| Author | Message | ||
| r4v5 |
Okay so I have an old HD130 with the tube phase inverter/driver (from the looks of it). From the day I got it (around two weeks ago) the tremolo didn't work. I tried putzing around with shorting out the footswitch connector and nothing happened. So I checked online and Ernie Ball (which, let's face it, kicks ass in the support department for amps that are 20+ years old -- especially since they DROPPED the line...) has the FAQ with the instructions to adjust the trimpot. Now opening up the chassis (which one could say was really careless and stupid of me...) there were two trimpots visible on the back of the "main" PCB. By my high-tech "eenie meenie miney mo" inspection abilities, I chose the one on the right (furthest from the power supply) and turned it slightly clockwise. The trem KICKED IN and i mean KICKED IN because i had speed and intensity both at 10. So question 1 is why did the trimpot need adjusting? Cap drift over time? Did shipping jostle it? Question 2: Are there any caps that obviously need replacing? there's no buzz on this amp but it's pretty old so if there're any caps that are prone to failure in MM techs' opinions... Question 3 is what does the other trimpot do? Bias setting for the 12ax7 (assuming i got the tube model right -- i don't actually see it 'cause it's in the metal case)? If that's the case do I have to remove the screws holding the PCB on to get to the resistors and such that I can measure the bias voltage on? Question 4: Mine arrived with an accutronics reverb pan on the floor of the combo and a short length of wire headphone style where it branched into two RCA jacks. Is this stock? It certainly sounds lush, though it can get really 'tinny' really quickly. Don't the extremely-large-magnets of the speakers stand to interfere with the pan? Questions 5/6: I'd like to build a footswitch for my unit. Here's what im thinking. It'd have six buttons ('cause i LOVE buttons...) One and two would be reverb and tremolo. They're simple RCA jacks on the back right? SPST and when they're closed the effect is off? The other four would be switching on the four input jacks. Channel one and channel two would each be separately enabled (I LOVE the sound i get from using my DOD icebox chorus as a splitter, even if it's off). The other two switches would control which jack it goes to -- normal, or attenuated. Do you think this is worthwhile, and will be used? Or should I just stick to normal channel switching? Q7: Where do the big manufacturers get their footswitches for stompboxes and footpedals? I want a LOT of 'em  | ||
| TERRY |
MAYBE YOU HAD A PIECE OF DIRT IN THE POT, WHEN YOU MOVED IT...IT KICKED IN. IF IT IS WORKING NOW, I WOULD LEAVE IT ALONE. YOU SHOULD REPLACE THE 2 PVC CAPACITORS ON TOP OF THE POWER TUBES WITH DISK CAPACITORS 470 OHM/3000V AS THEY WERE USING IN THE LATER MODELS. CHECK THE RESISTORS ON TOP OF THE POWER TUBES TO MAKE SURE THEY HAVEN'T DRIFTED TOO FAR APART. IF THEY ARE WITHIN 5, I WOULD LEAVE THEM ALONE. THE OTHER POT IS TO ADJUST THE BIAS ON THE AMP. GO TO THE FIRST POSTING AND IT WILL TELL YOU HOW TO DO IT. THAT REVERB LEAD DOES NOT SOUND LIKE A MUSICMAN UNLESS THE RCA JACKS ARE RED AND BLACK. YOU ARE ON YOUR OWN ON THE FOOT SWITCH. | ||
| Justin |
It's not just dirt. My 212-hd had the same problem. It is an old one, 1975 w PI tube. I turned the trim pot and it worked. The amp was my fathers originaly and he said it never worked for the first day he got it. He was just too busy traveling to return it for repair. There must have been a few that made it thru the inspection line. Maybe they turned the tremolo off to do other tests and some were'nt turned back on. And I suspect very few. You should replace the two transistors that run the tremolo circut. After doing that the tremolo was much better in my amp. But maybe your did'nt get as mush use, so it may not be needed. And make sure you adjust the internal pot so that second modulation starts to work with the intensity control set to around 5. Hope any of this helps. |
Tue, 03/25/2014 - 09:55
#1