Hi,
while replacing the Caps in my 35 year old rd50 i experienced the following:
after playing for about one hour while switching to the limiter channel suddenly there was a very loud sound like motorboating.
no problem in the clean channel, the motorboating sound could be dimmed with the volume pot in the limiter channel.
returning home from rehersal the problem was gone.
resoldered all the new caps. next rehearsal same thing happened again, after about one hour->motorboat limiter channel.
fired it up on the bench, tapping the board i found IC 2 to be the problem: tapping it could ewoke the motorboat....
took it out of the socket, cleaned the contacts, now it seemes good.
1st Question: i think i will replace the IC. i found this: Texas Instruments CD4016BE, can i replace the original with it?
2nd Question: should i Replace the other ICs (that all seem to be TL72 Opamps)?
Any reply appriciated, thanx in advance
Dirk
Picture: re-Cap-ed and re-IC-ed
Hi, not getting any replies in this forum to my questions about IC s and Cap s (in my first Posting) helps me making my own experiences. (See Pictures)
i have now replaced all electrolytic caps and all the ICs on the board of my 1981 RD-50 (the board is marked : a w 6-11-81)
For those, that might need the input, id like to share What i experienced:
- I cut the capacitor leads of the old caps and used them to solder joint the new ones
- on one cap the old lead went through the lug and i had to unscrew the whole board and solder from the temporarily lifted under side
- the ICs went in easy, because of the sockets.
- i changed some parts on the Limiter tube to the specs of the late 80s rd-50 (adding a bypassed cathode resistor to V1b and changing the values of the plate resistors
How does it sound?
Very Loud again
Very Clean again
The limiter channnel is much more usefull now
Question: (although i do not expect reactions) I ve read about some of the diodes going bad, wich of these would the experts advice to replace. Thank You again for any help........
Diodes gone bad
Nice looking re-cap job. Did you use F&T caps or Mundorf M-Lytic HV
I have and RD112-100...so not exactly the same...but similar...I had to replace the Zener diodes (IN 5353) the power supply, and the 390ohm 3watt resistors in the same area. They were over heated, and burnt the PCB. There is a post on this board somewhere.
Sorry no one more knowledgeable has replied...
Caps
Hi RD112,
thanks for Your post. Used F+T for the large Caps in the power supply.
concerning the replacement of the diodes, i think ill wait until its necessary ( Hopefully not necessary at all)
greetings