I am currently the proud owner of three MM 130HD212.:
Fan of the group Dire Straits for more than 25 years, it is quite naturally thanks to the MM 130HD212 that I found the sound of the first albums of my favorite group. Trained as an engineer, I quickly sought to service and maintain my vintage guitars and amplifiers. I spend a lot of time studying the 2475-130EX and its secrets! I come to share my passion with you and my work around the 130HD212!
Welcome aboard the MM site.
Welcome aboard the MM site. We have a dedicated group here, since they haven't MADE these in 30 years! Have not worked on any exports models but have seen the inside of the US versions a lot. That 130 in the pic looks nice! Cleaner than my 65 but mine has been used a lot. those corners look buffed or satiny. Is that just an illusion or did you do something to them?
I actually restored the fittings: chromatography for define the exact color of the original Nickel plated, electrolysis, sanding, polishing etc. : in short, a surface treatment including an additional layer compared to the original treatment: a layer of transparent varnish to prevent corrosion of the parts. It took me several weeks for obtain this result.
My amps are equipped with 2 Eminence speakers with square or round al-ni-co magnets. Indeed, at
At the time, the Leo Fender factory was actually mounting
Eminence loudspeakers featuring square magnets of different
sizes and shapes. Then, around 1980, the 130HD212 model was equipped with
Eminence speakers with round ceramic magnets. Moreover,
the amp was optionally available with Electro Voice speakers
EVM 12L : I will preserve the original configuration and create now a spare of the front cabinet for two EVM 12L...
2475-130 212HD 130 MM
Good Day, Just got one of these amps, replaced all of the electrolytics that were the originals. Used good quality F&T's. The amp was played through about 5 days prior with relatively good tones - just a bit of noise probably from the old capacitors. After replacing the caps, I slowly powered the amp through the variac. once the tubes were warmed up, I checked the plate voltage, and it was 603 volts. I attempted to adjust the bias to .5VDC and the highest it would go at that 10 ohm resistor on pin 8 was about .1VDC. I double checked all of the F&T's in the doghouse, the 5 150uf 50 volt ones are spragues - they appear to be okay and soldered well. All of the capacitors were installed correctly as far as to the positive and minus sides. Any ideas? Thanks!!!
Check Bias Supply
It sounds like the bias voltage is too negative. Check the circuit around C31, C32 and RV-2. Make sure the 2 zener regulators (D5 and D6) are working properly. Measure their voltages and also measure the output voltage range of RV-2 bias adjust pot. -mgriffin
2475-130 212HD 130 MM
Thanks for your fast reply, I supper appreciate it! Prior to the capacitor replacement - apparently the amplifier was played through. So now after the capacitors have been replaced I am checking each new capacitor. I will in fact go back the area your mentioned and double check everything. Thanks again! Added the schemated I'm using in troubleshooting.
Repaired with caps - Thanks! Quick question about tubes
The 212HD 130 (2475-130 with a 12AX7) is now working. I am thinking about replacing the original Sylvania 6CA7's with a matched quad set of JJ E34L's. Everything I am reading in reference to the to the amps high plate voltage I understand the bias should be set lower. What would be your opinion on the level for tube protection? I am using a Bias Probe that has been a good quality through all of my other amps in the process. I currently set the bias at the 10 ohm resistor to .5vdc after the repair. now considering a tube replacement to E34L's. I have experience with Fender's and Marshalls, but this is the first Music Man I have had, I sure do appreciate connecting with others experience! Thanks Again. Paul
That old 1/2v at point y won
That old 1/2v at point y won't cut it in today's world of junk tubes. I personally would put some one ohm resistors from the cathode to the 10 ohm and directly read the voltage across the one ohm resistor, giving you an accurate reading of EACH TUBE. Reading the sum of the volage is not going to do you any good if you have one tube hot and another one cool. You are going to get a total voltage that way. Today's tubes are way too flaky to handle that way. JMHO. Mike. PS- I'd set them at 21-22ma draw (MV) or even a tad lower.
N/S C007943 restored with two EV speakers
great sound !
Looks Good too!
Looks good too!
I recommend this video : https://www.youtube.com/watch?v=uyn080vOA34
a second part is being filmed. Thank's to Philippe !
As for me, I will be back soon with a new MM 130HD212 : N/S C003246 !
The N/S C007943 restored with two EV speakers in action : https://www.youtube.com/watch?v=JRALykaLq2A
Have a nice day !
The N/S C003246 on the workbench : https://www.youtube.com/watch?v=xjwzHXLA_eQ
An full original and early model in mint condition : The 2-130-E PT is here and the famous 12 AX-7 too : The 12AX7 provide gain and phase splitting. Without proper cooling the EL34's would overheat and fail. Tom Walker designed also a class B drive circuit, which used LM1458 and JE 1692 transistors to drive cathode of the EL34 instead of the original grid drive.
Have a nice day !