QSC 1100 amp repaired. I sent it to the Canadian importer/distributor of the brand here thinking they know best, right? The amp has a turn-on delay, it was defective, making a loud Buzz sound upon turn-on. They "fixed" it (buzz gone) and gave it back to me. The amp works and plays music.
But since that repair, I noted the heatsinks get unsusually warm/hot, even when nothing is connected to the amp, input or output! No speaker cables, no input cables connected, just the AC cord plugged and amp turned on, I can't keep my hand on the output transistors/heatsinks very long...
So I sent it back to these guys with explanation and mention it wasn't like this before the initial repair. They told me they adjusted the amp's bias, amp is ok, the heat is normal and its like that! Not admitting any issue created. Could it be a defective replacement part, or a solder/wire creating some short for example?
Not being a repair technician I've put the three such units I have side-by-side, cover off, trying to spot any notable problem or difference(s) that may explain the situation, but its not evident. I do see slight things not being the exact same but maybe they're not enough to explain things, and these could be manufacturing related as they were not all purchased the same time.
For sure the distributor is out of luck with his explanation, having three such amps, its easy to compare the heat made by one vs the others. With the same operational conditions the other two run dead cold! Moreover, there's no sign that these two units would then be the defective ones according to their logic!
This situation reminds me of another: I seem to remember a recent post from Barry where I think he mentioned he was about done with "repair shops". I'm pretty done with this one. They SHOULD know better. Sounds pretty much like "you go in there with a problem and come out with another one". I thought the grass was greener on the US side.
Sending it to QSC in California for expertise/repair would unfortunately be pretty costly, and they would probably refer me back to the local distributor who has exclusive rights/obligations, plus "factory repair service", for the product in my country, as I was told previously by another maker regarding its local distributor.
The heat related protection circuit hasn't triggered yet (spec sheet 90°+ C, service manual 105°C, will try to measure this temperature with a thermometer). Why bother then? Heat, at the level I feel it and in this setup isn't normal, also its a well-known enemy of electronic circuitry/components. Plus I'd like to keep this small versatile amp for many more years. They were relatively expensive back then for one rack space (895. CAD retail + tx), are compact size, nicely made, perform well and quite flexible: XLR Switchcraft, 1/4" TRS, Barrier strip, DIP switches, Octal sockets, can do 8/4/2 ohms, have a couple of db of dynamic headroom, etc. and made in good ole USA.
So, back to another repair shop next week, hopefully to find out what goes wrong. Since they repair mostly Pro stuff/high level gear, and are authorized service center for most Pro brand electronics (including JBL, probably QSC too), I figure there may be hope...
On a more positive note, all my new audio gear has finally arrived (took a month+ all together), same place where the QSC is going for diagnosis and repair. Four items had arrived about 2 wks+ ago, however six others were back order at the Canadian distributor(s) involved (Ashly, DBX, Tascam, AT, etc). Quite surprised by the delays considering there's nothing really complicated or unusual on the list. This may be a sign that local distributors stock more lower cost items or fast movers only and order the others from manufacturers as required. Doesn't look good for the Lowell rack (USA made, pricier vs size) I want to order when picking up the new gear...
Richard
P.S. I'll post a picture soon of the three QSC brothers side-by-side on the "examination table".
The new toys arrived home!
At last, my new toys have finally made it to their permanent residence. Picked them up yesterday, they are now lined up in their box in the basement for the time being, a few pictures to follow. I also got for the asking a small bag with a dozen and a half of various Euroblock connectors, which I never needed before (used mostly Neutrik or switchcraft XLR/1/4" connectors), but now Euroblocks appear everywhere (e.g. on my new Ashly amps, there may be some already in the boxes, which I don't know, some spares then!).
It will take some time to set up all the gear, more so since I need to pull out of the present rack a number of items to make space, reorganize everything, make many cable/connector sets and wait for a new rack... Some cabling is easier to reuse on something else, like those for the BGW amps given away, by simply changing the XLR Pin 3 hot connections to the present standard Pin 2 hot.
The easiest device to try quickly is probably the Rolls Sonic Maximizer (XLR/RCA), not rack mount, which I can plug fast in my hi-fi setup using RCA cables, between an Onkyo preamp and a NAD amp. A few things strike me about this not expensive "sonic magic" toy: Glass epoxy PC board, Pro grade connectors, silicone damped pots, subwoofer output with 18db/oct, USA made, vs tons of cheap throw away type of stuff from Asia. I guess there's still hope south of the border...
I did order at the same time, with a small deposit, the nicely US built 7 RU rack from Lowell (LDTR-718). Its all good metal construction (no cheap particle board here) appears being made to last forever, which I tend to like. The plan is to make a plywood base under the new rack to lift it up, put the new Allen & Heath mixer on top of that rack to end up at about waist level and it will sit next to the taller rack. Still need to figure out a logical way of spliting the equipment between the two racks though, this affects cabling length. Power (AC) distribution is another matter I need to tackle here...
As more or less expected in post # 20, the new rack is... not in stock with the Canadian importer/distributor! The vendor confirmed to me that since the Internet purchasing craze or wave even importers/distributors (and retailers) don't keep much stock anymore, except popular fast moving items. The couple of weeks delay expected doesn't bother me too much here considering that expense will then go towards the new 2019 audio budget, as I wished. 2018 money is gone now, except for the following issue, if reasonable.
While being there, I also dropped the overheating QSC amp with one of the the repair technicians on-site for testing/repair estimate, even providing a good such unit for comparison purposes, the tech thought it was a nice idea to have a good reference on-hand to compare with, in case its needed. Plus I gave him a USB flash drive with all the QSC amp info I have (schematic, service manual, owner manual, specs, etc.). Helping him to succeed, indirectly helps me! Wasting time looking for manuals on the Net doesn't.
Finally, I got a nice price (only) on the Rolls studio amp (RA 200, MOSFET, etc.) mentioned previously. Better than expected, but I want to see first the outcome on the QSC at the repair shop. This may orient or not my thinking about another amp, Ashly or a Rolls, in the new year. Rolls thinks differently and does things likewise, which I tend to like here, in addition to still making some stuff in the US.
Richard
P.S. I may post later a note I wrote recently about the mixer's choice made, sort of the control center of it all, and some issues related to it...