Please! someone help me
My Hot Rod Deluxe suddenly got stuck in the Drive Channel and doesn't switch to Clean Channel or to the More Drive Channel. I'm not a tech but I've made some of the Justin's Student Web Page mods and worked fine till yesterday. I oppened it to check and noticed that the CR13 just next to the 5W screen resistors were loose in one of the sides so I soldered it back in place but the problem remains. What could the problem be ? What can I do? I'll appreciate it. Thanx.
Imanidiot.
i can't help you...
but u might enjoy this anticdote; i was selling my last HRDlx,.....the potential buyer was playing it.
...it sounded good and was doing it's job well that day...then the guy says...i'd like to take it but there's a rattle....hmmmm?....rattle?...like some screws are loose...so i shrug my shoulders and say, whatever...that's cool, you don't want it....no biggie.......so my buddy looks inside...nothing...then feels inside, and all 4 screws holding in the speaker were loose, 2 practically fell off in his hand...he tightened it, the rattle went away, and the dood bought the amp
i thought he was giving me a line...instead he gave me cash.
sorry, wish i could help.
try doing a 'search'.....
Imanidiot.
Your words seems i have no chance to get it fix ... I will consider your advice if it don't have any chance to be back again. But i'll do the search or hope someone that has been through or something like this could give me some light with this problem. At least i'll learn a little more working with amps... nothing... me keeping faith. Thank you for your time and advice.
there r quite a few threads on the HRDlx.....
but i'm sure if someone here had your specific problem, they'll chime in.
Imanidiot.
From glancing at the schematic for this amp, the immediate culprit appears to be the K1 Switching Relay. I'm not certain if these relays are consumer replaceable or not. Your best bet would be to take it an amp tech that knows this amp.
POO DAT!!!
Channel switching issues almost always result from the overheating of the 5W power resistors (R78 & R79).
They get warm, then their solder joints get wacky, then all kinds of craziness happens. Don't believe it? Check this out (from mine when it was a HRDlx):
That's the back of the PCB where the afore mentioned resistors are mounted.
If you replace them, make sure you stand them up off the PCB and don't use silicone underneath. They really do need to breathe.
Mine got so bad, I had to run jumper wires in that area.
"...pray do not imagine that those who make the noise are the only inhabitants of the field;
that, of course, they are many in number; or that, after all, they are other than the little,
shriveled, meagre, hopping, though loud and troublesome, insects of the hour."
-Edmund Burke
Did you check the CR13 diode? Those commonly fail as well. Those HRD boards are pretty fragile. If you're not getting 16V at R78 or R79, then you have a failed diode. If that checks out then look at the switching relay. Good luck!Originally Posted by chikqo
Please! someone help me
My Hot Rod Deluxe suddenly got stuck in the Drive Channel and doesn't switch to Clean Channel or to the More Drive Channel. I'm not a tech but I've made some of the Justin's Student Web Page mods and worked fine till yesterday. I oppened it to check and noticed that the CR13 just next to the 5W screen resistors were loose in one of the sides so I soldered it back in place but the problem remains. What could the problem be ? What can I do? I'll appreciate it. Thanx.
do I look like I know what I'm doing?
Thank You guys for your time, i'll keep you inform in what results it will end. i'll see what happens after change again the screen resistors. I replaced them for 330 ohms 4 months ago, also will change the CR13 diode which was loose and was the only thing i noticed wrong after i first open the amp to see what could be happening. Thanks for your support.
It should be 470ohm, I thought? If you're down that low (330ohm) you might not have the right voltage switch to change channels. Does it stay in the drive channel when the footswitch is in use? Does it work with the on-board button?
Diodes don't really fail that often. Touching up the solder is always a good idea, though. Be sure you thoroughly de-solder before soldering again....but I really doubt it's the diode.
"...pray do not imagine that those who make the noise are the only inhabitants of the field;
that, of course, they are many in number; or that, after all, they are other than the little,
shriveled, meagre, hopping, though loud and troublesome, insects of the hour."
-Edmund Burke
NT...
I've had 2 in the shop so far that CR13 had failed... it obviously got hot enough to desolder itself and they are pretty heat sensitive critters.
Wow...that's the first I've heard of those diodes failing. Not that I don't believe it; the more I think of it the more surprised I am that I haven't heard more about them. They are in a bad spot for something that's sensitive to heat, eh?
Well, I guess there's no end to what troubles these power resistors cause.
"...pray do not imagine that those who make the noise are the only inhabitants of the field;
that, of course, they are many in number; or that, after all, they are other than the little,
shriveled, meagre, hopping, though loud and troublesome, insects of the hour."
-Edmund Burke
I think the diode failing has more to do with the 5 watt resistors shorting due to them desoldering themselves... It appears that there isn't a whole lot that doesn't suck about that board! It's unfortunate that Fender didn't opt for a thicker board with traces on both sides... it's not a bad sounding amp, it's just not going to last like the old hand-wired Fenders, though they are priced to be semi-disposable...
I have an extra set of the zener diodes if you need them.
I'm starting to familiarize with this kind of work, I'm maybe reading wrong. I checked it with my multimeter with the black wire in one bend of the resistor and the other with the red wire in the other side bend of the same resistor and it reads 31.1 V, the schematics says it is supposed to read 16 V one side and in the other 48 V, that confused me. The bias range affect that?, Is that o.k. or Am I checking it wrong? I'm not sure if thats the correct way. The solders on the swithching relay looks very well. But I'm not sure if everythings OK inside the relay.
Thank you JAM I'm very slow speed with this task just because I don't want to lose my amp and doing this very careful way. I want to make shure if theres something wrong with the diodes. If thats the problem I'll tell you. I appreciate it.
You're measuring the voltage drop across the resistor, while the schematic references are to ground. I dont offhand have the references (R??) but they should read +16v on one and -16v on the other resistor. (Referenced to ground as I stated)
No problem. I no longer have the amp, so if you need them you are welcome to have them.
NT, I replaced my 470 ohm R78-79 with 330 ohms. (As per J.Holten)
The amp works fine with the lower value. It makes sense to me.Less resistance,less heat to burn up the pads.
Not to be a thorn in your side, but it was once pointed out to me (*cough*thanksJAM*cough*) that less resistance = more current = more heat.
I guess as long as it still worked, right?
"...pray do not imagine that those who make the noise are the only inhabitants of the field;
that, of course, they are many in number; or that, after all, they are other than the little,
shriveled, meagre, hopping, though loud and troublesome, insects of the hour."
-Edmund Burke
Yes, I was at home yesterday studying the schematic and understood that it had to be tested to ground and they were OK... as it says... one side measured (+-)16 V and the other was supposed to measure (+-) 48 V though it said (+-)51.1 V wich is near, so I understand it is more or less in the range I assume its OK.
Testing other point, the U3 chip I accidentally touched toghether the two low terminals at the left side and I noticed that the channel indicator led which was stuck in the yellow color turned off. Then I connect my guitar touching the same terminals and sounded clean how it's supposed... but didn't found the way to switch it to the More Drive channel. What do you think guys could it be that chip? I call it chip because I don't know the name of it. I think I should see if I get that chip and replace it to see what happens.
I think the big (K1 & K2) chips are Omron switching relays. U3 looks like a 4560 opamp in the schematic.
One of these (opamps), right?
Or one of these (switch relay)?
"...pray do not imagine that those who make the noise are the only inhabitants of the field;
that, of course, they are many in number; or that, after all, they are other than the little,
shriveled, meagre, hopping, though loud and troublesome, insects of the hour."
-Edmund Burke
Yes the switching relays says Omron G6A 274P-ST-US 24 VDC (1288 c1, And checked the opamp number (BA4560) 826 H70.I think the big (K1 & K2) chips are Omron switching relays. U3 looks like a 4560 opamp in the schematic.
One of these (opamps), right?
Or one of these (switch relay)?
I dont think it's the relay. You need to be sure the +/- 16V supply is working right first and actually getting to the chips/relays. With the heat you may have lifted a pad. Sometimes you'll have to wire jumpers to fix the traces on these.
What I'm refering to in the quote above is the opamp number (BA4560) 826 H70.
chikgo,
I've got to run out for a bit. But I'll have a look at the schematic and see if there's some troubleshooting things you can check out.
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