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Messages - DrGonz78

#541
Amplifier Discussion / Re: Grounding techniques
October 12, 2012, 08:59:00 AM
Take out your DMM and make sure what color wire is hot and neutral through the power cable. Then remove the cable and get a 3 prong type power cable. (Assuming you are in the US) Basically, you have answered the solution all ready in your post. Drill a hole in the chassis and attach a ground wire. It is really easy as you said in your post. Sometimes I find Black hot and other times white is hot...? Look at the function of the power cord in relation to your DMM. Adding a ground wire should solve your problem.

P.S. - Star grounding is something totally more advanced in my thinking in relation to just adding a simple ground wire.
#542
Amplifier Discussion / Re: vox ad 100vt
October 05, 2012, 06:30:29 AM
Maybe that amp is trying to send a fax somewhere?? I recently had an AD30VT amp where luckily the speaker was the only thing bad. I decided to look in the amp just out of curiosity and pulling off the knobs loosened/cracked a couple pots. So I now have to take the whole thing apart...  :trouble

The stems pulled right out of the pots and I had to replace them, but they had legs that bent around. Very proprietary pots and so I clipped off the legs. I soldered the legs onto replacement pots, and that was actually fun. Like a MacGyver repair technique that this amp really deserves. So I got the thing all patched up and working. Sold that amp and now I don't think I will ever touch one ever again.

Playing the amp the decay of the strings was vibrating in some sort DSP way that just kills my heart. For loud playing the amp is ok. If you have any level of dynamics to your music then these amps do not do justice at lower dynamic playing level.
#543
Personally I would say that you need to start updating your power plugs in your home. Why would you not want to update, at least some of them around the house?

You could install on the amp a polarized power switch (probably a bad idea) and in conjunction w/ some other type of ground scheme chassis clip. That way you have control of ground loops that might occur w/ other devices that are on stage and then you could flip Hot and Neutral around to make sure there is no buzz too...

Why not just get a 3 to 2 ground lifted plug adapter>>>

http://www.filmtools.com/grliadco41.html

That way you can just plug straight into the now grounded power strip. Just got to bring a screw driver with you or just a piece of insulated wire to connect it to be grounded somehow. I would recommend just screwing in the lifted ground into the screw on the 2 prong face plate on the wall. Well the screw will only work if it is ground, but there still might be hope if you can find something that is grounded to connect to it. However, this is still not that safe and only is to reduce noise. The best solution is to have grounded outlets that connect to a GFI.
#544
Amplifier Discussion / Re: Randall RG80/100ES QUESTION
October 04, 2012, 03:24:37 AM
Well some of the early 90's amps were still great but by mid to late 90's are the models that are not collectors pieces of the future. However, some will swear by the 1969-1980 era of Randalls since they were not pushing for a distortion driven preamp, still I love the 80's series too. Randall commander iv Model is RG90-4 is pretty cool model that I have yet to come across at a lower price. I only buy these amps, or any amp for that matter when the price is right. I got a 1986 RG80 112sc combo for $50 and I paid $40 for a 1981 RG30 112 combo amp. Both of these amps are in great condition too and the RG30 is silent making it great for recording. The early eighties the strip that has the logo is a darker grey color and lighter later into the eighties. The 1969-80 years mostly had that off orange-red color where the logo was as in the commander type series. The bass amp that we had in middle school/High school band was Commander series bass amp from the 70's era. That amp was really nice and reminded me of the tone of Chris Squire from Yes. I miss that bass amp... <3)



Also, I am not sure about this amp really, but it looks like a winner!! Tube though on ssguitar site sorry. This is a modern version of Randall that looks appealing at least.

http://www.ebay.com/itm/Randall-MTS-RM20RP-Tube-Guitar-Amp-Amplifier-Combo-w-3-MTS-Modules-/330799939363?_trksid=p4340.m2109&_trkparms=aid%3D555001%26algo%3DPW.CURRENT%26ao%3D1%26asc%3D7%26meid%3D2499981840776463939%26pid%3D100010%26prg%3D1004%26rk%3D2%26sd%3D140858665691%26

or this solid state gem...>

http://www.ebay.com/itm/RANDALL-HARDROCK-RG-150-GUITAR-AMP-150-WATTS-1-2-PRICE-SHIPPING-VIA-INSTANT-REFU-/251114785839?_trksid=p4340.m2109&_trkparms=aid%3D555001%26algo%3DPW.CURRENT%26ao%3D1%26asc%3D7%26meid%3D2499981840776463939%26pid%3D100010%26prg%3D1004%26rk%3D3%26sd%3D140858665691%26
#545
Amplifier Discussion / Re: Randall RG80/100ES QUESTION
October 03, 2012, 05:54:32 AM
Those Transformers were really cool as kids!! Blaster turned into a Ghettoblaster!! Soundwave was a decepticon that was basically the same thing but way less Ghetto! In the comic book they had a CircuitBreaker character. I wonder if you asked that clerk in that store if they have a circuit breaker what his answer would have been. "Uh that never made it to the movies man..." The price of copper these days... Geesh these stores are run by morons huh? Good job cleaning house!

Oh and to the original poster... The Randall back then is not really the same Randall as today. Not saying they are bad now, just that they don't support lot's of older products. It's really hard to contact the company on anything before it was bought by US Music Corp. in the 90's. It was sold in 1987, so there is that grey area for almost 8 yrs before the bigger corporations took over. I like the older Randall stuff the best, but they still have cool amps today. Just gotta find info on the older amps somewhere other than Randall. Maybe they do support some stuff but I remember reading somewhere that they did not support older products.
#546
Amplifier Discussion / Re: Randall RG80/100ES QUESTION
October 02, 2012, 05:13:08 AM
Sorry Juan I was just having fun... I was goofing off and not being as serious as I should have been...

I miss details of a post every time either way and I find that my newbish ways are tell tale signs that my advice is not as good as it could be. I will try better in all my posts forward and not just be a goof.

#548
Okay I see... Yeah I am learning as well as we all go here too!! lol  :duh But I was imagining other type of thermistors than this one. Larger one's located near the fuse and transformer input stages on the board. Maybe I am even thinking of a different Fender FM65, princeton212 or something like the RocPro??? Props to Roly for his greater experience than mine.  :dbtu: Sorry I even had the wrong idea going on the output transistors for this amp...

Yeah if all the soldering looks nice and shiny that is good to know about the condition of the amp. If you flow solder on at least the components like wire wound resistors and filter caps that might be just enough. I like to practice soldering a whole board at a time as I am new at this and it helps to practice.

This might not fix anything yet, but now you will know the condition of the board as a whole. Also, this will get you really familiar with the entire amp. Be careful and take some care putting it back together. Remember to clean off the heat sink and apply new thermal grease when you put the board back together.
#549
The thermistors are there at the entrance of power stage and they are resistors that change their resistance in response to the amp heating up. This is different than the output transistors tip142 & tip147 that are mounted to a heat sink w/ the thermal compound coupling the connection between the two. Now those transistors I can imagine a white substance, but have only seen glue holding thermistors tightly to the PCB board.

So I have worked on a few of these 1999 boards and that would indicate to me that it is made in Mexico rather than China. My best recommendation is to fully solder up that board and make sure every connection is connected to the board nice. As you take off the board you will need to make sure that you document where each connection belongs. Take a sharpie and write J9 or J11 on the plastic part. When you get to putting it all back together you will need thermal grease on the heat sink and make sure the heat sink bar is on the right way. Take a sharpie and write an arrow pointing up to ensure this is correctly put back together. This amp probably just needing some solder, but then after you do all this play the amp and see if there is any noticeable changes. At that point this only can be good for the amp if you are handy w/ a solder iron...

If the amp is still acting up then we can start looking into troubleshooting.

#550
A thermistor covered in a white substance??? I want to see this... Take pics for me and all to see.

Or it's just the glue they put in there to hold in place just in case? This sounds strange.