Search found 15 matches

by diancarlo81
Fri Apr 05, 2019 9:04 am
Forum: Vintage Amps (Before 1991)
Topic: Mark III no distortion channel 3
Replies: 27
Views: 3451

Re: Mark III no distortion channel 3

I have replaced LDR2 and LDR5, R119, checked other resistor the reading was Good.... Any other idea for the problem?
Thanks guys... Will it fix the problem If i replace R26, R153, and C32?
by diancarlo81
Fri Apr 05, 2019 12:35 am
Forum: Vintage Amps (Before 1991)
Topic: Mark III no distortion channel 3
Replies: 27
Views: 3451

Re: Mark III no distortion channel 3

Hi guys,

I have replaced every resistor and LDR2... The same no Lead Channel. Do you have any other solution?

Thank You!!!
by diancarlo81
Mon Mar 18, 2019 2:50 pm
Forum: Vintage Amps (Before 1991)
Topic: Mark III no distortion channel 3
Replies: 27
Views: 3451

Re: Mark III no distortion channel 3

Just waiting for the LDR to arrive. Resistors are ok... Already opened it and test the resistor. LDR VTL5C1 would be the last shot. Thanks!
by diancarlo81
Mon Mar 04, 2019 6:47 am
Forum: Vintage Amps (Before 1991)
Topic: Mark III no distortion channel 3
Replies: 27
Views: 3451

Re: Mark III no distortion channel 3

Hi Everyone!!! Good day... Here is the 2nd Video just to be sure. And I have already ordered VTL5C1 for LDR2 3weeks delivery... I hope this video will help. Thank You So much for the help. I'll keep you all posted. https://drive.google.com/file/d/1YwdbeeOfsiePPpT4XbTSBLMDCOIPAe3I/view?usp=drivesdk
by diancarlo81
Wed Feb 27, 2019 8:30 am
Forum: Vintage Amps (Before 1991)
Topic: Mark III no distortion channel 3
Replies: 27
Views: 3451

Re: Mark III no distortion channel 3

Not yet... I will make video again to confirm as per jrb32. I will post it here tomorrow...
by diancarlo81
Mon Feb 04, 2019 11:12 pm
Forum: Vintage Amps (Before 1991)
Topic: Putting together a Mark III Guide
Replies: 35
Views: 4545

Re: Putting together a Mark III Guide

Hoping a guide for III+ (schematic)... Thanks!
by diancarlo81
Mon Feb 04, 2019 10:11 pm
Forum: Vintage Amps (Before 1991)
Topic: Mark III no distortion channel 3
Replies: 27
Views: 3451

Re: Mark III no distortion channel 3

Hi Guys, I took a video to make sure about the problem. The video will shows that Lead Channel Engage the Lead Drive is not working and Master Lead works but bright is not. While the Lead Channel is engage Treble Shift, Volume Bright, Bass Shift are working. Even the R2 and Deep are also working. Li...
by diancarlo81
Thu Jan 31, 2019 10:55 am
Forum: Vintage Amps (Before 1991)
Topic: Mark III no distortion channel 3
Replies: 27
Views: 3451

Re: Mark III no distortion channel 3

Lead Master = Yes Lead Gain = No (it plays like Volume no Distortion) Treble Shift = Yes Cool and Lead Master, Lead Gain and Treble Shift have no effect when in Rhythm 1 mode? LDR2 looks like the first thing to swap then. Should be a VTL5C1 :) May as well replace R119 if it's never been done too as...
by diancarlo81
Wed Jan 30, 2019 2:31 pm
Forum: Vintage Amps (Before 1991)
Topic: Mark III no distortion channel 3
Replies: 27
Views: 3451

Re: Mark III no distortion channel 3

LDR2 and LDR4 that needs to be replaced? I can replace the LDR myself. Hope this will work out fine.. THANK YOU SO MUCH!!! DO NOT REPLACE ANYTHING UNLESS YOU'RE SURE! But there is no harm in replacing the optocouplers (LDRs) like for like for the Lead Circuit if you can get hold of the same part nu...
by diancarlo81
Wed Jan 30, 2019 1:57 pm
Forum: Vintage Amps (Before 1991)
Topic: Mark III no distortion channel 3
Replies: 27
Views: 3451

Re: Mark III no distortion channel 3

Which channel isn't working? Lead channel or R2 channel? Do you get any sound at all? If so please be as specific as possible with what happens and whether the volume levels of each channel have been affected. Does it definitely switch channels etc? R2 isn't really a 'channel' is just adds a boost ...
by diancarlo81
Wed Jan 30, 2019 10:57 am
Forum: Vintage Amps (Before 1991)
Topic: Mark III no distortion channel 3
Replies: 27
Views: 3451

Re: Mark III no distortion channel 3

By the way guys... It's not Purple Stripe (mistake) it's Green Stripe mesa boogie Mark iii. The last production of mark iii series...

Thank you so much!!!
by diancarlo81
Wed Jan 30, 2019 10:50 am
Forum: Vintage Amps (Before 1991)
Topic: Mark III no distortion channel 3
Replies: 27
Views: 3451

Re: Mark III no distortion channel 3

Another thing to look at which is notorious on Mark III's is the under spec'd 680 ohm resistor on the low voltage rail... If that starts to cook out the first symptom will be switching problems...shortly after that it will burn right through the board. Hi, Do you know which resistor? Resistor Numbe...
by diancarlo81
Wed Jan 30, 2019 10:48 am
Forum: Vintage Amps (Before 1991)
Topic: Mark III no distortion channel 3
Replies: 27
Views: 3451

Re: Mark III no distortion channel 3

It seems most likely that LDR2 has taken a dump. It's what switches the signal into the lead drive circuit. LDR4 then directs the lead drive signal back into the main circuit. This means "Take it to a qualified amp tech who understands LDR switching.". LDR2 and LDR4 that needs to be replaced? I can...
by diancarlo81
Wed Jan 30, 2019 10:45 am
Forum: Vintage Amps (Before 1991)
Topic: Mark III no distortion channel 3
Replies: 27
Views: 3451

Re: Mark III no distortion channel 3

Which channel isn't working? Lead channel or R2 channel? Do you get any sound at all? If so please be as specific as possible with what happens and whether the volume levels of each channel have been affected. Does it definitely switch channels etc? R2 isn't really a 'channel' is just adds a boost ...
by diancarlo81
Fri Jan 25, 2019 1:53 pm
Forum: Vintage Amps (Before 1991)
Topic: Mark III no distortion channel 3
Replies: 27
Views: 3451

Mark III no distortion channel 3

Hi Guys, I have this purple stripe Mark III amp and the problem is the channel 3 it has no distortion, it only started when I change it to R2 mode. The distortion was not good anymore and suddenly went out. I have replaced all the tubes and reCap. Please help me... Im from Philippines Mesa Support i...