I see that the 4700 uses a 1.2VA, 240/6 transformer. Can you recommend a 120V part for us in the USA that would fit on the PCB?
K4700 units that are sold in the US via Velleman Inc. come with correct 115VAC transformer.
Ok, thanks for the update. Qkits needs to update their website.
one other question…perhaps modifications are not to be discussed here, but could I cut a lead to one of the relays and run jumpers to a third relay? Would it have the power to control that?
I’d like for it to control a relay that shunts the main amp power supply (not the K4700 transformer!) around an NTC thermistor after a 6 second delay. The thermistor will be preventing transformer in-rush. But I’d rather not leave the thermistor in-line during amp running because it gets hot.
Correct, we do not have the means to support modifications.
Please note that Qkits ship worldwide, so they probably stock both versions.
If the relay does not consume more than a couple of tens of mA it should not be a problem.
OK. I got the kit and assembled it. I have done some simply repairs before like capacitor upgrades (soldered), and built another vendor’s “multimode timer” kit that is almost as complicated. So I’m not a rank amateur.
However, I was rushing a bit at the end and put the IC in backwards. Ooops. This will destroy the IC, apparently. No problem, I ordered another LM324N from Mouser with other items I was buying for my amp project. This time I installed it correctly. Here’s the problem. The yellow light never goes out and the relays never click. HOWEVER the detection side of the circuit seems correct, because, if I apply DC to the PA terminal, the red light comes on. I’m wondering if putting the IC in backwards damaged T4 or T2, although this seems unlike as the voltages involved should be minimal. What little I know about electronics tells me that, w/o a timing IC present, the timing somehow involves C11?
Any suggestions to help debug this problem would be appreciated…thanks in advance.
EDIT: uh oh Velleman. You have a bit of explaining to do.
I ordered the kit from a distributor you list as authorized on your US website. The transformer was labeled 230V but I assumed it was perhaps an autosensing one and would be ok at 120V.
I thought the LED seemed a bit dim, so I was testing the voltages on the board and noticed that V- to G and V+ to G were -3 and +3 volts, respectively. This seemed wrong as the circuit is advertised to work at -6V & +6V. I disconnected AC and connected an ultra-cheap power supply I have. It’s not clear to me whether this thing is symmetric or asymmetric, but since it has a (-) and (+) terminal, I assume the former. I dialed it up to 12v and measured it with respect to ground: -6V and +6V. Connected it to the K4700 and lo and behold after 5-6 second, the sound of the relays clicking!
At this time, we do not know where something went wrong.
Did you order the K4700 (230VAC) or the K4700U (120VAC) ?
Did your supplier supply the wrong version ?
Did you contact your supplier ?
If you cannot solve this issue with your supplier, please call your US based support office at (817) 284 77 85