Just wondering if this is normal for these units. When running either my 100w JMP or 45w JTM45 into the PS-100 for more than a few minutes, I get a plastic-ish burning/melting smell blowing out from the fan.
I opened the unit up to see what was causing it, and I noticed two of the 4x 50w aluminum resistors in the back right are pushing the black core out. Searching this symptom shows that it is usually caused by excessive thermal load, and should not be used until the resistor is replaced. I’m content to replace the resistor myself, but if it’s caused by heat, what would be causing excessive heat? When using either of these amps, they are rarely turned up above 50%. It’s also only effecting two of the resistors.
Checking the heat with a temp-gun, I’m getting ~210º in that general area. Is that a normal operating temperature?
That’s not typical for a unit only operating for a few minutes.
If however, you’re using the PS-100 as a silent load, with the power off, the fan will not be running. In that case, the heat dissipated by the load resistors would spike pretty quickly.
Interesting. OK, anyway, we can get you the parts or you can send it here so we can see if we can identify something that may have helped aggravate the issue.
Please send:
your full name
address
phone
unit serial number
date and place of purchase
Thanks. E-mail incoming shortly. I can try swapping the parts and see if it happens again, and then maybe we go the route of sending it in if it’s still an issue.
Also, I don’t know if this is related, but my unit was one of the units that was originally shipped with bad power tubes causing the unit to go quiet/silent. Support sent new tubes, but the unit seemed quieter ever since. I sent it down for bench testing which didn’t uncover any issues, but is it possible this is related?
Hey, so I finally got some time to try swapping these parts, and I found that three of the resistors in my unit are 6.8Ω, and one is 3Ω. But support sent two of each. Just wondering if maybe my unit was built with the wrong part values (possibly causing the original issue), or did I just get sent the wrong count of replacement resistors?
Well, in the absence of any reply, I replaced the resistors with the same values as what was shipped with the unit, using one of the original 6.8s that hadn’t bulged, and verified that the input impedance measured the same as the switch settings.
After playing for about a minute, the resistors got extremely hot, and bulged the 6.8 that was reinstalled. I think it’s time to ship this thing down. Please advise on next steps. Thanks.
Just to provide an update here, as it seems there is some ongoing confusion on the support team’s side. I submitted an RMA request early last week and to date I have not received any confirmation. I did however receive a reply from support that they would send out another 3ohm resistor. I pointed out that another 3ohm resistor would not allow me to recreate the original circuit, but if three 3ohm resistors is the correct number, then I would need to know the configuration. Support sent another 3ohm resistor without any additional information. I’m not really understanding where the disconnect here is.
To simplify, if my unit was not built with the correct values, how many of each resistor type is needed in this circuit, and where do they go?
