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Issues with Rocktron Parchmate Bradshaw
Old 25th June 2020
  #1
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Issues with Rocktron Patchmate Bradshaw

Hi Everyone,

i'm having big issues with my rocktron Patchmate (the Bob Bradshaw version).
The machine starts up and the screen start flickering showing garbage characters then shuts itself off.

i've already replaced all the capacitor in the power section
and replaced the LDO(7805) powering the SC80C31 microcontroller.

The 12 MHZ Crystal (XT1) has already been replaced.

After tinkering with the machine i got it to work for 2 days then it happened again.

Could i try to replace all the discrete logic IC?
Could i replace the SC80C31 with another one?



Thanks in advance

emm853
Old 25th June 2020
  #2
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Rick Dalton's Avatar
Quote:
Originally Posted by emm853 View Post
Hi Everyone,

i'm having big issues with my rocktron PatcMate (the Bob Bradshaw version).
The machine starts up and the screen start flickering showing garbage characters then shuts itself off.

i've already replaced all the capacitor in the power section
and replaced the LDO(7805) powering the SC80C31 microcontroller.

The 12 MHZ Crystal (XT1) has already been replaced.

After tinkering with the machine i got it to work for 2 days then it happened again.

Could i try to replace all the discrete logic IC?
Could i replace the SC80C31 with another one?



Thanks in advance

emm853
Are the IC's socketed? If so remove/clean/reseat. I've had to do this on older gear,,, MOTU mostly.
Also did you remove that SC80C31 from its socket and clean it and the socket? You be surprised what that little bit of tarnish between the contacts on anything socketed will do.
Old 25th June 2020
  #3
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Quote:
Originally Posted by Rick Dalton View Post
Are the IC's socketed? If so remove/clean/reseat. I've had to do this on older gear,,, MOTU mostly.
Also did you remove that SC80C31 from its socket and clean it and the socket? You be surprised what that little bit of tarnish between the contacts on anything socketed will do.
Unfortunately the SC80C31 Is soldered.
All traces have been checked.
The strange thing Is that i've manage to reset It and It worked for likes 2 days.
Old 25th June 2020
  #4
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Quote:
Originally Posted by emm853 View Post
Unfortunately the SC80C31 Is soldered.
All traces have been checked.
The strange thing Is that i've manage to reset It and It worked for likes 2 days.
Dang, I was going to have you check if it was in a PLCC Socket, that I've seen these sockets fracture on all four corners as they age. What the backup battery like? if it has one.
Old 25th June 2020
  #5
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Quote:
Originally Posted by emm853 View Post
Unfortunately the SC80C31 Is soldered.
All traces have been checked.
The strange thing Is that i've manage to reset It and It worked for likes 2 days.
No Backup Battery, all the patches are saved ( i think ) in a XICOR EEPROM.

By fiddling with xt1 and xt2 ( oscillator input and output on the SC80C31) i've managed to reset the machine ( an OK is displayed and everything works again for a while).
but still no luck
Old 25th June 2020
  #6
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Quote:
Originally Posted by emm853 View Post
No Backup Battery, all the patches are saved ( i think ) in a XICOR EEPROM.

By fiddling with xt1 and xt2 ( oscillator input and output on the SC80C31) i've managed to reset the machine ( an OK is displayed and everything works again for a while).
but still no luck

Heres a manual, I think I seen where a 3 volt battery may be in the foot control, Not that it will help.


http://www.customaudioelectronics.co...1-1_Manual.pdf
Old 25th June 2020
  #7
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it tells of the battery at the bottom of page 13. Not sure where its located.
Old 25th June 2020
  #8
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Quote:
Originally Posted by Rick Dalton View Post
Heres a manual, I think I seen where a 3 volt battery may be in the foot control, Not that it will help.


http://www.customaudioelectronics.co...1-1_Manual.pdf
Thanks Rick,

my model is not an RSB18/12 is a Bradshaw made by rocktron


An example can be found HERE :

https://gsfanatic.com/en/hirdetes/27...idi-kontroller
Attached Thumbnails
Issues with Rocktron Parchmate Bradshaw-842949_elado3.jpg  
Old 25th June 2020
  #9
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Quote:
Originally Posted by emm853 View Post
Thanks Rick,

my model is not an RSB18/12 is a Bradshaw made by rocktron


An example can be found HERE :

https://gsfanatic.com/en/hirdetes/27...idi-kontroller
Sorry! I thought that was what I had.
Old 25th June 2020
  #10
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Quote:
Originally Posted by Rick Dalton View Post
Sorry! I thought that was what I had.
No problem these things all have similar names.

for now i've desoldered SC80C31BCCN40 and bought a new one ( identical same manufacturer ) with a socket.

in Addition to that i'm waiting for some 74HC573N (Latches) so i think i'll replace these one as well.

the only thing that jumped to my mind is that the old owner was using a 12v DC psu instead of a ( proper)9V AC PS, this caused the HUSH section to not work properly.


the thing that can't be replaced is the EPROM With the firmware on it because i can't find it anywhere.
Old 25th June 2020
  #11
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Quote:
Originally Posted by emm853 View Post
No problem these things all have similar names.

for now i've desoldered SC80C31BCCN40 and bought a new one ( identical same manufacturer ) with a socket.

in Addition to that i'm waiting for some 74HC573N (Latches) so i think i'll replace these one as well.

the only thing that jumped to my mind is that the old owner was using a 12v DC psu instead of a ( proper)9V AC PS, this caused the HUSH section to not work properly.


the thing that can't be replaced is the EPROM With the firmware on it because i can't find it anywhere.
Oh! 12v DC you might have a damaged diode or two, maybe a caps also? I was reading that one negative glitch will put that SC80C31 into shutdown mode.
Old 25th June 2020
  #12
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Also, could you almost time this after a reset, before it would happen again? if so that sounds like a leaky diode.
Plus You might get one of these, just to check component temps.
https://www.google.com/search?q=ther...47662432643829
Old 25th June 2020
  #13
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Quote:
Originally Posted by Rick Dalton View Post
Oh! 12v DC you might have a damaged diode or two, maybe a caps also? I was reading that one negative glitch will put that SC80C31 into shutdown mode.
in the rectifying part?

i've replaced a 1N4148 connected to a PC900V but i think that is for the MIDI port.
Old 25th June 2020
  #14
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Quote:
Originally Posted by Rick Dalton View Post
Also, could you almost time this after a reset, before it would happen again? if so that sounds like a leaky diode.
Plus You might get one of these, just to check component temps.
https://www.google.com/search?q=ther...47662432643829
as soon as i posted here we are again.

i've hand checked all temps on these chips and nothing gets hot (except some ferrite beads on power jack).


should i test all diodes on the relays? ore the 1n4002 on the rectification side?
Old 25th June 2020
  #15
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Quote:
Originally Posted by emm853 View Post
as soon as i posted here we are again.

i've hand checked all temps on these chips and nothing gets hot (except some ferrite beads on power jack).


should i test all diodes on the relays? ore the 1n4002 on the rectification side?
Do check those for the rectifier, use the eraser end of a pencil or something insulated too put a little pressure on and off while testing, to see if you get a different reading, but if not sure, I'd replace those. Also check any others.
Old 26th June 2020
  #16
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Quote:
Originally Posted by Rick Dalton View Post
Do check those for the rectifier, use the eraser end of a pencil or something insulated too put a little pressure on and off while testing, to see if you get a different reading, but if not sure, I'd replace those. Also check any others.
Thanks Rick, i'll test everything tommorow.
Old 28th June 2020
  #17
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Quote:
Originally Posted by Rick Dalton View Post
Do check those for the rectifier, use the eraser end of a pencil or something insulated too put a little pressure on and off while testing, to see if you get a different reading, but if not sure, I'd replace those. Also check any others.
So during this weekend i've replaced all the rectifier diodes and capacitors on power supply side.
the thing keeps shutting down and flickering all over.

i've read the SC80C31 datasheet and checked power states , it seems that the MCU keeps going in shutdown mode by itself.

i've bought 2 NOS SIGNETICS SC80C31BCCN40 let's see what happens....
Old 29th June 2020
  #18
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Quote:
Originally Posted by emm853 View Post
So during this weekend i've replaced all the rectifier diodes and capacitors on power supply side.
the thing keeps shutting down and flickering all over.

i've read the SC80C31 datasheet and checked power states , it seems that the MCU keeps going in shutdown mode by itself.

i've bought 2 NOS SIGNETICS SC80C31BCCN40 let's see what happens....
Your luck sound about like mine.
Old 29th June 2020
  #19
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It looks like anything under 2 volt or over 5.5 with put it into shutdown mode also. If you had a way to time it..., but I guess you say after replacing the caps and diodes, its really freaking out. maybe try an magnifying app on you phone and look over the solder joints. just one fracture can stress. I've been I that boat and last option was to hit all the joints, you be surprised how often that's all it takes. Also, it could be an Via. I've chased those, a real PITA.
Old 13th July 2020
  #20
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Quote:
Originally Posted by Rick Dalton View Post
It looks like anything under 2 volt or over 5.5 with put it into shutdown mode also. If you had a way to time it..., but I guess you say after replacing the caps and diodes, its really freaking out. maybe try an magnifying app on you phone and look over the solder joints. just one fracture can stress. I've been I that boat and last option was to hit all the joints, you be surprised how often that's all it takes. Also, it could be an Via. I've chased those, a real PITA.
So the new 80C31 has arrived, but no luck.
It keeps shutting down by itself and dispalying weird characters.
At this point i don't know what to try next
Old 14th July 2020
  #21
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Quote:
Originally Posted by emm853 View Post
So the new 80C31 has arrived, but no luck.
It keeps shutting down by itself and dispalying weird characters.
At this point i don't know what to try next
emm853, can you post a couple good pics of the PCB?
Also, what I find real handy and hard to do without, is an good magnifying app on a smartphone. You can really zoom in and look for any bad or fractured solder joints.
Old 22nd July 2020
  #22
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Originally Posted by Rick Dalton View Post
emm853, can you post a couple good pics of the PCB?
Also, what I find real handy and hard to do without, is an good magnifying app on a smartphone. You can really zoom in and look for any bad or fractured solder joints.
Hi Rick,

Sorry for the delay.

Here are some images of what i've already replaced.

Here

Here


All the power section has new components ( caps, diodes ...)

I've replaced the MCU and 2 of the latches (74HC137 and 74HC573N)

i've even tried to read the EPROM (27C64) and it seems to be OK ( but i can't be sure).

The EEPROM used for Saving presets has been replaced with an identical one.

I could try burning a new EEPROM and replace the 27C64 but i would need a working ROM dump.

i've checked every single solder joint and vias and everything seems to be ok.
Old 23rd July 2020
  #23
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Quote:
Originally Posted by emm853 View Post
Hi Rick,

Sorry for the delay.

Here are some images of what i've already replaced.

Here

Here


All the power section has new components ( caps, diodes ...)

I've replaced the MCU and 2 of the latches (74HC137 and 74HC573N)

i've even tried to read the EPROM (27C64) and it seems to be OK ( but i can't be sure).

The EEPROM used for Saving presets has been replaced with an identical one.

I could try burning a new EEPROM and replace the 27C64 but i would need a working ROM dump.

i've checked every single solder joint and vias and everything seems to be ok.
Hey there emm853, Still no go. Did the behavior change any? I notice what looks like some cold solder joints, what solder are you using? get a flux pen and hit those. Also, on the fuse, you need to take that big jumper out and use a small strand wire, But first cut that jumper in the center a hook an Amp Meter inline and see what current is being pulled. That may tell you something, but with that big jumper, it could be pulling just a little more that it should be, and you wouldn't be able to tell. Also, is that just an two layer PCB?

EDIT! I also noticed only one voltage regulator has a heatsink, that other one probably needs one also, that PCB silkscreen shows for one, and it probably wasn't by mistake. Also use heatsink compound/grease between both voltage regulators and heatsinks. Without the compound, you've an air-gap. Think of a computers CPU without heatsink compound or a heatsink.

Last edited by Rick Dalton; 23rd July 2020 at 01:15 AM.. Reason: added
Old 23rd July 2020
  #24
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Quote:
Originally Posted by Rick Dalton View Post
Hey there emm853, Still no go. Did the behavior change any? I notice what looks like some cold solder joints, what solder are you using? get a flux pen and hit those. Also, on the fuse, you need to take that big jumper out and use a small strand wire, But first cut that jumper in the center a hook an Amp Meter inline and see what current is being pulled. That may tell you something, but with that big jumper, it could be pulling just a little more that it should be, and you wouldn't be able to tell. Also, is that just an two layer PCB?

EDIT! I also noticed only one voltage regulator has a heatsink, that other one probably needs one also, that PCB silkscreen shows for one, and it probably wasn't by mistake. Also use heatsink compound/grease between both voltage regulators and heatsinks. Without the compound, you've an air-gap. Think of a computers CPU without heatsink compound or a heatsink.

I've checked the power usage with my multimeter and it uses between 650ma to 1A on the 9V AC side.

I've tested all the descrete logic by powering them up with an external power supply but the issues remain.

here you can see the behaviour :Video
Old 23rd July 2020
  #25
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Quote:
Originally Posted by emm853 View Post
I've checked the power usage with my multimeter and it uses between 650ma to 1A on the 9V AC side.

I've tested all the descrete logic by powering them up with an external power supply but the issues remain.

here you can see the behaviour :Video
U19 and U20 have the same function so did U20 (7915ct) Not have an heatsink when you got it? I also notice the C35 cap to 7915ct is smaller looking than the cap (i can see number) to 7815ct. So unless you've worked on that part of the power section or not, things aren't right. That 7915ct can be damaged, plus go into thermal shutdown. And i dont know why those two circuits (one positive output, the other negative output, would have different cap's, when they are to work in unison) either of those caps can be, end of life and cause ripple, plus they both need to be the same value, but at a glance they don't look right.
Also, if there's Any old caps, just replace them.



https://i.imgur.com/w3hLWr4.jpg
Look at the pitting below 74HC137, how many layer PCB.
Old 23rd July 2020
  #26
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Quote:
Originally Posted by Rick Dalton View Post
U19 and U20 have the same function so did U20 (7915ct) Not have an heatsink when you got it? I also notice the C35 cap to 7915ct is smaller looking than the cap (i can see number) to 7815ct. So unless you've worked on that part of the power section or not, things aren't right. That 7915ct can be damaged, plus go into thermal shutdown. And i dont know why those two circuits (one positive output, the other negative output, would have different cap's, when they are to work in unison) either of those caps can be, end of life and cause ripple, plus they both need to be the same value, but at a glance they don't look right.
Also, if there's Any old caps, just replace them.



https://i.imgur.com/w3hLWr4.jpg
Look at the pitting below 74HC137, how many layer PCB.
the 7915 is only used to power the HUSH section and it does not have a heatsink ( it only gets slightly warm) but it's regulating correctly.
the caps has been replaced with a new one with the same value as the old one (this one has a smaller footprint).

the 7815 is used to power the relays (and the hush section). it uses a lot more current and becomes qute warm to the touch.

I think it's a 2 layer PCB. Looking through the pcb with a light shows only vias on the other side.

both the latches( 74hc137 and 74hc573) have sockets now (i've added them).
The SC80C31 is new and now has a socket.
All the caps connected to 74's logic have been replaced. the only caps i haven't replaced yet are those in the HUSH section.
The crytal XT1 is new as the caps on C26 (near the MCU)
Old 23rd July 2020
  #27
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Quote:
Originally Posted by emm853 View Post
the 7915 is only used to power the HUSH section and it does not have a heatsink ( it only gets slightly warm) but it's regulating correctly.
the caps has been replaced with a new one with the same value as the old one (this one has a smaller footprint).

the 7815 is used to power the relays (and the hush section). it uses a lot more current and becomes qute warm to the touch.

I think it's a 2 layer PCB. Looking through the pcb with a light shows only vias on the other side.

both the latches( 74hc137 and 74hc573) have sockets now (i've added them).
The SC80C31 is new and now has a socket.
All the caps connected to 74's logic have been replaced. the only caps i haven't replaced yet are those in the HUSH section.
The crytal XT1 is new as the caps on C26 (near the MCU)
Is the power supply OEM, or whats the current output/rating.
Old 23rd July 2020
  #28
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Originally Posted by Rick Dalton View Post
Is the power supply OEM, or whats the current output/rating.
no the psu is not OEM, it's US Robotics transformer 9V AC 1000ma (it works with all my other rocktrons (intellifex , replifex).
Old 23rd July 2020
  #29
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Quote:
Originally Posted by emm853 View Post
no the psu is not OEM, it's US Robotics transformer 9V AC 1000ma (it works with all my other rocktrons (intellifex , replifex).
OK, just wondering, the OEM I looked at was 1145ma.
Old 23rd July 2020
  #30
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I remember reading a couple weeks back, about engaging more than 2 foot switches could cause a Brown Out or Shutdown, basically. But that would have to come from the phantom supply, and I don't see how a flaw like that would have ever made it out the door.
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